Application of ruthenium and osmium tris-bipyridine frameworks as mass markers in MALDI-TOF experiments involving covalently labeled peptide chains

CHED 264

Paige E. Callan, pec001@lvc.edu, Walter A. Patton, patton@lvc.edu, and Marc Harris, harris@lvc.edu. Department of Chemistry, Lebanon Valley College, Garber Science Center, Annville, PA 17003
Two ruthenium and three osmium bipyridine analogues were synthesized with the general formula [M(bpy*)3](PF6)2 where bpy* = 2,2'-bipyridine, 4,4'-dimethyl-2,2'-bipyridine, 4,4'-diformyl-2,2'-bipyridine, or 4'-methyl-2,2'-bipyridine-4-carboxaldehyde. The ruthenium and osmium salts were purified via ion exchange column chromatography and characterized using 1H NMR, MALDI-TOF mass spectrometry, absorbance, and fluorescence spectroscopes. All of these systems displayed long-lived emission in the visible region of the spectrum with fluorescence bands between 550 and 650 nm. In addition, a 20-30 nm shift in the emission spectra was observed for the methyl substituted bipyridine ligands relative to their non-methylated analogues. The electronic tenability of the emission wavelengths of these complexes suggests that multiple tags may be used to image the same protein, eliminating the problem of overlapping emission. In addition, the inherent stability created by the tris-chelated framework makes them excellent candidates for mass markers in protein mass spectrometry experiments.