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

• Poly(ϵ-caprolactone)/siloxane biohybrids electrolytes were prepared by sol-gel method.
• The polymer electrolytes were doped with copper perchlorate salt.
• The ionic, paramagnetic and photophysical properties of the samples were evaluated.
• The samples were analyzed by means of impedance spectroscopy, electron paramagnetic resonance (EPR) and photoluminescence spectroscopy.

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 S cm−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.

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