Controlled microwave synthesis of RuII synthons and chromophores relevant to solar energy conversion

Here we describe the efficient high yield atmospheric pressure microwave-assisted synthesis for seven distinct RuII coordination complexes relevant to solar energy conversion schemes and dye sensitized solar cells. In all instances, the reaction times have been markedly shortened, concomitant with higher yields with little or no need for subsequent purification and several multi-step reactions proceeded flawlessly in a single pot. Importantly, we observed no evidence for the decarboxylation of the essential metal oxide surface-anchoring 4,4′-diethylester-2,2′-bipyridine or 4,4′-dicarboxy-2,2′-bipyridine ligands as long as open reaction vessel conditions were utilized; these functionalities are not tolerant to sealed microwave reaction (superheated solvent/pressurized) conditions. The combined results suggest that microwave-assisted chemistry is indeed a valuable tool as far as RuII coordination chemistry is concerned and can likely be applied in the combinatorial pursuit of new dyes bearing sensitive functionalities.