USE OF A DIHYDROGEN OSMIUM COMPLEX AS A VERSATILE H-1-NMR RECOGNITION PROBE

A new recognition probe for biomolecules, [en2OS(eta-2-H-2)]2+ (1; en, ethylenediamine), is reported. In aqueous solution, 1 binds readily to a variety of biomolecules, including nucleotides, RNA, amino acids, peptides, and phospholipids. In each case, binding leads to a characteristic proton nuclear magnetic resonance (H-1 NMR) for the dihydrogen that appears in a spectral window in the range delta = 0 to -20 parts per million, and as well to characteristic values of the coupling J(HD) and of the relaxation time T1. Small structural differences in molecules such as DGMP (2'-deoxyguanosine 5'-monophosphate) and IMP (inosine 5'-monophosphate) or Asp and Glu can readily be distinguished, such as when 1 binds to the N-7 position of the nucleobase of DGMP or IMP and when 1 binds to the carboxylate of Asp or Glu. Upon one-electron oxidation of the metal center, diamagnetic 1 is converted to a paramagnetic probe.