Investigation of the Structure of the Columnar Liquid-crystalline Phase of Copper(l1) Carboxylates. An FTlR Spectroscopic Study

Abstract

The FTlR spectra of a series of anhydrous copper(it) carboxylates of general formula Cu,[CH,(CH,),CO,], (n = 4-8, 10, 12, 14 and 16) have been studied as a function of temperature. The spectra show notable changes associated with the phase transition from the crystalline to the columnar liquid-crystalline phase which indicate that the coordination of the carboxylate groups to the bimetallic centre changes from bridging bidentate to chelating bidentate. The observed change in the type of coordination is induced by the conformational disordering to the carbon chains and does not affect strongly the chemical environment around the copper atoms (in particular the Cu-Cu and Cu-0 distances), in agreement with previous Cu-Ka EXAFS spectroscopic results.