Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.
Single-Molecule Insight into Heterogeneous Catalysis, Substrate-Mediated Interactions, and Buried Interface Structures
A. R. Kurland and P. S. Weiss, Departments of Chemistry & Physics, Pennsylvania State University, University Park, PA 16802, USA
Because molecular thiophene (and its heterocyclic analogues) poses a significant challenge to desulfurization due to its strongly interacting p electrons, it is an ideal candidate for investigating the mechanism of hydrodesulfurization. The electronic structure of thiophene on Pd{111} and Pd{110} has been elucidated through differential conductance imaging and spectroscopy, and the single-molecule vibrational fingerprint has been acquired via inelastic electron tunneling spectroscopy. Interestingly, the observation of the electronic structure of thiophene on Pd reveals that the surface state may play a significant role in molecular adsorption via substrate-mediated interactions. Further, these techniques will be used both to manipulate single adsorbates into proximity of subsurface hydride and to induce the reaction in situ.
Additionally, the controversy of STM image interpretation of self-assembled monolayers has been resolved using a technique that images both the chemically bound head-groups and exposed tail-groups in bi-component alkanethiolate self-assembled monolayers on Au{111} simultaneously, with molecular resolution. The polar tilt and azimuthal angles of single molecules within monolayers have been measured and demonstrate that ordered domains with different superstructures also have varied buried sulfur head-group structures. We place single molecules and larger groups into precisely controlled environments on surfaces. Monolayer matrices and inserted molecules can be designed so as to interact directly, and to confer stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and their assemblies. This, in turn, is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. Hybrid methods enable such chemical patterning methods to be combined with conventional and unconventional lithographies. A suite of nanoscale analysis tools is being developed to provide unprecedented information on the structures and properties of these assemblies. In parallel, widely applicable metrology tools for chemical patterns are being developed that can be applied by the nanofabrication community with a minimum of new infrastructure investment.
Opportunities and Challenges in Nanoscience and Nanotechnology
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Measurements and Control of Single Molecules and their Nanoscale Assemblies to Develop Molecular Machinery
Ajeet Kumar, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA
We have assembled various types of single-molecule switches and motors in well-defined nanoscale assemblies on surfaces to induce and to control conductivity and motion with light, electrons, and ions. We use custom-built scanning tunneling microscopes (STMs) to measure the motion of molecules and use these and other microscopic methods to follow the actions of assemblies.
Azobenzene-funtionalized molecules, which can switch between two different structures upon illumination, are assembled as isolated units on gold surfaces. We control the switching of isolated molecules by irradiation with appropriate light. We have lined up molecules in one-dimensional assemblies on Au{111} and characterized the strong electronic coupling between the molecular units of the assembly using scanning tunneling microscopy and spectroscopy.
Rotaxane, a synthetic motor molecule, can change its structure by gaining or losing electrons (redox processes). The motion generated in the molecule by the redox process can be used to generate microscale motions if arranged to work together. We assembled these molecules on microscale levers to produce forces that bend the levers reversibly and generate microscale motions. The use of the cooperative forces generated by these artificial molecular muscles constitutes a seminal step toward molecular-machine-based nano-electro-mechanical (NEMs) devices.
Measurements and Control of Single Molecules and their Nanoscale Assemblies to Develop Molecular Machinery
Ajeet Kumar, Departments of Chemistry and Physics, The Pennsylvania State University, University Park, PA 16802, USA
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
S. A. Claridge and P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Eyes of the 21st Century: Controlling the Placement and Environments of Molecules at All Scales
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.
Eyes of the 21st Century: Controlling the Placement and Environments of Molecules at All Scales
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Single component self-assembled monolayers (SAMs) of an amide-containing alkanethiol, 3-mercapto-N-nonylpropionamide (1ATC9), consist of two phases with apparent heights dependent on the orientation of the hydrogen bonds. Hydrogen bonding interactions between buried amide groups impact on the structure, ordering, and orientation of the monolayers. While the single-electron reductive desorption of self-assembled n-alkanethiolates is understood, we report unexpected electrochemical effects for 1ATC9 SAMs. The presence of two well-resolved cathodic peaks in voltammograms of pure 1ATC9 monolayers show that at least two distinct processes occur during reductive desorption. We use the application of the lower of two cathodic potentials to drive to the lower energy electrochemical reaction, which results in a structural transformation. The controlled potential electrolysis transforms the hexagonally close-packed, strongly-interacting monolayer into a striped, lying-down phase that may be exploited to create precise molecular assemblies.
