Insights into the phototautomerism of free-base 5, 10, 15, 20-tetrakis(4-sulfonatophenyl) porphyrin.
Photochem Photobiol Sci
; 22(8): 1825-1838, 2023 Aug.
Article
em En
| MEDLINE
| ID: mdl-37038020
ABSTRACT
Phototautomerism in the excited states of free-base 5, 10, 15, 20-tetrakis(4-sulfonatophenyl) porphyrin (H2TPPS4-) has been investigated combining, for the first time, advanced Electron Paramagnetic Resonance (EPR) with fluorescence and Raman spectroscopy. Triplet EPR spectroscopy, performed in protic and deuterated solvents and in the presence of photoselection, confirms the occurrence of phototautomerization and additionally suggests the formation of the cis tautomer as a minor component. The zero-field splitting parameters and triplet sublevel populations indicate that the process is slow in the triplet state. The results obtained by EPR combined with photoselection and fluorescence anisotropy have been interpreted within a model which accounts for a fast trans-trans tautomerization promoted by a spin-vibronic coupling mechanism for intersystem crossing, with an even distribution of the two trans tautomers at liquid nitrogen temperatures for H2TPPS4-.
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1
Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Photochem Photobiol Sci
Assunto da revista:
BIOLOGIA
/
QUIMICA
Ano de publicação:
2023
Tipo de documento:
Article
País de afiliação:
Itália