Polymorphism in mechanochromic luminogens: recent advances and perspectives

Abstract

Polymorphism in mechanochromic materials is a subject of growing research interest due to its implication in various optoelectronic devices. Polymorphs refer to materials or substances that, despite having identical chemical compositions, exhibit different crystal structures, leading to variations in emission colors. The occurrence of polymorphism in a compound is often a result of various factors, such as temperature, pressure as well as the solvents used in the recrystallization methods and such polymorphs might respond differently to external mechanical stimuli. This review focuses on the development of polymorphic mechanochromic luminogens and their emission in response to a mechanical stimulus along with their polymorphs; moreover it highlights the importance of intermolecular interactions and packing modes in regulating mechanofluorochromic performance. The review aims to reveal the mechanisms behind polymorphism, exploring how intermolecular interactions, crystal packing, and molecular conformation contribute to the generation of different emission colors. The present review provides an elucidative assessment of recently developed organic mechanochromic polymorphic materials, focusing on the factors influencing their formation and properties.