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 UV-vis spectroscopy. Two polycations containing charged aromatic residues (imidazolium and pyridinium) have been easily synthesized by Paal-Knorr 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 self-aggregation. 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 self-aggregation and acid base behavior. (C) 2013 Elsevier Ltd. All rights reserved.