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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MDPI AG
2018-03-01
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| Series: | Molecules |
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| author | Michal Hricovíni Milan Mazúr Angela Sîrbu Oleg Palamarciuc Vladimir B. Arion Vlasta Brezová |
| author_facet | Michal Hricovíni Milan Mazúr Angela Sîrbu Oleg Palamarciuc Vladimir B. Arion Vlasta Brezová |
| author_sort | Michal Hricovíni |
| collection | DOAJ |
| 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. |
| first_indexed | 2024-04-13T07:44:52Z |
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| id | doaj.art-8e023ef45621409e80127419a4f8a7db |
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| issn | 1420-3049 |
| language | English |
| last_indexed | 2024-04-13T07:44:52Z |
| publishDate | 2018-03-01 |
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| series | Molecules |
| spelling | doaj.art-8e023ef45621409e80127419a4f8a7db2022-12-22T02:55:43ZengMDPI AGMolecules1420-30492018-03-0123472110.3390/molecules23040721molecules23040721Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State StudyMichal Hricovíni0Milan Mazúr1Angela Sîrbu2Oleg Palamarciuc3Vladimir B. Arion4Vlasta Brezová5Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, SlovakiaInstitute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, SlovakiaDepartment of Chemistry, Moldova State University, A. Mateevici Street 60, MD-2009 Chisinau, MoldovaDepartment of Chemistry, Moldova State University, A. Mateevici Street 60, MD-2009 Chisinau, MoldovaInstitute of Inorganic Chemistry, University of Vienna, Währinger Strasse 42, A-1090 Vienna, AustriaInstitute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology in Bratislava, Radlinského 9, SK-812 37 Bratislava, SlovakiaX- 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.http://www.mdpi.com/1420-3049/23/4/721sodium 5-sulfonate-salicylaldehyde thiosemicarbazonescopper(II) complexesQ- and X-band EPR spectroscopyspin trappingUVA exposurereactive oxygen species |
| spellingShingle | Michal Hricovíni Milan Mazúr Angela Sîrbu Oleg Palamarciuc Vladimir B. Arion Vlasta Brezová Copper(II) Thiosemicarbazone Complexes and Their Proligands upon UVA Irradiation: An EPR and Spectrophotometric Steady-State Study Molecules sodium 5-sulfonate-salicylaldehyde thiosemicarbazones copper(II) complexes Q- and X-band EPR spectroscopy spin trapping UVA exposure reactive oxygen species |
| 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 | sodium 5-sulfonate-salicylaldehyde thiosemicarbazones copper(II) complexes Q- and X-band EPR spectroscopy spin trapping UVA exposure reactive oxygen species |
| url | http://www.mdpi.com/1420-3049/23/4/721 |
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