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Organic chemistry

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https://www.readbyqxmd.com/read/28930696/impact-of-a-newly-formed-periglacial-environment-and-other-factors-on-fresh-water-chemistry-at-the-western-shore-of-admiralty-bay-in-the-summer-of-2016-king-george-island-maritime-antarctica
#1
Małgorzata Szopińska, Danuta Szumińska, Robert Józef Bialik, Stanisław Chmiel, Joanna Plenzler, Żaneta Polkowska
This study provides a comprehensive analysis of the inorganic chemistry of flowing water at the western shore of Admiralty Bay. In the water samples, ions, and major and trace metals (and B) were detected and quantified. Additionally, the parameters of pH, specific electrolytic conductivity (SEC25) and total organic carbon (TOC) were determined. Moreover, multivariate data set was created and Principal Component Analysis (PCA) was performed. Generally, the water has low total content of the measured mineral constituents <100mgL(-1)...
September 17, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28930435/new-triplet-sensitization-routes-for-photon-upconversion-thermally-activated-delayed-fluorescence-molecules-inorganic-nanocrystals-and-singlet-to-triplet-absorption
#2
Nobuhiro Yanai, Nobuo Kimizuka
Photon upconversion based on triplet-triplet annihilation (TTA-UC) has attracted much interest because of its possible applications to renewable energy production and biological fields. In particular, the UC of near-infrared (NIR) light to visible (vis) light is imperative to overcome the Shockley-Queisser limit of single-junction photovoltaic cells, and the efficiency of photocatalytic hydrogen production from water can also be improved with the aid of vis-to-ultraviolet (UV) UC. However, both processes have met limitations in the wavelength range, efficiency, and sensitivity for weak incident light...
September 20, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28930177/molecules-new-aims-and-scope
#3
EDITORIAL
Derek J McPhee
As we approach the end of our 22nd year as the pioneering and preeminent Open Access journal in the field of organic chemistry and natural products, time has come to formally announce what has been the de facto reality of the journal for the past few years, the expansion of the range of topics we cover.[...].
September 20, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28927524/genotoxicity-of-metal-based-engineered-nanoparticles-in-aquatic-organisms-a-review
#4
REVIEW
N Mahaye, M Thwala, D A Cowan, N Musee
Engineered nanoparticles (ENPs) are an emerging class of environmental contaminants, but are generally found in very low concentrations and are therefore likely to exert sub-lethal effects on aquatic organisms. In this review, we: (i) highlight key mechanisms of metal-based ENP-induced genotoxicity, (ii) identify key nanoparticle and environmental factors which influence the observed genotoxic effects, and (iii) highlight the challenges involved in interpreting reported data and provide recommendations on how these challenges might be addressed...
July 2017: Mutation Research
https://www.readbyqxmd.com/read/28926233/copper-i-catalyzed-regio-and-stereoselective-intramolecular-alkylboration-of-propargyl-ethers-and-amines
#5
Hiroaki Iwamoto, Yu Ozawa, Koji Kubota, Hajime Ito
The copper(I)-catalyzed regio- and stereoselective intramolecular alkylation of propargyl ethers and amines bearing an alkyl electrophilic moiety has been developed. The reaction showed high functional group tolerance and gave highly functionalized alkenylboronates bearing heterocyclic rings, which are versatile synthetic intermediates in organic chemistry. The borylation products can be transformed into multi-substituted alkenes through stereospecific transformations. Mechanistic studies showed that the chemo- and stereoselectivity of copper(I)-catalyzed borylation depends on the type of leaving group...
September 19, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28925326/a-nitrogen-transformation-model-for-multi-layer-enhanced-groundwater-remediation-technology
#6
Yu Yang, Zhifei Ma, Yonghai Jiang, Xinying Lian, Beidou Xi, Yu Pei
The multi-layer enhanced groundwater remediation technology (MET) is an innovative platform that integrates physical chemistry, bioremediation, and phytoremediation technology to safely and effectively remediate ammonia nitrogen in groundwater. A nitrogen transformation model was established to study the mechanism of nitrogen transformation within ammonia nitrogen removal in the MET. The model considered organic nitrogen, ammonia nitrogen, and nitrate nitrogen as the variables, and ammonification, nitrification, denitrification, microbial assimilation, plant absorption, adsorption-desorption, and volatilization as the influencing factors...
September 19, 2017: Environmental Technology
https://www.readbyqxmd.com/read/28924613/ligand-induced-twisting-of-nanoplatelets-and-their-self-assembly-into-chiral-ribbons
#7
Santanu Jana, Marta de Frutos, Patrick Davidson, Benjamin Abécassis
The emergence of chirality is a central issue in chemistry, materials science, and biology. In nanoparticle assemblies, chirality has been shown to arise through a few different processes, but chiral organizations composed of plate-like nanoparticles, a class of material under scrutiny due to their wide applicative potential, have not yet been reported. We show that ribbons of stacked board-shaped cadmium selenide (CdSe) nanoplatelets (NPLs) twist upon the addition of oleic acid ligand, leading to chiral ribbons that reach several micrometers in length and display a well-defined pitch of ~400 nm...