Best poster award winner!
Azobenzenes are potential molecular switch candidates, which can reversibly isomerize between a high conductance trans state and a low conductance cis state upon irradiation with UV and visible light, respectively. We have assembled, controlled, and measured the reversible isomerization of these molecules on Au{111} using a scanning tunneling microscope (STM). Tethers were designed and attached to azobenzene functional groups to control the decoupling of the functional moiety from the substrate both physically and electronically. The length and composition of the tethers have been modified to determine the effects of tether conductivity on the efficiency and quenching of isomerization. Efficiencies of STM-tip-induced and photo-isomerization of isolated molecules (0D) and one-dimensional (1D) molecular chain assemblies have also been compared. It has been observed that as the conductivity of the tether increases, the isomerization is quenched and that the switching efficiency is reduced when molecules are assembled in linear 1D chains.
Single-molecule measurement techniques have opened the door to unprecedented details of chemical behavior, including observations of the motion of a single molecule on a surface, or even the vibration of a single bond within a molecule. Such measurements are critical to our understanding of entities ranging from single atoms to the most complex proteins. However, the same techniques become even more powerful when large numbers of single-molecule measurements are combined, effectively taking a census of molecular behavior that provides both the detail of a single-molecule technique and the breadth and confidence of a bulk measurement. We discuss strategies for making such observations using scanning tunneling microscopy, including inelastic tunneling spectroscopy and barrier height measurements, and place these in the context of approaches used in areas ranging from single-molecule biophysics to inorganic nanocrystal assembly.
We report a novel method for a facile, one-pot preparation of alkanethiolate self-assembled monolayers (SAMs) on Ge(100). Additionally, we have used this principle to enable chemical patterning on Ge via microcontact printing. Our approach for developing patterning techniques for technological substrates is to mimic the advantages of gold-thiol self-assembly and translate them to apply for other material systems. Self-assembly on gold is popular for several reasons: the ease of gold surface preparation, the instability of the gold oxide, the tendency for thiols to displace contaminants during monolayer deposition, and the molecular mobility of adsorbed molecules that subsequently leads to molecular ordering. We are able to manipulate reaction conditions to enable the spontaneous formation of monolayers on untreated Ge, opening new avenues for the exploitation of self-assembly on technologically relevant semiconductor surfaces.
Eyes of the 21st Century: Controlling the Placement, Environments, and Interactions of Molecules at All Scales
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, interactions, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We discuss initial applications of this work in functionally directed proteomics. We anticipate that advances in this area will ultimately revolutionize structural molecular biology, and discuss how we expect this to occur.
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.
Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations.
Monday 26 April 2010 4 PM
Department of Energy Contractors' Meeting, Baltimore, MD, USA
DC to Daylight: Local Spectroscopy with the Scanning Tunneling Microscope
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We couple electromagnetic radiation into the tunneling junctions of scanning tunneling microscopes such that we can record local spectra with submolecular resolution. We associate these spectra with their macroscopic, ensemble-averaging equivalents in order to understand nanoscale phenomena and environments. The ability to measure molecular polarizability gives us a means to explore the buried bonds/contacts between adsorbed molecules and their substrates. In one system, we employ multiple microwave signals in order to heterodyne to convenient low frequencies and to avoid the effects of stray capacitance. Close coupling to theory enables significant insight into the meaning of the measurements and the character of the buried interface bonds. Visible excitation of well-defined isolated molecules will enable measurements of intrinsic photoconductance, so as to yield a useful figure of merit for optimizing the designs, connections, and environments of molecules for photovoltaics and photo-induced capacitance. Local infrared excitation should ultimately yield chemical identification and bonding changes. In each of these microscopes, general approaches are employed in order to yield the widest applicability.
