Controlling the aggregation of 5,10,15,20-tetrakis-(4-sulfonatophenyl)- porphyrin by the use of polycations derived from polyketones bearing charged aromatic groups

The interaction between 5,10,15,20-tetrakis-(4-sulfonatophenyl)-porphyrin and different polycations is studied by UVevis spectroscopy. Two polycations containing charged aromatic residues (imidazolium and pyridinium) have been easily synthesized by PaaleKnorr reaction of alternating aliphatic polyketones with histamine and 4-picolylamine. It was found that these polymers stabilize the tetra-anionic form of the porphyrin at acidic conditions, and avoid the formation of H- and J-type self-aggregates. Other polycations such as poly(allylamine) and poly(decylviologen) enhance porphyrin selfaggregation. As the latter polymer has also aromatic charged groups, the influence of the polymer structure as a whole in the behavior of the porphyrin/polycation system is highlighted. In this context, similar but not equal results have been found comparing the influence of the polyketone derivative containing pyridinium groups and the polycation poly(4-vinylpyridine) on the porphyrin selfaggregation and acidebase behavior.