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Issue 1, 1999
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Aza analogs of nucleic acid bases: infrared and Raman spectra of 5-azauracil and crystal structure of 5-azauracil monohydrate

Abstract

The X-ray crystal structure of 5-azauracil monohydrate (C3H3O2N3·H2O, Mr=131.10 Da) has been determined from X-ray diffraction data. In the crystal structure all atoms of the 5-azauracil molecule and the solvated water, including hydrogens, lie exactly in the mirror plane perpendicular to b at y=1/4 in the monoclinic space group P21/m and therefore exhibit symmetry m (Cs). The crystal structure comprises solvate-promoted hydrogen-bonded layers in the ac plane, separated by b/2=3.1054 Å. The X-ray structure of 5-azauracil monohydrate is compared with the previously reported data for uracil, 6-azauracil and a complex of 5-azauracil with its own hydrolysis product. The presence of bands due to C[double bond, length as m-dash]O stretching vibrations in the infrared and Raman spectra confirms that 5-azauracil exists in its dioxo tautomeric form in both the anhydrous and hydrated crystal forms. The position of a strong Raman band due to the ring breathing vibration is found to be a marker for the state of hydration of 5-azauracil; it appears at 804 cm-1 in the solid state Raman spectrum of 5-azauracil and shifts upwards in wavenumber to 816 cm-1 in the spectrum of 5-azauracil monohydrate.

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Article type: Paper
DOI: 10.1039/A804613A
Citation: New J. Chem., 1999,23, 117-122
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    Aza analogs of nucleic acid bases: infrared and Raman spectra of 5-azauracil and crystal structure of 5-azauracil monohydrate

    B. S. Potter, R. A. Palmer, R. Withnall and B. Z. Chowdhry, New J. Chem., 1999, 23, 117
    DOI: 10.1039/A804613A

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