Nuclear magnetic resonance spectrometric investigations of calcium antagonist drugs. III: Conformational and dynamic features of diltiazem in solution.
Conformational features of diltiazem in D2O have been delineated by measuring 13C and 1H NMR parameters. The data obtained by interpretation of spin-lattice relaxation rates and 13C-[1H] nuclear Overhauser effects were used to build a model of the most probable arrangement in solution. The molecular motion of the two aromatic rings and of the thiazepinic ring is anisotropic, and the assumption that the molecule is an ellipsoid undergoing Brownian motion leads to calculation of the diffusion constants for the rotation around the longer axis and the shorter axis. The dimethylaminoethyl chain seems folded back, and it displays the typical features of segmental motion; in the same way, the methoxy- and the acetyloxymethyls behave like free rotors.
Gaggelli
E
E
Department of Chemistry, University of Basilicata, Potenza, Italy.
Maccotta
A
A
Valensin
G
G
D002121:Calcium Channel Blockers / Q000737:chemistry*; D002247:Carbon Isotopes; D004110:Diltiazem / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D012996:Solutions; D013057:Spectrum Analysis / Q000379:methods; D013816:Thermodynamics
D002121:Calcium Channel Blockers; D002247:Carbon Isotopes; D012996:Solutions; D004110:Diltiazem