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https://www.readbyqxmd.com/read/28724190/testing-limits-of-bophy-platform-preparation-characterization-and-theoretical-modeling-of-bophys-bophys-with-electron-withdrawing-groups-at-b-pyrrolic-and-bridging-positions
#1
Victor N Nemykin, Yuriy V Zatsikha, Dion B Nemez, Rebecca L Davis, Simarpreet Singh, David E Herbert, Alex J King, Christopher J Ziegler
Several BOPHY derivatives with and without ferrocene fragments and with electron-withdrawing carbethoxy groups appended to the -pyrrolic positions have been prepared and characterized by NMR, UV-Vis-NIR, APCI MS, and fluorescence spectroscopy as well as X-ray crystallography. The redox properties of new BOPHYs were probed by electrochemical (CV and DPV) and spectroelectrochemical methods. In attempt for the preparation of the BOPHY derivatives with cyano group at bridging position using similar to recently communicated BODIPY cyanation approach (Chem...
July 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28723923/on-the-mechanism-of-candida-tropicalis-biofilm-reduction-by-the-combined-action-of-naturally-occurring-anthraquinones-and-blue-light
#2
Juliana Marioni, Roger Bresolí-Obach, Montserrat Agut, Laura R Comini, José L Cabrera, María G Paraje, Santi Nonell, Susana C Núñez Montoya
The photoprocesses involved in the photo-induced Candida tropicalis biofilm reduction by two natural anthraquinones (AQs), rubiadin (1) and rubiadin-1-methyl ether (2), were examined. Production of singlet oxygen (1O2) and of superoxide radical anion (O2•-) was studied. Although it was not possible to detect the triplet state absorption of any AQs in biofilms, observation of 1O2 phosphorescence incubated with deuterated Phosphate Buffer Solution, indicated that this species is actually formed in biofilms...
2017: PloS One
https://www.readbyqxmd.com/read/28723219/factors-governing-and-application-of-the-cope-rearrangement-of-3-3-dicyano-1-5-dienes-and-related-studies
#3
Ehsan Fereyduni, Alexander J Grenning
Cope and co-workers reported the [3,3] rearrangement of 3,3-dicyano-1,5-dienes in the early 1940s ("The Cope rearrangement"). However, these original substrates have remained largely unstudied until recently. Herein we explore styrene-deconjugating Cope rearrangements, a diastereoselective Cope rearrangement/deconjugative α-allylation sequence, and factors governing α- vs γ-allylation regioselectivity of Knoevenagel adduct allyl anions. Ultimately, these studies result in the synthesis of diverse and functionally dense polycycloalkane frameworks from abundant reagents using simple chemistry...
July 19, 2017: Organic Letters
https://www.readbyqxmd.com/read/28723138/hand-held-femtogram-detection-of-hazardous-picric-acid-with-hydrophobic-ag-nanopillar-sers-substrates-and-mechanism-of-elasto-capillarity
#4
Aron Hakonen, FengChao Wang, Per Ola Andersson, Håkan Wingfors, Tomas Rindzevicius, Michael Stenbæk Schmidt, Venugopal Rao Soma, Shicai Xu, YingQi Li, Anja Boisen, HengAn Wu
Picric acid (PA) is a severe environmental and security risk due to its unstable, toxic, and explosive properties. It is also challenging to detect in trace amounts and in situ because of its highly acidic and anionic character. Here, we assess sensing of PA under nonlaboratory conditions using surface-enhanced Raman scattering (SERS) silver nanopillar substrates and hand-held Raman spectroscopy equipment. The advancing elasto-capillarity effects are explained by molecular dynamics simulations. We obtain a SERS PA detection limit on the order of 20 ppt, corresponding attomole amounts, which together with the simple analysis methodology demonstrates that the presented approach is highly competitive for ultrasensitive analysis in the field...
February 24, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28723078/covalency-competition-in-the-quadruple-perovskite-cdcu3fe4o12
#5
Ikuya Yamada, Akihiko Takamatsu, Naoaki Hayashi, Hidekazu Ikeno
Cadmium ions (Cd(2+)) are similar to calcium ions (Ca(2+)) in size, whereas the Cd(2+) ions tend to form covalent bonds with the neighboring anions because of the high electronegativity. The covalent Cd-O bonds affect other metal-oxygen bonds, inducing drastic changes in crystal structures and electronic states. Herein, we demonstrate high-pressure synthesis, crystal structure, and properties of a new quadruple perovskite CdCu3Fe4O12. This compound exhibits an electronic phase transition accompanying a charge disproportionation of Fe ions without charge ordering below ∼200 K, unlike charge-disproportionation transition with rock-salt-type charge ordering for CaCu3Fe4O12...
