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Organic chemistry

Pollyana Trigueiro, Silvia Pedetti, Baptiste Rigaud, Sebastien Balme, Jean-Marc Janot, Ieda M G Dos Santos, Régis Gougeon, Maria G Fonseca, Thomas Georgelin, Maguy Jaber
Wine chemistry inspires and challenges with its complexity and intriguing composition. In this context, the composites based on the use of a model protein, a polyphenol of interest and montmorillonite in a model hydroalcoholic solution have been studied. A set of experimental characterization techniques highlighted the interactions between the organic and the inorganic parts in the composite. The amount of the organic part was determined by ultraviolet-visible (UV-VIS) and thermal analysis. X-ray diffraction (XRD) and transmission electronic microscopy (TEM) informed about the stacking/exfoliation of the layers in the composites...
March 6, 2018: Colloids and Surfaces. B, Biointerfaces
Stéphanie Essafi, Jeremy N Harvey
For condensed-phase reactions, commonly used kinetic models assume that energy exchange from and to solvent molecules is much faster than any reactive steps. However, it is becoming increasingly evident that this does not always hold true. In this work, we use molecular dynamics simulations to explore the timescale for energy transfer between solvent and solute in some typical organic solvents. As a reference, energy transfer between solvent molecules is also considered. The timescale is found to depend most strongly on the identity of the solvent...
March 16, 2018: Journal of Physical Chemistry. A
Pengfei Zhang, Yu Zhou, Xu Han, Jinyi Xu, Hong Liu
The dearomatizing annulation reaction is a significant challenge in organic chemistry. The direct activation of α-carbons of simple saturated esters, as nucleophiles, is an important synthesis strategy. In the present study, we disclose [3+2] dearomatizing annulation reactions with direct activating α-carbons of saturated carboxylic esters and N-iminoisoquinolinium ylides, which possess highly enantioselective characteristics, catalyzed by N-heterocyclic carbenes (NHCs). The protocol achieves isoquinoline dearomatization and the construction of tricyclic chiral products under mild conditions with good yield, substrate tolerance, diastereoselectivity, and excellent enantioselectivity...
March 16, 2018: Journal of Organic Chemistry
Peter L Cummins, Babu Kannappan, Jill E Gready
The ubiquitous enzyme Ribulose 1,5-bisphosphate carboxylase-oxygenase (RuBisCO) fixes atmospheric carbon dioxide within the Calvin-Benson cycle that is utilized by most photosynthetic organisms. Despite this central role, RuBisCO's efficiency surprisingly struggles, with both a very slow turnover rate to products and also impaired substrate specificity, features that have long been an enigma as it would be assumed that its efficiency was under strong evolutionary pressure. RuBisCO's substrate specificity is compromised as it catalyzes a side-fixation reaction with atmospheric oxygen; empirical kinetic results show a trend to tradeoff between relative specificity and low catalytic turnover rate...
2018: Frontiers in Plant Science
Makoto Ashiuchi, Yuichi Hakumai, Sawami Nakayama, Haruna Higashiuchi, Kosuke Shimada
We are now entering a new age of intelligent material development using fine, sustainable polymers from extremophiles. Herein we present an innovative (but simple) means of transforming archaeal poly-γ-glutamate (PGA) into extremely durable polyionic complexes with potent antimicrobial performance. This new supra-polymer material (called PGA/DEQ) was subjected to nuclear magnetic resonance and X-ray diffraction spectroscopies to characterize in structural chemistry. Calorimetric measurements revealed its peculiar thermal properties; to the best of our knowledge, it is one of the most heat-resistant biopolymer-based polyionic complexes developed to date...
March 15, 2018: Scientific Reports
Julien Arsenault, Julie Talbot, Tim R Moore
Pools are common in northern peatlands but studies have seldom focused on their nutrient biogeochemistry, especially in relation to their morphological characteristics and through seasons. We determined the environmental characteristics controlling carbon (C), nitrogen (N) and phosphorus (P) biogeochemistry in pools and assessed their evolution over the course of the 2016 growing season in a subboreal ombrotrophic peatland of eastern Canada. We showed that water chemistry variations in 62 pools were significantly explained by depth (81...
