THE INCLUSION OF THE ENANTIOMERS OF N-TRIFLUOROACETYL-4-FLUOROPHENYLALANINE AND N-TRIFLUOROACETYLPHENYLALANINE BY CYCLOMALTOHEXAOSE: A 2H- AND 19F-N.M.R. STUDY

Article abstract of DOI:10.1016/0008-6215(89)85160-2

19F-N.m.r. studies show that N-trifluoroacetyl-D- and -L-4-fluorophenylalanine and N-trifluoroacetyl-D- and -L-phenylalanine form 1:1 inclusion complexes with cyclomaltohexaose (α-cyclodextrin) characterised by stability constants of 11.44 +/- 1.13, 11.40 +/- 1.09, 6.15 +/- 0.59, and 6.37 +/- 0.81 M^-1, respectively, in aqueous 0.1M NaCl at pH 6.5 and 25 deg C.Under similar conditions, the correlation time of N-trifluoroacetyl-<2H8>phenylalanine changed from 65 +/- 4 ps in the free state to 320 +/- 40 ps in the complex, consistent with there being little freedom of movement of the guest in the inclusion complex.