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Organic chemistry

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https://www.readbyqxmd.com/read/28448934/release-of-dissolved-phosphorus-from-riparian-wetlands-evidence-for-complex-interactions-among-hydroclimate-variability-topography-and-soil-properties
#1
Sen Gu, Gérard Gruau, Rémi Dupas, Cornélia Rumpel, Alexandra Crème, Ophélie Fovet, Chantal Gascuel-Odoux, Laurent Jeanneau, Guillaume Humbert, Patrice Petitjean
In agricultural landscapes, establishment of vegetated buffer zones in riparian wetlands (RWs) is promoted to decrease phosphorus (P) emissions because RWs can trap particulate P from upslope fields. However, long-term accumulation of P risks the release of dissolved P, since the unstable hydrological conditions in these zones may mobilize accumulated particulate P by transforming it into a mobile dissolved P species. This study evaluates how hydroclimate variability, topography and soil properties interact and influence this mobilization, using a three-year dataset of molybdate-reactive dissolved P (MRDP) and total dissolved P (TDP) concentrations in soil water from two RWs located in an agricultural catchment in western France (Kervidy-Naizin), along with stream P concentrations...
April 24, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28448621/biochar-from-kon-tiki-flame-curtain-and-other-kilns-effects-of-nutrient-enrichment-and-kiln-type-on-crop-yield-and-soil-chemistry
#2
Naba Raj Pandit, Jan Mulder, Sarah Elisabeth Hale, Hans Peter Schmidt, Gerard Cornelissen
Biochar application to soils has been investigated as a means of improving soil fertility and mitigating climate change through soil carbon sequestration. In the present work, the invasive shrub "Eupatorium adenophorum" was utilized as a sustainable feedstock for making biochar under different pyrolysis conditions in Nepal. Biochar was produced using several different types of kilns; four sub types of flame curtain kilns (deep-cone metal kiln, steel shielded soil pit, conical soil pit and steel small cone), brick-made traditional kiln, traditional earth-mound kiln and top lift up draft (TLUD)...
2017: PloS One
https://www.readbyqxmd.com/read/28447369/distortion-interaction-activation-strain-model-to-analyze-reaction-rates
#3
F Matthias Bickelhaupt, Kendall Newcomb Houk
The Activation Strain or Distortion/Interaction Model is a tool to analyze activation barriers that determine reaction rates. For bimolecular reactions, the activation energies are the sum of the energies to distort the reactants into geometries they have in transition states plus the energies of interaction between the two distorted molecules. The energy to distort the molecules is called the activation strain or distortion energy. This energy is the principal contribution to the activation barrier. The transition state occurs when this activation strain is overcome by stabilizing interaction energy...
April 26, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28446711/chemical-roots-of-biological-evolution-the-origins-of-life-as-a-process-of-development-of-autonomous-functional-systems
#4
REVIEW
Kepa Ruiz-Mirazo, Carlos Briones, Andrés de la Escosura
In recent years, an extension of the Darwinian framework is being considered for the study of prebiotic chemical evolution, shifting the attention from homogeneous populations of naked molecular species to populations of heterogeneous, compartmentalized and functionally integrated assemblies of molecules. Several implications of this shift of perspective are analysed in this critical review, both in terms of the individual units, which require an adequate characterization as self-maintaining systems with an internal organization, and also in relation to their collective and long-term evolutionary dynamics, based on competition, collaboration and selection processes among those complex individuals...
April 2017: Open Biology
https://www.readbyqxmd.com/read/28445639/toward-covalent-organic-frameworks-bearing-three-different-kinds-of-pores-the-strategy-for-construction-and-cof-to-cof-transformation-via-heterogeneous-linker-exchange
#5
Cheng Qian, Qiao-Yan Qi, Guo-Fang Jiang, Fu-Zhi Cui, Yuan Tian, Xin Zhao
Covalent organic frameworks (COFs) are an emerging class of crystalline porous organic materials which are fabricated via reticular chemistry. Their topologic structures can be precisely predicted on the basis of the structures of building blocks. However, constructing COF with complicated structures has remained a great challenge, due to the limited strategies that can access to structural complexity of COFs. In this work, we have developed a new approach to produce COFs bearing three different kinds of pores...