Thursday 29 April 2010 130 PM, 102 Chemistry Building
Department of Chemistry, Penn State University, University Park, PA, USA
Ph.D. Thesis Defense:
Measurements and Control of Single Molecules and Their Nanoscale Assemblies to Develop Molecular Machinery
Ajeet Kumar, Department of Chemistry, Penn State University, University Park, PA, USA
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We study motion in single synthetic molecules and assemblies driven by electric fields, light, electrochemical potentials, or chemical interactions. We control the motions of individual molecules and determine the underlying phenomena responsible for motion or actuation, as well as the related factors that limit motion. Each of these measurements requires specialized nanoscale analysis tools. We also use new acquisition and analysis tools to acquire and to mine statistically significant functional data sets on driven motion. We are thereby able to vary molecular designs, environmental conditions, measurement conditions, and other aspects in order to understand and to optimize driven motion. We assemble these systems to understand concerted operation, in analogy to hierarchical assemblies of biomolecular motors enabling motion in living systems. We address how concerted nanoscale motions can be used to drive motion at larger scales in synthetic systems. The nanoscale details provide surprising and useful insights into the limitations of and opportunities for cooperative motion.
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We study motion in single synthetic molecules and assemblies driven by electric fields, light, electrochemical potentials, or chemical interactions. We control the motions of individual molecules and determine the underlying phenomena responsible for motion or actuation, as well as the related factors that limit motion. Each of these measurements requires specialized nanoscale analysis tools. We also use new acquisition and analysis tools to acquire and to mine statistically significant functional data sets on driven motion. We are thereby able to vary molecular designs, environmental conditions, measurement conditions, and other aspects in order to understand and to optimize driven motion. We assemble these systems to understand concerted operation, in analogy to hierarchical assemblies of biomolecular motors enabling motion in living systems. We address how concerted nanoscale motions can be used to drive motion at larger scales in synthetic systems. The nanoscale details provide surprising and useful insights into the limitations of and opportunities for cooperative motion.
Tuesday 25 May 2010
Order of the Blue Shield, UCLA
Eyes of the 21st Century
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
with an introduction by Gov. Gray Davis
Friday 28 May 2010 130 PM, 102 Chemistry Building
Department of Chemistry, Penn State University, University Park, PA, USA
Ph.D. Thesis Defense:
Scanning Tunneling Microscopy and Spectroscopy of Nanoscale Assemblies
Meaghan Blake, Department of Chemistry, Penn State University, University Park, PA, USA
Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules.1 Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We quantitatively compare the conductances of molecule-substrate junctions.
We study motion in single synthetic molecules and assemblies driven by electric fields, light, electrochemical potentials, or chemical interactions.2 We control the motions of individual molecules and determine the underlying phenomena responsible for motion or actuation, as well as the related factors that limit motion. We assemble these systems to understand concerted operation, in analogy to hierarchical assemblies of biomolecular motors enabling motion in living systems. The nanoscale details provide surprising and useful insights into the limitations of and opportunities for cooperative motion.
References
1) P. S. Weiss, Acc. Chem. Res. 2008, 41, 1772.
2) D. B. Li, R. Baughman, T. J. Huang, J. F. Stoddart, P. S. Weiss, MRS Bulletin 2009, 34, 671.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations. The next step in these devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological structures. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Wednesday 23 June 2010 2 PM, 102 Chemistry Building
Department of Chemistry, Penn State University, University Park, PA, USA
MS Thesis Defense
Andrea Giordano, Department of Chemistry, Penn State University, University Park, PA, USA
Wednesday 23 June 2010 430 PM, 216 EES Building
Department of Engineering Science & Mechanics, Penn State University, University Park, PA, USA
MS Thesis Defense
Jeffrey Lawrence, Department of Engineering Science & Mechanics, Penn State University, University Park, PA, USA
Eyes of the 21st Century: Controlling the Placement and Environments of Functional Assemblies at All Scales
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.
Eyes of the 21st Century: Patterning and Imaging from the Subnanometer to the Wafer Scale
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies. Part of this effort is aimed at developing single-molecule and single-assembly structural molecular biology.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales (Paper 7759-32)
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. At the same time, a suite of tools is being developed to give unprecedented information on the structures and properties of these assemblies.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
Designing, Measuring and Controlling Molecular- and Supramolecular-Scale Properties for Molecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms.
