Surface grafting of cobalt complexes on polymeric supports: Evidence for site isolation and applications to reversible dioxygen binding

Imprinted polymers were synthesized using the surface-grafting technique wi th [Co(III)1(vpy)(dmap)]PF6 {1, bis[2-hydroxy-4-(4-vinylbenzyloxy)benzaldeh yde] ethylene-diimine; vpy: 4 -vinylpyridine; dmap : N,N'-dimethyl-4-aminop yridine} as the template. The metallated sites were probed using spectrosco pic techniques including UV-vis, Fourier transform infrared, and electron p aramagnetic resonance (EPR) spectroscopies to investigate the site architec ture and isolation of the immobilized sites in the surface-grafted polymers . EPR studies showed a distribution of four and five coordinated sites simi lar to the bulk copolymers, and the surface-grafted polymer showed reversib le binding to dioxygen in multiple cycles. Both results indicated site isol ation in the surface-grafted polymers analogous to the bulk polymers. Altho ugh the dioxygen binding in surface-grafted polymers is reversible, the spi n 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. (C) 2001 John Wiley & Sons, Inc.