Crystals as Rockets: Modulation of the Salient Temperature in Cocrystals by Solvent Mixture Composition

Abstract

ABSTRACT Harnessing mechanical motion in molecular crystals is a critical goal for developing novel energy conversion materials. Among known strategies, the ejection of guest molecules from the lattice via the jumping‐mate approach offers a direct means of propulsion. Here, we present isostructural cocrystals of indolo[3,2‐ a ]carbazole (ICZ) and ( E )‐1,2‐di(pyridin‐4‐yl)ethene (BPE) that incorporate solvents such as acetone, ethyl acetate, or tetrahydrofuran. X‐ray diffraction and solid‐state nuclear magnetic resonance (NMR) studies confirmed the presence of solvents or solvent mixtures. Upon heating, these channel‐type cocrystals exhibit a thermosalient effect, with temperature regulation achieved by releasing pure or solvent mixtures. Differential scanning calorimetry and thermogravimetry (DSC–TGA) analyses revealed that the transition temperatures changed progressively, demonstrating controllable thermal actuation through the release of occluded solvents. This work demonstrates a simple yet powerful way to regulate mechanical responses in molecular crystals, thereby advancing the design of responsive energy conversion materials.