UCLA CNSI: Global Research Networks
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
A Career in Nanoscience (So Far)
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are now developing the equivalent of resists for chemical patterning, which can remain compatible with conventional lithography so as to enable new hybrid lithographies combining physical and materials patterning of materials with simultaneous chemical patterning of their surfaces. Further, we are developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, measuring, and controlling molecular and supramolecular devices
Paul S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, measuring, and controlling molecular and supramolecular devices (Keynote Lecture)
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations. The next step in these devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Keywords: self-assembly, supramolecular assembly, molecular devices, scanning tunneling microscopy
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations. The next step in these devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations. The next step in these devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.
A Career in Nanoscience (So Far)
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Control at All Scales in Chemistry, Physics, Biology, and Engineering
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Atomic-Scale Studies of Heterogeneous Catalysis, Substrate-Mediated Interactions, and Interface Structures
Adam Kurland, Department of Chemistry, Penn State University, University Park, PA, USA
Atomic-Scale Chemical, Physical, and Electronic Properties of the Subsurface Hydride of Palladium
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
As we learn to measure the precise structures, environments, and functions of molecules at the molecular scale, we are learning to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Hierarchical patterning enables simultaneous control at many levels, all the way from the macroscale through the microscale, ultimately to the subnanometer scale. Interactions within and between molecules can be designed, directed, measured, understood, and exploited. We examine how these interactions influence the chemistry, dynamics, structure, electronic function and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. New tools are needed and are being developed both for patterning and for measurements to advance this approach further.
A Career in Nanoscience (So Far)
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measurements of single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. We examine how these interactions influence the chemistry, dynamics, structure, electronic function, and other properties. Such interactions can be used to advantage to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. These nanostructures can be taken all the way down to atomic-scale precision or can be used at larger scales. We select and tailor molecules to choose the intermolecular interaction strengths and the structures formed within the film. We selectively test hypothesized mechanisms for electronic switching and driven motion by varying molecular design, chemical environment, and measurement conditions to enable or to disable functions and control of these molecules using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the measurements. We quantitatively compare the conductances of molecule-substrate junctions. We find that the contacts and substrate play critical roles in switching. Switching of rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. We are able to measure the coupling of the electrons of the molecules and substrate by measuring the polarizabilities of the connected functional molecules in high and low conductance states. These polarizabilities are compared to those of other families of molecules and to detailed calculations. The next step in these devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
Thursday 13 January 2011
JAIST-CNSI Workshop, CNSI, UCLA
Eyes of the 21st Century and the Role of CNSI
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Sunday 16 January 2011, 915 AM
Jacob Sagiv Birthday Symposium, Weizmann Institute of Science, Rehovot, Israel
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Wednesday 19 January 2011
Bar Ilan University, Tel Aviv, Israel
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Thursday 20 January 2011
Ben Gurion University, Be'er Sheva, Israel
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Sunday 23 January 2011, 410 PM
Nanoseminar Forum, Hebrew University of Jerusalem, Jerusalem, Israel
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
The Future of Nanoscience and Nanotechnology
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules.1 Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns,2 and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules.3 The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles.4 We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
[1] P. S. Weiss, Accounts of Chemical Research 41, 1772 (2008).
[2] H. Saavedra, T. J. Mullen, P. P. Zhang, D. C. Dewey, S. A. Claridge, and P. S. Weiss, Reports on Progress in Physics 73, 036501 (2010).
[3] A. M. Moore, S. Yeganeh, Y. Yao, J. M. Tour, M. A. Ratner, and P. S. Weiss, ACS Nano 4, 7630 (2010).
[4] D. B. Li, W. F. Paxton, J. F. Stoddart, R. H. Baughman, T. J. Huang, and P. S. Weiss, MRS Bulletin 34, 671 (2009).
Precise Functional Assemblies: First Glimpses and Upcoming Challenges
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Ethics in publishing: Editorial and related experiences
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Upon establishing ACS Nano, as editors, we were immediately confronted with a variety of ethical issues. These came not only from inexperienced authors, but from all corners. Sitting at the crossroads of many fields gives us an interesting perspective on the approaches taken across fields and borders. A selection of these will be discussed.
