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Aggregation and Metal-Complexation Behaviour of THPP Porphyrin in ethanol/water Solutions as Function of pH

Aggregation and Metal-Complexation Behaviour of THPP Porphyrin in ethanol/water Solutions as Function of pH

Marco Zannotti, Rita Giovannetti, Babak Minofar, David Řeha, Lydie Plačková, Chiara A D'Amato, Elena Rommozzi, Hanna V Dudko, Nuerguli Kari, Marco Minicucci

Spectrochim Acta A Mol Biomol Spectrosc. 2018 Mar 15;193:235-248.

PMID: 29247920

Abstract:

The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-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.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP51094178	5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine		51094-17-8	Price

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