Abstract
The adsorption behavior of protonated species of 5,10-diphenyl-15,20-di(4-pyridyl)porphyrin (DPyP) on saponite clay surface was examined under PH=1 in aqueous solution. Beer's plot at Soret band and Q-band indicated that H_4DPyP^<4+> adsorbs on the clay surface without aggregation up to 15% and 100% versus CEC, respectively. The λ_<max> of Soret band slightly shifted to longer wavelength, as porphyrin loading level increased. These indicate that neutral molecule with pyridyl and pyrrole groups can adsorb on the clay surface under acidic conditions, although weak aggregation behavior was observed. The incomplete matching of inter-charge distances in porphyrin molecule and on the clay surface would be a reason for such aggregation behavior.
