Columnar mesophase from non-symmetrical tapered hydrazide derivatives

A new series of liquid-crystalline tapered hydrazide derivatives with an amino head group, e.g. N-(3,4,5-trialkoxylbenzoyl)-N′-(4′-aminobenzoyl) hydrazine (Dn, where n is the number of carbon atoms in the alkyl chains, n = 6, 8, 16), were designed and synthesized. Results of 1H NMR diluting experiment and FTIR spectroscopy revealed that the amide protons of the central hydrazide group in Dn participated in intermolecular double hydrogen bonds based on Cdouble bond; length as m-dashO and single bondNH in liquid crystalline phase. Investigations on the liquid crystalline properties showed that the D6 exhibited non-mesophase, D8 exhibited monotropic hexagonal columnar mesophase, while D16 exhibited enantiotropic oblique columnar mesophase with increasing the length of the terminal chains.