A Photochemical/Thermal Switch Based on 4,4′‐Bis(benzimidazolio)stilbene: Synthesis and Supramolecular Properties.

Abstract

Stilbene derivatives are well‐recognised substructures of molecular switches based on photochemically and/or thermally induced (E)/(Z) isomerisation. We combined a stilbene motif with two benzimidazolium arms to prepare new sorts of supramolecular building blocks and examined their binding properties towards cucurbit[n]urils (n=7, 8) and cyclodextrins (β‐CD, γ‐CD) in water. Based on the 1H NMR data and molecular dynamics simulations, we found that two distinct complexes with different stoichiometry, i. e., guest@β‐CD and guest@β‐CD2, coexist in equilibrium in a water solution of the (Z)‐stilbene‐based guests. We also demonstrated that the bis(benzimidazolio)stilbene guests can be transformed from the (E) into the (Z) form via UV irradiation and back via thermal treatment in DMSO.