Synthesis and characterisation of photochromic dithienylcyclopentene liquid crystal with thermal irreversibility

Abstract

ABSTRACTA series of photochromic liquid crystal dithienylcyclopentene derivatives were synthesised from the initial material 2-chloro-5-methylthiophene. They were characterised by 1H NMR, high resolution mass spectrometer, differential scanning calorimetry (DSC) and polarised optical microscopy (POM) with a hot stage. All of them exhibited excellent photochemically reversible isomerisation between the open-ring form and the closed-ring form in both organic solvents and LC media, resulting in the colour change between colourless and purple under different light irradiations. The typical textures from POM showed that their isomers both had nematic phase and smectic phase with different colours. These compounds with bent shape were more sensitive to light than those of diarylethenes reported.