abstract
2-Vinyl-5,10,15,20-tetraphenylporphyrinatozinc(II) reacts with nitrile imines, generated in situ from ethyl hydrazono-alpha-bromoglyoxylates, affording the corresponding pyrazolines in good to excellent yields. Treatment of pyrazoline derivatives with DDQ affords the corresponding pyrazole derivatives with moderate to excellent yields. When the hydrolysis of ester group in the pyrazoline derivatives was considered, it was observed the concomitant oxidation of the heterocyclic unit, which allowed directly obtaining porphyrin-pyrazole derivatives with a carboxylic group, in very good yields. The photophysical properties of the pyrazoline and pyrazole porphyrin derivatives show that the influence of the heterocyclic substituents is limited by the tendency of these molecules to aggregate. All other properties and especially the triplet kinetics remain unaffected. The adducts with low tendency to aggregate showed very high singlet oxygen yield, which makes these compounds interesting for their use as photosensitizers for PDT. (C) 2012 Elsevier Ltd. All rights reserved.
keywords
1,3-DIPOLAR CYCLOADDITION REACTIONS; CAMBRIDGE STRUCTURAL DATABASE; SENSITIZED SOLAR-CELLS; 1,3,5-TRISUBSTITUTED PYRAZOLINES; HANTZSCH 1,4-DIHYDROPYRIDINES; AZOMETHINE YLIDES; FACILE SYNTHESIS; OXIDIZING-AGENT; OXIDATION; AROMATIZATION
subject category
Chemistry
authors
Moura, NMM; Faustino, MAF; Neves, MGPMS; Tome, AC; Rakib, EM; Hannioui, A; Mojahidi, S; Hackbarth, S; Roder, B; Paz, FAA; Silva, AMS; Cavaleiro, JAS
our authors
Filipe Alexandre Almeida Paz
Principal Researcheracknowledgements
Thanks are due to FCT and FEDER for funding the QOPNA unit (project PEst-C/QUI/UI0062/2011), CICECO (PEst-C/CTM/LA0011/2011), the Portuguese National NMR Network and a specific funding towards the purchase of the single-crystal X-ray diffractometer. N.M. thanks FCT for the PhD grant SFRH/BD/44630/2008. The authors also thank the Transnational cooperation programs, FCT-CNRST (Morocco) and FCT-DAAD, for financial assistance.