Evaluation of carborane-containing nematic liquid crystals for electro-optical applications

Three new structurally similar compounds in series 1[2] and 2 containing 12- and 10-vertex p-carborane units (A and B) were prepared. Their thermal properties were investigated in the pure state and compared to those of their carbocyclic analogues. Using several higher homologues in the series 1[n], clearing temperatures for the unknown 1[4] and 1[10] were predicted. Optical, dielectric and rotational viscosity parameters for carborane derivatives 1[2] and 2 and their cyclohexane analogies were obtained by extrapolation of values measured for 10% solutions in a standard nematic host. The observed trends were rationalised using computed molecular parameters.