Ionic, paramagnetic and photophysical properties of a new biohybrid material incorporating copper perchlorate

Abstract

The sol-gel method was employed in the synthesis of di-urethane cross-linked poly(ϵ-caprolactone) (d-PCL(530)/siloxane biohybrid ormolytes incorporating copper perchlorate (Cu(ClO4)2). The highest ionic conductivity of the d-PCL(530)/siloxanenCu(ClO4)2 system is that with n=10 (1.4×10−7 and 1.4×10−5 Scm−1, at 25 and 100°C, respectively). In an attempt to understand the ionic conductivity/ionic association relationship, we decided to inspect the chemical environment experienced by the Cu2+ ions in the d-PCL(530)/siloxane medium. The observed EPR spectra are typical of isolated monomeric Cu2+ ions in axially distorted sites. The molecular orbital coefficients obtained from the EPR spin Hamiltonian parameters and the optical absorption band suggests that bonding between the Cu2+ and its ligand in the ormolytes are moderately ionic. Investigation by photoluminescence spectroscopy did not evidence or allow selective excitation of transitions corresponding to complexed Cu2+ species.