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Photoinduced work function changes by isomerization of a densely packed azobenzene-based SAM on Au: a joint experimental and theoretical study. Phys Chem Chem Phys 2011; 13:14302-10. [DOI: 10.1039/c1cp20851a] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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252
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Corrigendum: A Conjugated Thiophene-Based Rotaxane: Synthesis, Spectroscopy, and Modeling. Chemistry 2010. [DOI: 10.1002/chem.201090230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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253
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Atomistic Simulations of 2D Bicomponent Self-Assembly: From Molecular Recognition to Self-Healing. J Am Chem Soc 2010; 132:17880-5. [DOI: 10.1021/ja107882e] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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254
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Bottom-up fabricated asymmetric electrodes for organic electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:5018-5023. [PMID: 20809516 DOI: 10.1002/adma.201002215] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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255
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Towards supramolecular engineering of functional nanomaterials: pre-programming multi-component 2D self-assembly at solid-liquid interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:3506-3520. [PMID: 20626011 DOI: 10.1002/adma.201001582] [Citation(s) in RCA: 217] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Materials with a pre-programmed order at the supramolecular level can be engineered with a sub-nanometer precision making use of reversible non- covalent interactions. The intrinsic ability of supramolecular materials to recognize and exchange their constituents makes them constitutionally dynamic materials. The tailoring of the materials properties relies on the full control over the self-assembly behavior of molecular modules exposing recognition sites and incorporating functional units. In this review we focus on three classes of weak-interactions to form complex 2D architectures starting from properly designed molecular modules: van der Waals, metallo-ligand and hydrogen bonding. Scanning tunneling microscopy studies will provide evidence with a sub-nanometer resolution, on the formation of responsive multicomponent architectures with controlled geometries and properties. Such endeavor enriches the scientist capability of generating more and more complex smart materials featuring controlled functions and unprecedented properties.
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Nanoscale quantitative measurement of the potential of charged nanostructures by electrostatic and Kelvin probe force microscopy: unraveling electronic processes in complex materials. Acc Chem Res 2010; 43:541-50. [PMID: 20058907 DOI: 10.1021/ar900247p] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In microelectronics and biology, many fundamental processes involve the exchange of charges between small objects, such as nanocrystals in photovoltaic blends or individual proteins in photosynthetic reactions. Because these nanoscale electronic processes strongly depend on the structure of the electroactive assemblies, a detailed understanding of these phenomena requires unraveling the relationship between the structure of the nano-object and its electronic function. Because of the fragility of the structures involved and the dynamic variance of the electric potential of each nanostructure during the charge generation and transport processes, understanding this structure-function relationship represents a great challenge. This Account discusses how our group and others have exploited scanning probe microscopy based approaches beyond imaging, particularly Kelvin probe force microscopy (KPFM), to map the potential of different nanostructures with a spatial and voltage resolution of a few nanometers and millivolts, respectively. We describe in detail how these techniques can provide researchers several types of chemical information. First, KPFM allows researchers to visualize the photogeneration and splitting of several unitary charges between well-defined nano-objects having complementary electron-acceptor and -donor properties. In addition, this method maps charge injection and transport in thin layers of polycrystalline materials. Finally, KPFM can monitor the activity of immobilized chemical components of natural photosynthetic systems. In particular, researchers can use KPFM to measure the electric potential without physical contact between the tip and the nanostructure studied. These measurements exploit long-range electrostatic interactions between the scanning probe and the sample, which scale with the square of the probe-sample distance, d. While allowing minimal perturbation, these long-range interactions limit the resolution attainable in the measurement of potentials. Although the spatial resolution of KPFM is on the nanometer scale, it is inferior to that of other related techniques such as atomic force or scanning tunneling microscopy, which are based on short-range interactions scaling as d(-7) or e(-d), respectively. To overcome this problem, we have recently devised deconvolution procedures that allow us to quantify the electric potential of a nano-object removing the artifacts due to its nanometric size.
