G. Bandoli, A. Grassi, E. Montoneri
Feb 1, 1988
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Influential Citations
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Journal
Journal of Molecular Structure
Abstract
Abstract The crystal and molecular structure of the cognition activator 3-phenoxypyridine sulphate has been determined by X-ray analysis. The conformation in solution has been deduced from NMR spectroscopy and MO theoretical calculations of the MNDO type. From the 1H NMR and 13C NMR spectra, run in 2H2O at 500 and 125 MHz, respectively, and the aid of 1H1H and 13C1H shift correlation experiments, spectral assignments are made. Crystals are monoclinic with unit cell dimensions a = 7.967(4), b = 5.899(4), c = 25.480(10) A, β = 96.90(5)°; space group P21/c. The structure is determined from 1307 three-dimensional counter data and refined to convergence factor values of R = 0.048 and Rw = 0.058. The rings of the 3-phenoxypyridinium cation, which is linked to the hydrogensulphate anion by a strong hydrogen bond, are planar and almost perpendicular to each other (89.6°). The twisted conformation in the solid parallels the minimum energy conformation calculated by the MNDO method in which the pyridinic and phenyl rings are rotated in opposite directions out of coplanarity with the COC plane, by 57° and 68°, respectively. The occurrence of a single conformation in solution is in agreement with results from NMR spectra analyses.