Photo-active dithienylcyclopentene-derived room temperature nematics

Abstract

Functional photo-active organic materials possessing self-assembly behaviour at room temperature and below always attract considerable attention of the scientific community due to their potential applications. In this study, we introduce the design and synthesis of dithienylcyclopentene (DTCP)-derivatives that exhibit room-temperature liquid crystalline (LC) properties, marking the first example of such compounds in the known literature. Compared to conventional liquid crystal materials, which typically transition to the liquid crystal phase driven by planar π–π stacking forces, these new non-planar liquid crystal compounds transition to the liquid crystal phase induced by dispersion interactions CF–π, CH–π and van der Waals forces, resulting in the formation of photochromic liquid crystal materials. The DTCP core is meticulously engineered with biphenyl, naphthyl, and phenyl groups to forge both symmetrical and unsymmetrical configurations. Through fine-tuning of the molecular structure, these DTCP derivatives exhibited LC phases, reversible changes upon UV/visible light irradiation, fast response, and distinct optical and alignment properties. An unsymmetrical design with the biphenyl and phenyl moieties connected to the central DTCP core results in derivatives exhibiting a stable room-temperature enantiotropic nematic phase. Additionally, this study focuses on the closed-ring isomers’ characteristics of LCs, a subject yet to be explored. Our findings not only prove the possibility of crafting room-temperature photo-active LC materials but also pave the path for the creation of unconventional functional LC materials destined for use in display technologies, sensor devices, and smart window applications.