Molecular dynamics in polycrystalline testosterone studied by proton NMR.
Polycrystalline testosterone (17 beta-hydroxy-4-androsten-3-one, C19H28O2) has been investigated by proton NMR methods between 70 K and the melting point 428 K. Reductions in dipolar second moment and two well-resolved minima in the spin-lattice relaxation time measured at 25 MHz are ascribed to reorientation of the two methyl groups in the molecule. Activation energies Ea characterizing the motions were 6.1 +/- 0.5 and 11.9 +/- 0.9 kJ/mol; the pre-exponential time factors tau 0 were (2.3 +/- 0.1) x 10(-13) and (2.85 +/- 0.2) x 10(-13) s, respectively.
Andrew
E R
ER
Department of Physics, University of Florida, Gainesville 32611.
Radomski
J M
JM
D009682:Magnetic Resonance Spectroscopy; D013696:Temperature; D013739:Testosterone / Q000737:chemistry*
D013739:Testosterone