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A Small Molecule Walks Along a Surface Between Porphyrin Fences That Are Assembled In Situ |
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| Authors: | Dr. Sam Haq Bareld Wit Hongqian Sang Dr. Andrea Floris Prof. Yu Wang Prof. Jianbo Wang Dr. Lluïsa Pérez‐García Prof. Lev Kantorovitch Prof. David B. Amabilino Prof. Rasmita Raval |
| Affiliation: | 1. Surface Science Research Centre, Department of Chemistry, University of Liverpool, Liverpool L69 3BX (UK);2. School of Physics and Technology, Center for Electron Microscopy and MOE, Key Laboratory of Artificial Micro‐ and Nano‐structures, Wuhan University, Wuhan 430072 (China);3. Physics Department, King's College London, Strand, London, SE2 0LR (UK);4. Laboratori de Química Orgànica, Facultat de Farmàcia and Institut de Nanociència i Nanotecnologia, Universitat de Barcelona, 08028 Barcelona (Catalonia, Spain);5. Institut de Ciència de Materials de Barcelona (CSIC), Campus Universitari, 08193 Bellaterra (Catalonia, Spain);6. Present address: School of Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD (UK) |
| Abstract: | An on‐surface bimolecular system is described, comprising a simple divalent bis(imidazolyl) molecule that is shown to “walk” at room temperature via an inchworm mechanism along a specific pathway terminated at each end by oligomeric “fences” constructed on a monocrystalline copper surface. Scanning tunneling microscopy shows that the motion of the walker occurs along the [1$bar 1$ 0] direction of the Cu surface with remarkably high selectivity and is effectively confined by the orthogonal construction of covalent porphyrin oligomers along the [001] surface direction, which serve as barriers. Density functional theory shows that the mobile molecule walks by attaching and detaching the nitrogen atoms in its imidazolyl “legs” to and from the protruding close‐packed rows of the metal surface and that it can transit between two energetically equivalent extended and contracted conformations by overcoming a small energy barrier. |
| Keywords: | diffusion molecular machines nanomaterials scanning tunneling microscopy surface chemistry |