Confining and controlling photoreactive molecules on surfaces
Moonhee Kim, J. Nathan Hohman, Hong Ma, Alex K.-Y. Jen, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA; Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA; Department of Materials Science and Engineering, University of Washington, Seattle, Washington, USA
Controlling how, where, and when molecules react remains a central goal of nanoscience. By manipulating the conformation, location, environment, and orientation of molecules with sub-nanometer precision, we can achieve direct control over the activity, reactivity, and selectivity of individual molecules. We have developed a system for monitoring and harnessing photochemical reactions and photocurrent/photoconductance generation of individual organic molecules with Ångstrom-scale spatial precision. Self- and directed assembly enable the design of the local environment around functional molecules. Photoreactive molecules may be deposited into defect sites singly, in pairs, or in groups within a well-defined self-assembled monolayer matrix. Photon scanning tunneling microscopy (PhotonSTM) enables measurements of molecules before, during, and after photoillumination and photoreaction.
Single molecule manipulation of double-decker pthalocyanine molecules using scanning tunneling microscope under ambient conditions
Moonhee Kim, J. Nathan Hohman, Hong Ma, Alex K.-Y. Jen, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA; 4-13-13 Jingumae, VRI, Inc., Shibuya, Tokyo, Japan; Department of Chemistry, University of Science and Technology Beijing, Beijing, China
Precise control over the position and orientation of organic molecules at the nanoscale is critical for the development of molecular-scale devices. Scanning tunneling microscopy (STM) has proven to be an effective tool for manipulating atoms and small molecules at low temperature and under ultra-high vacuum conditions. Here, we demonstrate single molecule manipulation of isolated pthalocyanine-based double-decker molecules on highly ordered pyrolitic graphite (HOPG) using an STM probe tip under ambient conditions. Metal-free pthalocyanine H2Pc(OC8H17)8 was co-adsorbed with lanthanide sandwich complex molecules (Pc)Lu[Pc(OC8H17)8] on HOPG at 80 °C, and the surface-adsorbate and adsorbate-adsorbate interactions were studied. We exhibit successful manipulation of isolated double-decker molecules to fabricate features of interest. We explore the role of the structure of the bottom ligand of the double-decker molecules during and after the manipulation process. This manipulation capability paves the way to synthesize and to study novel one-dimensional functional materials for the development of molecular electronics.
Liquid metal nanoparticles by molecular dissassembly
James N. Hohman, Garrett Wadsworth, Heidi R. Bednar, Jun Jiang, Moonhee Kim, Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA; Department of Chemistry, Dickinson College, Carlisle, PA, USA; Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
We report the development of simple synthetic route for the preparation of room-temperature liquid metal nanoparticles by exploiting directed self-assembly. Generally, metallic nanoparticles are produced by a carefully controlled reduction of metal salts, but this strategy is untenable for many metals, alloys, and semiconductors. Low-melting metals and alloys based on gallium, indium, and mercury have been used previously as substrates for thiol-based self-assembled monolayers (SAMs). We have adopted an approach where we prepare nanoparticles from these liquid alloys by agitation in the presence of a thiol solution. As the liquid metal separates into particles of decreasing size, SAMs rapidly form on the newly exposed metal surfaces. By designing intermolecular interactions between the adsorbed molecules, strain is induced at the interface to assist the disassembly of these soft metals into spherical particles with a diameter between 5 and 50 nm.