July 19, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28722416/character-of-localization-and-microenvironment-of-the-solvatochromic-reichardt-s-betaine-dye-in-sds-and-ctab-micelles-md-simulation-study
#6
Vladimir S Farafonov, Alexander V Lebed, Nikolay O Mchedlov-Petrossyan
The problem of using the surfactant micellar aqueous solutions as reaction media centers on estimating the polarity of the micellar pseudophase. The most popular approach is the utilization of solvatochromic dyes. Among the last, the strongest ones are the dipolar pyridinium N-phenolate dyes. The complication of such approach, however, consists in the non-uniform character of the environment of the indicator fixed in the micellar pseudophase. The aim of this study is to reveal the character of localization and orientation of the standard solvatochromic pyridinium N-phenolate dye, 4-(2,4,6-triphenylpyridinium-1-yl)-2,6-diphenylphenolate, the so-called Reichardt's dye, within the micellar pseudophase of an anionic (sodium n-dodecyl sulfate, SDS) and cationic (cetyltrimethylammonium bromide, CTAB) surfactants using MD simulations...
July 19, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28722411/pathways-in-the-degradation-of-geminal-diazides
#7
Kristina Holzschneider, Andreas P Häring, Alexander Haack, Daniel J Corey, Thorsten Benter, Stefan F Kirsch
The degradation of geminal diazides is described. We show that diazido acetates are converted into tetrazoles through the treatment with bases. The reaction of dichloro ketones with azide anions provides acyl azides, through in situ formation of diazido ketones. We present experimental and theoretical evidence that both fragmentations may involve the generation of acyl cyanide intermediates. The controlled degradation of terminal alkynes into amides (by loss of one carbon) or ureas (by loss of two carbons) is also shown...
July 19, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28722404/high-performance-colorimetric-detection-of-thiosulfate-by-using-silver-nanoparticles-for-smartphone-based-analysis
#8
Chen Dong, Zhuqing Wang, Yujie Zhang, Xuehua Ma, M Zubair Iqbal, Lijing Miao, Zhuangwei Zhou, Zheyu Shen, Aiguo Wu
Developing thiosulfate (S2O32-) sensors with silver nanoparticles (AgNPs) for analysis of aqueous solutions with the interference of other anions remains challenging. In this study, we propose a new strategy for excellent selective colorimetric detection of S2O32-. The non-morphological transition of AgNPs leading to a color change from yellow to brown is verified by UV-vis, TEM, DLS, SEM, and XPS analyses. The sensor exhibits high sensitivity with detection limits of 1.0 µM by naked-eye determination and 0...
July 19, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28722395/salt-removal-from-microliter-sample-volumes-by-multiple-phase-micro-electromembrane-extractions-across-free-liquid-membranes
#9
Pavel Kuban
A new concept for rapid and efficient salt removal from minute volumes of saline samples is presented by using multiple phase micro-electromembrane extraction (μ-EME). Disposable μ-EME unit is filled with five consecutive plugs of immiscible aqueous and organic solutions; the aqueous sample forms the central phase and is encompassed by two free liquid membranes (FLMs) and two extraction solutions. Salt cations and anions migrate in opposite directions from the sample solution on application of 300 V d.c. electric potential, cross the neighboring FLM and are transferred to the corresponding extraction solution...
July 19, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28722226/biology-of-slac1-type-anion-channels-from-nutrient-uptake-to-stomatal-closure
#10
REVIEW
Rainer Hedrich, Dietmar Geiger
Contents 1 I. 1 II. 2 III. 5 IV. 8 V. 11 VI. 12 13 13 References 13 SUMMARY: Stomatal guard cells control leaf CO2 intake and concomitant water loss to the atmosphere. When photosynthetic CO2 assimilation is limited and the ratio of CO2 intake to transpiration becomes suboptimal, guard cells, sensing the rise in CO2 concentration in the substomatal cavity, deflate and the stomata close. Screens for mutants that do not close in response to experimentally imposed high CO2 atmospheres identified the guard cell-expressed Slowly activating anion channel, SLAC1, as the key player in the regulation of stomatal closure...
