1,721,031 research outputs found
5-Amino-1-benzoyl-3-methylpyrazole: complex sheets built from N—H...N, C—H...O and C—H...?(arene) hydrogen bonds
No full textMolecules of the title compound [systematic name: (5-amino-3-methylpyrazol-1-yl)(phenyl) methanone], C(11)H(11)N(3)O, contain an intramolecular hydrogen bond. The molecules are linked into sheets by a combination of N-H center dot center dot center dot N, C-H center dot center dot center dot O and C-H center dot center dot center dot pi(arene) hydrogen bonds. Comparisons are made with the hydrogen-bonded structures of some related compounds
A hydrogen-bonded dimer in 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazolo[3,4-b]pyridine and a chain of rings built from N—H...N and C—H...?(pyridine) hydrogen bonds in 3-(4-nitrophenyl)-4-phenyl-1H-pyrazolo[3,4-b]pyridine
No full textIn 6-(4-bromophenyl)-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazolo[ 3,4-b] pyridine, C(19)H(16)BrN(3), the reduced pyridine ring adopts a conformation that is close to a screw-boat form. Molecules are linked by pairs of symmetry-related C-H center dot center dot center dot pi (arene) hydrogen bonds into cyclic centrosymmetric dimers. Molecules of 3-(4-nitrophenyl)-4-phenyl-1H-pyrazolo[3,4-b] pyridine, C(18)H(12)N(4)O(2), are linked into centrosymmetric R(2)(2)(8) dimers by pairs of symmetry-related N-H center dot center dot center dot N hydrogen bonds, and these dimers are linked by pairs of C-H center dot center dot center dot pi (pyridine) hydrogen bonds to form a chain of edge-fused rings, or a molecular ladder, along [100]. The molecular aggregation in this compound is completed by two weak C-H center dot center dot center dot O hydrogen bonds, one of which links the chains along [100] into sheets
2-Cyano-N-(2,6-dimethoxypyrimidin-4-yl)-3-[4-(dimethylamino)phenyl]acrylamide and dimethylammonium 6-cyano-1,3-dimethyl-2,4,5-trioxo-1,2,3,4,5,8-hexahydropyrido[2,3-d]pyrimidin-8-ide: a ?-stacked dimer and a hydrogen-bonded ribbon containing three types of ring
No full textThe bond distances in 2-cyano-N-(2,6-dimethoxypyrimidin-4-yl)-3-[4-(dimethylamino)phenyl]acrylamide, C(18)H(19)N(5)O(3), (I), and in the anionic component of the salt dimethylammonium 6-cyano-1,3-dimethyl-2,4,5-trioxo-1,2,3,4,5,8-hexahydropyrido[2,3-d]pyrimidin-8-ide, C(2)H(8)N(2)(+)center dot C(10)H(7)N(4)O(3)(-), (II), provide evidence for the occurrence of electronic polarization. There are no hydrogen bonds in the structure of (I), instead pairs of molecules are linked into centrosymmetric dimers by a single pi-pi stacking interaction. In (II), a combination of a two-centre N-H center dot center dot center dot O hydrogen bond, a three-centre N-H center dot center dot center dot(O)(2) hydrogen bond, together utilizing all three O atoms, and a two-centre C-H center dot center dot center dot N hydrogen bond, link the components into a ribbon containing R(1)(2)(6), R(2)(2)(10) and R(6)(6)(30) rings
(E)-N2-{4-[(E)-2-(4-Chlorobenzoyl)ethenyl]-3-methyl-1-phenyl-1H-pyrazol-5-yl}-N1,N1-dimethylformamidine: polarized molecules within sheets of ?-stacked hydrogen-bonded chains
No full textThe molecules of the title compound, C22H21ClN4O, are conformationally chiral, and in the space group P2(1)2(1)2(1) each crystal contains only one conformational enantiomer. The intramolecular dimensions provide evidence for polarization of the electronic structure. Molecules are linked by a single C-H center dot center dot center dot pi(arene) hydrogen bond into chains, which are themselves weakly linked into sheets by an aromatic pi-pi stacking interaction
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Catalyst-, solvent- and desiccant-free three-component synthesis of novel C-2,N-3 disubstituted thiazolidin-4-ones
Get PDFHerein it is provided an efficient, environmentally friendly and one-pot procedure for the synthesis of a library of new and diversely substituted 1,3-thiazolidin-4-ones in short reaction times and good yields through a solvent-, catalyst- and desiccant-free three-component process. Reactions proceeded by treatment of primary benzyl(aryl)amines with aromatic aldehydes (and ketones) and 2-mercaptoacetic acid acting as both reagent and self-catalyst. All reactions were performed in sand bath instead of the commonly used oil bath avoiding the generation of undesired volatile materials proceeding of the thermal decomposition of the oils. IR, Mass and NMR experiments as well as X-ray diffraction confirmed structures of the obtained products.Fil: Abonia, Rodrigo. Universidad del Valle; ColombiaFil: Castillo, Juan. Universidad de los Andes; Colombia. Universidad del Valle; ColombiaFil: Insuasty, Braulio. Universidad del Valle; ColombiaFil: Quiroga, Jairo. Universidad del Valle; ColombiaFil: Sortino, Maximiliano Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Departamento de Química Orgánica. Área Farmacognosia; ArgentinaFil: Nogueras, Manuel. Universidad de Jaén; EspañaFil: Cobo, Justo. Universidad de Jaén; Españ
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Synthesis of 3-aryl-1,2,4-benzotriazines via intramolecular cyclization of solid-supported o-hydrazidoanilines
Get PDFAn efficient solid-phase protocol for the rapid generation of libraries of biologically promising 1,2,4-benzotriazines, including amino acid-derived components, is described.Fil: Cortés, Edwar. Universidad del Valle; ColombiaFil: Mendez, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Mata, Ernesto Gabino. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Química Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Química Rosario; ArgentinaFil: Abonia, Rodrigo. Universidad del Valle; ColombiaFil: Quiroga, Jairo. Universidad del Valle; ColombiaFil: Insuasty, Braulio. Universidad del Valle; Colombi
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