Copper(II) complexes of a new N-picolylated bis benzimidazolyl diamide ligand: Synthesis, crystal structure and catechol oxidase studies

► Cu(II) complexes of N-picolyl-N,N′-bis(2-methylbenzimidazolyl)hexanediamide are prepared. ► Compounds oxidize ditertbutylcatechol using molecular oxygen as the oxidant. ► Low temperature EPR study implicates an active copper species with fairly low A‖ value. ► Anion and pH dependence show that presence of proton acceptors are crucial in the oxidation process. ► Picolyl groups on the ligand serve as a proton sponge giving higher rates of oxidation reactions.