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Cover Picture: A Conjugated Thiophene-Based Rotaxane: Synthesis, Spectroscopy, and Modeling (Chem. Eur. J. 13/2010). Chemistry 2010. [DOI: 10.1002/chem.201090057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Titelbild: Dynamers at the Solid-Liquid Interface: Controlling the Reversible Assembly/Reassembly Process between Two Highly Ordered Supramolecular Guanine Motifs (Angew. Chem. 11/2010). Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201000346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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261
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Macromolecular scaffolding: the relationship between nanoscale architecture and function in multichromophoric arrays for organic electronics. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:E81-E88. [PMID: 20217805 DOI: 10.1002/adma.200903672] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The optimization of the electronic properties of molecular materials based on optically or electrically active organic building blocks requires a fine-tuning of their self-assembly properties at surfaces. Such a fine-tuning can be obtained on a scale up to 10 nm by mastering principles of supramolecular chemistry, i.e., by using suitably designed molecules interacting via pre-programmed noncovalent forces. The control and fine-tuning on a greater length scale is more difficult and challenging. This Research News highlights recent results we obtained on a new class of macromolecules that possess a very rigid backbone and side chains that point away from this backbone. Each side chain contains an organic semiconducting moiety, whose position and electronic interaction with neighboring moieties are dictated by the central macromolecular scaffold. A combined experimental and theoretical approach has made it possible to unravel the physical and chemical properties of this system across multiple length scales. The (opto)electronic properties of the new functional architectures have been explored by constructing prototypes of field-effect transistors and solar cells, thereby providing direct insight into the relationship between architecture and function.
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Cover Picture: Dynamers at the Solid-Liquid Interface: Controlling the Reversible Assembly/Reassembly Process between Two Highly Ordered Supramolecular Guanine Motifs (Angew. Chem. Int. Ed. 11/2010). Angew Chem Int Ed Engl 2010. [DOI: 10.1002/anie.201000346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Dynamers at the Solid-Liquid Interface: Controlling the Reversible Assembly/Reassembly Process between Two Highly Ordered Supramolecular Guanine Motifs. Angew Chem Int Ed Engl 2010; 49:1963-6. [DOI: 10.1002/anie.200905827] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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264
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Dynamers at the Solid-Liquid Interface: Controlling the Reversible Assembly/Reassembly Process between Two Highly Ordered Supramolecular Guanine Motifs. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200905827] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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265
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Solvent vapour annealing of organic thin films: controlling the self-assembly of functional systems across multiple length scales. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b921612j] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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266
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Micron-sized [6,6]-phenyl C61 butyric acid methyl ester crystals grown by dip coating in solvent vapour atmosphere: interfaces for organic photovoltaics. Phys Chem Chem Phys 2010; 12:4473-80. [DOI: 10.1039/b923496a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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267
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Light-responsive reversible solvation and precipitation of gold nanoparticles. Chem Commun (Camb) 2010; 46:1147-9. [DOI: 10.1039/b915491d] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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268
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Tuning the charge injection of P3HT-based organic thin-film transistors through electrode functionalization with oligophenylene SAMs. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm03363d] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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269
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Nanopatterning the surface with ordered supramolecular architectures of N9-alkylated guanines: STM reveals. Chem Commun (Camb) 2010; 46:4493-5. [DOI: 10.1039/c0cc00443j] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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270
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Facile covalent functionalization of graphene oxide using microwaves: bottom-up development of functional graphitic materials. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm01242d] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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271
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Phase separation and affinity between a fluorinated perylene diimide dye and an alkyl-substituted hexa-peri-hexabenzocoronene. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/b915484a] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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272
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Solid–solid transfer of organic semiconductors for field-effect transistor fabrication. ACTA ACUST UNITED AC 2010. [DOI: 10.1039/c0jm02173c] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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273
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High-Contrast Visualization of Graphene Oxide on Dye-Sensitized Glass, Quartz, and Silicon by Fluorescence Quenching. J Am Chem Soc 2009; 131:15576-7. [DOI: 10.1021/ja9055382] [Citation(s) in RCA: 266] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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274
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Single-molecule wires get a lift. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:1927-1930. [PMID: 19634188 DOI: 10.1002/smll.200900650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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275
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Tailoring Bicomponent Supramolecular Nanoporous Networks: Phase Segregation, Polymorphism, and Glasses at the Solid−Liquid Interface. J Am Chem Soc 2009; 131:13062-71. [DOI: 10.1021/ja9032428] [Citation(s) in RCA: 126] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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276
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Competitive physisorption among alkyl-substituted pi-conjugated oligomers at the solid-liquid interface: towards prediction of self-assembly at surfaces from a multicomponent solution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:1521-1526. [PMID: 19319916 DOI: 10.1002/smll.200801901] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
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277
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Self-assembly of alkoxy-substituted bis(hydrazone)-based organic ligands and of a metallosupramolecular grid on graphite. Chemphyschem 2009; 10:699-705. [PMID: 19219889 DOI: 10.1002/cphc.200800733] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Self-assembly of a bis(hydrazone) chelating ligand functionalized with octadecyloxy substituents is described, as well as the reproducible thermally activated self-assembly of its metallosupramolecular cationic Co(II) [2x2] grid-type complex, on a highly oriented pyrolitic graphite (HOPG) substrate. Scanning tunnelling microscopy measurements at the solid/liquid interface reveal that the grid units of the annealed films are oriented edge-on to the basal plane of the HOPG, which indicates that the influence of the octadecyl chains is not sufficient to tie the grids into a face-on orientation. To gain a detailed understanding of the self-assembly behaviour of the grid on HOPG, the results for the grid itself have been compared to those of its constituent ligands.
