Tag: EPR

Exploring the boundaries of direct detection and characterization of labile isomers – a case study of copper(II)–dipeptide systems

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Eszter Tóth, Nóra V. May, Antal Rockenbauer, Gábor Peintler and Béla Gyurcsik Dalton Trans., 2017,46, 8157-8166 ABSTRACT The investigation of the linkage isomers of biologically essential and kinetically labile metal complexes in aqueous solutions poses a challenge, as these microspecies cannot be separately studied. Therefore, derivatives are commonly used to initially determine the stability or spectral characteristics of at least one of the isomers. Here we directly detect the isomers, describe the metal ion coordination sphere, speciation and thermodynamic parameters by Read More …

A novel 1,3,5-triaminocyclohexane-based tripodal ligand forms a unique tetra(pyrazolate)-bridged tricopper(II) core: solution equilibrium, structure and catecholase activity

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Attila Szorcsik, Ferenc Matyuska, Attila Bényei, Nóra V. Nagy, Róbert K. Szilágyi and Tamás Gajda* Dalton Trans., 2016, 45, 14998-15012   ABSTRACT Copper(II) complexes of a polydentate tripodal ligand L × 3HCl (L = N,N’,N’’-tris(5-pyrazolylmethyl)-cis, cis-1,3,5-triaminocyclohexane) were characterized in both solution and solid states. Combined evaluation of potentiometric, UV-VIS, and EPR data indicated the formation of two mononuclear (CuHL, CuL) and three trinuclear (Cu3H−xL2, x = 2, 3, 4) complexes. The high stability and spectroscopic properties of the CuL species indicate Read More …

Vanadium(IV/V) complexes of Triapine and related thiosemicarbazones: Synthesis, solution equilibrium and bioactivity

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Kowol CR, Nagy NV, Jakusch T, Roller A, Heffeter P, Keppler BK, Enyedy ÉA Journal of Inorganic Biochemistry 152 (2015) 62–73 Abstract The stoichiometry and thermodynamic stability of vanadium(IV/V) complexes of Triapine and two related α(N)-heterocyclic thiosemicarbazones (TSCs) with potential antitumor activity have been determined by pH-potentiometry, EPR and 51V NMR spectroscopy in 30% (w/w) dimethyl sulfoxide/water solvent mixtures. In all cases, mono-ligand complexes in different protonation states were identified. Dimethylation of the terminal amino group resulted in the formation of Read More …