Coordination Chemistry of Glycolic Acid and Uranyl
Glycolic acid (α-hydroxyacetic acid, HA) is a simple, water-soluble carboxylic acid ligand commonly found in the environment. It can coordinate with metal ions through both its carboxyl and hydroxyl oxygen atoms. The complexation of uranyl ions with HA has been investigated using potentiometry, abso...
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Editorial Board of Atomic Energy Science and Technology
2025-03-01
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| author | ZENG Deli1, LIU Qian1, YANG Qi1, LI Jiale1, PU Tongkai1, YANG Suliang1, TIAN Guoxin1, 2 |
| author_facet | ZENG Deli1, LIU Qian1, YANG Qi1, LI Jiale1, PU Tongkai1, YANG Suliang1, TIAN Guoxin1, 2 |
| author_sort | ZENG Deli1, LIU Qian1, YANG Qi1, LI Jiale1, PU Tongkai1, YANG Suliang1, TIAN Guoxin1, 2 |
| collection | DOAJ |
| description | Glycolic acid (α-hydroxyacetic acid, HA) is a simple, water-soluble carboxylic acid ligand commonly found in the environment. It can coordinate with metal ions through both its carboxyl and hydroxyl oxygen atoms. The complexation of uranyl ions with HA has been investigated using potentiometry, absorption spectroscopy and Raman spectroscopy. Five complex species were identified: (UO2A)+, UO2A2, (UO2A3)–, (UO2A3H–1)2– and (UO2A3H–2)3–. Their stability constants were determined through potentiometric and absorption spectroscopic methods, and the coordination modes of HA were elucidated using Raman spectroscopy in aqueous solutions with pH＜5. For the first three species (UO2A)+, UO2A2 and (UO2A3)–, the stability constants measured by potentiometry are 2.36±0.09, 4.02±0.01 and 5.33±0.27 respectively, which are consistent with the results that calculated from absorption spectroscopy and previous reports. The latter two species, (UO2A3H–1)2– and (UO2A3H–2)3–, are reported here for the first time, with stability constants determined by potentiometry as 1.66±0.05 and –3.11±0.06, respectively. The molar absorption spectra of the five complexes were obtained using absorption spectroscopy. The spectra of the first three species are quite similar, while the characteristic peaks of uranyl in the latter two species are nearly absent. This indicates that the dissociation of hydrogen atoms from the hydroxyl groups of glycolic acid significantly affects the uranyl absorption spectra. Raman spectroscopy was used to infer the coordination modes of glycolic acid in the complexes. The Raman shift peaks for
, (UO2A)+, UO2A2 and (UO2A3)– were found at 869, 858.7, 848.4, and 843.3 cm–1, respectively. According to the empirical relationship between the Raman shift of the uranyl group and ligand ability (i.e. a larger Raman shift corresponds to a stronger ligand ability), in the (UO2A)+ and UO2A2, glycolate forms a five-membered ring chelate with uranyl through both a carboxyl and a hydroxyl oxygen atom. Due to steric hindrance, the uranyl equatorial plane cannot accommodate three five-membered cyclic ligands simultaneously. Consequently, in the complex (UO2A3)–, two ligands form a five-membered ring chelate, while the third ligand is coordinated in a four-membered ring mode through two carboxyl oxygen atoms. The simpler carboxyl-terminal coordination results in smaller Raman shifts compared to the more stable chelating coordination mode. In (UO2A3)–, the hydrogen atoms from the glycolate hydroxyl groups in the five-membered ring can sequentially dissociate, forming (UO2A3H–1)2– and (UO2A3H–2)3–, and resulting the Raman peak of uranyl to a lower wavenumber. |
| format | Article |
| id | doaj-art-28ccf5e2b95d462eae8a1cad79b1eff6 |
| institution | DOAJ |
| issn | 1000-6931 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Editorial Board of Atomic Energy Science and Technology |
| record_format | Article |
| series | Yuanzineng kexue jishu |
