Improving the kinetics and dark equilibrium of donor-acceptor Stenhouse adduct by triene backbone design

Chem Commun (Camb). 2022 Feb 15;58(14):2303-2306. doi: 10.1039/d1cc06235b.

Abstract

DFT calculations were used to find an optimal substitution site on the triene backbone of a donor-acceptor Stenhouse adduct photoswitch to tune the equillibrium and switching kinetics of DASA without modifying the donor and acceptor groups. Using this approach we demonstrate a new means to tuning DASA based photoswitches by increasing the energy of the closed form relative to the open form. To highlight the potential of this approach a new DASA derivative bearing a methyl substituent on the 5-position of the triene was synthesized and the effect of this substitution was studied using 1H NMR spectroscopy, time-dependent UV-Vis and solvatochromic analysis. The new DASA derivative shows a higher dark equillibrium, favoring the open form, and drastically faster thermal recovery than the unsubstituted derivative with the same donor and acceptor.