Influence of surface coverage on the formation of 4, 4′-bipyridinium (viologen) single molecular junctions

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 …

Año de publicación:

2017

Keywords:

Fuente:

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