Two-dimensional transferred-echo double resonance study of molecular motion in a fluorinated polycarbonate

A two-dimensional version of the transferred-echo double resonance (TEDOR) experiment is introduced to measure strong heteronuclear magnetic dipolar interactions between rare spins. A quantitative description of this 2D-TEDOR experiment is given for an I-S pair of spins undergoing relative motion. 2D-TEDOR calculations are consistent with data for a calibration model: the directly bound C-13-P-31 pair in [3-C-13]glyphosate, (HO3PCH2NHCH2COOH)-P-31-C-13. Analysis shows that the indirect spin-spin interaction and the dipole-dipole interaction have opposite signs in this system. The 2D-TEDOR experiment is then used to measure heteronuclear C-13-F-19 interactions in a fluorinated polycarbonate in which an aromatic proton is replaced by a fluorine on every fourth ring. Results from the 2D-TEDOR experiment show that the aromatic ring flips that occur in ordinary polycarbonate are blocked for a fluorinated ring. (C) 1998 Elsevier Science B.V. All rights reserved.