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https://www.readbyqxmd.com/read/28636761/molecular-tools-for-facilitative-carbohydrate-transporters
#1
Marina Tanasova, Joseph R Fedie
Facilitative carbohydrate transporters - Gluts - have received a wide attention over decades due to their essential role in the nutrient uptake and links with various metabolic disorders, including diabetes, obesity, and cancer. Endeavors into understanding mechanisms of Glut-mediated nutrient uptake have resulted in the multidisciplinary research field, branching protein chemistry, chemical biology, organic synthesis, crystallography, and biomolecular modeling. Gluts became attractive targets for cancer research and medicinal chemistry, leading to the development of new approaches to cancer diagnostics and providing avenues for cancer-targeting therapeutics...
June 21, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28636596/selective-sp-3-c-h-alkylation-via-polarity-match-based-cross-coupling
#2
Chip Le, Yufan Liang, Ryan W Evans, Ximing Li, David W C MacMillan
The functionalization of carbon-hydrogen (C-H) bonds is one of the most attractive strategies for molecular construction in organic chemistry. The hydrogen atom is considered to be an ideal coupling handle, owing to its relative abundance in organic molecules and its availability for functionalization at almost any stage in a synthetic sequence. Although many C-H functionalization reactions involve C(sp(3))-C(sp(2)) coupling, there is a growing demand for C-H alkylation reactions, wherein sp(3) C-H bonds are replaced with sp(3) C-alkyl groups...
June 21, 2017: Nature
https://www.readbyqxmd.com/read/28636383/gene-expression-profiling-in-human-lung-cells-exposed-to-isoprene-derived-secondary-organic-aerosol
#3
Ying-Hsuan Lin, Maiko Arashiro, Phillip W Clapp, Tianqu Cui, Kenneth G Sexton, William Vizuete, Avram Gold, Ilona Jaspers, Rebecca C Fry, Jason Douglas Surratt
Secondary organic aerosol (SOA) derived from the photochemical oxidation of isoprene contributes a substantial mass fraction to atmospheric fine particulate matter (PM2.5). The formation of isoprene SOA is influenced largely by anthropogenic emissions through multiphase chemistry of its multi-generational oxidation products. Considering the abundance of isoprene SOA in the troposphere, understanding mechanisms of adverse health effects through inhalation exposure is critical to mitigating its potential impact on public health...
June 21, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28636366/oxygenation-via-c-h-c-c-bond-activation-with-molecular-oxygen
#4
Yu-Feng Liang, Ning Jiao
The selective oxidation of organic molecules is a fundamentally important component of modern synthetic chemistry. In the past decades, direct oxidative C-H and C-C bond functionalization has proved to be one of the most efficient and straightforward methods to synthesize complex products from simple and readily available starting materials. Among these oxidative processes, the use of molecular oxygen as a green and sustainable oxidant has attracted considerable attention because of its highly atom-economical, abundant, and environmentally friendly characteristics...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636358/transferable-atom-centered-potentials-for-the-correction-of-basis-set-incompleteness-errors-in-density-functional-theory
#5
Alberto Otero-de-la-Roza, Gino A DiLabio
Recent progress in the accurate calculation of non-covalent interactions has enabled density-functional theory (DFT) to model systems relevant in biological and supramolecular chemistry. The application of DFT methods using atom-centered Gaussian basis sets to large systems is limited by the number of basis functions required to accurately model thermochemistry and, in particular, weak intermolecular interactions. Basis-set incompleteness error (BSIE) arising from the use of incomplete basis sets leads to erroneous intermolecular energies, bond dissociation energies, and structures...
June 21, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28636351/heats-of-formation-of-medium-size-organic-compounds-from-contemporary-electronic-structure-methods
#6
Yury Minenkov, Heng Wang, Zhandong Wang, S Mani Sarathy, Luigi Cavallo
Computational electronic structure calculations are routinely undertaken to predict thermodynamic properties of the various species. However, the application of highly accurate wave function theory methods, such as the "gold standard" coupled cluster approach including single, double and partly triple excitations in perturbative fashion, CCSD(T), to large molecules is limited due to high computational cost. In this work, the promising domain based local pair natural orbital coupled cluster approach, DLPNO-CCSD(T), has been tested to reproduce 113 accurate formation enthalpies of medium-size molecules (few dozens heavy atoms) important for bio- and combustion chemistry via the reaction based Feller-Peterson-Dixon approach...
June 21, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28636313/iodine-iii-reagents-in-radical-chemistry
#7
Xi Wang, Armido Studer
The chemistry of hypervalent iodine(III) compounds has gained great interest over the past 30 years. Hypervalent iodine(III) compounds show valuable ionic reactivity due to their high electrophilicity but also express radical reactivity as single electron oxidants for carbon and heteroatom radical generation. Looking at ionic chemistry, these iodine(III) reagents can act as electrophiles to efficiently construct C-CF3, X-CF3 (X = heteroatom), C-Rf (Rf = perfluoroalkyl), X-Rf, C-N3, C-CN, S-CN, and C-X bonds...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636310/sensing-mechanisms-in-the-redox-regulated-2fe-2s-cluster-containing-bacterial-transcriptional-factor-soxr
#8
Kazuo Kobayashi
Bacteria possess molecular biosensors that enable responses to a variety of stressful conditions, including oxidative stress, toxic compounds, and interactions with other organisms, through elaborately coordinated regulation of gene expression. In Escherichia coli and related bacteria, the transcription factor SoxR functions as a sensor of oxidative stress and nitric oxide (NO). SoxR protein contains a [2Fe-2S] cluster essential for its transcription-enhancing activity, which is regulated by redox changes in the [2Fe-2S] cluster...
