Nanotube effect on a liquid-phase photoreaction in mesoporous silica

The photoreaction of xanthone in an alcoholic solution flowing through a co lumn reactor filled with the mesoporous silica MCM-41 was performed. It was found that the product yields depend greatly on both the pore size of the filler and the nature of the solvent. The product yields of this reaction, which involves a pair of radicals as an intermediate, were dependent on the magnetic field as well. These results were interpreted with a model wherei n the lifetime of the radical pair was elongated by several hundred times o r more in the mesopore, or nanotube, compared with that in the bulk solutio n. This unusual phenomenon was attributed to the collective movement of the solvent molecules in the nanotube, which would thereby inhibit the transla tional diffusion of the solute molecules.