pH-Controlled Self-Assembling of meso-Tetrakis(4-sulfonatophenyl)porphyrin−Chitosan Complexes

Solid meso-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4)−chitosan supramolecular complexes were prepared by addition of porphyrin to an aqueous solution of chitosan at pH values. The precipitates obtained were assigned as 1 (pH 6.8) and 2 (pH 2.5) and characterized by spectroscopic, thermal, and microscopic methods. Spectroscopic investigation confirmed the presence of TPPS4 and chitosan in both products and that the porphyrin is highly self-associated. H-type (stacked) of TPPS4 aggregation was proposed for 1 and J-type (tilted) for 2. Thermal analysis revealed different pyrolysis routes of the complexes depending on their structural diversity. Light microscopic analysis indicated fibrous and lamellar microstructures, respectively, for 1 and 2. SEM and AFM analysis showed that both complexes consist of compact nanostructures; their size and interconnection is different for 1 and 2. Based on structural inferences, self-assembling hierarchy models were proposed for both of the TPPS4−chitosan supramolecular complexes.