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PubMed | Sunway University, University of Texas at San Antonio and Chemical Abstracts Service
Type: Journal Article | Journal: Acta crystallographica. Section E, Crystallographic communications | Year: 2016

The common feature of the mol-ecular structures of the title compounds, [Zn(C


Lujan-Montelongo J.A.,Duquesne University | Lu P.,Duquesne University | Liu W.,Chemical Abstracts Service | Fleming F.F.,Duquesne University
Chemistry - A European Journal | Year: 2013

"Black belt" SNi and SNi: Deuterium labeling revealed an inherent preference of N- and C-metalated nitriles for SNi, rather than SNi displacement. The fundamental reactivity preferences are harnessed in a series of cyclizations to cis- and trans-decalins that install contiguous quaternary-tertiary and quaternary-quaternary stereocenters (see scheme). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


News Article | March 4, 2016
Site: cen.acs.org

More than 1 million people a year die from mosquito-borne illnesses such as malaria, dengue virus, and West Nile virus. And earlier this year, a dramatic increase in birth defects in Brazil was linked to the Zika virus, another mosquito-transmitted disease. Suppressing and controlling the spread of mosquito populations remains a major health challenge for nations in tropical and subtropical regions. Researchers and companies are working worldwide to develop new agents that are safe, effective, and affordable to protect people from mosquitoes. Here, we highlight three patents reporting new mosquito-control strategies from the databases of Chemical Abstracts Service (CAS). Jump to Topics: - Attacking a mosquito’s sweet tooth - A fatty solution to insecticide resistance - One-two punch for resistant mosquitoes Mosquitoes rely on plant sugars for energy. While female mosquitoes also drink blood, plant sugars are the only food source for male mosquitoes. Noting this, Michelle A. Brown, Martin A. Lomeli Jr., and Samer Elkashef of Olfactor Laboratories, a California-based biotech firm, developed a sugar mixture that kills mosquitoes (WO 2015200753) by exploring the mosquito-killing power of several mixtures of toxic and nontoxic sugars. They found that a 1:1 mixture of sucrose with glycyrrhizin was the most effective, with the sucrose attracting hungry insects and glycyrrhizin killing them through an unknown mechanism. After mosquitoes were fed the mixture for three days, about 50% of the insects died compared with only 2% of mosquitoes fed a sucrose-only diet. Not surprisingly, more male mosquitoes died than did female ones after being exposed to the toxic mixture. The scientists claim in the filing that because the mixture is derived from natural products, it should be less harmful to the environment and human health than synthetic insecticides. Pyrethroids are a class of insecticides that cause paralysis by preventing sodium ion channels from closing in insect nerve cells. Unfortunately, pyrethroid resistance is becoming a major hurdle in effectively suppressing mosquito populations. The usual approach to addressing such resistance—rotating through conventional insecticides—has created mosquitoes resistant to multiple classes of compounds. A serendipitous discovery from Valent BioSciences suggests a new approach to attacking resistant mosquitoes (US 20150094367). The Valent team found a mixture of permethrin, a commonly used pyrethroid, and fatty acids, such as octanoic, nonanoic, and decanoic acids, knocked down drug-resistant mosquitoes better than it did their nonresistant brethren. The amount of time to kill 50% of the resistant mosquitoes was 3.2 minutes, compared with 5.3 minutes for the nonresistant insects. The fatty acids alone were equally nonlethal to both mosquito groups, and exposure to just permethrin had the expected result of killing nonresistant mosquitoes quicker. Valent did not respond to C&EN’s request to elaborate on the possible mechanism behind this phenomenon before press time. But in its filing, the firm says that this fatty acid formulation may allow for the reuse of other pesticides that are no longer effective on resistant mosquitoes. Insecticide resistance in mosquitoes is a complex phenomenon that arises from constant exposure to the same class of compounds over multiple insect generations. Scientists at Bayer CropScience recently patented the simultaneous use of two different classes of insecticides, pyrethroids and neonicotinoids, to combat resistant mosquitoes (WO 2015197482). These two compound classes act on different proteins on the surfaces of insect cells, but they both cause paralysis and eventual death in insects. The Bayer team sprayed deltamethrin and clothianidin—a pyrethroid and a neonicotinoid, respectively—on different types of surfaces to test how well the mixture killed resistant mosquitoes. Five weeks after the treatment of a concrete surface, up to 97% of the mosquitoes that came into contact with the surface died within 24 hours. The mortality rate 60 weeks after treatment was still an impressive 83% for insects bumping into the surface in the past 24 hours. Justin McBeath, a vector control specialist at Bayer, tells C&EN that the firm has started a trial program in several endemic countries to test the real-world efficacy of the mixture.


