Solution equilibrium and redox properties of metal complexes with 2-formylpyridine guanylhydrazone derivatives: Effect of morpholine and piperazine substitutions
- Author(s)
- Gerda T. Gátszegi, Tatsiana V. Petrasheuskaya, Nóra V. May, Bálint Hajdu, Gabriella Spengler, Felix Bacher, Sergiu Shova, Vladimir B. Arion, Éva A. Enyedy
- Abstract
Schiff bases derived from aminoguanidine are extensively investigated for their structural versatility. The tridentate 2-formylpyridine guanylhydrazones act as analogues of 2-formyl or 2-acetylpyridine thiosemicarbazones, where the thioamide unit is replaced by the guanidyl group. Six derivatives of 2-formylpyridine guanylhydrazone were synthesized and their proton dissociation and complex formation processes with Cu(II), Fe(II) and Fe(III) ions were studied using pH-potentiometry, UV–visible, NMR and electron paramagnetic resonance spectroscopic methods. The ligands have substituents such as amine, morpholine, N-methyl-piperazine at different positions of the pyridine ring. The influence of the different structural elements on the solution chemical properties and cytotoxicity has been disclosed. The solid state structure of four ligands was determined by X-ray crystallography. The ligands bind to Cu(II) in a tridentate fashion via an (N,N,N) donor set, forming mono-ligand complexes. However, for ligands with heterocyclic morpholine and piperazine nitrogen atoms in coordination position a tetradentate binding was observed. Despite the additional coordinating donor atom, the stability of these Cu(II) complexes showed little or no increase. The Cu(II), Fe(II) and Fe(III) complexes of the studied 2-formylpyridine guanylhydrazones exhibited significantly lower stability compared to their corresponding 2-formyl or 2-acetylpyridine thiosemicarbazone analogues. The ligands underwent slow partial hydrolysis (and oxidation) in the presence of Cu(II) ions, leading to the formation of new ligands through the reorganization of structural components around the metal ion. Additionally, the studied Cu(II) complexes demonstrated a great propensity for reduction by glutathione. All these features contributed to the finding that these 2-formylpyridine guanylhydrazones and their Cu(II) complexes did not display measurable cytotoxic activity.
- Organisation(s)
- Department of Inorganic Chemistry
- External organisation(s)
- University of Szeged, Hungarian Academy of Sciences, Petru Poni Institute of Macromolecular chemistry
- Journal
- Journal of Inorganic Biochemistry
- Volume
- 264
- ISSN
- 0162-0134
- DOI
- https://doi.org/10.1016/j.jinorgbio.2024.112812
- Publication date
- 03-2025
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 104003 Inorganic chemistry, 106002 Biochemistry
- Keywords
- ASJC Scopus subject areas
- Biochemistry, Inorganic Chemistry
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/d8f5b5e5-4dfa-4232-8884-3a4967966166