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278
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Modulating Large-Area Self-Assembly at the Solid-Liquid Interface by pH-Mediated Conformational Switching. Chemistry 2009; 15:4788-92. [DOI: 10.1002/chem.200802566] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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279
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The Relationship between Nanoscale Architecture and Charge Transport in Conjugated Nanocrystals Bridged by Multichromophoric Polymers. J Am Chem Soc 2009; 131:7055-63. [DOI: 10.1021/ja809731e] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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280
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STM Insight into Hydrogen-Bonded Bicomponent 1 D Supramolecular Polymers with Controlled Geometries at the Liquid-Solid Interface. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200805680] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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281
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STM Insight into Hydrogen-Bonded Bicomponent 1 D Supramolecular Polymers with Controlled Geometries at the Liquid-Solid Interface. Angew Chem Int Ed Engl 2009; 48:2039-43. [DOI: 10.1002/anie.200805680] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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282
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283
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Temperature-enhanced solvent vapor annealing of a C3 symmetric hexa-peri-hexabenzocoronene: controlling the self-assembly from nano- to macroscale. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2009; 5:112-119. [PMID: 19130429 DOI: 10.1002/smll.200801002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Temperature-enhanced solvent vapor annealing (TESVA) is used to self-assemble functionalized polycyclic aromatic hydrocarbon molecules into ordered macroscopic layers and crystals on solid surfaces. A novel C3 symmetric hexa-peri-hexabenzocoronene functionalized with alternating hydrophilic and hydrophobic side chains is used as a model system since its multivalent character can be expected to offer unique self-assembly properties and behavior in different solvents. TESVA promotes the molecule's long-range mobility, as proven by their diffusion on a Si/SiO(x) surface on a scale of hundreds of micrometers. This leads to self-assembly into large, ordered crystals featuring an edge-on columnar type of arrangement, which differs from the morphologies obtained using conventional solution-processing methods such as spin-coating or drop-casting. The temperature modulation in the TESVA makes it possible to achieve an additional control over the role of hydrodynamic forces in the self-assembly at surfaces, leading to a macroscopic self-healing within the adsorbed film notably improved as compared to conventional solvent vapor annealing. This surface re-organization can be monitored in real time by optical and atomic force microscopy.
