SELF-ASSEMBLY IN WATER OF THE SODIUM SALTS OF MESO-SULFONATOPHENYL SUBSTITUTED PORPHYRINS

The aggregation in water of the free bases and the diprotonated forms of p-sulfonatophenyl and phenyl meso-substituted porphyrins [sodium salts of 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3), 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2A), 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyrin (TPPS2O), 5-(4-sulfonatophenyl)-10,15,20-diphenylporphyrin (TPPS1) and 5,15-bis(4-sulfonatophenyl)porphine (DPPS2O)] was studied by UV/Vis, 1H-NMR, fluorescence, polarized fluorescence and resonance light scattering. The presence of hydrophobic phenyl groups favours the aggregation. The free bases TPPS4 and TPPS3 aggregate into stacks of ill-defined geometry. TPPS2A and DPPS2O give H-aggregates. TPPS2O and TPPS1 give J-aggregates through interaction of the hydrophobic phenyl groups, that is their geometry corresponds to edge-to-edge arrangements. All these porphyrins give J-aggregates upon diprotonation, through electrostatic interactions between the positively charged porphyrin ring and the sulfonato group. These J-aggregates give different arrays depending on the meso-substitution pattern.