Electrochemically-driven conformational shift in mono- and di-copper constrained macrotricyclic cyclen receptors

Abstract

An electrochemical study of mono- and di-copper constrained cyclen macrotricycles is presented. Electrochemical data in DMF solution indicate that the reduction of dinuclear complexes occurs in two steps in the −0.4 to −0.8 V vs.AgCl/Ag potential range yielding Cu^IICu^I and Cu^ICu^I species further reduced to Cu metal at highly negative potentials. Mononuclear complexes are reduced in two steps to Cu^I and Cu metal. Electrochemical data suggest that reduction of both mononuclear and dinuclear complexes approach a square scheme involving electrochemically-driven conformational shifts for metal ions. The presence of endo- and exo-forms of the complexes are revealed by changes in the electrochemical response of the complexes in the presence of tetraethylammonium chloride, 1-azabicyclo[2.2.2]octane and diazabicyclo[2.2.2]octane competing ligands.