We have discovered that the supramolecular host [Cp*Rh(2′-deoxyadenosine)]3(OTf)3 (1, Cp* = η5-C5Me5, OTf = CF3SO3-) has utility as a new, aqueous 1H NMR shift reagent, via a host-guest molecular recognition process that occurs by non-covalent π-π and hydrophobic interactions, 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 1H NMR shift reagent, encompass examples such as aromatic carboxylic acids, phenylacetic acid (G1), 1-naphthoic acid (G2), and 2-naphthoic acid (G3), an aliphatic carboxylic acid, cyclohexylacetic 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 parameters that effect the 1H NMR shifts of the organic guests and a comparison with the water-soluble lanthanide shift reagents (LSRs) will be presented to demonstrate the usefulness of this aqueous molecular receptor as an aid for organic compound structural analysis.
All Science Journal Classification (ASJC) codes
- Organic Chemistry