Design and preparation of polyphenyl distance markers for solid-state F-19NMR

With C-13-labeled samples, it is possible to measure internuclear distances up to 7 Angstrom by solid-state NMR, thus providing a powerful tool for pr obing ligand-receptor interactions. However, limitations in measurable dist ances and appreciable natural abundant C-13 background signals present prob lems in solid-state C-13 NMR. In order to overcome these disadvantages, a s et of reference compounds with known F-F distances, namely, quinolinol, p-b iphenyl, and p-terphenyl-bearing trifluoromethyl and trifluoromethylthio gr oups, have been synthesized. The preparation of these reference compounds a nd means for diluting these references in solid-state NMR are described.