Solvent effects on the crystallization and structure of ternary copper(ii) coordination compounds with l-threonine and 1,10-phenanthroline

Darko Vušak; Katarina Ležaić; Jurica Jurec; Dijana Žilić; Biserka Prugovečki

doi:10.1016/j.heliyon.2022.e09556

Solvent effects on the crystallization and structure of ternary copper(ii) coordination compounds with l-threonine and 1,10-phenanthroline

Heliyon. 2022 Jun 3;8(6):e09556. doi: 10.1016/j.heliyon.2022.e09556. eCollection 2022 Jun.

Authors

Darko Vušak¹, Katarina Ležaić¹, Jurica Jurec², Dijana Žilić², Biserka Prugovečki¹

Affiliations

¹ Department of Chemistry, Faculty of Science, University of Zagreb, Horvatovac 102a, HR-10000, Zagreb, Croatia.
² Laboratory for Magnetic Resonances, Division of Physical Chemistry, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia.

Abstract

Solution-based and solid-state reactions of copper(ii) compounds, 1,10-phenanthroline and l-threonine were investigated. Eight new ternary coordination compounds were obtained: [Cu(l-Thr)(H₂O)(phen)]₂SO₄∙10H₂O (1a∙10H ₂ O), [Cu(l-Thr)(H₂O) (phen)]₂SO₄∙4.3H₂O (1a∙4.3H ₂ O), {[Cu(μ-l-Thr)(phen)]₂SO₄∙3.5H₂O} _n (1b∙3.5H ₂ O), [Cu(l-Thr)(H₂O)(phen)][Cu(l-Thr)(CH₃OH)(phen)]SO₄∙2H₂O∙CH₃OH (1c∙2H ₂ O∙CH ₃ OH), [Cu(l-Thr)(H₂O)(phen)][Cu(l-Thr)(CH₃OH)(phen)]SO₄∙4H₂O (1c∙4H ₂ O), [Cu(l-Thr)(CH₃OH)(phen)]₂SO₄∙H₂O (1d∙H ₂ O), [Cu(l-Thr)(H₂O)(phen)][Cu(l-Thr)(CH₃OH)(phen)][Cu(SO₄)(l-Thr)(phen)]HSO₄∙H₂O∙3CH₃OH (1e·H ₂ O·3CH ₃ OH), [Cu(l-Thr)(H₂O)(phen)][Cu(l-Thr)(phen)(py)]SO₄ (1f) (phen = 1,10-phenanthroline, l-Thr = l-threoninate, py = pyridine). X-ray crystal structure analysis of the prepared ternary coordination compounds revealed extensive hydrogen bonding and π-interactions that link complex species, anions and solvent molecules into 3D architectures. The water/methanol solvent molecules are found in pockets and/or channels in seven solvates. ESR spectra of different types of compounds were also investigated. In all measured compounds the unpaired electron of the copper(II) ion is located in the d_x2-y2 orbital which is in agreement with elongated square-pyramidal geometry. Compound 1a∙10H ₂ O showed substantial cytotoxic activity toward human hepatocellular carcinoma (HepG2) and acute monocytic leukaemia (THP-1) cell lines.

Keywords: 1,10-Phenanthroline; Copper complexes; Crystal structures; ESR spectra; Mechanochemical synthesis; Solution-based synthesis; Solvatomorphs; Ternary coordination compounds; l-threonine.