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Acta Crystallogr Sect E Struct Rep Online ; 64(Pt 2): o355, 2008 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-21201387


Urea forms a 1:1 solvate with N,N-dimethyl-acetamide (DMA) [systematic name: diamino-methanal-N,N-dimethyl-acetamide (1/1), C(4)H(9)NO·CH(4)N(2)O] with both mol-ecules positioned on a twofold axis, giving rise to rotational disorder of the DMA mol-ecule. The mol-ecules display a layered structure in which urea mol-ecules form hydrogen-bonded ribbons bounded by mol-ecules of solvent.

Acta Crystallogr C ; 63(Pt 11): o659-63, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17989490


Bendroflumethiazide, or 3-benzyl-6-(trifluoromethyl)-3,4-dihydro-2H-1,2,4-benzothiadiazine-7-sulfonamide 1,1-dioxide, is reported to crystallize as 1:1 solvates with acetone, C(15)H(14)F(3)N(3)O(4)S(2).C(3)H(6)O, and N,N-dimethylformamide, C(15)H(14)F(3)N(3)O(4)S(2).C(3)H(7)NO. A detailed investigation of the crystal packing and intermolecular interactions is presented by means of Hirshfeld surface analysis. This analysis confirms the atomic positions of methyl H atoms of the solvent molecules that were inferred from the X-ray data and provides a useful tool for structure validation.

Anti-Hipertensivos/química , Bendroflumetiazida/química , Diuréticos/química , Acetona/química , Cristalografia por Raios X , Hidrogênio/análise , Conformação Molecular , Estrutura Molecular , Soluções
J Am Chem Soc ; 129(50): 15606-14, 2007 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-18034480


Hydrogen chloride gas (HCl) is absorbed (and reversibly released) by a nonporous crystalline solid, [CuCl2(3-Clpy)2] (3-Clpy = 3-chloropyridine), under ambient conditions leading to conversion from the blue coordination compound to the yellow salt (3-ClpyH)2[CuCl4]. These reactions require substantial motions within the crystalline solid including a change in the copper coordination environment from square planar to tetrahedral. This process also involves cleavage of the covalent bond of the gaseous molecules (H-Cl) and of coordination bonds of the molecular solid compound (Cu-N) and formation of N-H and Cu-Cl bonds. These reactions are not a single-crystal-to-single-crystal transformation; thus, the crystal structure determinations have been performed using X-ray powder diffraction. Importantly, we demonstrate that these reactions proceed in the absence of solvent or water vapor, ruling out the possibility of a water-assisted (microscopic recrystallization) mechanism, which is remarkable given all the structural changes needed for the process to take place. Gas-phase FTIR spectroscopy has permitted us to establish that this process is actually a solid-gas equilibrium, and time-resolved X-ray powder diffraction (both in situ and ex situ) has been used for the study of possible intermediates as well as the kinetics of the reaction.

Gases/química , Cristalização , Ácido Clorídrico/química , Cinética , Modelos Moleculares , Conformação Molecular , Transição de Fase , Porosidade , Espectrofotometria Infravermelho , Água/química , Difração de Raios X
J Pharm Sci ; 96(5): 1192-202, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17455337


The crystal structures of gamma-carbamazepine (P1, Z' = 4) and chlorothiazide N,N-dimethylformamide solvate (1/2) (P2(1)/c, Z' = 2) have been determined from synchrotron and laboratory X-ray powder diffraction data, respectively, using simulated annealing. Both structures represent a significant challenge for global optimization and the successful solutions and subsequent refinements highlight the ever-expanding range of applicability of powder diffraction to structural problems of pharmaceutical relevance.

Anticonvulsivantes/química , Carbamazepina/química , Clorotiazida/química , Cristalografia por Raios X , Diuréticos/química , Formamidas/química , Difração de Pó , Solventes/química , Química Farmacêutica , Cristalização , Dimetilformamida , Ligação de Hidrogênio , Modelos Moleculares , Conformação Molecular , Estrutura Molecular , Pós , Síncrotrons , Temperatura