American Chemical Society
jz100228w_si_002.cif (22.23 kB)

Remarkable Acceleration for Back-Reaction of a Fast Photochromic Molecule

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posted on 2015-12-16, 16:30 authored by Yuka Harada, Sayaka Hatano, Atsushi Kimoto, Jiro Abe
We demonstrate that photochromism based on light-driven reversible C−N single bond cleavage can enable rapid coloration upon UV light irradiation and successive fast thermal back-reaction within tens of microseconds at room temperature. According to Marcus theory, the thermal back-reaction would be accelerated with increasing ΔG0, which is closely linked to the decrease in ΔG. We have considered that the ΔG0 of the thermal back-reaction could be enlarged by destabilizing the colored species and designed pseudogem-DPI-PI[2.2]PC, with a [2.2]paracyclophane moiety that couples diphenylimidazole and phenanthroimidazole groups. The present study demonstrates that controlling the stability of the biradical state is effective in accelerating the thermal back-reaction for the photochromic [2.2]paracyclophane-bridged imidazole dimer.