April 26, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28443929/construction-of-protein-assemblies-by-host-guest-interactions-with-cucurbiturils
#6
REVIEW
Chunxi Hou, Zupeng Huang, Yu Fang, Junqiu Liu
Protein assemblies are extremely interesting in chemistry and supramolecular chemistry. How to design protein assemblies with dimensional structures is important for applications. To address this challenge, cucurbituril (CB[n]s)-based strategies have been explored owing to their high affinity toward small peptide motifs, organic cations and amines. By incorporation of a small molecule guest and a peptide motif guest into N-terminals of oligomeric proteins, CB[n]s could recognize and bind to the N-terminal guests, leading to dimensional protein assemblies...
April 26, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28443923/use-of-alcl3-in-friedel-crafts-arylation-type-reactions-and-beyond-an-overview-on-the-development-of-unique-methodologies-leading-to-n-heteroarenes
#7
REVIEW
Rajnikanth Sunke, Suresh Babu Nallapati, Jetta Sandeep Kumar, K Shiva Kumar, Manojit Pal
As a privileged class of heterocyclic compounds N-heteroarenes have found enormous applications in many areas including medicinal/pharmaceutical chemistry and drug discovery. Consequently, a wide variety of methods have been reported for their synthesis. While not free from their own limitations the AlCl3 mediated methods appeared to have some particular advantages in preparing a number of useful N-heteroarenes. Besides the famous Friedel-Crafts (FC) alkylation/acylation reactions one such example is AlCl3-induced heteroarylation of arenes and heteroarenes (FC arylation type reactions) that can be used to prepare a certain class of N-heteroarenes in an operationally simple, efficient and cost effective manner...
April 26, 2017: Organic & Biomolecular Chemistry
https://www.readbyqxmd.com/read/28443894/taste-and-smell-in-aquatic-and-terrestrial-environments
#8
REVIEW
E Mollo, M J Garson, G Polese, P Amodeo, M T Ghiselin
Covering: up to 2017The review summarizes results up to 2017 on chemosensory cues occurring in both aquatic and terrestrial environments. The chemicals are grouped by their physicochemical properties to compare their potential mobility in the different media. In contrast to what is widely asserted in the literature, the report emphasizes that living organisms encounter and sense molecules of various degrees of solubility and volatility both on land and in aquatic environments. The picture that emerges from the review suggests a substantial revision of the traditional definitions of the chemical senses based on their spatial range, which is currently orienting the literature on chemosensory signaling, in favor of a new vision based on the natural products that are the actual mediators of the chemosensory perceptions...
April 26, 2017: Natural Product Reports
https://www.readbyqxmd.com/read/28443869/a-chiral-member-of-the-family-of-organic-hexameric-cages
#9
M Wierzbicki, A A Głowacka, M P Szymański, A Szumna
A cubic nanocage (O symmetry) that exhibits inherent chirality and has a covalent, rigid skeleton with molecule-sized entrance portals was obtained by means of dynamic covalent chemistry using a reaction between aldehyde-functionalized resorcin[4]arene and hydrazine.
April 26, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28443863/-fefe-hydrogenase-active-site-model-chemistry-in-a-uio-66-metal-organic-framework
#10
Sonja Pullen, Souvik Roy, Sascha Ott
The reactivity of [Fe2(dcbdt)(CO)6] (1) confined in a UiO-66(Zr) metal-organic framework towards CO ligand substitutions with phosphines of different sizes was investigated. The reaction with smaller phosphines (PX3, X = Me, Et) is more selective compared to analogous reactions in homogenous solution phase, and two CO ligands at up to 80% of all [FeFe] sites in UiO-66-1 are replaced. The produced [Fe2(dcbdt)(CO)4(PX3)2] complexes in the UiO-66 matrix behave like typical [FeFe] hydrogenase active site model complexes, are reduced at more cathodic potentials than their hexacarbonyl analogues, and form bridging hydrides under acidic conditions...
