Synthesis, Structures, and Redox Properties of Copper Complexes with Chiral and Achiral Amino Acid Derived Ligands

Abstract

A series of copper(II) complexes containing the amino acid derived ligands bpaAc-Gly-OEt {1; [bis(picolyl)amino]acylglycine ethyl ester} and bpaAc-Phe-OMe {2; [bis(picolyl)amino]acylphenylalanine methyl ester} were synthesized and characterized in solution and in the solid state. This was done in order to evaluate the relevance of weak aromatic interactions between a metal center and amino acid side chains in square-pyramidal or octahedral coordination environments. The results showed that the structural, spectroscopic, and

The structural mobility of zinc complexes with tetradentate tripodal ligands derived from the amino acids glycine and phenylalanineElectronic supplementary information (ESI) available: Fig. S1: 1H NMR spectra (CDCl3 solutions) of the bpaAc–Phe–OMe complexes 1b/2b, 3bo, 5b and 8b at room temperature. See http://www.rsc.org/suppdata/dt/b2/b212049f/

“…X-Ray crystallographic data of related copper() complexes clearly show that the phenylalanine side chain is free to rotate in square-pyramidal or octahedral complexes. 18 Our NMR results therefore prove that 3b does not retain its five-coordinate solid state structure but binds an additional sixth ligand. This structural change is presumably driven by solvation effects.…”

Synthesis and Evaluation of Structural and Functional Biomimetic Models of Oxidase-Type Metalloenzymes Based on Polynuclear Compounds with Copper (II) and Manganese (II) Ions

“…Niklas et al [39] reported only the Cu 2+/+ redox couple for chiral and achiral derivatives of [bis(picolyl)amino]acylglycine ethyl ester and [bis(picolyl)amino]acylphenylalanine methyl ester complexes of Cu 2+ , complexes with square pyramidal or distorted octahedral geometry and N3O coordination of the amino acid ligands; additional ligands such as acetonitrile, oxygen, and chloride complete the coordination spheres. These studies were conducted under similar conditions (in methanol, with 0.1 M tetrabutylammonium hexafluorophosphate as the supporting electrolyte), but with a smaller electrochemical window of -0.4 to 0.2 V versus NHE.…”

Metal complexes of amino acids and amino acid side chain groups. Structures and properties

“…97 In the corresponding Cu(II) complex the side chain benzyl group was not in contact with the Cu center in a square-pyramidal geometry with the axial coordination of the side chain amide oxygen atom. 98 Kinetic resolution of DL-Phe was attained by stereoselective incorporation into the Co(III) complex of a chiral ligand, N-carboxymethyl-N-pyridylethyl-Lleucine; 99 the ternary complex crystallized in two forms, one of which exhibited a p-p stacking interaction between the benzene ring of L-Phe and the coordinated pyridine ring while the other containing D-Phe had no such interaction. Formation of the L-Phe-containing complex was 6 times faster than that of the D-Phe-containing one, enabling the kinetic resolution of DL-Phe.…”