title: NMR characterisation of dynamics in solvates and desolvates of formoterol fumarate.
abstract: Solid-state NMR is used to characterise dynamics in the ethanol solvate of the pharmaceutical material formoterol fumarate and its associated desolvate. Jump rates and activation barriers for dynamic processes such as phenyl ring rotation and methyl group rotational diffusion are derived from 1D-EXSY and (13)C spin-lattice relaxation times respectively. (2)H and (13)C spin-lattice relaxation times measured under magic-angle spinning conditions are used to show that the fumarate ion in the desolvate is undergoing small-amplitude motion on a frequency scale of 100s of MHz at ambient temperature with an activation parameter of about 32 kJ mol(-1). Exact calculations of relaxation times under MAS provide a simple and robust means to test motional models in cases where relaxation rate maxima are observed, including for systems where the crystal structure of the material is unknown.
authors.affiliation: Department of Chemistry, University of Durham, Durham, UK.
authors.forename: David C
authors.initials: DC
authors.lastname: Apperley
authors.forename: A Fraser
authors.initials: AF
authors.lastname: Markwell
authors.forename: Ilya
authors.initials: I
authors.lastname: Frantsuzov
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Ilott
authors.forename: Robin K
authors.initials: RK
authors.lastname: Harris
authors.forename: Paul
authors.initials: P
authors.lastname: Hodgkinson
mesh_terms: D004983:Ethanolamines / Q000737:chemistry*; D000068759:Formoterol Fumarate; D009682:Magnetic Resonance Spectroscopy; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D012995:Solubility
chemical_list: D004983:Ethanolamines; D000068759:Formoterol Fumarate