1,720,971 research outputs found
Synthesis and Physico-chemical studies of a new non-centrosymmetric organic-inorganic hybrid material: [2,3-(CH3)2C6H3NH3]4 BiBr6NO3·2H2O
No full textOrganic-inorganic hybrid single crystals of [2,3-(CH3)(2)C6H3NH3](4)BiBr6NO3.2H(2)O were obtained by slow evaporation at room temperature and characterized by X-ray diffraction, IR and solid state NMR. This compound crystallizes in orthorhombic non-centrosymmetric space group Pca2(1) with the following lattice parameters: a= 25.8217(1), b= 7.8909(2), c= 21.4328(3) angstrom, V= 4367.07(13) angstrom(3) and Z= 4. The structure was refined to R = 0.057 for 7069 independent reflections. The crystal is built up of 2,3-dimethylanilinium cations, [BiBr6](3-), disordered [NO3] anions and water molecules. The crystal packing is governed by a threedimensional network of O-H ...O, N-H...O and N-H...Br hydrogen bonds and van derWaals interaction. The infrared spectrum has been interpreted on the basis of literature data. Solid state C-13 CP-MAS-NMR spectrum is in agreement with the X-ray structure
Crystal structure, Hirshfeld surface and spectroscopic studies of the noncentrosymmetric Bi(III) halide complex: [C8H12N]3BiCl6
No full textA new organic–inorganic hybrid material with the formula [C8H12N]3BiCl6 has been synthesized and characterized by spectroscopic techniques and single crystal X-ray structure determination. This compound crystallizes in the non-centrosymmetric space group Pna21 of the orthorhombic system with crystallographic parameters a = 25.5620(2), b = 16.7170(5), c = 7.8840(4) Å, V = 3369.0(2) Å3 and Z = 4. Its structure consists of discrete [BiCl6]3− anions, showing the distorted octahedral geometry, surrounded by three crystallographically independent 2-phenylethylammonium cations. The crystal packing is governed by the formation of a number of N–H⋯Cl hydrogen bonds arranged in a three-dimensional network. Crystal structure analysis supported with the Hirshfeld surface and fingerprint plots enabled the identification of the significant intermolecular interactions. The 13C and 15N CP-MAS NMR spectra are in agreement with the X-ray structure. The optical properties of [C8H12N]3BiCl6 were investigated by UV–Vis and luminescence spectroscopy. The differential scanning calorimetry (DSC) revealed that the title compound is stable up to 210 °C
Synthesis, crystal structure and vibrational spectroscopic analysis of tetrakis(5-amino-1-H-1,2,4-triazol-4-ium) decachlorodibismuthate(III):[C<inf>2</inf>H<inf>5</inf>N<inf>4</inf>]<inf>4</inf>Bi<inf>2</inf>Cl<inf>10</inf>
No full textPhysico-chemical properties of a new organic bismuthate(III), [C2H5N4]4Bi2Cl10 are discussed on the basis
of X-ray crystal structure investigation. This compound crystallizes in the monoclinic space group C2/c,
with a = 16.3622(3), b = 12.7941(2), c = 14.8178(2) Å, b = 98.5660(10), V = 3067.35(8) Å3 and Z = 4. The
crystal structure consists of discrete binuclear [Bi2Cl10]4 anions and 3-amino-1-H-1,2,4-triazolium
cations. The crystal packing is governed by strong N-H...N and weak N-H...Cl hydrogen bonds and
Pi...Pi stacking interactions to form three-dimensional network. The 13C CP-MAS NMR spectrum is in
agreement with the X-ray structure. The infrared study confirms the presence of the organic cation
[C2H5N4]+. The vibrational absorption bands were identified by infrared spectroscopy and DFT calculations
allowed their attribution
Synthesis, structural and vibrational investigation for Tetrakis(2,6-diethylanilinium) decabromodibismuthate(III) hexahydrate [C10H16N]4Bi2Br10·6H2O
No full textThe new organic-inorganic compound, Tetrakis(2,6-diethylanilinium) decabromodibismuthate(III) hexahydrate, has been synthesized and characterized by single-crystal X-ray diffraction at room temperature. It crystallizes in the monoclinic system (P2(1)/c space group). The structure consists of discrete dinuclear [Bi2Br10](4-) anions, [C10H16N](+) cations and water molecules. The organic part consists of two organic cations which orient their two amine groups to the neighboring anions. The inorganic entity is made up by [Bi2Br10](4-) dimers composed of two equivalent irregular octahedra sharing one edge. The water molecules are sandwiched between the [Bi2Br10](4-) anions and the neighboring [C10H16N](+) cations. The crystal packing is governed by N(O)-H...Br and N-H...O-w hydrogen bonds and pi-pi interactions to built a three dimensional network. The nature of the inorganic polyhedra distortion, which can be attributed to the stereo-activity of the Bi(III) lone electron pair, has been studied. The infrared and NMR spectra were calculated by Density Functional Theory (DFT) using the B3LYP method with the 6 -311++G** basis set A good consistency was found between the calculated and experimental data. The vibrational absorption bands were identified by infrared spectroscopy
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
Synthesis, crystal structure, and spectroscopic studies of organic-inorganic hybrid material: [C7H10NO]2BiBr5
No full textA novel organic-inorganic hybrid compound, 2-methoxyanilinium pentabromobismuthate(III), [C7H10NO](2)BiBr5, was synthesized and its structure determined by means of single crystal X-ray diffraction studies at room temperature. The molecule crystallizes in the orthorhombic C222(1) space group with cell parameters a = 11.8870(4), b = 23.4775(8), c = 8.1232(3) angstrom, V = 2267.0(1) angstrom(3) and four molecules in the unit cell. The structure of the title compound is built up from one-dimensional [BiBr5](2n-)n polyanionic zig-zag chains composed of deformed BiBr6 octahedra share Br(2) apex and 2-methoxyanilinium cations. The assignment of the vibrational bands was based on comparison with vibrational mode frequencies of homologous compounds. Theoretical calculations were performed using density functional theory (DFT) for studying the vibrational spectrum of the investigated molecule in its ground state. The C-13 CP-MAS NMR spectrum is in agreement with the X-ray structure
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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