Liquid-crystal behavior in ionic complexes of silver(I): Molecular structure-mesogenic activity relationship

Abstract

The liquid-crystal behavior of four series of ionic complexes of silver(I) with structure [AgL2]+X- have been investigated by using differential scanning calorimetry (DSC), optical microscopy, and X-ray diffraction techniques. Two different nonmesogenic pyridine derivatives, NC5H4CH=NC6H4OCnH 2n+1 and NC5H4COOC6H4OCnH 2n+1, were used as ligands (L) and four anions, BF4 -, CF3SO3 -, NO3 -, and PF6 -, as counterions (X-). The influence of both the organic ligand and counterion on the liquid-crystal properties of these complexes was studied. These complexes displayed mesogenic behavior identical with that exhibited by typical calamitic liquid crystals. Some of the complexes exhibited additional stable phases between the low-temperature solid phase and the liquid-crystalline phase. A comparative study has shown that pyridinecarboxylate derivatives show higher transition temperatures and wider mesophase ranges than similar imine derivatives. With regard to counterions, the less voluminous the anion, the broader the mesophase range and the lower the melting point. © 1990 American Chemical Society.