Molecular Engineering of Sexiphenyl Nematics: Lateral Substitution for Phase Tuning and Fluorescence Enhancement

A series of novel sexiphenyl liquid crystals featuring terminal pentyl chains and lateral alkyl/fluoro substituents were synthesised via a palladium-catalysed route using novel 2,4-dialkylphenyl boronic esters. Compounds exhibited stable nematic mesophases, with lateral substitution reducing clearing points by 300-380 degrees C versus unsubstituted sexiphenyl - with methylated compounds showing supercooling to near-ambient temperatures. Photophysical studies revealed UV-range fluorescence with quantum yields up to 94%, modulated by substituent sterics/electronics. These materials demonstrate exceptional potential for low-temperature nematic applications requiring tunable optoelectronic properties.