Substituent‐Regulated Photophysical Properties and Self‐Reversible Mechanochromism in Luminescent Pyrrolone Derivatives

ABSTRACT

Monocyclic compounds with excellent photophysical properties are relatively uncommon compared to fluorophores featuring extensive π‐conjugation and polycyclic frameworks. Herein, we describe a series of 2,2‐dimethyl‐1,2‐dihydro‐3 H ‐pyrrol‐3‐ones and a systematic investigation of their photophysical properties. Strategic substitution at N ‐1, C‐4, and C‐5 along the periphery of this nonaromatic five‐membered N ‐heterocyclic scaffold endowed it with interesting photophysical properties. Specifically, the C‐4/C‐5 positions were functionalized with phenyl, anisyl, and styryl moieties, while the N ‐1 position was modified with alkyl, acetyl, and Boc groups. A combination of steric and electronic effects exerted by these substituents enabled the pyrrolone derivatives to exhibit large Stokes shifts, aggregation‐ and viscosity‐dependent emission, and dual‐state emission (DSE) in selected derivatives. Some of these derivatives also exhibited self‐reversible mechanochromism, which could be reproduced over multiple cycles.