Relation between the catalytic efficiency of the synthetic analogues of catechol oxidase with their electrochemical property in the Free State and substrate-bound state

A library of 15 dicopper complexes as synthetic analogues of catechol oxidase has been synthesized with the aim to determine the relationship between the electrochemical behavior of the dicopper(II) species in the absence as well as in the presence of 3,5-di-tert-butylcatechol (3,5-DTBC) as model substrate and the catalytic activity, kcat, in DMSO medium. The complexes have been characterized by routine physicochemical techniques as well as by X-ray single-crystal structure analysis in some cases. Fifteen “end-off” compartmental ligands have been designed as 1 + 2 Schiff-base condensation product of 2,6-diformyl-4-R-phenol (R = Me, tBu, and Cl) and five different amines, N-(2-aminoethyl)- piperazine, N-(2-aminoethyl)pyrrolidine, N-(2-aminoethyl)- morpholine, N-(3-aminopropyl)morpholine, and N-(2-aminoethyl)piperidine