Luminescence Switching and Thermoresponsive Actuation in a Thiophene–Carbazide-Based Molecular Crystal

Abstract

Stimuli-responsive dynamic crystals, capable of revealing macroscopic responses to assorted varieties of stimuli such as light of various wavelengths, pressure, electricity, heat, and humidity, are an emerging class of smart materials compatible with designing actuators, soft robots, machinery devices, sensors, and more. It is thus an arduous endeavor to develop multistimuli-responsive dynamic actuators that can display multifaceted property changes by varying external stimuli. In this work, we report a thiophene-carbazide-based organic crystal (TME) that exhibits thermoresponsive actuation and solid-state luminescence switching in the presence of various stimuli. With the aid of single-crystal XRD, PXRD, DSC, and theoretical studies on intermolecular interactions, we establish that thermoresponsive actuation is due to thermosalient phase transition, whereas fluorescence switching is rooted in an order–disorder phase transition in the solid state.