Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH

0489820 - MBÚ 2019 RIV GB eng J - Článek v odborném periodiku
Zannotti, M. - Giovannetti, R. - Minofar, Babak - Řeha, David - Plačková, Lydie - D'Amato, C.A. - Rommozzi, E. - Dudko, H. V. - Kari, N. - Minicucci, M.
Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH.
Spectrochimica Acta Part A-Molecular and Biomolecular Spectroscopy. Roč. 193, MAR 15 (2018), s. 235-248. ISSN 1386-1425. E-ISSN 1873-3557
Grant CEP: GA ČR GA15-12816S; GA MŠMT(CZ) LM2015055
Institucionální podpora: RVO:61388971
Klíčová slova: Porphyrin dyes * Aggregation * Binary solvent mixture
Obor OECD: Biochemistry and molecular biology
Impakt faktor: 2.931, rok: 2018

The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxypheny1)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV-vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study.
In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence, at this low pH, increasing the water amount, the acidic form (THPPH2)(2+) resulted more stable due to a polar environment with stronger interaction by hydrogen bonding.
In basic pH, reached by NH4OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M2THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.
Trvalý link: http://hdl.handle.net/11104/0286597