July 19, 2017: New Phytologist
https://www.readbyqxmd.com/read/28722072/highly-efficient-cr2o7-2-removal-of-a-3d-metal-organic-framework-fabricated-by-tandem-single-crystal-to-single-crystal-transformations-from-a-1d-coordination-array
#11
Cheng-Peng Li, Hang Zhou, Si Wang, Jing Chen, Zhong-Liang Wang, Miao Du
The single-crystal to single-crystal (SC-SC) transformation from a 1D coordination chain to a 3D coordination network, which is triggered by both solvent and anion exchanges, has been revealed to suffer from a tandem mechanism as proved by isolation of the intermediate state. The resulting porous crystalline material shows a high efficiency for the capture of dichromates (207 mg g(-1)) via the SC-SC anion-exchange.
July 19, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28722047/the-effect-of-hofmeister-anions-on-water-structure-at-protein-surfaces
#12
Euihyun Lee, Jun-Ho Choi, Minhaeng Cho
To understand the effects of specific ions on protein-water interactions and the thermodynamic stability of proteins in salt solutions, we use a molecular dynamics (MD) simulation to examine the water structure, orientational distribution, and dynamics near the surface of ubiquitin. In particular, we consider NaCl, NaBF4, NaSCN, and NaClO4 salt solutions containing ubiquitin, where the anions of the latter three salts are well-known chaotropic ions in the Hofmiester anion series. The number of hydrogen bonds (H-bonds) per water molecule is found to decrease significantly at the ubiquitin-water interface, indicating a significant disruption of the water H-bonding network...
July 19, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28721299/development-of-ionophore-based-nanosphere-emulsion-incorporating-ion-exchanger-for-complexometric-titration-of-thiocyanate-anion
#13
Fatehy M Abdel-Haleem, Mahmoud S Rizk
Ionophore-based ion-exchange nanosphere emulsion was prepared and tested for the determination of thiocyanate. The emulsified nanosphere contained the cationic additive tridodecylmethyl ammonium chloride (TDMAC), the plasticizer, and the ionophore Mn(III)-salophen or Mn(III)-salen. This emulsion was used as titrating agent for thiocyanate complexation with ionophores, which could be transduced using an ion-selective electrode (ISE) as an indicator electrode for the end point detection. The method showed no need for pH control and reliable selectivity, as thiocyanate could be determined in presence of other interfering ions with high accuracy...
July 2017: Journal of Advanced Research
https://www.readbyqxmd.com/read/28721160/genetic-disruption-of-multidrug-resistance-associated-protein-1-improves-endothelial-function-and-attenuates-atherosclerosis-in-mrp1-ldlr-double-knockout-mice
#14
Julian Jehle, Cornelius F H Müller, Adem Aksoy, Sebastian Zimmer, Georg Nickenig, Vedat Tiyerili
INTRODUCTION: Multidrug resistance-associated protein 1 (MRP1) is an anion transporter which is implicated in the efflux of the intracellular antioxidant anion glutathione as well as leukotrienes. Pharmacological inhibition of MRP1 exhibits antioxidative and anti-atherosclerotic effects both in vitro and in vivo. However, pharmacological inhibitors of MRP1 lack selectivity, which prompted us to study the in vivo impact of a genetic disruption of MRP1 on endothelial dysfunction, reactive oxygen species formation and atherogenesis in an atherosclerotic mouse model...
June 2017: Archives of Medical Science: AMS
https://www.readbyqxmd.com/read/28720589/dynamic-role-of-the-tether-helix-in-pip2-dependent-gating-of-a-g-protein-gated-potassium-channel
#15
Emre Lacin, Prafulla Aryal, Ian W Glaaser, Karthik Bodhinathan, Eric Tsai, Nidaa Marsh, Stephen J Tucker, Mark S P Sansom, Paul A Slesinger
G protein-gated inwardly rectifying potassium (GIRK) channels control neuronal excitability in the brain and are implicated in several different neurological diseases. The anionic phospholipid phosphatidylinositol 4,5 bisphosphate (PIP2) is an essential cofactor for GIRK channel gating, but the precise mechanism by which PIP2 opens GIRK channels remains poorly understood. Previous structural studies have revealed several highly conserved, positively charged residues in the "tether helix" (C-linker) that interact with the negatively charged PIP2 However, these crystal structures of neuronal GIRK channels in complex with PIP2 provide only snapshots of PIP2's interaction with the channel and thus lack details about the gating transitions triggered by PIP2 binding...
