Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution
A combined spectroscopic and computational approach has been used to study in detail the complexation between Ga(III) and ARS in solution. The NMR results revealed the formation of four Ga(III)/ARS complexes, at pH 4, differing in their metal:ligand stoichiometries or configuration, and point to a c...
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MDPI AG
2023-01-01
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| Series: | Photochem |
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| author | Licínia L. G. Justino Sofia Braz M. Luísa Ramos |
| author_facet | Licínia L. G. Justino Sofia Braz M. Luísa Ramos |
| author_sort | Licínia L. G. Justino |
| collection | DOAJ |
| description | A combined spectroscopic and computational approach has been used to study in detail the complexation between Ga(III) and ARS in solution. The NMR results revealed the formation of four Ga(III)/ARS complexes, at pH 4, differing in their metal:ligand stoichiometries or configuration, and point to a coordination mode through the ligand positions C-1 and C-9. For equimolar metal:ligand solutions, a 1:1 [Ga(ARS)(H<sub>2</sub>O)<sub>4</sub>]<sup>+</sup> complex was formed, while for 1:2 molar ratio solutions, a [Ga(ARS)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]<sup>−</sup> complex, in which the two ligands are magnetically equivalent, is proposed. Based on DFT calculations, it was determined that this is a centrosymmetric structure with the ligands in an <i>anti</i> configuration. For solutions with a 1:3 molar ratio, two isomeric [Ga(ARS)<sub>3</sub>]<sup>3−</sup> complexes were detected by NMR, in which the ligands have a <i>mer</i> and a <i>fac</i> configuration around the metal centre. The DFT calculations provided structural details on the complexes and support the proposal of a 1,9 coordination mode. The infrared spectroscopy results, together with the calculation of the infrared spectra for the theoretically proposed structures, give further support to the conclusions above. Changes in the UV/vis absorption and fluorescence spectra of the ligand upon complexation revealed that ARS is a highly sensitive fluorescent probe for the detection of Ga(III). |
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| spelling | doaj.art-d818fa9813e14c7ab8df3dc92614bce12023-11-17T13:17:58ZengMDPI AGPhotochem2673-72562023-01-0131618110.3390/photochem3010005Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous SolutionLicínia L. G. Justino0Sofia Braz1M. Luísa Ramos2CQC-IMS, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, PortugalCQC-IMS, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, PortugalCQC-IMS, Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, PortugalA combined spectroscopic and computational approach has been used to study in detail the complexation between Ga(III) and ARS in solution. The NMR results revealed the formation of four Ga(III)/ARS complexes, at pH 4, differing in their metal:ligand stoichiometries or configuration, and point to a coordination mode through the ligand positions C-1 and C-9. For equimolar metal:ligand solutions, a 1:1 [Ga(ARS)(H<sub>2</sub>O)<sub>4</sub>]<sup>+</sup> complex was formed, while for 1:2 molar ratio solutions, a [Ga(ARS)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]<sup>−</sup> complex, in which the two ligands are magnetically equivalent, is proposed. Based on DFT calculations, it was determined that this is a centrosymmetric structure with the ligands in an <i>anti</i> configuration. For solutions with a 1:3 molar ratio, two isomeric [Ga(ARS)<sub>3</sub>]<sup>3−</sup> complexes were detected by NMR, in which the ligands have a <i>mer</i> and a <i>fac</i> configuration around the metal centre. The DFT calculations provided structural details on the complexes and support the proposal of a 1,9 coordination mode. The infrared spectroscopy results, together with the calculation of the infrared spectra for the theoretically proposed structures, give further support to the conclusions above. Changes in the UV/vis absorption and fluorescence spectra of the ligand upon complexation revealed that ARS is a highly sensitive fluorescent probe for the detection of Ga(III).https://www.mdpi.com/2673-7256/3/1/5Ga<sup>3+</sup>alizarin sulfonateARSNMRATR-FTIRDFT |
| spellingShingle | Licínia L. G. Justino Sofia Braz M. Luísa Ramos Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution Photochem Ga<sup>3+</sup> alizarin sulfonate ARS NMR ATR-FTIR DFT |
| title | Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution |
| title_full | Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution |
| title_fullStr | Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution |
| title_full_unstemmed | Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution |
| title_short | Spectroscopic and DFT Study of Alizarin Red S Complexes of Ga(III) in Semi-Aqueous Solution |
| title_sort | spectroscopic and dft study of alizarin red s complexes of ga iii in semi aqueous solution |
| topic | Ga<sup>3+</sup> alizarin sulfonate ARS NMR ATR-FTIR DFT |
| url | https://www.mdpi.com/2673-7256/3/1/5 |
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