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Gomes L.R.,University of Porto | Low J.N.,University of Aberdeen | Wardell J.L.,University of Aberdeen | Pinheiro A.C.,Institute Tecnologia em Farmacos Farmangunhos | And 2 more authors.
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2013

The molecular conformations of three N-alkyl-2-(methylsulfanyl)nicotinamide derivatives, namely N-cyclohexyl-2-(methylsulfanyl)nicotinamide, C 13H18N2OS, (I), N-isopropyl-2-(methylsulfanyl) nicotinamide, C10H14N2OS, (II), in which there are two molecules in the asymmetric unit which were chosen to form a hydrogen-bonded pair, and N-(2-hydroxyethyl)-2-(methylsulfanyl)nicotinamide dihydrate, C9H12N2O2S·2H 2O, (III), are compared with those of four unsubstituted N-alkylnicotinamide compounds. The substituted compounds show a higher degree of torsion of the pyridine ring with respect to the amide group than do the unsubstituted compounds, with dihedral angles in the range 40-60° for the former and 20-35° for the latter. In (I) and (II), the supramolecular structure is defined by amide-N to carbonyl-O chains. In (III), the nicotinamide molecules are linked by hydrogen bonds to two water molecules resulting in two linked chains of rings which form the three-dimensional network. Copyright © 2013 International Union of Crystallography.


Ferreira V.F.,Federal University of Fluminense | Leal K.Z.,Federal University of Fluminense | Lindgren E.B.,Federal University of Fluminense | De Oliveira M.R.P.,Federal University of Fluminense | And 6 more authors.
Journal of Molecular Structure | Year: 2013

A single crystal X-ray diffraction and theoretical study has been carried out on mono hydrates of three 2H-pyrazolo[4,3-c]quinolin-3(5H)-one derivatives, namely 6-methyl-2-phenylpyrazolo[4,3-c]quinolin-3-one, 3, 6-methyl-2-(4- chlorophenyl)pyrazolo[4,3-c]quinolin-3-one, 4, and 8-methyl-2-(4-nitrophenyl) pyrazolo[4,3-c]quinolin-3-one, 5. The monohydrates were obtained on recrystallization from moist solvents. While there are three tautomeric forms possible for such pyrazolo[4,3-c]quinolin-3-one molecules, the sole form isolated in the solid [(X)×(H2O)] (X = 3, 4 and 5) compounds was the quinoloid form - the one calculated to be the most stable at the M06-2X/6-311++G(d,p) level of theory. Excellent agreement was found between the calculated and X-ray determined structures. Molecule 5 in [(5)×(H 2O)] is very near planar while both molecules 3 and 4 in their respective hydrates are much less so as a consequence of angles about 24 between the two aromatic rings. In each hydrate, the pyrazolo[4,3-c]quinolin-3-one molecule is bonded to three water molecules and each water molecule is likewise H-bonded to three pyrazolo[4,3-c]quinolin-3-one molecules. While the water molecules are H-bonded to 3 and 4 via the pyridinyl N and 2x the carbonyl O atoms, in [(5)×(H2O)] the H-bonds are to pyridinyl N, carbonyl O and a nitro O atoms. Calculations indicated that the found arrangement in [(5)×(H2O)] is more stable than one using the connections as found in [(3)×(H2O)] and [(4)×(H2O)]. While each of the hydrates possess strong N-H⋯O and O-H⋯O hydrogen bonds, and weaker C-H⋯π and π⋯π interactions, the supramolecular arrays are very different. © 2013 Elsevier B.V. All rights reserved.


Gomes L.R.,University of Porto | Low J.N.,University of Aberdeen | Wardell J.L.,University of Aberdeen | Cardoso L.N.D.F.,Institute Tecnologia em Farmacos Farmangunhos | De Souza M.V.N.,Institute Tecnologia em Farmacos Farmangunhos
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2013

The molecules of 4-allyloxy-7-chloroquinoline, C12H10ClNO, (I), 7-chloro-4-methoxyquinoline, C10H8ClNO, (II), and 7-chloro-4-ethoxyquinoline, C11H10ClNO, (III), are all planar. In all three structures, π- π interactions between the quinoline ring systems are generated by unit-cell translations along the a axes, irrespective of space group. These structures are the first reported for 4-alkoxyquinolines.


Gomes L.R.,University of Porto | Low J.N.,University of Aberdeen | Rodrigues A.S.M.C.,University of Porto | Wardell J.L.,Institute Tecnologia em Farmacos Farmangunhos | And 3 more authors.
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2013

(E)-2-(2-Benzylidenehydrazinylidene)quin oxaline, C15H12N4, crystallized with two molecules in the asymmetric unit. The structures of six halogen derivatives of this compound were also investigated: (E)-2-[2-(2- chlorobenzylidene)hydrazinyl idene]quinoxaline, C15H11ClN4; (E)-2-[2-(3- chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)-2-[2-(4- chlorobenzylidene)hydrazinylidene]quinoxaline, C15H11ClN4; (E)-2-[2-(2- bromobenzylidene)hydrazinylidene]quinoxaline, C15H11BrN4; (E)-2-[2-(3- bromobenzylidene)hydrazinylidene]quino xaline, C15H11BrN4; (E)-2-[2-(4- bromobenzylidene)hydrazin yl idene]quinoxaline, C15H11BrN4. The 3-Cl and 3-Br com pounds are isomorphous, as are the 4-Cl and 4-Br compounds. In all of these compounds, it was found that the supramolecular structures are governed by similar predominant patterns, viz. strong intermolecular N - H⋯N(pyrazine) hydrogen bonds supplemented by weak C - H⋯N(pyrazine) hydro gen-bond interactions in the 2- and 3-halo compounds and by C - H⋯Cl/Br interactions in the 4-halo compounds. In all compounds, there are π-π stacking interactions. © 2013 International Union of Crystallography.


Gomes L.R.,University of Porto | Low J.N.,University of Aberdeen | Rodrigues A.S.M.C.,University of Porto | Wardell J.L.,University of Aberdeen | And 3 more authors.
Acta Crystallographica Section C: Crystal Structure Communications | Year: 2013

The compounds N'-benzylidene-N-methylpyrazine-2-carbohydrazide, C 13H12N4O, (IIa), N'-(2-methoxybenzylidene)-N- methylpyrazine-2-carbohydrazide, C14H14N4O 2, (IIb), N'-(4-cyanobenzylidene)-N-methylpyrazine-2-carbohydrazide dihydrate, C14H11N5O·2H2O, (IIc), N-methyl-N'-(2-nitrobenzylidene)pyrazine-2-carbohydrazide, C 13H11N5O3, (IId), and N-methyl-N'-(4-nitrobenzylidene)pyrazine-2-carbohydrazide, C13H 11N5O3, (IIe), have dihedral angles between the pyrazine rings and the benzene rings in the range 55-78°. These methylated pyrazine-2-carbohydrazides have supramolecular structures which are formed by weak C - H···O/N hydrogen bonds, with the exception of (IIc) which is hydrated. There are π-π stacking interactions in all five compounds. Three of these structures are compared with their nonmethylated counterparts, which have dihedral angles between the pyrazine rings and the benzene rings in the range 0-6°. © 2013 International Union of Crystallography.

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