Achiral diprotonated porphyrins, forming homoassociates in aqueous solution, lead to spontaneous chiral symmetry breaking. The unexpected result is that the chirality sign of these homoassociates can be selected by vortex motion during the aggregation process. This result is confirmed by means of circular dichroism spectra. These experimental findings are rationalized in terms of the asymmetric influence of macroscopic forces on bifurcation scenarios and by considering the specific binding characteristics of the porphyrin units to form the homoassociates.

The title porphyrin shows non ideal cmc with formation of J-aggregates, due to the formation of intermolecularly stabilized zwitterions, which at high concentration also results in H-aggregates.

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 (TPPS_2A), 5,15-bis(4-sulfonatophenyl)-10,20-diphenylporphyrin (TPPS_2O), 5-(4-sulfonatophenyl)-10,15,20-diphenylporphyrin (TPPS₁) and 5,15-bis(4-sulfonatophenyl)porphine (DPPS_2O)] 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. TPPS_2A and DPPS_2O give H-aggregates. TPPS_2O 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.

There are few unambiguous reports describing the transfer of chirality from stirring vortices down to the level of electronic transitions. In this tutorial review the methods reported are discussed as well as the structural trends that seem to be necessary conditions in order to detect this phenomenon.