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Influence of the counter ion on the structure of two new copper(I) coordination polymers: Synthesis, structural characterization and thermal analysis
No full textTwo new coordination polymers [Cu2(mu3-SCN)2(mu-bbd)]n (1) and {[Cu(mu-bbd)1.5](PF6)}n (2) were synthesized
by the reactions of 1,4-bis(3,5-dimethylpyrazol-1-yl)butane (bbd) with the corresponding copper(I)
salts, in order to evaluate the effect of the counter anion on the structure of the resulting products. The
structure of these compounds were determined by X-ray crystallography; Compound 1 is a 2D coordination
polymer, in which the thiocyanate ligand adopts uncommon mu3-1k1N; 2:3k2S coordination mode to
link three tetrahedrally coordinated copper centers. The fourth coordination site on each copper atom is
occupied by a pyrazole nitrogen atom belonging to a l-bbd ligand. In contrast to 1, 2 is a 1D chain coordination
polymer in which the copper atoms, adopting a distorted trigonal planar geometry, are linked by
bridging bbd ligands having alternately two different conformations. The results indicate that the use of a
coordinating counter anion as thiocyanate which is capable of bridging more than one metal center
instead of non-coordinating hexafluorophosphate anion, promotes the formation of a 2D polymer over
a 1D polymeric chain. The complexes have also been characterized by elemental analysis, IR spectroscopy,
XRPD and thermal analysis
Influence of the counter anion and steric hindrance of pyrazolyl and imidazolyl flexible ligands on the structure of zinc-based coordination polymers
Get PDFTreatments of flexible 1,4-bis(3,5-dimethylpyrazolyl)butane (bbd), 1,4-bis(imidazolyl)butane (bib) and
1,4-bis(2-methylimidazolyl)butane (bmib) ligands with zinc salts at room temperature, resulted in the
formation of four novel metal–organic coordination architectures: [ZnI2(l-bbd)]n (1), [Zn(NCS)2(l-bbd)]n
(2), {[Zn(l-bib)2](ClO4)2 (Et2O)0.5 (H2O)0.25}n (3) and {[Zn(l-bmib)2](ClO4)2 (H2O)4}n (4). X-ray crystallographic
analyses show different 1D and 3D polymeric structures for compounds 1–4 due to the variation
of the counter anions, solvent, steric hindrance and position of donating atoms in the structure of flexible
ligands. In 1 and 2, one-dimensional (1D) zig-zag polymeric chains are formed via metal centers and
l-bbd ligands. Complex 3 shows a 3-fold interpenetrated 3D architecture with 10^3-ths network topology.
In contrast to 3, in the structure of 4 neighboring Zn(II) ions are interconnected by a double-bridging
l-bmib ligands to form an infinite 1D polymeric double chain. The conformations of the flexible ligands
were analyzed in detail
Self-assembly of three cationic silver(I) coordination networks with flexible bis(pyrazolyl)-based linkers
Get PDFThree new cationic silver(I) coordination polymers, {[Ag(mu-bpmb)](SO3CF3)}n (1), {[Ag(mu-bdb)1.5] (SO3CF3)}n (2) and {[Ag(mu-bpb)2](NO3)}n (3), with flexible 1,4-bis[(pyrazolyl)methyl]benzene (bpmb), 1,4-bis[(3,5-dimethylpyrazolyl)methyl]benzene (bdb), and 1,4-bis(pyrazolyl)butane (bpb) have been prepared at room temperature by the solvent layering method. The three compounds were characterized by FT-IR spectroscopy, PXRD, elemental analyses and single-crystal X-ray diffraction. Compound 1 is a highly undulated polymeric 1D chain in which the silver ions adopt a linear geometry, coordinating two bpmb linkers. Compounds 2 and 3 are both 2D coordination polymers with their silver atoms being three and four coordinated, and resulting in 6^3-hcb and 4^4-sql underlying net topologies, respectively. The flexible bispyrazolyl ligands display various conformations in the solid state, causing the formation of different Ag. . .Ag separations in the polymeric structures
Capture of volatile iodine by newly prepared and characterized non-porous [CuI]n-based coordination polymers
Get PDFFour new non-porous CuI-coordination polymers [Cu-2(mu(3)-I)(2)(mu-bpb)](n) (1a), [Cu(mu(2)-I)(mu-bpb)](n) (1b), [Cu-4(mu(2)-I)(4)(mu-bpmb)(4)](n) (2), and [CuI(mu-bdb)](n) (3) (bpb = 1,4-bis(pyrazolyl) butane; bpmb = 1,4-bis[(pyrazolyl)methyl]benzene; bdb = 1,4-bis[(3,5-dimethylpyrazolyl)methyl] benzene) have been successfully prepared and their structures fully characterized by single-crystal X-ray diffraction, FT-IR spectroscopy, PXRD and elemental analysis. Crystallographic investigation revealed that 1a, 1b, and 2 exhibit two-dimensional (2D) structures; in 1a parallel [Cu2I2](n) staircase motifs are cross-linked into two-dimensional sheets by bpb linkers with a fully extended conformation, while in the structures of 1b and 2 Cu2I2 rhomboid dimers are linked by bpb and pbmb ligands, respectively, into two-dimensional sheets with a 4(4)-sql net. Differently, compound 3 shows a one-dimensional (1D) zigzag chain structure with monomeric CuI units. All the four non-porous coordination polymers show the ability to capture volatile iodine in the gas phase. The solid-state photoluminescence properties of 1a, 1b, and 2 have also been investigated. The iodine-adsorbed samples 1a-I-2, 1b-I-2, and 2-I-2 show no fluorescence behavior
Diorganotin(IV) complexes with 2-furancarboxylic acid hydrazone derivative of benzoylacetone : synthesis, X-ray structure, antibacterial activity, DNA cleavage and molecular docking
Get PDFTwo new diorganotin(IV) complexes, Me2SnL and Ph2SnL, have been synthesized from the reaction of
Me2SnCl2 and Ph2SnCl2 with the hydrazone H2L [H2L 1⁄4 (Furan-2-yl) (5-hydroxy-3-methyl-5-phenyl-4,5-
dihydro-1H-pyrazol-1-yl)-methanone] derived from furan-2-carbohydrazide and benzoylacetone. The
new compounds have been characterized by elemental and spectroscopic analyses. The crystal structures
of the monohydrate form of the ligand and of the Me2SnL derivative have been also determined by X-ray
crystallography. Experimental evidences confirm the existence of the hydrazone ligand exclusively in
cyclic form in both solution and solid state. On coordination to tin the hydrazone undergoes a ring
opening reaction and a doubly deprotonation to act as a tridentate ligand via imine nitrogen and enolic
oxygens. The tin atom in the complexes is five coordinate with geometry between square-pyramidal and
trigonal-bipyramidal. The in vitro antibacterial activity of ligand and its complexes has been evaluated
against Gram-positive (Bacillus subtilis and Staphylococcus aureus) and Gram-negative (Escherichia coli
and Pseudomonas aeruginosa) bacteria. The interaction between compounds with bacterial DNA was also
studied by molecular docking. Our findings indicate that diphenyltin(IV) complex, by binding to DNA via
minor groove to TATA sequence in genes upstream, has good activities along with the standard antibacterial
drugs. Our agarose-gel electrophoresis experiments show that the ligand exert DNA cleavage,
while Me2SnL and Ph2SnL did not
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
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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