Self-assembly of novel tris(p-carboxyphenyl) porphyrin monomer and its copolymers with acrylamide in aqueous media

The novel porphyrin monomer 5-(4-acryloyloxylphenyl)-10,15,20-tris(4-carboxyphenyl)porphyrinate zinc(II) (ZnAOTCPP) and its corresponding sodium salt (ZnAOTCPP-Na) were synthesized. The latter compound exhibited a new band in excitation spectra due to formation of porphyrin aggregates in water, which were derived from its surface-activity when the concentration was higher than its critical association concentration (CAC). The porphyrins were copolymerized with acrylamide (AM) to prepare water-soluble copolymers with random and micro-blocky structures, which all displayed very new absorption and fluorescence emission bands in the long wavelength region compared with the porphyrin monomer. Furthermore, the micro-blocky copolymer exhibited an additional new absorption band at even longer wavelength region compared with the random copolymer . The experimental results and analysis showed that the porphyrin units in the random copolymer chains self-assembled to form porphyrin association complexes by hydrophobic association and π–π stacking interactions, and covalent restrictions of polymer chains in the micro-blocky copolymer. ► The synthesis of novel tricarboxylphenyl porphyrin monomer and its corresponding sodium salt. ► The preparation of random copolymer and micro-blocky copolymer with porphyrins and acrylamide. ► The self-assembly of sodium salt of porphyrin monomer and copolymers in water. ► The characteristic absorption of porphyrin assemblies exhibiting at long wavelength region. ► The mimic light-harvesting system of water-soluble polymer containing porphyrins.