136 - Microwave-modulated scanning tunneling spectroscopy of self-assembled peptides
Shelley A. Claridge, Jeffrey J. Schwartz, Amanda M. Moore, Sina Yeganeh, Yuxing Yao, James M. Tour, Mark A. Ratner, Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry, Materials Science & Engineering, and Physics, UCLA, Los Angeles, CA 90095, USA; Department of Chemistry, The Pennsylvania State University, University Park, PA, USA; ; Department of Chemistry, The Pennsylvania State University, State College, PA, United States; Department of Chemistry, Northwestern University, Evanston, IL, USA; Department of Chemistry and Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, TX, USA
We apply microwave-modulated spectroscopy in a scanning tunneling microscope (STM) to measure local molecular polarizability simultaneously with surface topography. This enables us to probe the conductance of the buried interface and to associate this with the conductance states of single-molecule switches. Since these measurements are sensitive to both topography and electronic structure with submolecular resolution, they are promising for single-molecule structural identification if appropriate spectroscopic modes can be developed. We have applied this technique to a variety of molecules, including amyloid-derived peptides self-assembled on surfaces, as a first step toward single-molecule measurements of protein structure.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies. We use these assemblies to control precise interactions with the chemical, physical, and biological worlds. In particular, we target the capture of membrane-associated proteins on the basis of their function for further study in single-molecule/assembly structural molecular biology, proteomics, and neuroscience.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Friday 22 April 2011, 12 noon, 210 Hallowell Building, Penn State
Development and Characterization of Small-Molecule-Functionalized Capture Surfaces
Amit Vaish, Penn State Department of Bioengineering and California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
Monday 26 April 2011, 1045 AM
Spring 2011 Materials Research Society Meeting, Symposium Z: Nanoscale Electromechanics of Inorganic, Macromolecular, and Biological Systems, San Francisco, CA
Design, Control, and Measurement of Molecular-Scale Assemblies
Bala Krishna Pathem, Department of Chemistry & Biochemistry and California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
Friday 29 April 2011
University of California, Merced, Merced, CA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Quantitative Measurements of Surface Interactions and Dynamics: Potentials and Functional Properties
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Interactions within and between atoms and molecules can be designed, directed, measured, understood and exploited at unprecedented scales. We use quantitative measurements of these interactions to illustrate approaches to making statistically significant data sets, comparable to those found in ensemble-averaging measurements, while retaining the heterogeneity of the single-molecule/assembly measurements. In these and other areas, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the heterogeneous single-molecule/assembly and environmental information. This approach yields new insights into precise and hierarchical assembly, as well as function at the nanoscale. What we learn is enabling us to design precise assemblies, and to measure their structures, functions, and spectra simultaneously.
Addressing Questions of Nanoscale Dynamics and Function with New Experimental Tools
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
S. A. Claridge and P. S. Weiss, California NanoSystems Institute and Department of Chemistry & Biochemistry, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies. We use these assemblies to control precise interactions with the chemical, physical, and biological worlds. In particular, we target the capture of membrane-associated proteins on the basis of their function for further study in single-molecule/assembly structural molecular biology, proteomics, and neuroscience.
Regioselectivity for organic synthesis is critically important to produce wanted chemicals with high yield, usually by the geometric restriction of approaching reactants to favor the preferred products. Bulky ligands on metal complex catalysts or encapsulated reactants in host-guest complexes can guide incoming reactants and control reaction pathways. On surfaces, n alkanethiolate self-assembled monolayers (SAMs) can be used to direct geometrically unfavorable photochemical reactions between individual organic molecules.
We have used defect sites in n-dodecanethiolate (C12) SAMs on gold surfaces to control molecular placement and the environment of anthracene terminated phenylethynyl-thiolates in order to enable regioselective photocycloaddition that is geometrically unfavorable in solution. Ultraviolet (UV) illumination of phenyl-ethynylanthracene (PEA) in solution triggers a [4+2] Diels-Alder addition reaction between the ethynyl moiety and the central ring of the other anthracene. However, when one pair of 9-(4-mercaptophenylethynyl)anthracene (MPEA, a thiol form of PEA) was inserted into preformed C12 monolayer, they undergo a regioselective [4+4] photodimerization [1].
High conductivity and stochastic switching of MPEAs within C12 monolayers have been observed with scanning tunneling microscopy (STM). In situ photochemical transformations also have been monitored by time-lapse STM imaging. An increase in the apparent heights of optically excited molecules is a manifestation of electronically excited states.
Reference:
[1] M. Kim, J. N. Hohman, Y. Cao, K. N. Houk, H. Ma, A. K.-Y. Jen, and P. S. Weiss, Science 331, 1312 (2011).
