Electrochemical Aspects of Restricted Rhenium(i)-Based Supramolecular Complexes with Semi-Rigid Benzimidazolyl and Rigid Hydroxyquinone Ligands

Supramolecular coordination complex [(Re(CO)3)2(dhnq)(L2)] (3) containing two fac-Re(CO)3 cores, rigid dianionic dhnq (H2-dhnq = 6,11-dihydroxy-5,12-naphthacenedione) motif and semi-rigid ditopic nitrogen donor 1,2-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (o-Nbenzbix = L2) was synthesized. Compounds o-Nbenzbix and 3 were characterized using various analytical and spectroscopic methods. The electrochemical properties of 3 were studied using cyclic voltammetric measurements. SCCs [(Re(CO)3)2(dhnq)(L1)] (1) and [(Re(CO)3)2(dhaq)(L1)] (2) possessing p-xylene spacer 1,4-bis(2-nonylbenzimidazol-1-ylmethyl)benzene (L1) and 1,4-dihydroxy-9,10-anthraquinone (H2-dhaq) were also synthesized as reported previously. SCCs 1–3 were investigated via electrochemical methods. A plot of the Randles-Sevcik equation yielded a straight line for complex 3 thus, establishing that the redox processes were diffusion-controlled.