McCue C.,Chemical Abstracts Service
Information Services and Use | Year: 2010

Chemical Abstracts Service (CAS) has been an industry pioneer, adopting the newest technologies, meeting the needs of its customers thoughtfully and thoroughly, and developing new offerings that deliver exceptional service. In addition to compiling the most authoritative databases of their kind, CAS technologists build innovative search tools like STN® and SciFinder® that enable researchers to explore CAS' extensive content easily. Using the new SciFinder collaboration tools from CAS, users can connect with others within their own research site or by inviting or accepting invitations to connect from SciFinder users they know, share research content with their groups, share information through reference tags, tag user-created labels, and comment on any user's content. In 2009, CAS developed an iPhone application that made CAS' Colors of Chemistry calendar content available to customers and the public alike.


Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,Nanyang Technological University | Tiekink E.R.T.,University of Malaya
CrystEngComm | Year: 2010

Supramolecular interwoven double chains are found in two isomeric zinc thiolate complexes which differ in terms of the tautomeric forms of the bridging ligands, i.e. 3-NC5H4CH2N(H)C(O)C(O)N(H) CH2C5H4N-3 or 3-NC5H 4CH2NC(OH)C(OH)NCH2C5H 4N-3. In each case, the bridging ligands are threaded through 28-membered rings mediated by O-H⋯O hydrogen bonding. Hydrogen bonding interactions between the rings and threading molecules, i.e. O-H⋯O carbonyl or O-H⋯Nimine, are dependent on the tautomeric form of the threading molecules. © 2010 The Royal Society of Chemistry.


Arman H.D.,University of Texas at San Antonio | Kaulgud T.,University of Texas at San Antonio | Miller T.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Journal of Chemical Crystallography | Year: 2012

The common feature of each of the title 2:1 cocrystals is the formation of the O-H⋯N(pyridyl) hydrogen bonds leading to three-molecule aggregates. The persistent formation of the O-H⋯N(pyridyl) hydrogen bonds where other functionalities are present, e.g. amide, indicates the robustness of this supramolecular synthon. In the structure of the 2:1 4-nitrophenylacetic acid N,N'-bis (pyridin-3-ylmethyl)oxalamide cocrystal, (1), the amide-H forms a hydrogen bond with the hydroxyl group so that rows of N,N'-bis(pyridin-3- ylmethyl)oxalamide molecules are linked into a supramolecular tape via 4-nitrophenylacetic acid molecules. In the N,N'-bis(pyridin-3-ylmethyl) thioxalamide derivative, (2), the thioamide-H atom only forms an intramolecular N-H⋯S contact. Nevertheless, a supramolecular tape is formed but mediated by C-H⋯O(nitro) interactions. Compound (1) crystallizes in the triclinic space group P1 with a = 8.195(2) Å , b = 9.502(3) Å , c = 9.999(3) Å , α = 90.631(3)8, β = 102.796(5)8, γ = 108.075(5)8, and Z = 1 (three molecule aggregate). Compound (2) also crystallizes in the triclinic space group P1with a = 8.0772(12)Å , b = 10.2111(12) Å , c = 10.2563(17) Å , α = 71.319(10)8, β = 77.777(11)8, γ = 67.660(9)8, andZ = 1 (threemolecule aggregate). © Springer Science+Business Media, LLC 2012.


Richardson E.,Chemical Abstracts Service
IEEE Software | Year: 2011

You'll have to read further to find out! There are so many interesting things about this articleit's the first in a series based on presentations from the SATURN conference. My first college degree was in chemistry, so there was an immediate connection for me with this story about chemical abstracts. The author brings us architectural wisdom, combined with an agile point of view and weather forecasting. © 2011 IEEE.


