TY - JOUR

T1 - Interactions of nitrogen-donor biomolecules with copper(II) complexes in Tris buffer

AU - Selimović, Enisa

AU - Komolkin, Andrei V.

AU - Davletbaeva, Diana A.

AU - Egorov, Andrei V.

AU - Soldatović, Tanja V.

PY - 2020/1/2

Y1 - 2020/1/2

N2 - Comprehensive mole-ratio, kinetic, EPR and X-ray studies were performed to investigate substitution reactions between square-planar [CuCl2(en)] (en = ethylenediamine) and square-pyramidal [CuCl2(terpy)] (terpy = 2,2’:6’,2”-terpyridine) complexes with bio-relevant nucleophiles at 295 K in 0.010 M Tris-HCl buffer (pH = 7.4) in the presence of 0.010 M NaCl. According to mole-ratio and EPR studies, Tris buffer reacts with [CuCl2(en)], and likely the complex geometry remains square-planar. Kinetic results have shown that the order of reactivity of nucleophiles towards [CuCl2(en)] in solution for both reaction steps is 1,2,4-triazole > imidazole > pyrazine. The order of reactivity of the azole and diazine ligands toward [CuCl2(terpy)] for the first reaction step is imidazole > 1,2,4-triazole > pyrazine, while for the second one is pyrazine > 1,2,4-triazole > imidazole. X-ray studies indicate great affinity of ethylenediamine toward Cu(II), which results in crystal structures of [Cu(en)2]Cl2·H2O and [Cu(en)2][ZnCl4], instead of dinuclear or heteronuclear complexes with a bridging pyrazine ligand. The recorded EPR spectra demonstrate that all ligands interact with Cu(II) complexes, except in the case of the [CuCl2(en)] complex, where the competition between ligand and Tris molecules might be observed.

AB - Comprehensive mole-ratio, kinetic, EPR and X-ray studies were performed to investigate substitution reactions between square-planar [CuCl2(en)] (en = ethylenediamine) and square-pyramidal [CuCl2(terpy)] (terpy = 2,2’:6’,2”-terpyridine) complexes with bio-relevant nucleophiles at 295 K in 0.010 M Tris-HCl buffer (pH = 7.4) in the presence of 0.010 M NaCl. According to mole-ratio and EPR studies, Tris buffer reacts with [CuCl2(en)], and likely the complex geometry remains square-planar. Kinetic results have shown that the order of reactivity of nucleophiles towards [CuCl2(en)] in solution for both reaction steps is 1,2,4-triazole > imidazole > pyrazine. The order of reactivity of the azole and diazine ligands toward [CuCl2(terpy)] for the first reaction step is imidazole > 1,2,4-triazole > pyrazine, while for the second one is pyrazine > 1,2,4-triazole > imidazole. X-ray studies indicate great affinity of ethylenediamine toward Cu(II), which results in crystal structures of [Cu(en)2]Cl2·H2O and [Cu(en)2][ZnCl4], instead of dinuclear or heteronuclear complexes with a bridging pyrazine ligand. The recorded EPR spectra demonstrate that all ligands interact with Cu(II) complexes, except in the case of the [CuCl2(en)] complex, where the competition between ligand and Tris molecules might be observed.

KW - bio-relevant nucleophiles

KW - Cu(II) complexes

KW - structure–reactivity correlation

KW - Tris buffer

KW - ELECTRON-SPIN-RESONANCE

KW - EPR

KW - HETEROLIGAND COMPLEXES

KW - TERNARY

KW - ETHYLENEDIAMINE

KW - AQUEOUS-SOLUTION

KW - COORDINATION MODES

KW - MIXED-LIGAND COMPLEXES

KW - ALANINEPHOSPHONIC ACID

KW - REDOX

KW - structure - reactivity correlation

UR - http://www.scopus.com/inward/record.url?scp=85080994978&partnerID=8YFLogxK

U2 - 10.1080/00958972.2020.1730336

DO - 10.1080/00958972.2020.1730336

M3 - Article

AN - SCOPUS:85080994978

VL - 73

SP - 17

EP - 34

JO - Journal of Coordination Chemistry

JF - Journal of Coordination Chemistry

SN - 0095-8972

IS - 1

ER -