Molecular photonics of polymethine dyes in complexes with cucurbit[7, 8]urils

Abstract

Thiacarbo- and thiadicarbocyanine indolenine and thiazoline polymethine dyes form host‒guest complexes with cucurbit[7,8]urils in water. Cucurbit[7]uril forms preferentially 1: 1 and 1: 2 monomeric complexes and cucurbit[8]uril forms 2: 1 and 2: 2 dimeric complexes. On the basis of quantum-chemical calculations, the structure of monomeric and dimeric complexes has been suggested. The complexation manifested itself in absorption, prompt and thermally activated delayed fluorescence spectra, as well as in the triplet‒triplet absorption spectra. Dimeric complexes in the triplet state are involved in one-electron oxidation and participate in triplet‒triplet energy transfer.