title: Molecular motions in solid estradiol studied by nuclear magnetic resonance spectroscopy.
abstract: The temperature dependence of the proton nuclear magnetic resonance (NMR) relaxation time T1 and second moment M2 of polycrystalline beta-estradiol hemihydrate (1,3,5-estratriene-3,17 beta-diol) is measured at frequencies of 14 and 25 MHz. Below 260 K relaxation is found to be dominated by C3 reorientation of the single methyl group in each molecule, characterized by an activation energy of 9.4 +/- 0.1 kJ/mol. Above 260 K another relaxation mechanism becomes evident, characterized by an activation energy of 22 +/- 2 kJ/mol and ascribed to motion of the water molecules in the solid.
authors.affiliation: Department of Physics, University of Florida, Gainesville 32611, USA.
authors.forename: E R
authors.initials: ER
authors.lastname: Andrew
authors.forename: M
authors.initials: M
authors.lastname: Kempka
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004958:Estradiol / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D013696:Temperature; D013816:Thermodynamics
chemical_list: D004958:Estradiol