June 21, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28636272/development-of-biotic-ligand-model-based-freshwater-aquatic-life-criteria-for-lead-following-us-environmental-protection-agency-guidelines
#9
David K DeForest, Robert C Santore, Adam C Ryan, Brian G Church, M Jasim Chowdhury, Kevin V Brix
The US Environmental Protection Agency's (USEPA's) current ambient water quality criteria (AWQC) for lead (Pb) in freshwater were developed in 1984. The criteria are adjusted for hardness, but more recent studies have demonstrated that other parameters, especially dissolved organic carbon (DOC) and pH, have a much stronger influence on Pb bioavailability. These recent studies have been used to support development of a biotic ligand model (BLM) for Pb in freshwater, such that acute and chronic Pb toxicity can be predicted over a wide range of water chemistry conditions...
June 21, 2017: Environmental Toxicology and Chemistry
https://www.readbyqxmd.com/read/28634602/recent-advances-in-the-computational-chemistry-of-soft-porous-crystals
#10
Guillaume Fraux, François-Xavier Coudert
Here we highlight recent progress in the field of computational chemistry of nanoporous materials, focusing on methods and studies that address the extraordinary dynamic nature of these systems: the high flexibility of their frameworks, the large-scale structural changes upon external physical or chemical stimulation, and the presence of defects and disorder. The wide variety of behavior demonstrated in soft porous crystals, including the topical class of metal-organic frameworks, opens new challenges for computational chemistry methods at all scales...
June 21, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28632984/aging-induced-changes-in-biochar-s-functionality-and-adsorption-behavior-for-phosphate-and-ammonium
#11
Shamim Mia, Feike A Dijkstra, Balwant Singh
Biochar, a form of pyrogenic carbon, can contribute to agricultural and environmental sustainability by increasing soil reactivity. In soils, biochar could change its role over time through alterations in its surface chemistry. However, a mechanistic understanding of the aging process and its role in ionic nutrient adsorption and supply remain unclear. Here, we aged a wood biochar (550 °C) by chemical oxidation with 5-15% H2O2 and investigated the changes in surface chemistry and the adsorption behavior of ammonium and phosphate...
June 20, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28632338/difluoromethylation-reactions-of-organic-compounds
#12
Damian E Yerien, Sebastian Barata-Vallejo, Al Postigo
The relevance of the -CF2H moiety has attracted considerable attention from organic synthetic and medicinal chemistry communities, because this group can act as a more lipophilic isostere of the carbinol, thiol, hydroxamic acid or amide groups. Being weakly acidic, the CF2H moiety can establish hydrogen bonding interactions to improve the binding selectivity of biologically active compounds. Therefore, the hydroxyl, amino, and thio substituents of lead structures are routinely replaced by a CF2H motif in drug discovery, with great benefits in the pharmacological activity of drugs and drug candidates and agrochemicals...
June 20, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28631486/melding-caged-compounds-with-supramolecular-containers-photogeneration-and-miscreant-behavior-of-the-coumarylmethyl-carbocation
#13
Nareshbabu Kamatham, José P Da Silva, Richard S Givens, V Ramamurthy
By merging well-established concepts of supramolecular chemistry, protecting group strategy, and photochemistry, we have solubilized in water hydrophobic organic molecules consisting of a photoactive protecting group and masked carboxylic acids, released the desired acid, and confined a reactive carbocation intermediate within a capsule. Confinement of the photogenerated carbocation brought out the latent radical-like behavior. This observation is consistent with the recent theoretical prediction of the 7-(diethylamino)coumarinyl-4-methyl carbocation having a triplet diradical ground-state electronic contribution...
June 20, 2017: Organic Letters
https://www.readbyqxmd.com/read/28631435/polar-intermetallics-pr5co2ge3-and-pr7co2ge4-with-planar-hydrocarbon-like-metal-clusters
#14
Qisheng Lin, Kaiser Aguirre, Scott M Saunders, Timothy A Hackett, Yong Liu, Valentin Taufour, Durga Paudyal, Sergey Budko, Paul C Canfield, Gordon J Miller
Planar hydrocarbon-like metal clusters may foster new insights linking organic molecules with conjugated - bonding interactions and inorganic structures in terms of their bonding characteristics. However, such clusters are uncommon in polar intermetallics. Herein, we report two polar intermetallic phases, Pr5Co2Ge3 and Pr7Co2Ge4, both of which feature such planar metal clusters, viz., ethylene-like [Co2Ge4] clusters plus the concatenated forms and polyacene-like [Co2Ge2]n ribbons in Pr5Co2Ge3, and 1,2,4,5-tetramethylbenzene-like [Co4Ge6] cluster in Pr7Co2Ge4...
