Environmental Dependence of Artifact CD Peaks of Chiral Schiff Base 3d-4f Complexes in Soft Mater PMMA Matrix

Abstract

Four chiral Schiff base binuclear 3d-4f complexes (NdNi, NdCu, GdNi, and GdCu) have been prepared and characterized by means of electronic and CD spectra, IR spectra, magnetic measurements, and X-ray crystallography (NdNi). A so-called artifact peak of solid state CD spectra, which was characteristic of oriented molecules without free molecular rotation, appeared at about 470 nm. Magnetic data of the complexes in the solid state (powder) and in PMMA cast films or solutions indicated that only GdCu preserved molecular structures in various matrixes of soft maters. For the first time, we have used the changes of intensity of artifact CD peaks to detect properties of environmental (media solid state (KBr pellets), PMMA cast films, concentration dependence of PMMA in acetone solutions, and pure acetone solution) for chiral 3d-4f complexes (GdCu). Rigid matrix keeping anisotropic orientation exhibited a decrease in the intensity of the artifact CD peak toward negative values. The present results suggest that solid state artifact CD peaks can be affected by environmental viscosity of a soft mater matrix.