Photoswitching of Conductance of Diarylethene-Gold Nanoparticle Network Based on the Alteration of π-Conjugation

Diarylethenes, which have same core structures but have different positions of thiol groups that are bound to gold nanoparticles, were prepared. In one diarylethene, which has two thiol groups at the positions equivalent to 5,5'-positions of di(3-thienyl)ethene, the pi-connectivity between two thiol groups increases upon photocyclization, but in the other diarylethene, which has two thiol groups at 2- and 5-positions of one of the 3-thenyl group, the pi-connectivity decreases upon photocyclization. The gold nanoparticle networks of these diarylethenes were prepared and the change in conductance was measured upon alternate irradiation with UV and visible light. For two diarylethenes, the direction of the photoswitching was opposite, reflecting the difference in the pi-connectivity. The result suggests that the topology of pi-conjugation between electrodes is the decisive factor in the conductance of gold nanoparticle network.