September 2017: Science Advances
https://www.readbyqxmd.com/read/28923590/isoprostanes-neuroprostanes-and-phytoprostanes-an-overview-of-25years-of-research-in-chemistry-and-biology
#8
REVIEW
Jean-Marie Galano, Yiu Yiu Lee, Camille Oger, Claire Vigor, Joseph Vercauteren, Thierry Durand, Martin Giera, Jetty Chung-Yung Lee
Since the beginning of the 1990's diverse types of metabolites originating from polyunsaturated fatty acids, formed under autooxidative conditions were discovered. Known as prostaglandin isomers (or isoprostanoids) originating from arachidonic acid, neuroprostanes from docosahexaenoic acid, and phytoprostanes from α-linolenic acid proved to be prevalent in biology. The syntheses of these compounds by organic chemists and the development of sophisticated mass spectrometry methods has boosted our understanding of the isoprostanoid biology...
September 15, 2017: Progress in Lipid Research
https://www.readbyqxmd.com/read/28922501/formation-and-structural-diversity-of-organo-functionalized-tin-silver-selenide-clusters
#9
Stefanie Dehnen, Niklas Rinn, Lukas Guggolz, Katharina Gries, Kerstin Volz, Jürgen Senker
When reacting the organic functionalized tin selenide clusters [(SnR1)3Se4Cl] (A, R1 = CMe2CH2C(O)Me) or [(SnR1)4Se6] (B) with (SiMe3)2Se and [Ag(PPh3)3Cl] at -78°C in CH2Cl2, a microcrystalline, intermediate (compound 1) precipitates, which was investigated by magic angle spinning (MAS) NMR spectroscopy, powder X-ray diffraction (PXRD), energy dispersive X-ray (EDX) spectroscopy, and quantum chemistry. From these studies, a suggestion about its identity was derived. Compound 1 re-dissolves under reorganization into the organo-functionalized Ag/Sn/Se cluster compound [Ag6(μ6 Se)(Ag8Se12){(R1Sn)2Se2}6] (2), or the mixed-valence cluster [(AgPPh3)2(SnIICl)2Se2{(R1SnIV)2Se2}2] (3), depending on the presence or the exclusion of daylight, respectively...
September 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28922481/photo-induced-assembly-of-a-luminescent-tetraruthenium-square
#10
Baptiste Laramée-Milette, Francesco Nastasi, Fausto Puntoriero, Sebastiano Campagna, Garry S Hanan
Self-assembly is a powerful synthetic tool that has led to the development of one-, two- and three-dimensional architectures. From MOFs to molecular flasks, self-assembled materials have proven to be of great interest to the scientific community. Here we describe a strategy for the construction and de-construction of a supramolecular structure through unprecedented photo-induced assembly and dis-assembly. The combination of two approaches, a [n×1]-directional bonding strategy and a ligand photo-dissociation strategy, allows the photo-induced assembly of a polypyridyl Ru(II) precursor into a discrete molecular square...
September 18, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28921969/flow-electrolysis-cells-for-the-synthetic-organic-chemistry-laboratory
#11
Derek Pletcher, Robert A Green, Richard C D Brown
Electrosynthesis has much to offer to the synthetic organic chemist. But in order to be widely accepted as a routine procedure in an organic synthesis laboratory, electrosynthesis needs to be presented in a much more user-friendly way. The literature is largely based on electrolysis in a glass beaker or H-cells that often give poor performance for synthesis with a very slow rate of conversion and, often, low selectivity and reproducibility. Flow cells can lead to much improved performance. Electrolysis is participating in the trend toward continuous flow synthesis, and this has led to a number of innovations in flow cell design that make possible selective syntheses with high conversion of reactant to product with a single passage of the reactant solution through the cell...
September 18, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28920010/exploring-step-by-step-assembly-of-nanoparticle-cytochrome-biohybrid-photoanodes
#12
Ee Taek Hwang, Katherine L Orchard, Daisuke Hojo, Joseph Beton, Colin W J Lockwood, Tadafumi Adschiri, Julea N Butt, Erwin Reisner, Lars J C Jeuken
Coupling light-harvesting semiconducting nanoparticles (NPs) with redox enzymes has been shown to create artificial photosynthetic systems that hold promise for the synthesis of solar fuels. High quantum yields require efficient electron transfer from the nanoparticle to the redox protein, a property that can be difficult to control. Here, we have compared binding and electron transfer between dye-sensitized TiO2 nanocrystals or CdS quantum dots and two decaheme cytochromes on photoanodes. The effect of NP surface chemistry was assessed by preparing NPs capped with amine or carboxylic acid functionalities...
