Synthesis and characteristics of the redox behavior of a ditopic compound contaiing tetraaza macrocyclic and crown ether fragments

Abstract

A new ditopic compound has been obtained from monocyclic fragments by the reaction of formylbenzo-15-crown-5 with a macrocyclic complex of nickel(II) that contains a pendant amino group and it is characterized by methods of electron and IR spectroscopy, FAB mass spectrometry, and cyclic voltammetry. It was established that binding of protonated amines (methylamine, β-alanine) to crown ether receptor centers causes a cathodic shift of the redox potential (by 100–160 mV) of the NiIIIL/ NiIIL pair of the ditopic complex. Ditopic and monocyclic complexes of nickel(III) were prepared by preparative electrolysis in acetonitrile solutions. The kinetics of the reduction of nickel(III) by bifunctional substrates capable of binding with the crown ether was investigated. The rate of reduction of Ni(III) in the reaction with m-aminophenol in the ditopic complex is 50 times less than in the monocyclic complex and 6 times greater in the reaction with β-alanine hydrazide.