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Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study

X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosem...

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Autores principales: Hricovíni, Michal, Mazúr, Milan, Sîrbu, Angela, Palamarciuc, Oleg, Arion, Vladimir B., Brezová, Vlasta
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017935/
https://www.ncbi.nlm.nih.gov/pubmed/29561827
http://dx.doi.org/10.3390/molecules23040721
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author Hricovíni, Michal
Mazúr, Milan
Sîrbu, Angela
Palamarciuc, Oleg
Arion, Vladimir B.
Brezová, Vlasta
author_facet Hricovíni, Michal
Mazúr, Milan
Sîrbu, Angela
Palamarciuc, Oleg
Arion, Vladimir B.
Brezová, Vlasta
author_sort Hricovíni, Michal
collection PubMed
description X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments.
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spelling pubmed-60179352018-11-13 Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study Hricovíni, Michal Mazúr, Milan Sîrbu, Angela Palamarciuc, Oleg Arion, Vladimir B. Brezová, Vlasta Molecules Article X- and Q-band electron paramagnetic resonance (EPR) spectroscopy was used to characterize polycrystalline Cu(II) complexes that contained sodium 5-sulfonate salicylaldehyde thiosemicarbazones possessing a hydrogen, methyl, ethyl, or phenyl substituent at the terminal nitrogen. The ability of thiosemicarbazone proligands to generate superoxide radical anions and hydroxyl radicals upon their exposure to UVA irradiation in aerated aqueous solutions was evidenced by the EPR spin trapping technique. The UVA irradiation of proligands in neutral or alkaline solutions and dimethylsulfoxide (DMSO) caused a significant decrease in the absorption bands of aldimine and phenolic chromophores. Mixing of proligand solutions with the equimolar amount of copper(II) ions resulted in the formation of 1:1 Cu(II)-to-ligand complex, with the EPR and UV-Vis spectra fully compatible with those obtained for the dissolved Cu(II) thiosemicarbazone complexes. The formation of the complexes fully inhibited the photoinduced generation of reactive oxygen species, and only subtle changes were found in the electronic absorption spectra of the complexes in aqueous and DMSO solutions upon UVA steady-state irradiation. The dark redox activity of copper(II) complexes and proligand/Cu(II) aqueous solutions towards hydrogen peroxide which resulted in the generation of hydroxyl radicals, was confirmed by spin trapping experiments. MDPI 2018-03-21 /pmc/articles/PMC6017935/ /pubmed/29561827 http://dx.doi.org/10.3390/molecules23040721 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Hricovíni, Michal
Mazúr, Milan
Sîrbu, Angela
Palamarciuc, Oleg
Arion, Vladimir B.
Brezová, Vlasta
Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title_full Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title_fullStr Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title_full_unstemmed Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title_short Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study
title_sort copper(ii) thiosemicarbazone complexes and their proligands upon uva irradiation: an epr and spectrophotometric steady-state study
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6017935/
https://www.ncbi.nlm.nih.gov/pubmed/29561827
http://dx.doi.org/10.3390/molecules23040721
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