August 2017: ChemElectroChem
https://www.readbyqxmd.com/read/28918628/breaking-benzene-aromaticity-computational-insights-into-the-mechanism-of-the-tungsten-containing-benzoyl-coa-reductase
#13
Martin Culka, Simona G Huwiler, Matthias Boll, G Matthias Ullmann
Aromatic compounds are environmental pollutants with toxic and carcinogenic properties. Despite the stability of aromatic rings, bacteria are able to degrade the aromatic compounds into simple metabolites and use them as growth substrates under oxic or even under anoxic conditions. In anaerobic microorganisms, most monocyclic aromatic growth substrates are converted to the central intermediate benzoyl-coenzyme A, which is enzymatically reduced to cyclohexa-1,5-dienoyl-CoA. The strcitly anaerobic bacterium \textit{Geobacter metallireducens} uses the class II benzoyl-CoA reductase complex for this reaction...
September 18, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28915454/assessing-the-potential-contributions-of-additional-retention-processes-to-pfas-retardation-in-the-subsurface
#14
Mark L Brusseau
A comprehensive understanding of the transport and fate of per- and poly-fluoroalkyl substances (PFAS) in the subsurface is critical for accurate risk assessments and design of effective remedial actions. A multi-process retention model is proposed to account for potential additional sources of retardation for PFAS transport in source zones. These include partitioning to the soil atmosphere, adsorption at air-water interfaces, partitioning to trapped organic liquids (NAPL), and adsorption at NAPL-water interfaces...
September 12, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28915446/embracing-chemical-and-structural-diversity-with-uconga-a-universal-conformer-generation-and-analysis-program
#15
Nathaniel R Gunby, Sarah L Masters, Deborah L Crittenden
Molecular properties depend on molecular structure, so the first step in any computational chemistry investigation is to generate all thermally accessible conformers. Typically it is necessary to make a trade-off between the number of conformers to be explored and the accuracy of the method used to calculate their energies. Ab initio potential energy surface scans can, in principle, be applied to any molecule, but their conformational cost scales poorly with both molecular size and dimensionality of the search space...
September 6, 2017: Journal of Molecular Graphics & Modelling
https://www.readbyqxmd.com/read/28915088/abiotic-and-biotic-formation-of-amino-acids-in-the-enceladus-ocean
#16
Elliot L Steel, Alfonso Davila, Christopher P McKay
The active plume at Enceladus' south pole makes the indirect sampling of its global ocean possible. The partially resolved chemistry of the plume, which points to conditions that are seemingly compatible with life, has made orbital sampling missions a priority. We present a conceptual model of energy flux, hydrothermal H2 production, and both abiotic and biotic production of amino acids. Based on the energy flux observed at the south pole and the inferred internal hydrothermal activity, we estimate an H2 production of 0...
September 2017: Astrobiology
https://www.readbyqxmd.com/read/28914790/ancient-living-organisms-escaping-from-or-imprisoned-in-the-vents
#17
REVIEW
J Baz Jackson
We have recently criticised the natural pH gradient hypothesis which purports to explain how the difference in pH between fluid issuing from ancient alkali vents and the more acidic Hadean ocean could have driven molecular machines that catalyse reactions that are useful in prebiotic and autotrophic chemistry. In this article, we temporarily suspend our earlier criticism while we consider difficulties for primitive organisms to have managed their energy supply and to have left the vents and become free-living...
September 15, 2017: Life
https://www.readbyqxmd.com/read/28914473/ethers-on-si-001-a-prime-example-for-the-common-ground-between-surface-science-and-molecular-organic-chemistry
#18
Lisa Pecher, Slimane Laref, Marc Raupach, Ralf Ewald Tonner
Using computational chemistry, we show that the adsorption of ether molecules on Si(001) under ultra-high vacuum conditions can be understood with textbook organic chemistry. The two-step reaction mechanism of (1) dative bond formation between the ether oxygen and a Lewis acidic surface atom and (2) a nucleophilic attack of a nearby Lewis basic surface atom is analysed in detail and found to mirror the acid-catalysed ether cleavage in solution. The O-Si dative bond is found to be the strongest of its kind and reactivity from this state defies the Bell-Evans-Polanyi principle...
September 15, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28913536/isoreticular-expansion-of-polymofs-achieves-high-surface-area-materials
#19
Giulia E M Schukraft, Sergio Ayala, Benjamin L Dick, Seth M Cohen
The concept of isoreticular chemistry has become a core principle in metal-organic framework (MOF) materials. Isoreticular chemistry has shown that organic ligands of different sizes, but with a common geometry/symmetry can be used to generate MOFs of related topologies, but with expanded pore sizes and volumes. In this report, polymer-MOF hybrid materials (polyMOFs) with a UiO (UiO = University of Oslo) architecture are shown to adhere to the principle of isoreticular expansion, generating polyMOFs with large surface areas and enhanced stability...
September 15, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28913530/why-microfluidics-merits-and-trends-in-chemical-synthesis
#20
REVIEW
Yong Liu, Xingyu Jiang
The intrinsic limitations of conventional batch synthesis have hindered its applications in both solving classical problems and exploiting new frontiers. Microfluidic technology offers a new platform for chemical synthesis toward either molecules or materials, which has promoted the progress of diverse fields such as organic chemistry, materials science, and biomedicine. In this review, we focus on the improved performance of microreactors in handling various situations, and outline the trend of microfluidic synthesis (microsynthesis, μSyn) from simple microreactors to integrated microsystems...
September 15, 2017: Lab on a Chip
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