Resonance Raman studies on ZnII tetraphenylporphyrin encapsulated into MCM-41 and CuIIAlMCM-41: catalytic ionization of ZnIITPP and its central metal ion exchange

We have encapsulated ZnII tetraphenylporphyrin (ZnIITPP) into MCM-41 and CuIIAlMCM-41. Raman and UV–Vis spectroscopic investigations allow us to conclude that ZnIITPP in MCM-41 is oxidized to a considerable extent. This is consistent with the well-known fact that the mesoporous silicate framework in MCM-41 plays the role of a good electron acceptor. Central metal ion exchange of ZnIITPP encapsulated into CuIIAlMCM-41 gives CuII tetraphenylporphyrin (CuIITPP) with almost unit transformation efficiency. We will discuss the interesting reaction which occurred in nanometer-sized pores in terms of the characteristics of the mesoporous silica and the nature of the encapsulated ZnIITPP.