T-Shaped donor–acceptor–donor type tetraphenylethylene substituted quinoxaline derivatives: aggregation-induced emission and mechanochromism

Abstract

Smart mechanofluorochromic materials are of great importance owing to their wide range of applications and have been effectively synthesized by incorporating aggregation-induced emission (AIE) active luminogens. In this contribution, we have synthesized two novel T-shaped D–A–D type luminophores, tetraphenylethylene (TPE) substituted acenapthene-quinoxaline 1 and TPE substituted phenanthrene quinoxaline 2, by the Suzuki cross-coupling reaction. Their solavatochromism, AIE and mechanochromism were evaluated. The D–A–D structured luminophores 1 and 2 show solvent-dependent intramolecular charge transfer (ICT) transitions, which were explored using solvatochromism, and also exhibit strong AIE behaviour. Luminophores 1 and 2 show highly reversible mechanochromism with a good colour contrast, which was further studied using photophysical properties, powder X-ray diffraction and theoretical calculations. The powder XRD study reveals a morphological change from crystalline to amorphous, which is responsible for mechanochromism.