Electrochemical aspects of restricted rhenium(I)-based supramolecular complexes with semi-rigid benzimidazolyl and rigid hydroxyquinone ligands

Abstract

Abstract: 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. Graphic abstract: Ditopic N donor containing o-xylene spacer (L2) and its cyclic complex 1 are designed and synthesized. The electrochemical properties of 1 and complexes 2-3 having p-xylene spacer based N donor (L1) are investigated. [Figure not available: see fulltext.].