Surface Grafting of Cobalt Complexes on Polymeric Supports: Evidence for Site Isolation and Applications to Reversible Dixoygen Binding

摘要

Imprinted polymers were synthesized using the surface-grafting tech- nique with [Co(lll)l(vpy)(dmap)]PF 6 11, bis[2-hydroxy-4-(4-Vinylbenzyloxy)benzal- dehyde]ethylene-diimine; vpy: 4-vinylpyridine; dmap: N oN' -dimethyl-4-aminopyri- dine} as the template. The metallated sites were probed using spectroscopic tech- niques including UV-vis, Fourier transform infrared, and electron paramagnetic resonance (EPR) spectroscopies to investigate the site architecture and isolation of the immobilized sites in the surface-grafted polymers. EPR studies showed a dis- tribution of four and five coordinated sites similar to the bulk copolymers, and the surface-grafted polymer showed reversible binding to dioxygen in multiple cycles. Both results indicated site isolation in the surface-grafted polymers analogous to the bulk polymers. Although the dioxygen binding in surface-grafted polymers is reversible, the spin density decreases to 50% in the third cycle as opposed to bulk copolymers. This indicates that the sites are more heterogeneous and more exposed to the environment than the analogous sites in bulk copolymers.