Parallel Synthesis and Rapid Photochemical Screening of Organosoluble Ru^II Photosensitizers

Abstract

Ru(II) complexes of heteroaromatic ligands are photosensitizers of interest in such applications as photovoltaic cells. Their bulk preparation is tedious, time-consuming, and expensive. Their assessments, by measurement of the individual excited-state lifetimes, is incomplete and requires specialized equipment and expertise, as well as time. The identification of new, promising photosensitizers would, therefore, greatly benefit from any time- and cost-saving protocol, if absolute purity is not required for assessment. This paper details a protocol for the fairly rapid preparation, in parallel and on a small scale, of organosoluble Ru(II) complexes in a state ready for screening for photosensitization ability. The protocol was tested with a small set of bidentate ligands, generating 20 possible complexes, many of which are known. The protocol was found to produce predominantly the desired species in all cases except those with three different ligands. The batch screening results for the remaining 16 complexes were entirely consistent with those obtained with pure samples of the most promising materials prepared in bulk and were consistent with known photophysical properties.

Solid-Phase Synthesis as a Platform for the Discovery of New Ruthenium Complexes for Efficient Release of Photocaged Ligands with Visible Light

“…In comparison to organic compounds, methods to synthesize libraries of inorganic compounds are grossly underdeveloped. Most attention has focused on the discovery of metal-based catalysts for organic reactions, − selective metal-binding agents, − and new photosensitizers . Peptide- and oligonucleotide conjugates of metal complexes have been synthesized by solid phase for biological applications, and these compounds have enjoyed great success as biologically active agents and tool compounds. − However, their synthesis often involves late-stage attachment of the complex (or ligand) to the biomolecule, where the coordination environment of the complex is preset.…”

Catechol‐Bearing Dipyrazinylpyridine Complexes of Ruthenium(II)

“…Samples of all four new complexes were submitted to the assessment protocol [23] that we have used several times to gauge photosensitizer ability [9,12,14,24,25] 2+ and TEOA, were all required to produce the precipitation. We also found that no precipitation occurred in the dark; light -even sunlight through a window -was required.…”