INVESTIGATION OF THE STRUCTURE OF THE COLUMNAR LIQUID-CRYSTALLINE PHASE OF COPPER(II) CARBOXYLATES - AN FTIR SPECTROSCOPIC STUDY

The FTIR spectra of a series of anhydrous copper(II) carboxylates of g eneral formula CU2[CH3(CH2)(n)CO2](4) (n = 4-8, 10, 12, 14 and 16) hav e been studied as a function of temperature. The spectra show notable changes associated with the phase transition from the crystalline to t he columnar liquid-crystalline phase which indicate that the coordinat ion of the carboxylate groups to the bimetallic centre changes from br idging bidentate to chelating bidentate. The observed change in the ty pe of coordination is induced by the conformational disordering to the carbon chains and does not affect strongly the chemical environment a round the copper atoms (in particular the Cu-Cu and Cu-O distances), i n agreement with previous Cu-K alpha EXAFS spectroscopic results.