July 18, 2017: Journal of General Physiology
https://www.readbyqxmd.com/read/28719875/novel-magnetic-carboxyl-modified-hypercrosslinked-resins-for-effective-removal-of-typical-ppcps
#16
Jing Jin, Tianyu Feng, Yan Ma, Wei Wang, Yunshu Wang, Qing Zhou, Aimin Li
A series of novel magnetic carboxyl modified hypercrosslinked resins were successfully prepared via a sequence of suspension polymerization, hydrolysis and post-crosslinking reactions. The serial resins possessed both high cation exchange capacity and high specific surface area with MA-10 having the supreme specific surface area of 1238.65 m(2)/g and MA-70 having the largest exchange capacity of 6.45 mmol/g. The serial resins exhibited excellent adsorption capacity of typical PPCPs including chloramphenicol, atenolol, ibuprofen and tetracycline, which were neutral, cationic, anionic and zwitterionic respectively in natural water...
July 14, 2017: Chemosphere
https://www.readbyqxmd.com/read/28719869/effectiveness-of-table-top-water-pitcher-filters-to-remove-arsenic-from-drinking-water
#17
Roxanna Barnaby, Amanda Liefeld, Brian P Jackson, Thomas H Hampton, Bruce A Stanton
Arsenic contamination of drinking water is a serious threat to the health of hundreds of millions of people worldwide. In the United States ~3 million individuals drink well water that contains arsenic levels above the Environmental Protection Agency (EPA) maximum contaminant level (MCL) of 10μg/L. Several technologies are available to remove arsenic from well water including anion exchange, adsorptive media and reverse osmosis. In addition, bottled water is an alternative to drinking well water contaminated with arsenic...
July 15, 2017: Environmental Research
https://www.readbyqxmd.com/read/28719751/determining-the-mechanism-and-efficiency-of-industrial-dye-adsorption-through-facile-structural-control-of-organo-montmorillonite-adsorbents
#18
Peng Huang, Algy Kazlauciunas, Robert Menzel, Long Lin
The structural evolution of cost-effective organo-clays (montmorillonite modified with different loadings of CTAB (cetyltrimethylammonium bromide)) is investigated and linked to the adsorption uptake and mechanism of an important industrial dye (hydrolyzed Remazol Black B). Key organo-clay characteristics, such as the intergallery spacing and the average number of well-stacked layers per clay stack are determined by low-angle X-ray diffraction (XRD), while differential thermo-gravimetric analysis (DTGA) is used to differentiate between surface-bound and intercalated CTAB...
July 18, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28719189/determination-of-double-bond-positions-in-polyunsaturated-fatty-acids-using-the-photochemical-patern%C3%A3-b%C3%A3-chi-reaction-with-acetone-and-tandem-mass-spectrometry
#19
Robert C Murphy, Toshiaki Okuno, Christopher A Johnson, Robert M Barkley
The position of double bonds along the carbon chain of methylene interrupted polyunsaturated fatty acids are unique identifiers of specific fatty acids derived from biochemical reactions that occur in cells. It is possible to obtain direct structural information as to these double bond positions using tandem mass spectrometry after collisional activation of the carboxylate anions of an acetone adduct at each of the double bond positions formed by the photochemical Paternò-Büchi reaction with acetone. This reaction can be carried out by exposing a small portion of an inline fused silica capillary to UV photons from a mercury vapor lamp as the sample is infused into the electrospray ion source of a mass spectrometer...
July 18, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28718634/porous-uranyl-borophosphates-with-unique-three-dimensional-open-framework-structures
#20
Yucheng Hao, Gabriel L Murphy, Dirk Bosbach, Giuseppe Modolo, Thomas E Albrecht-Schmitt, Evgeny V Alekseev
Two novel alkali-metal uranyl borophosphates have been prepared and characterized for the first time, namely, K5(UO2)2[B2P3O12(OH)]2(OH)(H2O)2 and K2(UO2)12[B(H2PO4)4](PO4)8(OH)(H2O)6 denoted as KUPB1 and KUPB2, respectively. KUPB1 was obtained hydrothermally at 220 °C and crystallizes in a monoclinic structure in the chiral space group P21. The unit cell parameters of KUPB1 are a = 6.7623(2) Å, b = 19.5584(7) Å, c = 11.0110(4) Å, α = γ = 90°, β = 95.579(3)°, and V = 1449.42(8) Å(3). It features a unique three-dimensional (3D) open-framework structure, composed of two corner-sharing linked one-dimensional (1D) anionic borophosphates (BP), [B2P3O13](5-), along the a axis and uranyl phosphate (UP), [(UO2)(PO4)3](7-), chains along the c axis, further bridged by PO4 tetrahedra...
July 18, 2017: Inorganic Chemistry
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