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Quantum Interference Enhanced Chemical Responsivity in Single-Molecule Dithienoborepin Junctions |
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| Authors: | Dr Masoud Baghernejad Dr Colin Van Dyck Dr Justin Bergfield Dr David R Levine Dr Agnes Gubicza Prof?Dr John D Tovar Prof?Dr Michel Calame Dr Peter Broekmann Prof?Dr Wenjing Hong |
| Institution: | 1. Transport at Nanoscale Interface Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland;2. Department of Physics, University of Mons, 20, place du parc, 7000 Mons, Belgium;3. Department of Physics and Department of Chemistry, Illinois State University, Moulton Hall, USA;4. Department of Chemistry and Department of Materials Science and Engineering, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218 USA;5. Transport at Nanoscale Interface Laboratory, Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Department of Physics, University of Basel, Klingelbergstrasse 56, 4056 Basel, Switzerland;6. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland;7. Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland State Key Laboratory of Physical Chemistry of Solid Surfaces, iChEM, NEL, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China |
| Abstract: | Providing a chemical control over charge transport through molecular junctions is vital to developing sensing applications at the single-molecule scale. Quantum-interference effects that affect the charge transport through molecules offer a unique chance to enhance the chemical control. Here, we investigate how interference effects can be harnessed to optimize the response of single molecule dithienoborepin (DTB) junctions to the specific coordination of a fluoride ion in solution. The single-molecule conductance of two DTB isomers is measured using scanning tunneling microscopy break-junction (STM-BJ) before and after fluoride ion exposure. We find a significant change of conductance before and after the capture of a fluoride ion, the magnitude of which depends on the position of the boron atom in the molecular structure. This single-molecule sensor exhibits switching ratios of up to four orders of magnitudes, suggesting that the boron–fluoride coordination can lead to quantum-interference effects. This is confirmed by a quantum chemical characterization, pointing toward a cross-conjugated path through the molecular structure as the origin of the effect. |
| Keywords: | break-junction technique fluoride ions quantum interference scanning tunneling microscopy single-molecule charge transport |