title: Grinding-induced equimolar complex formation between thiourea and ethenzamide.
abstract: We prepared and characterized a grinding-induced equimolar complex of thiourea with ethenzamide. When thiourea and ethenzamide were co-ground at a molar ratio of 3 : 1, new powder X-ray diffraction (PXRD) peaks were observed in addition to PXRD peaks of thiourea crystals. The optimum stoichiometry of the new structure was confirmed as 1 : 1 mol/mol. Effect of grinding time on the thiourea-ethenzamide equimolar complex formation was investigated by using PXRD, differential scanning calorimetry and Fourier transform infrared spectroscopy. The equimolar crystal structure was confirmed by X-ray diffraction measurements of the single crystal which was recrystallized from ethanol. It was found that the intermolecular hydrogen bond formations between thiourea and ethenzamide molecules contributed to the equimolar complex formation. The complex formation was not observed in the cases where benzamide, salicylamide or 3-ethoxybenzamide was co-ground with thiourea. 2-Alcoxyl benzamide structures should be required for the grinding-induced equimolar complex formation with thiourea.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, Japan. moribe@p.chiba-u.ac.jp
authors.forename: Kunikazu
authors.initials: K
authors.lastname: Moribe
authors.forename: Masami
authors.initials: M
authors.lastname: Tsuchiya
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tozuka
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Toshio
authors.initials: T
authors.lastname: Oguchi
authors.forename: Keiji
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D012457:Salicylamides / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D013678:Technology, Pharmaceutical / Q000379:methods*; D013890:Thiourea / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism*; D014961:X-Ray Diffraction / Q000379:methods
chemical_list: D012457:Salicylamides; D013890:Thiourea; C018935:ethenzamide