Complexes of pyridoxal thiosemicarbazones formed with vanadium(IV/V) and copper(II)
- Author(s)
- Tamas Jakusch, Karoly Kozma, Eva A. Enyedy, Nora V. May, Alexander Roller, Christian R. Kowol, Bernhard K. Keppler, Tamas Kiss
- Abstract
The stoichiometry and thermodynamic stability of vanadium(IV/V) and copper(II) complexes of pyridoxal thiosemicarbazone and pyridoxal-N-3, N-3-dimethylthiosemicarbazone have been determined by pH-potentiometry ((VO)-O-IV), EPR ((VO)-O-IV/Cu-II), UV-Vis (Cu-II, (VO)-O-IV and V-V) and V-51 NMR spectroscopy (V-V) in 30% (w/w) dimethyl sulfoxide/water solvent mixture. In all cases, mono-ligand complexes are formed in different protonation states. In addition, the proton-dissociation constants of the ligands were also determined by pH-potentiometry, UV-Vis and H-1 NMR spectroscopy. The solid state structures of the monoprotonated forms ((VO2)-O-V((LH)-H-1)x1.5H(2)O and (VO2)-O-V(L2(H))x0.8H(2)O) of the V-V complexes were characterized by single-crystal X-ray diffraction analysis. The mono-ligand complexes of Cu-II and V-V are dominant at physiological pH. With all investigated metal ions the pyridoxal moiety of the ligand causes an extra deprotonation step between pH 4 and 7 due to the non-coordinating pyridine-NH+. The pyridoxal-containing ligands form somewhat more stable complexes with both (VO)-O-IV and Cu-II ions than the reference compound salicylaldehyde thiosemicarbazone. Dimethylation of the terminal amino group resulted in the formation of V-V and Cu-II complexes with even higher stability. (C) 2017 Elsevier B.V. All rights reserved.
- Organisation(s)
- Department of Inorganic Chemistry, Core Facility Crystal Structure Analysis
- External organisation(s)
- University of Szeged, Hungarian Academy of Sciences
- Journal
- Inorganica Chimica Acta
- Volume
- 472
- Pages
- 243-253
- No. of pages
- 11
- ISSN
- 0020-1693
- DOI
- https://doi.org/10.1016/j.ica.2017.08.018
- Publication date
- 03-2018
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104003 Inorganic chemistry
- Keywords
- ASJC Scopus subject areas
- Materials Chemistry, Inorganic Chemistry, Physical and Theoretical Chemistry
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/d8141c7d-ed2a-48ce-bc4a-929898f3b5ad