INTERCALATION OF A FREE-BASE PORPHYRIN INTO LAYERED TETRATITANIC ACID

An intercalation compound of layered H2Ti4O9 with 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin (H-2tmpyp4+) was synthesised by a guest-exchange method using the NPrH3+-HxTi4O9 intercalation compound as intermediate. The porphyrin is present as the free base without protonation. Its molecules are arranged with their planes inclined to the [Ti4O9]2- layers because of the high charge density of the host layers. Whereas the fluorescence spectrum of the intercalated H-2tmpyp4+ indicated that the porphyrin is present as a monomer without stacked aggregation, the fluorescence decayed as rapidly as that of solid powders of H-2tmpyp4+41-, suggesting the porphyrin molecules interact with one another in the interlayer space.