June 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28630318/reducing-secondary-organic-aerosol-formation-from-gasoline-vehicle-exhaust
#15
Yunliang Zhao, Rawad Saleh, Georges Saliba, Albert A Presto, Timothy D Gordon, Greg T Drozd, Allen H Goldstein, Neil M Donahue, Allen L Robinson
On-road gasoline vehicles are a major source of secondary organic aerosol (SOA) in urban areas. We investigated SOA formation by oxidizing dilute, ambient-level exhaust concentrations from a fleet of on-road gasoline vehicles in a smog chamber. We measured less SOA formation from newer vehicles meeting more stringent emissions standards. This suggests that the natural replacement of older vehicles with newer ones that meet more stringent emissions standards should reduce SOA levels in urban environments. However, SOA production depends on both precursor concentrations (emissions) and atmospheric chemistry (SOA yields)...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28630316/recombinant-silicateins-as-model-biocatalysts-in-organosiloxane-chemistry
#16
S Yasin Tabatabaei Dakhili, Stephanie A Caslin, Abayomi S Faponle, Peter Quayle, Sam P de Visser, Lu Shin Wong
The family of silicatein enzymes from marine sponges (phylum Porifera) is unique in nature for catalyzing the formation of inorganic silica structures, which the organisms incorporate into their skeleton. However, the synthesis of organosiloxanes catalyzed by these enzymes has thus far remained largely unexplored. To investigate the reactivity of these enzymes in relation to this important class of compounds, their catalysis of Si-O bond hydrolysis and condensation was investigated with a range of model organosilanols and silyl ethers...
June 19, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28629133/propolis-diterpenes-as-a-remarkable-bio-source-for-drug-discovery-development-a-review
#17
REVIEW
Noushin Aminimoghadamfarouj, Alireza Nematollahi
Propolis is one of the complex, but valuable, bio-sources for discovering therapeutic compounds. Diterpenes are organic compounds composed of four isoprene units and are known for their biological and pharmacological characteristics, such as antibacterial, anticancer, and anti-inflammatory activities. Recently, advancements have been made in the development of antibacterial and anticancer leads from propolis-isolated diterpenes, and scrutiny of these compounds is being pursued. Thus, this review covers the progress in this arena, with a focus on the chemistry and biological activities of propolis diterpenes...
June 17, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28628253/3d-atomic-scale-insights-into-anisotropic-core-shell-structured-ingaas-nanowires-grown-by-metal-organic-chemical-vapor-deposition
#18
Jiangtao Qu, Sichao Du, Tim Burgess, Changhong Wang, Xiangyuan Cui, Qiang Gao, Weichao Wang, Hark Hoe Tan, Hui Liu, Chennupati Jagadish, Yingjie Zhang, Hansheng Chen, Mansoor Khan, Simon Ringer, Rongkun Zheng
III-V ternary InGaAs nanowires have great potential for electronic and optoelectronic device applications; however, the 3D structure and chemistry at the atomic-scale inside the nanowires remain unclear, which hinders tailoring the nanowires for specific applications. Here, atom probe tomography is used in conjunction with a first-principles simulation to investigate the 3D structure and chemistry of InGaAs nanowires, and reveals i) the nanowires form a spontaneous core-shell structure with a Ga-enriched core and an In-enriched shell, due to different growth mechanisms in the axial and lateral directions; ii) the shape of the core evolves from hexagon into Reuleaux triangle and grows larger, which results from In outward and Ga inward interdiffusion occurring at the core-shell interface; and iii) the irregular hexagonal shell manifests an anisotropic growth rate on {112}A and {112}B facets...
June 19, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28628248/kinetic-selectivity-and-thermodynamic-features-of-competitive-imine-formation-in-dynamic-covalent-chemistry
#19
Jean-Marie Lehn, Sirinan Kulchat, Manuel N Chaur
The kinetic and thermodynamic selectivities of imine formation have been investigated for several dynamic covalent libraries of aldehydes and amines. Two systems were examined, involving the reaction of different types of primary amino groups (aliphatic amines, alkoxy-amines, hydrazides and hydrazines) with two types of aldehydes, sulfobenzaldehyde and pyridoxal phosphate in aqueous solution at different pD (5.0, 8.5, 11.4) on one hand, 2-pyridinecarboxaldehyde and salicylaldehyde in organic solvents on the other hand...
June 19, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28626563/chemistry-with-semi-classical-electrons-reaction-trajectories-auto-generated-by-sub-atomistic-force-fields
#20
Chen Bai, Seyit Kale, Judith Herzfeld
For a century now, "Lewis dots" have been a mainstay of chemical thinking, teaching and communication. However, chemists have assumed that this semi-classical picture of electrons needs to be abandoned for quantitative work, and the recourse in computational simulations has been to the extremes of first principles treatments of electrons on the one hand and force fields that avoid explicit electrons on the other hand. Given both the successes and limitations of these highly divergent approaches, it seems worth considering whether the Lewis dot picture might be made quantitative after all...
June 1, 2017: Chemical Science
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