Mesophase behavior of new linear supramolecular hydrogen-bonding complexes

Thermal and mesophase behavior of four new series of hydrogen-bonded supramolecular complexes (In/IIm) were investigated by differential scanning calorimetry and phases identified by polarized light microscopy. All hydrogen-bonded complexes formed from 4-alkoxyphenylazobenzoic acid (In) and 4-(4′-pyridylazophenyl)-4′′-alkoxybenzoates (IIm). The results revealed that the prepared complexes are dimorphic, possessing smectic C and nematic phases. The comparison, made between the present series and previously investigated simpler, In/IIIm and angular, In/IVm analogues, revealed that increasing the length of the mesogenic core and/or linearity of complex increase the stabilities of both the smectic C and nematic phases.