Thermally programmable SmA liquid crystals based on chlorine functionalized imine-ester architectures

In this study, we report the synthesis and characterization of a new series of 3,5-dichlorinated imine-ester liquid crystalline compounds (4a-4d), which form a homologous series differing in terminal alkoxy chain length (C8-C14). All compounds exhibit enantiotropic smectic A (SmA) phases with broad thermal ranges and pronounced hysteresis. Notably, compound 4d retains its layered SmA order down to room temperature and can exist in two distinct, thermally reprogrammable optical states (transparent vs. opaque) depending on the cooling rate, without the need for alignment layers or external dopants. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) confirm the reversible mesophase transitions and long-range thermal persistence. Density functional theory (DFT) calculations reveal high dipole moments, narrow energy gaps, and enhanced (hyper)polarizabilities, supporting the correlation between molecular structure and nonlinear optical (NLO) behavior. These results demonstrate the potential of halogenated imine-ester systems as thermally programmable soft materials for memory and photonic applications.