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284
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Photoinduced structural modifications in multicomponent architectures containing azobenzene moieties as photoswitchable cores. ACTA ACUST UNITED AC 2009. [DOI: 10.1039/b905287a] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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285
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Engineering of Supramolecular H-Bonded Nanopolygons via Self-Assembly of Programmed Molecular Modules. J Am Chem Soc 2008; 131:509-20. [DOI: 10.1021/ja807530m] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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286
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The Relationship between Nanoscale Architecture and Function in Photovoltaic Multichromophoric Arrays as Visualized by Kelvin Probe Force Microscopy. J Am Chem Soc 2008; 130:14605-14. [DOI: 10.1021/ja804069n] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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287
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Azobenzenes as Light-Controlled Molecular Electronic Switches in Nanoscale Metal−Molecule−Metal Junctions. J Am Chem Soc 2008; 130:9192-3. [DOI: 10.1021/ja8018093] [Citation(s) in RCA: 232] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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288
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Innentitelbild: Light-Powered Electrical Switch Based on Cargo-Lifting Azobenzene Monolayers (Angew. Chem. 18/2008). Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200890080] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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289
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Inside Cover: Light-Powered Electrical Switch Based on Cargo-Lifting Azobenzene Monolayers (Angew. Chem. Int. Ed. 18/2008). Angew Chem Int Ed Engl 2008. [DOI: 10.1002/anie.200890080] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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290
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Light-Powered Electrical Switch Based on Cargo-Lifting Azobenzene Monolayers. Angew Chem Int Ed Engl 2008; 47:3407-9. [DOI: 10.1002/anie.200705339] [Citation(s) in RCA: 263] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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291
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292
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Subnanometer-Resolved Patterning of Bicomponent Self-Assembled Monolayers on Au(111). Angew Chem Int Ed Engl 2008; 47:2484-8. [DOI: 10.1002/anie.200704731] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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293
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Subnanometer-Resolved Patterning of Bicomponent Self-Assembled Monolayers on Au(111). Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704731] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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294
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Abstract
We report on the self-assembly of a functionalized hexaazatriphenylene into supramolecular architectures where the single hexaazatriphenylene molecules are held together primarily through intermolecular hydrogen bonds between amide units. Wide and small angle X-ray scattering, polarized light microscopy, and differential scanning calorimetry revealed bulk self-organization into columnar structures. At the surfaces, scanning force microscopy experiments showed that it is possible to drive the self-organization from solutions of N-(2-ethylhexyl)-hexacarboxamidohexaazatriphenylene, towards either layers on a conductive surface like graphite or supramolecular anisotropic assemblies on an electrically insulating substrate such as muscovite mica. The growth of this latter type of architecture is primarily driven by the physical dewetting of the solution cast on the surface combined with intermolecular hydrogen bonds between the amide moieties exposed in the peripheral positions that lead to the formation of the columnar stack. Therefore, the anisotropic supramolecular azatriphenylene assemblies observed in the bulk have been also observed in thin films on a substrate poorly interacting with the adsorbate. In view of the interesting electronic properties of hexaazatriphenylene based architectures as n-type semiconductors, these results might be of interest for applications in the field of organic electronics.
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Pre-programmed bicomponent porous networks at the solid–liquid interface: the low concentration regime. Chem Commun (Camb) 2008:5289-91. [DOI: 10.1039/b811534f] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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296
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Photovoltaic Charge Generation Visualized at the Nanoscale: A Proof of Principle. J Am Chem Soc 2007; 130:780-1. [DOI: 10.1021/ja075291r] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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297
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Unconventional nanotubes self-assembled in alumina channels: morphology and surface potential of isolated nanostructures at surfaces. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2007; 365:1577-88. [PMID: 17428761 DOI: 10.1098/rsta.2007.2032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Synthetic nanographenes have been self-assembled from solution on the surface of nanometric channels of an alumina membrane template. By controlling the interplay between intermolecular and interfacial interactions, the molecules have been adsorbed either 'face-on' or 'edge-on' on the pore's surfaces, leading to the formation of columnar stacks in the latter case. Upon thermal treatment at high temperature, the molecular cross-linking of the columns has been triggered, transforming the delicate supramolecular arrangement into robust carbon nanotubes, with the graphitic planes at predetermined orientations with respect to the tube axis. Scanning force microscopy characterization of single nanotubes deposited from suspensions on mica showed that the nanotubes can self-assemble on flat surfaces adopting preferential alignments which reflect the threefold symmetry of the mica substrate. Kelvin probe force microscopy studies revealed that the nanotubes possess a surface potential much smaller than the work function of both graphite and conventional vacuum-processed nanotubes, providing evidence for their more confined electronic structure.
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Cooperative light-induced molecular movements of highly ordered azobenzene self-assembled monolayers. Proc Natl Acad Sci U S A 2007; 104:9937-42. [PMID: 17535889 PMCID: PMC1891213 DOI: 10.1073/pnas.0703748104] [Citation(s) in RCA: 198] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Photochromic systems can convert light energy into mechanical energy, thus they can be used as building blocks for the fabrication of prototypes of molecular devices that are based on the photomechanical effect. Hitherto a controlled photochromic switch on surfaces has been achieved either on isolated chromophores or within assemblies of randomly arranged molecules. Here we show by scanning tunneling microscopy imaging the photochemical switching of a new terminally thiolated azobiphenyl rigid rod molecule. Interestingly, the switching of entire molecular 2D crystalline domains is observed, which is ruled by the interactions between nearest neighbors. This observation of azobenzene-based systems displaying collective switching might be of interest for applications in high-density data storage.
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