Charge Transport in Photoswitchable Dimethyldihydropyrene-Type Single-Molecule Junctions

Abstract

The conductance properties of a photoswitchable dimethyldihydropyrene (DHP) derivative have been investigated for the first time in single-molecule junctions using the mechanically controllable break junction technique. We demonstrate that the reversible structure changes induced by isomerization of a single bispyridine-substituted DHP molecule are correlated with a large drop of the conductance value. We found a very high ON/OFF ratio (>10(4)) and an excellent reversibility of conductance switching.

Reactivity of a pyridinium-substituted dimethyldihydropyrene switch under aerobic conditions: self-sensitized photo-oxygenation and thermal release of singlet oxygen

“…Importantly, the properties of this molecule can be finely tuned by chemical functionalization, a feature that has enabled the recent development of very promising DHP-based multi-functional materials and opto-electronic devices. 10,[37][38][39][40][41][42][43][44] We have recently investigated the behavior of 1 (closed isomer as PF 6 salt, Scheme 1) under an inert atmosphere. 45 The presence of the pyridinium substituents on the DHP core has been shown to significantly improve the photoisomerization efficiency in terms of photoconversion rate and to allow a significant decrease of the irradiation energy (from green to red light).…”

Single-Molecule Electronics: Chemical and Analytical Perspectives

“…The Z isomer has been shown through in situ break junctions and I(s) measurements to exhibit a higher conductance given it facilitates stronger coupling between the phenyl groups and the gold contacts (100). Greater single-molecule conductance switching could be achieved with a photoswitchable dimethyldihydropyrene derivative, through a reversible ring opening/closing isomerization (101). Both of these previous examples represent sequential single-molecule conductance measurements, first of one isomer, followed by photoswitching and then a set of measurements on the other isomer.…”

Single‐Molecule Sensing of Environmental pH—an STM Break Junction and NEGF‐DFT Approach

“…Previous work investigated the conductance switching effects on single molecules through electrochemical gating, [11][12][13][14][15][16][17][18][19] photo switching, [20][21][22][23][24][25][26][27] and mechanically controlling molecular configurations. [28] The few prior reports of the modulation of molecular conductance through changes in the solution pH show either a small switching effect (on/off ratio of about 2), [29] or the detection of only one state at one pH, presumably the high conductance state, while the conductance value of the second state was not detected, either because a junction could not be formed or the conductance was too low.…”