Spectroscopic investigation of the encapsulation and the reactivity towards NO of a Co(II)-porphyrin inside a cross-linked polymeric matrix

A highly dispersed cobalt(II) porphyrin (PhCoII) encapsulated inside a highly cross-linked poly(4-ethylstyrene-co-divinylbenzene) matrix (St-DVB) is investigated by means of FTIR, Raman, UV-Vis and EPR spectroscopies. The adoption of the highly porous St-DVB support is the key factor in reaching an optimum porphyrin dispersion in undiluted conditions (similar to 10 wt% of porphyrin). It is demonstrated that the encapsulated PhCoII are characterized by the absence of any axial interactions involving the polymeric matrix, that can be considered a "non-coordinating'' solvent. Finally, the permanent porosity of the encapsulating matrix allows gaseous molecules to reach the Co-II cations also in the absence of swellable solvents. In particular, the reactivity of the isolated Co-II porphyrin species towards nitric oxide (NO) is investigated, with possible implications in the understanding of the crucial role played by NO in biological systems.