April 26, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28442410/subchronic-feeding-study-of-high-free-lysine-transgenic-rice-in-sprague-dawley-rats
#11
Qing-Qing Yang, Xiao-Yun He, Hong-Yu Wu, Chang-Quan Zhang, Shi-Ying Zou, Tian-Qi Lang, Samuel Sai-Ming Sun, Qiao-Quan Liu
Lysine is considered to be the first essential amino acid in rice. An elite High-Free-Lysine transgenic line HFL1 was previously produced by metabolic engineering to regulate lysine metabolism. In this study, a 90-day toxicology experiment was undertaken to investigate the potential health effect of feeding different doses of HFL1 rice to Sprague-Dawley rats. During the trial, body weight gain, food consumption and food efficiency were recorded, and no adverse effect was observed in rats fed transgenic (T) rice diets compared with non-transgenic (N) or control diets...
April 22, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/28441481/best-practices-of-computer-aided-drug-discovery-cadd-lessons-learned-from-the-development-of-a-preclinical-candidate-for-prostate-cancer-with-a-new-mechanism-of-action
#12
Fuqiang Ban, Kush Dalal, Huifang Li, Eric LeBlanc, Paul S Rennie, Artem Cherkasov
Small-molecule drug design is a complex and iterative decision-making process relying on pre-existing knowledge and driven by experimental data. Low molecular weight chemicals represent an attractive therapeutic option as they are readily accessible to organic synthesis and can easily be characterized.1 Their potency, as well as pharmacokinetic and pharmacodynamic properties can be systematically and rationally investigated, and ultimately optimized via expert science behind medicinal chemistry and methods of computer-aided drug design (CADD)...
April 25, 2017: Journal of Chemical Information and Modeling
https://www.readbyqxmd.com/read/28440646/aqueous-reaction-of-dicarbonyls-with-ammonia-as-a-potential-source-of-organic-nitrogen-in-airborne-nanoparticles
#13
Christopher M Stangl, Murray V Johnston
Nitrogen-containing organic species such as imines and imidazoles can be formed by aqueous reactions of carbonyl-containing compounds in the presence of ammonia. In the work described here, these reactions are studied in airborne aqueous nanodroplets containing ammonium sulfate and glyoxal, methylglyoxal, or glycolaldehyde using a combination of online and offline mass spectrometry. N/C ratios attributed to the organic fraction of the particles (N/Corg) produced from glyoxal and methylglyoxal were quantified across a wide relative humidity range...
April 25, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28439687/colloid-characterization-and-in-situ-release-in-shallow-groundwater-under-different-hydrogeology-conditions
#14
Jingjing Zhou, Dan Liu, Wenjing Zhang, Xuequn Chen, Ying Huan, Xipeng Yu
Changes to groundwater hydrodynamics and chemistry can lead to colloid release that can have a major impact on the groundwater environment. To analyze the effects of colloid release caused by artificial groundwater recharge, field and laboratory tests on colloid characterization and colloid release were conducted. The field tests were carried out at an artificial recharge test site in Shandong Province. In the field investigation, one recharge water sample and five groundwater samples were collected and filtered through three levels of ultrafiltration membranes, with pore sizes of 0...
April 24, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28437104/redox-active-macrocycles-for-organic-rechargeable-batteries
#15
Dong Jun Kim, Keith R Hermann, Aleksandrs Prokofjevs, Michael T Otley, Cristian Pezzato, Magdalena Owczarek, J Fraser Stoddart
Organic rechargeable batteries, composed of redox-active molecules, are emerging as candidates for the next generation of energy storage materials because of their large specific capacities, cost effectiveness, and the abundance of organic precursors, when compared with conventional lithium-ion batteries. Although redox-active molecules often display multiple redox states, precise control of a molecule's redox potential, leading to a single output voltage in a battery, remains a fundamental challenge in this popular field of research...