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Precise Assemblies, Clusters, Superatoms, and Cluster-Assembled Materials
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Self-Assembly by Design: From Structure and Function to Nanoscale Construction
J. Nathan Hohman, Department of Chemistry, Penn State University, University Park, PA, USA and California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Beyond Molecular Assemblies and Scanning Tunneling Microscopy
Moonhee Kim, California NanoSystems Institute, UCLA, Los Angeles, CA 90095, USA
Self-assembled monolayers (SAMs) of organic thiols on Au{111} are examined, with an emphasis on structure/function relationships, especially related to how the interplay between molecular geometry and intermolecular forces translate to the structure and properties of a supramolecular assembly. A SAM is composed of three parts: a substrate support, a 'head group' functionality that binds molecules to the substrate, and a 'tail group' that self-organizes with neighboring molecules and sets the interfacial chemistry. Each of these components is altered in turn and exploited to test fundamental assumptions and to construct new classes of materials. Cage molecules, based on adamantane and carborane frameworks, are used to investigate the cooperative effects of intermolecular interactions and molecular geometry on the structure and properties of the supramolecular assembly. The head group attachment atom is changed from S to Se, resulting in a complex, dynamic double lattice of 1-adamantaneselenolate on Au{111}. Finally, self-assembly is extended to technological substrates; germanium and the liquid metallic gallium-indium eutectic. Both substrates are passivated by a native oxide; an in-situ etch is described for simplifying self-assembly on germanium substrates, while a mechanical approach is used to separate the gallium-indium alloy from its oxide and to enable molecular self-assembly.
Small is Beautiful: Everyday Applications and Advances in Nanochemistry
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Single-Molecule Insights into Heterogeneous Catalysis, Substrate-Mediated Interactions, and Buried Interface Structures
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Interactions within and between surface adsorbates can be designed, directed, measured, understood, and exploited at unprecedented scales. In these and other measurements, we collect substantial data sets in order to generate distributions with the statistics of ensemble-averaging techniques, while retaining all the single-molecule and environmental information. This requires new automated tools for acquisition and analyses. This approach, in combination with multiple modalities of atomic-resolution measurements, enables new insights into precise and hierarchical assembly, as well as function at the nanoscale.
Manipulation of Adsorbed Atoms and Molecules
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use the manipulation of adsorbed atoms and molecules with the scanning tunneling microscope (STM) to probe interadsorbate and adsorbate-substrate interactions. The STM has the unique ability to map the perturbed electronic structure of and due to adsorbates. We use this capability to quantify such interactions and to elucidate the roles of perturbed electronic structure in surface chemistry, structures, dynamics, and catalysis.
Single-molecule peptide structure determination via AC scanning tunneling microscopy
Shelley A. Claridge, Jeffrey J. Schwartz, and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Understanding protein structure and correlating it with function is one of the critical problems of the 21st century. However, many of the most biologically important proteins do not crystallize and have not proved amenable to nuclear magnetic resonance measurements. Thus, an alternative that circumvents the limitations of these measurements could constitute a major advance. Toward this goal, we perform single-molecule measurements of peptide structure using a custom-built scanning tunneling microscope that enables both nonperturbative low-current measurements and simultaneous mapping of local polarizability. We assemble amyloid-derived peptides on highly oriented pyrolytic graphite, and identify different amino acids in a single peptide, as well as features corresponding to coupling between individual amino acids in adjacent peptides in single beta sheets. Importantly, the ability to deconvolve contributions to what is traditionally considered to be topographic STM imaging enables more rigorous analysis of high-complexity structures such as peptides.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
With precise, rigid synthetic molecules and assemblies, we seek to understand and to mimic nature's complex molecular machines. We use these synthetic molecular machines capable of performing mechanical motion in response to external stimuli to understand the limits of controlled and cooperative motion at the nanoscale. We use molecular design, tailored syntheses, and intermolecular interactions to create functional and interacting nanostructures on solid substrates. We explore and exploit adsorbate-adsorbate and substrate-adsorbate interactions to fabricate precise nanostructures, patterns, and assemblies on surfaces. Using custom-built scanning tunneling microscopes (STMs), we measure the motion of molecules driven by light, electric field, or electrochemical potential. We vary the molecular design, environmental conditions, and other aspects to understand and to optimize the function and motion at molecular scale. In order to understand the concerted operation of the functional molecules, we assemble the functional molecules into linear one-dimensional arrays or two dimensional clusters. We discuss families of three artificial molecular machines that utilize light, electric field, or electrochemical potential to perform mechanical motion.
