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Routzomani A, Lada ZG, Angelidou V, P. Raptopoulou C, Psycharis V, Konidaris KF, Chasapis CT, Perlepes SP. Confirming the Molecular Basis of the Solvent Extraction of Cadmium(II) Using 2-Pyridyl Oximes through a Synthetic Inorganic Chemistry Approach and a Proposal for More Efficient Extractants. Molecules 2022; 27:molecules27051619. [PMID: 35268720 PMCID: PMC8911866 DOI: 10.3390/molecules27051619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The present work describes the reactions of CdI2 with 2-pyridyl aldoxime (2paoH), 3-pyridyl aldoxime (3paoH), 4-pyridyl aldoxime (4paoH), 2-6-diacetylpyridine dioxime (dapdoH2) and 2,6-pyridyl diamidoxime (LH4). The primary goal was to contribute to understanding the molecular basis of the very good liquid extraction ability of 2-pyridyl ketoximes with long aliphatic chains towards toxic Cd(II) and the inability of their 4-pyridyl isomers for this extraction. Our systematic investigation provided access to coordination complexes [CdI2(2paoH)2] (1), {[CdI2(3paoH)2]}n (2), {[CdI2(4paoH)2]}n (3) and [CdI2(dapdoH2)] (4). The reaction of CdI2 and LH4 in EtOH resulted in a Cd(II)-involving reaction of the bis(amidoxime) and isolation of [CdI2(L'H2)] (5), where L'H2 is the new ligand 2,6-bis(ethoxy)pyridine diimine. A mechanism of this transformation has been proposed. The structures of 1, 2, 3, 4·2EtOH and 5 were determined by single-crystal X-ray crystallography. The complexes have been characterized by FT-IR and FT-Raman spectra in the solid state and the data are discussed in terms of structural features. The stability of the complexes in DMSO was investigated by 1H NMR spectroscopy. Our studies confirm that the excellent extraction ability of 2-pyridyl ketoximes is due to the chelating nature of the extractants leading to thermodynamically stable Cd(II) complexes. The monodentate coordination of 4-pyridyl ketoximes (as confirmed in our model complexes with 4paoH and 3paoH) seems to be responsible for their poor performance as extractants.
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Affiliation(s)
- Anastasia Routzomani
- Department of Chemistry, University of Patras, 265 04 Patras, Greece; (A.R.); (Z.G.L.); (V.A.)
| | - Zoi G. Lada
- Department of Chemistry, University of Patras, 265 04 Patras, Greece; (A.R.); (Z.G.L.); (V.A.)
- Institute of Chemical Engineering Sciences (ICE-HT), Foundation for Research and Technology-Hellas (FORTH), Platani, P.O. Box 1414, 265 04 Patras, Greece
| | - Varvara Angelidou
- Department of Chemistry, University of Patras, 265 04 Patras, Greece; (A.R.); (Z.G.L.); (V.A.)
| | - Catherine P. Raptopoulou
- Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Aghia Paraskevi, Attikis, 153 10 Athens, Greece;
| | - Vassilis Psycharis
- Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, Aghia Paraskevi, Attikis, 153 10 Athens, Greece;
- Correspondence: (V.P.); (K.F.K.); (C.T.C.); (S.P.P.); Tel.: +30-210-650-3346 (V.P.); +39-031-238-6472 (K.F.K.); +30-261-0 99-6261 (C.T.C.); +30-261-099-6730 (S.P.P.)
| | - Konstantis F. Konidaris
- Department of Science and High Technology and INSTM, University of Insubria, 22 100 Como, Italy
- Correspondence: (V.P.); (K.F.K.); (C.T.C.); (S.P.P.); Tel.: +30-210-650-3346 (V.P.); +39-031-238-6472 (K.F.K.); +30-261-0 99-6261 (C.T.C.); +30-261-099-6730 (S.P.P.)
| | - Christos T. Chasapis
- Institute of Chemical Engineering Sciences (ICE-HT), Foundation for Research and Technology-Hellas (FORTH), Platani, P.O. Box 1414, 265 04 Patras, Greece
- NMR Facility, Instrumental Analysis Laboratory, School of Natural Sciences, University of Patras, 265 04 Patras, Greece
- Correspondence: (V.P.); (K.F.K.); (C.T.C.); (S.P.P.); Tel.: +30-210-650-3346 (V.P.); +39-031-238-6472 (K.F.K.); +30-261-0 99-6261 (C.T.C.); +30-261-099-6730 (S.P.P.)
| | - Spyros P. Perlepes
- Department of Chemistry, University of Patras, 265 04 Patras, Greece; (A.R.); (Z.G.L.); (V.A.)
- Institute of Chemical Engineering Sciences (ICE-HT), Foundation for Research and Technology-Hellas (FORTH), Platani, P.O. Box 1414, 265 04 Patras, Greece
- Correspondence: (V.P.); (K.F.K.); (C.T.C.); (S.P.P.); Tel.: +30-210-650-3346 (V.P.); +39-031-238-6472 (K.F.K.); +30-261-0 99-6261 (C.T.C.); +30-261-099-6730 (S.P.P.)
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