Dasgupta, Tara, P.; Gooden, V.; Cai, H.; Gordon, N.; Hughes, L.; Sadler, Garfield G.
Author Affiliation, Ana.
Chemistry; Faculty of Pure and Applied Sciences
The synthesis and characterization of monomeric complexes of [Ru(bpy)2] with dihydroxyanthraquinones
Inorganica Chimica Acta
Date of Publication
The monomeric complexes, Ru(bpy)21,4-DHAQ+ and Ru(bpy)21,5-DHAQ+ (bpy=2,2’-bipyridine and DHAQ=dihydroxyanthraquinone), were synthesized by the reaction of Ru(bpy)2Cl2.2H2O with an excess of either 1,4-DHAQ or 1,5-DHAQ. The complexes were purified chromatographically and chacterized spectroscopically and electrochemically. Comparisons between the data for these monomers and data from the corresponding free ligands and ruthenium bipyridyl dimers were made. The lowest energy spectral transition in the visible region was assigned as MLCT transition to the DHAQ based on the red shifting from monomer to the corressponding dimer and the solvatochromism of the transition. In aqueous solution the pKa for both the 1,4- and 1,5-DHAQ monomer was determined to be 10.1 + 0.2 and for the 1,8-DHAQ monomer, 10.5 + 0.2. In all cases, pKa1 of the uncomplexed dihydroxyanthraquinoes was more acidic measured under the same conditions. From the properties of coordinated DHAQs attempts were made to evaluate whether they were s donating or p accepting....