An electron spin resonance study of the formation of mixed-ligand chelates of copper(II) with amino-acids and certain 3,4-dihydroxyphenols

Abstract

Room-temperature e.s.r. measurements indicate that copper(II) forms monomeric chelates with 5,6-dihydroxybenzene-1,3-disulphonates or 3,4-dihydroxyphenylalanine. With simple amino-acids such as glycine or threonine, copper(II) and 3,4-dihydroxyphenols form mixed-ligand complexes which are monomeric in aqueous solution. The ΔM= 1 and ΔM= 2 transitions indicate the formation of dimeric species in frozen aqueous solution. By a computer lineshape simulation procedure, the magnetic parameters and the copper(II)–copper(II) distances in the dimeric species have been determined and suitable structures proposed.