April 24, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28437097/total-syntheses-of-vancomycin-related-glycopeptide-antibiotics-and-key-analogues
#16
Akinori Okano, Nicholas A Isley, Dale L Boger
A review of efforts that have provided total syntheses of vancomycin and related glycopeptide antibiotics, their agylcons, and key analogues is provided. It is a tribute to developments in organic chemistry and the field of organic synthesis that not only can molecules of this complexity be prepared today by total synthesis but such efforts can be extended to the preparation of previously inaccessible key analogues that contain deep-seated structural changes. With the increasing prevalence of acquired bacterial resistance to existing classes of antibiotics and with the emergence of vancomycin-resistant pathogens (VRSA and VRE), the studies pave the way for the examination of synthetic analogues rationally designed to not only overcome vancomycin resistance but provide the foundation for the development of even more powerful and durable antibiotics...
April 24, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28436674/general-dialdehyde-click-chemistry-for-amine-bioconjugation
#17
Sina Elahipanah, Paul J O'Brien, Dmitry Rogozhnikov, Muhammad N Yousaf
The development of methods for conjugating a range of molecules to primary amine functional groups has revolutionized the fields of chemistry, biology, and material science. The primary amine is a key functional group and one of the most important nucleophiles and bases used in all of synthetic chemistry. Therefore, tremendous interest in the synthesis of molecules containing primary amines and strategies to devise chemical reactions to react with primary amines has been at the core of chemical research. In particular, primary amines are a ubiquitous functional group found in biological systems as free amino acids, as key side chain lysines in proteins, and in signaling molecules and metabolites and are also present in many natural product classes...
April 24, 2017: Bioconjugate Chemistry
https://www.readbyqxmd.com/read/28436651/synthesis-of-dicarba-closo-dodecaborane-1-carboxamides
#18
Matthias S Scholz, Lukas M Wingen
Amide bond formation is one of the most important chemical reactions. In peptide and organic chemistry, the application of amide coupling reagents is a routine strategy, but surprisingly not in carborane chemistry. Thus, we now report a fast, safe, and robust protocol to couple amines to m- and p-dicarba-closo-dodecaborane-1-carboxylic acids. The procedure comprises the activation of carboxylic acid with the coupling reagent (1-cyano-2-ethoxy-2-oxoethylidenaminooxy)(dimethylamino)morpholinocarbenium hexafluorophosphate, extraction of the product using the hydrophobic nature of the cluster, and a straightforward chromatographic purification...
April 24, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28436505/well-defined-functional-mesoporous-silica-polymer-hybrids-prepared-by-an-icar-atrp-technique-integrated-with-bio-inspired-polydopamine-chemistry-for-lithium-isotope-separation
#19
Yuekun Liu, Xuegang Liu, Gang Ye, Yang Song, Fei Liu, Xiaomei Huo, Jing Chen
Mesoporous silica/polymer hybrids with well-preserved mesoporosity were prepared by integrating the initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) technique with the bio-inspired polydopamine (PDA) chemistry. By manipulating the auto-oxidative polymerization of dopamine, uniform PDA layers were deposited on the surfaces and pore walls of ordered mesoporous silicas (OMSs), thereby promoting the immobilization of ATRP initiators. Poly(glycidyl methacrylate) (PGMA) brushes were then grown from the OMSs by using the ICAR ATRP technique...
April 24, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28436497/metal-ion-binding-by-laterally-non-symmetric-macrobicyclic-oxa-aza-cryptands
#20
Parimal K Bharadwaj
Macrobicyclic cryptands incorporating amine groups along with oxygen donors that are laterally non-symmetric constitute an important class of organic compounds. These molecules can form inclusion complexes with different transition and main group metal ions. It is also possible to modify the binding characteristics of these compounds through attachment of different groups. Some of these metal complexes can be useful homogeneous catalysts in different organic transformations. If there are chiral centers present in the cryptands, they can be useful in asymmetric syntheses...
April 24, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
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