Harnessing liquid crystal attributes of near-unit photoluminescent benzothioxanthene photosensitizers: Photophysical profiling in solution, solid state, and polymer matrix embedding

Abstract

Liquid crystals (LCs) have garnered significant attention for their unique optical and electrical properties, making them promising candidates in various technological applications such as smart displays, sensors, telecommunications, biomedicals or wearable electronics. In this study, we explore the potential of several highly emissive benzothioxanthene imide (BTI) derivatives as LC materials with a focus on their robustness and temperature-stable emission behavior. By tailoring the molecular structure of BTIs, we have accomplished exceptional emissive properties while maintaining the inherent advantages of LCs, such as their self-organizing ability and responsive nature. We describe the formation of enantiotropic liquid crystals whose mesomorphic properties dependent on the nature, length, and position of the side chain. Moreover, we have investigated the thermal stability of their emission spectra over a wide range of temperature, highlighting their potential use in demanding conditions where precise optical performances are critical. Our findings underscore the importance of molecular design in achieving highly emissive LC materials with enhanced robustness and temperature stability, opening new avenues for the use of BTI derivatives.