We drive reversible photo- and STM probe tip-induced switching of single or bundles of azobenzene-functionalized molecules isolated in tailored alkanethiolate monolayer matrices on Au{111}. We employ tethers that decouple the functional moiety from the conductive substrate thereby eliminating quenching of surface states. We assemble precisely defined 1D linear chain structures of azobenzene-functionalized molecules using self- and directed-assembly. We control in situ photo- and electron-induced switching of these linear chains and study the effects of local environments and coupling on switching efficiency. Oligo(phenylene ethynylene) molecules assembled on Au{111} are shown to undergo stochastic and driven conductivity switching in the highly localized electric field of the STM tunneling junction. We establish that the contacts between the substrate and the molecule play a critical role in switching. Switching of the rigid, conjugated molecules is due to changes in the molecule-substrate bonds, which involves motion of the molecules and of substrate atoms. Furthermore, by controlling the concerted nanoscale motion of billions of palindromic bistable rotaxane molecules bound to gold film, we demonstrate that the cumulative nanoscale motion of the artificial muscle molecules can be harnessed to induce motion at a macroscale.
Controlling how, where, and when molecules react remains a central goal of nanoscience. By manipulating the conformation, location, environment, and orientation of molecules with sub nanometer precision, we can achieve direct control over the activity, reactivity, and selectivity of individual molecules. We have developed a system for monitoring and harnessing photochemical reactions and photocurrent/photoconductance generation of individual organic molecules with Ångström-scale spatial precision. Self- and directed assembly enable the design of the local environment around functional molecules.
We control the molecular conductance of isolated single organic molecules by regioselective photoreaction. Photoinduced molecular structural changes are used to control the conductance of isolated molecules. 9-(4-Mercaptophenylethynyl)anthracene (MPEA) changes conductance via photodimerization of anthracene moieties [1]. Photoreactive molecules can be deposited into defect sites singly, in pairs, or in larger groups within a well-defined self-assembled monolayer matrix. Photon scanning tunneling microscopy (PhotonSTM) enables measurements of molecules before, during, and after photoillumination and photoreaction.
[1] M. Kim, J. N. Hohman, Y. Cao, K. N. Houk, H. Ma, A. K.-Y. Jen and P. S. Weiss, Science 331, 1312 (2011).
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Precise Assemblies, Clusters, Superatoms, and Cluster-Assembled Materials
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Designing, Measuring, and Controlling Molecular and Supramolecular Devices
Shelley A. Claridge and Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We use molecular design, tailored syntheses, intermolecular interactions, and selective chemistry to direct molecules into desired positions to create nanostructures, to connect functional molecules to the outside world, and to serve as test structures for measuring single or bundled molecules. Interactions within and between molecules can be designed, directed, measured, understood, and exploited at unprecedented scales. Such interactions can be used to form precise molecular assemblies, nanostructures, and patterns, and to control and to stabilize function. We selectively test hypothesized mechanisms by varying molecular design, chemical environment, and measurement conditions to enable or to disable function and control using predictive and testable means. Critical to understanding these variations has been developing the means to make tens to hundreds of thousands of independent single-molecule measurements in order to develop sufficiently significant statistical distributions, while retaining the heterogeneity inherent in the measurements. We measure the electronic coupling of the molecules and substrates by measuring the polarizabilities of the connected functional molecules. The next step in such devices is to learn to assemble and to operate molecules together, both cooperatively and hierarchically, in analogy to biological muscles. We discuss our initial efforts in this area, in which we find both interferences and cooperativity.
Seeing
Shelley A. Claridge, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
Communicating Science - Connecting
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
New Dimensions in Patterning: Placement and Metrology of Chemical Functionality at All Scales
Paul S. Weiss, California NanoSystems Institute and Departments of Chemistry & Biochemistry and Materials Science & Engineering, UCLA, Los Angeles, CA 90095, USA
We place single molecules and larger groups into precisely controlled environments on surfaces. The monolayer matrices and the inserted molecules can be designed so as to interact directly, to give stability or other properties to supramolecular assemblies. New families of molecules are being developed to yield even greater control and are enabling determination of the key design parameters of both the molecules and assemblies. This in turn is enabling controlled chemical patterning from the sub-nanometer to the centimeter scales. We are simultaneously developing a suite of metrology tools for these methods to give unprecedented information on the structures and properties of these assemblies.
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27 December 2011