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 5,1 0,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfon atophenyl)-20-phenylporphyrin (TPPS3), 5,10-bis(4-sulfonalophenyl)-15,20-di phenylporphyrin (TPPS2A), 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyr in (TPPS2O), 5-(4-sulfonatophenyl)-10,15,20-diphenylporphyrin (TPPS1) and 5 ,15-bis(4-sulfonatophenyl)porphine (DPPS2O)] was studied by UV/Vis, H-1-NMR , fluorescence, polarized fluorescence and resonance light scattering. The presence of hydrophobic phenyl groups favours the aggregation. The free bas es TPPS4 and TPPS3 aggregate into stacks of ill-defined geometry. TPPS2A an d DPPS2O give H-aggregates. TPPS2O and TPPS3 give J-aggregates through inte raction of the hydrophobic phenyl groups, that is their geometry correspond s to edge-to-edge arrangements. All these porphyrins give J-aggregates upon diprotonation, through electrostatic interactions between the positively c harged porphyrin ring and the sulfonato group. These J-aggregates give diff erent arrays depending on the meso-substitution pattern.