| spelling | doaj-art-28ccf5e2b95d462eae8a1cad79b1eff62025-08-20T03:10:06ZengEditorial Board of Atomic Energy Science and TechnologyYuanzineng kexue jishu1000-69312025-03-0159353253910.7538/yzk.2024.youxian.0455Coordination Chemistry of Glycolic Acid and UranylZENG Deli1, LIU Qian1, YANG Qi1, LI Jiale1, PU Tongkai1, YANG Suliang1, TIAN Guoxin1, 201. China Institute of Atomic Energy, Beijing 102413, China 2. Tsinghua University, Beijng 100084, ChinaGlycolic acid (α-hydroxyacetic acid, HA) is a simple, water-soluble carboxylic acid ligand commonly found in the environment. It can coordinate with metal ions through both its carboxyl and hydroxyl oxygen atoms. The complexation of uranyl ions with HA has been investigated using potentiometry, absorption spectroscopy and Raman spectroscopy. Five complex species were identified: (UO2A)+, UO2A2, (UO2A3)–, (UO2A3H–1)2– and (UO2A3H–2)3–. Their stability constants were determined through potentiometric and absorption spectroscopic methods, and the coordination modes of HA were elucidated using Raman spectroscopy in aqueous solutions with pH＜5. For the first three species (UO2A)+, UO2A2 and (UO2A3)–, the stability constants measured by potentiometry are 2.36±0.09, 4.02±0.01 and 5.33±0.27 respectively, which are consistent with the results that calculated from absorption spectroscopy and previous reports. The latter two species, (UO2A3H–1)2– and (UO2A3H–2)3–, are reported here for the first time, with stability constants determined by potentiometry as 1.66±0.05 and –3.11±0.06, respectively. The molar absorption spectra of the five complexes were obtained using absorption spectroscopy. The spectra of the first three species are quite similar, while the characteristic peaks of uranyl in the latter two species are nearly absent. This indicates that the dissociation of hydrogen atoms from the hydroxyl groups of glycolic acid significantly affects the uranyl absorption spectra. Raman spectroscopy was used to infer the coordination modes of glycolic acid in the complexes. The Raman shift peaks for , (UO2A)+, UO2A2 and (UO2A3)– were found at 869, 858.7, 848.4, and 843.3 cm–1, respectively. According to the empirical relationship between the Raman shift of the uranyl group and ligand ability (i.e. a larger Raman shift corresponds to a stronger ligand ability), in the (UO2A)+ and UO2A2, glycolate forms a five-membered ring chelate with uranyl through both a carboxyl and a hydroxyl oxygen atom. Due to steric hindrance, the uranyl equatorial plane cannot accommodate three five-membered cyclic ligands simultaneously. Consequently, in the complex (UO2A3)–, two ligands form a five-membered ring chelate, while the third ligand is coordinated in a four-membered ring mode through two carboxyl oxygen atoms. The simpler carboxyl-terminal coordination results in smaller Raman shifts compared to the more stable chelating coordination mode. In (UO2A3)–, the hydrogen atoms from the glycolate hydroxyl groups in the five-membered ring can sequentially dissociate, forming (UO2A3H–1)2– and (UO2A3H–2)3–, and resulting the Raman peak of uranyl to a lower wavenumber.https://yznkxjs.xml-journal.net/article/doi/10.7538/yzk.2024.youxian.0455glycolic aciduranylcompound composition and structurepotentiometryabsorption spectrumraman spectrum |
| spellingShingle | ZENG Deli1, LIU Qian1, YANG Qi1, LI Jiale1, PU Tongkai1, YANG Suliang1, TIAN Guoxin1, 2 Coordination Chemistry of Glycolic Acid and Uranyl Yuanzineng kexue jishu glycolic acid uranyl compound composition and structure potentiometry absorption spectrum raman spectrum |
| title | Coordination Chemistry of Glycolic Acid and Uranyl |
| title_full | Coordination Chemistry of Glycolic Acid and Uranyl |
| title_fullStr | Coordination Chemistry of Glycolic Acid and Uranyl |
| title_full_unstemmed | Coordination Chemistry of Glycolic Acid and Uranyl |
| title_short | Coordination Chemistry of Glycolic Acid and Uranyl |
| title_sort | coordination chemistry of glycolic acid and uranyl |
| topic | glycolic acid uranyl compound composition and structure potentiometry absorption spectrum raman spectrum |
| url | https://yznkxjs.xml-journal.net/article/doi/10.7538/yzk.2024.youxian.0455 |
| work_keys_str_mv | AT zengdeli1liuqian1yangqi1lijiale1putongkai1yangsuliang1tianguoxin12 coordinationchemistryofglycolicacidanduranyl |