Induced Smectic-G Phase Through Intermolecular H-Bonding: Part III. Influence of Alkyl Chain Length of p-n-Alkoxybenzoic Acids on Thermal and Phase Behaviour

Abstract

A novel series of intermolecular hydrogen bonding complexes have been synthesized by using p-n-alkoxybenzoic acids (alkyl chain length varies from propyl- to decyl and dodecyl-) (ABA) and a non-mesogenic moiety, 2-amino-5-chloro-pyridine (ACP), The thermal and phase behaviour of these complexes are studied by thermal microscopy (TM) and differential scanning calorimetry (DSC) techniques. The stabilization of intermolecular hydrogen bonding is studied by IR spectra. A detailed IR spectral investigation in solid and solution states suggest that both acid and pyridine nitrogens are complementary to one another by acting as proton donor and acceptor respectively. The comparative thermal studies with free benzoic acids and the corresponding analogous hydrogen bonded complexes reveal the inducement of a monotropic smectic-G phase with simultaneous quenching of nematic and smectic-C phases.