Switchable Photoluminescence Properties of a 1,8-Naphthalimide Derivative via Polymorphism, Pseudopolymorphism, and Mechanochromism

Polymorphism, pseudopolymorphism, and mechanochromism phenomena have been demonstrated using a 1,8-naphthalimide derivative. Depending upon the crystallization conditions, the dye produced different supramolecular arrangements, leading to polymorphism and pseudopolymorphism. By grinding, one polymorph could be converted to another polymorph. All of the polymorphs and pseudopolymorphs displayed different emission maxima ranging from 551 to 577 nm. The different supramolecular species are interconvertible via physical processes, such as grinding and heating. Our investigations on fine-tuning of emission behavior of naphthalimide derivative demonstrated their potential applications as multi-stimulus-responsive, switchable luminescent materials.