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Influence of surface coverage on the formation of 4,4′-bipyridinium (viologen) single molecular junctions
| Content Provider | Semantic Scholar |
|---|---|
| Author | Osorio, Henrry M. Martín, Santiago Milán, David Costa González-Orive, Alejandro Gluyas, Josef B. G. Higgins, Simon J. Low, Paul J. Nichols, Richard J. Cea, Pilar |
| Copyright Year | 2017 |
| Abstract | Single-molecule conductance experiments using the STM-based I(s) method and samples of N,N′-di(4-(trimethylsilylethynyl)benzyl)-4,4′-bipyridinium bis(tetrafluoroborate) ([1](BF4)2) prepared on gold substrates with low-surface coverage of [1](BF4)2 (Γ = 1.25 × 10−11 mol cm−2) give rise to molecular junctions with two distinct conductance values. From the associated break-off distances and comparison experiments with related compounds, the higher conductance junctions are attributed to molecular contacts between the molecule and the electrodes via the N,N′-dibenzyl-4,4′-bipyridinium (viologen) moiety and one trimethylsilylethynyl (TMSE) group (G = (5.4 ± 0.95) × 10−5 G0, break-off distance (1.56 ± 0.09) nm). The second, lower conductance junction (G = (0.84 ± 0.09) × 10−5 G0) is consistent with an extended molecular conformation between the substrate and tip contacted through the two TMSE groups giving rise to a break-off distance (1.95 ± 0.12) nm that compares well with the Si⋯Si distance (2.0 nm) in the extended molecule. Langmuir monolayers of [1](BF4)2 formed at the air–water interface can be transferred onto a gold-on-glass substrate by the Langmuir–Blodgett (LB) technique to give well-ordered, compact films with surface coverage Γ = 2.0 × 10−10 mol cm−2. Single-molecule conductance experiments using the STM-based I(s) method reveal only the higher conductance junctions (G = (5.4 ± 0.95) × 10−5 G0, break-off distance (1.56 ± 0.09) nm) due to the restricted range of molecular conformations in the tightly packed, well-ordered LB films. |
| Starting Page | 11717 |
| Ending Page | 11723 |
| Page Count | 7 |
| File Format | PDF HTM / HTML |
| DOI | 10.1039/C7TC03624H |
| Volume Number | 5 |
| Alternate Webpage(s) | http://www.rsc.org/suppdata/c7/tc/c7tc03624h/c7tc03624h1.pdf |
| Alternate Webpage(s) | https://livrepository.liverpool.ac.uk/3014458/1/Viologen%20paper-Final%20Version.pdf |
| Alternate Webpage(s) | https://doi.org/10.1039/C7TC03624H |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