Arman H.D.,University of Texas at San Antonio | Miller T.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Zeitschrift fur Kristallographie | Year: 2013

The co-crystallisation of two equivalents of 2,6- dinitrobenzoic acid (1) with one equivalent of a member of the isomeric N,N′-bis(pyridin-n- ylmethyl)ethanediamides, n = 2, 3 and 4, resulted in the anticipated 2 : 1 salts, 2-4. The central core, i.e. CH2N(H)C(= O)C(= O)N(H)CH 2, of the isomeric di-cations are superimposable and chemically equivalent pairs of carbonyl, amide and pyridinium groups have an anti conformation. By contrast, the relative orientations of the terminal pyridinium rings from the central core vary significantly across the series as do the relative disposition of the acidic-H atoms. This feature of the structure influences the nature of N-H...O hydrogen bonding and, therefore, the observed supramolecular aggregation patterns. Thus, in 2, the syn-disposition of the nitrogenbound hydrogen atoms enables the benzoate residue to interact via the two oxygen atoms with both pyridiniumand amine-H atoms to yield a zero-dimensional aggregate. By contrast, in each of 3 and 4, having further distance between the acidic-H atoms, the benzoate residues still interact (either through one both or both oxygen atoms) with pyridinium- and amine-H atoms but those derived from symmetry related molecules to generate one-dimensional aggregates. The three-dimensional architectures of 1-3 are consolidated, in the main, by C-H...O interactions. The structure of 1 revealed the benzoic acid residue to be perpendicular in contrast to the co-planar conformations of the nitro groups. In the crystal packing, O-H...O hydrogen bonding lead to a helical supramolecular chain. © 2013 by Oldenbourg Wissenschaftsverlag, München.


Arman H.D.,University of Texas at San Antonio | Poplaukhin P.,Chemical Abstracts Service | Tiekink E.R.T.,University of Malaya
Acta Crystallographica Section E: Structure Reports Online | Year: 2012

The asymmetric unit of the title compound, [Zn(C 4H 8NOS 2) 2(C 18H 12N 6)]·1.5C 4H 8O 2, comprises a Zn-containing molecule and one and a half dioxane molecules as one of the solvent molecules is located about a crystallographic inversion centre. The approximately squarepyramidal N 3S 2 donor set is defined by two monodentate dithiocarbamate ligands and two pyridine and one triazine N atom from the tridentate triazine ligand. molecules are connected into a supramolecular array via O - H⋯S and O - H⋯N hydrogen bonds. These stack along the b axis and the solvent molecules reside in the channels thus formed.


Poplaukhin P.,Chemical Abstracts Service | Arman H.D.,University of Texas at San Antonio | Tiekink E.R.T.,University of Malaya
Zeitschrift fur Kristallographie | Year: 2012

Distinct molecular structures and supramolecular association is found in the title crystal structures. When chloroform was diffused into a solution of {Zn[S 2CN(Me)CH 2CH 2OH)] 2} 2(N,N'-bis(pyridin-3-ylmethyl) thioxalamide) in acetonitrile, it was found to have cocrystallised (2 : 1) with S 8 (1) as partial desulphurisation had occurred during crystallisation. By contrast, when dimethylformamide was diffused in an acetonitrile solution of the same compound, a 2 : 1 dimethylformamide solvate (2) was isolated. The zinc atom coordination geometry is based on a NS4 donor set in each case but, this defines an approximate square pyramidal geometry in (1) and a geometry intermediate between square pyramidal and trigonal bipyramidal in (2). This difference is ascribed to the hydrogen bonding considerations. The hydroxyl groups in (1) self-associate leading to a two-dimensional array; the S 8 molecules occupy space between successive layers. The aforementioned hydrogen bonding is disrupted in (2) where one hydroxyl group interacts with the solvent dimethylformamide molecule. Accordingly, the supramolecular association between molecules is restricted to a onedimensional chain. © by Oldenbourg Wissenschaftsverlag, München.

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