Adsorption of a cationic porphyrin onto mesoporous silicas

The adsorption of a cationic porphyrin, tetrakis-(N-methyl-4-pyridiniumyl)porphine, into mesoporous silicas from solution of tetrakis-(N-methyl-4-pyridiniumyl)porphine p-toluene sulfonate was investigated. Irrespective of the pore size (2.4, 3.5 and 4.2 nm), the cationic porphyrin was adsorbed effectively onto mesoporous silicas to give brown-colored powders. Depending on the amounts adsorbed, which correlate with the average intermolecular distance, the porphines tend to aggregate (dimer).