Synthesis, spectroscopic, and electrochemical studies of bis-ruthenium (II) polypyridyl complexes bridged by dipyrromethenes

By combining substituted aromatic aldehydes and isoquinopyrrole in a reaction flask and heating the reactants in the absence of solvent two new dipyrromethenes have been prepared. The resulting dipyrromethenes show intense absorption bands in the visible region of the spectrum. Ruthenium(II) polypyridyl groups were coordinated to the peripheral nitrogens of the dipyrromethenes to give bimetallic ruthenium(II) complexes in good yield. The ruthenium complexes display interesting spectral properties in the visible region of the spectrum with overlapping intra-ligand (ILCT) and metal-to-ligand (MLCT) charge transfer transitions. Bulk oxidation of the ruthenium(II) centers show a decrease in the MLCT and a shift to lower energy of the ILCT. These complexes may have potential solar cell or theranostic applications. (C) 2016 Elsevier B.V. All rights reserved.