Synthesis and characterization of copper(II) complexes containing tridentate modified amino acid ligands, [CuL(H2O)(Pyz)] [L = {(3,5-di-tert-butyl-2 hydroxybenzyl)amino}acetic acid and S(−)2-(3,5-di-tert-butyl-2-hydroxy-benzylamino)-3-methyl-butyric acid;

Two new ternary copper complexes, [CuL1(H2O) (Pyz)] (1) [L1H2 = {(3,5-di-tert–butyl–2-hydroxybenzyl)amino}acetic acid] and [CuL2(H2O) (Pyz)] (2) [L2H2 = 2-(3,5-di-tert-butyl-2-hydroxy-benzylamino)-3-methyl-butyric acid; Pyz = pyrazole] have been synthesized. The compounds have been characterized by various techniques including IR, UV–visible, circular dichroism (CD) (2) and EPR spectroscopy, electrochemical and magnetic susceptibility measurements. The crystal structure of 1 has been determined. The compound crystallizes in the space group P21/a, with a = 10.6217(2) Å, b = 10.1645(2) Å, c = 19.4909(5) Å, β = 90.7729(9)°, V = 2104.13(8) Å3, Z = 4. Cyclic voltammetry of the compounds show two reversible oxidative peaks due to metal centered and ligand centered oxidations. The compounds have been oxidized electrochemically and chemically and the oxidized species have been characterized by UV–visible and EPR spectroscopy.

Graphical abstractTwo modified amino acid ligands and their ternary copper(II) complexes have been synthesized and characterized. On chemical oxidation these complexes generate copper(III) coordinated phenoxyl radicals. The oxidized species have been characterized by EPR and UV–visible spectroscopy.Figure optionsDownload full-size imageDownload as PowerPoint slide