A NEW, AQUEOUS H-1-NMR SHIFT-REAGENT BASED ON HOST-GUEST MOLECULAR RECOGNITION PRINCIPLES FOR ORGANIC-COMPOUND STRUCTURAL-ANALYSIS - NONCOVALENT PI-PI AND HYDROPHOBIC INTERACTIONS USING A SUPRAMOLECULAR HOST, [CP-ASTERISK-RH(2'-DEOXYADENOSINE)](3)(OTF)(3)

We have discovered that the supramolecular host [CpRh(2'-deoxyadenosi ne)](3)(OTf)(3) (1, Cp = eta(5)-C5Me5, OTf = CF3SO3-) has utility as a new, aqueous H-1 NMR shift reagent, via a host-guest molecular recog nition process that occurs by non-covalent pi-pi and hydrophobic inter actions, with a wide variety of H2O-soluble organic substrates. These organic compound guests that we present, to illustrate the utility of host 1 as a novel, aqueous IH NMR shift reagent, encompass examples su ch as aromatic carboxylic acids, phenylacetic acid (G1), 1-naphthoic a cid (G2), and 2-naphthoic acid (G3), an aliphatic carboxylic acid, cyc lohexylacetic acid (G4), as well as biological compounds, a di- and a tetrapeptide containing terminal L-tryptophan (Trp) or L-phenylalanine (Phe) groups, L-Trp-L-Phe (G5) and L-Trp-L-Met-L-Asp-L-Phe amide (G6) in the pH range 5-10. A discussion of the molecular recognition param eters that effect the 1H NMR shifts of the organic guests and a compar ison with the water-soluble lanthanide shift reagents (LSRs) will be p resented to demonstrate the usefulness of this aqueous molecular recep tor as an aid for organic compound structural analysis.