The indanone N–H type excited-state intramolecular proton transfer (ESIPT); the observation of a mechanically induced ESIPT reaction

Abstract

We report the design and synthesis of indanone derivatives 1–4 with RR′N–H⋯OC intramolecular hydrogen bonds, in which ESIPT takes place and its dynamics and thermodynamics correlate with H-bond strength, facilitated by electron-withdrawing R′ groups. Compound 4 (R′ = COCF₃) shows mechanically induced ESIPT for the first time, where –CF₃⋯HN– interaction plays a key role in the non-centrosymmetric crystal packing.