Martensitic phase transition and stimuli responsive effects in thermosalient cocrystal of 9,10-dimethylanthracene with F2TCNQ

Abstract

Martensitic single-crystal-to-single-crystal phase transitions, being rare in organic crystals, can result in several phenomena with promising potential applications, including thermosalient effect, shape memory and self-healing. We report here the first charge-transfer cocrystal of 9,10-dimethylanthracene and 2,5-difluoro-7,7,8,8-tetracyanoquinodimethane, exhibiting a unique combination of dynamic properties stemming from a martensitic phase transition. This organic material demonstrates thermosalient and self-healing behavior, alongside shape recovery during heating and cooling cycles. These effects are driven by collective rotational and translational movements of rigid molecular frameworks, resulting in significant structural changes, while maintaining the process reversibility. Raman spectroscopy, combined with DFT calculations and electron density distribution analysis, provides insight into intermolecular interactions and the potential mechanism of the phase transition. Concurrently, the system displays characteristics of a narrow-gap semiconductor based on transport properties.