March 12, 2018: Science of the Total Environment
Debra A Davis, Sparkle L Malone, Charles R Lovell
Drought has many consequences in the tidally dominated Spartina sp. salt marshes of the southeastern US; including major dieback events, changes in sediment chemistry and obvious changes in the landscape. These coastal systems tend to be highly productive, yet many salt marshes are also nitrogen limited and depend on plant associated diazotrophs as their source of 'new' nitrogen. A 4-year study was conducted to investigate the structure and composition of the rhizosphere diazotroph assemblages associated with 5 distinct plant zones in one such salt marsh...
March 15, 2018: Microorganisms
Qing Li, Biao Yang, Jonas Björk, Qigang Zhong, Huanxin Ju, Junjie Zhang, Nan Cao, Ziliang Shi, Haiming Zhang, Daniel Ebeling, Andre Schirmeisen, Junfa Zhu, Lifeng Chi
Hierarchical control of chemical reactions is being considered as one of the most ambitious and challenging topics in modern organic chemistry. In this study, we have realized the one-by-one scission of the X-H bonds (X=N and C) of aromatic amines in a controlled fashion on the Cu(111) surface. Each dehydrogenation reaction leads to certain metal-organic supramolecular structures, which were monitored in single-bond resolution via scanning tunneling microscopy and non-contact atomic force microscopy. Moreover, the reaction pathways were elucidated from X-ray photoelectron spectroscopy measurements and density functional theory calculations...
March 15, 2018: Journal of the American Chemical Society
Beatriz Bernardo-Maestro, Elisa Garrido-Martín, Fernando López-Arbeloa, Joaquín Pérez-Pariente, Luis Gómez-Hortigüela
In an attempt to promote the crystallization of chiral inorganic frameworks, we explore the ability of chiral (1R,2S)-ephedrine and its diastereoisomer (1S,2S)-pseudoephedrine to act as organic building blocks for the crystallization of hybrid organo-inorganic aluminophosphate frameworks in the presence of fluoride. These molecules were selected because of their particular molecular asymmetric structure, which enables a rich supramolecular chemistry and a potential chiral recognition phenomenon during crystallization...
March 15, 2018: Physical Chemistry Chemical Physics: PCCP
Penny S Reynolds, Bernard J Fisher, Jacquelyn McCarter, Christopher Sweeney, Erika J Martin, Paul Middleton, Matthew Ellenberg, Evan Fowler, Donald F Brophy, Alpha A Fowler, Bruce D Spiess, Ramesh Natarajan
BACKGROUND: Coagulopathy and inflammation induced by hemorrhagic shock and traumatic injury are associated with increased mortality and morbidity. Vitamin C (VitC) is an antioxidant with potential protective effects on the pro-inflammatory and pro-coagulant pathways. We hypothesized that high-dose VitC administered as a supplement to fluid resuscitation would attenuate inflammation, coagulation dysfunction, and end-organ tissue damage in a swine model of polytrauma and hemorrhage. METHODS: Male Sinclair swine (n = 24; mean body weight 27 kg) were anesthetized, intubated, mechanically ventilated, and instrumented for physiological monitoring...
March 12, 2018: Journal of Trauma and Acute Care Surgery
Anchal Gahlaut, Manikandan Paranjothy
Formamide (NH2 CHO), being the simplest organic molecule containing an amide functional group, serves as a prototype to study protein and peptide chemistry. Formamide has been found in Comets and interstellar media and its decomposition results in smaller molecules such as NH3 , CO, HCN, HNCO, etc. These smaller molecules are considered to have been potential precursors for the formation of complex biological molecules, such as nucleic acids and nucleobases, in the early Earth. Several experimental and theoretical investigations of formamide decomposition have been reported in the literature...
March 14, 2018: Physical Chemistry Chemical Physics: PCCP
Hiang Kwee Lee, Charlynn Sher Lin Koh, Yih Hong Lee, Chong Liu, In Yee Phang, Xuemei Han, Chia-Kuang Tsung, Xing Yi Ling
Electrochemical nitrogen-to-ammonia fixation is emerging as a sustainable strategy to tackle the hydrogen- and energy-intensive operations by Haber-Bosch process for ammonia production. However, current electrochemical nitrogen reduction reaction (NRR) progress is impeded by overwhelming competition from the hydrogen evolution reaction (HER) across all traditional NRR catalysts and the requirement for elevated temperature/pressure. We achieve both excellent NRR selectivity (~90%) and a significant boost to Faradic efficiency by 10 percentage points even at ambient operations by coating a superhydrophobic metal-organic framework (MOF) layer over the NRR electrocatalyst...
March 2018: Science Advances
Ayda Nemati Vesali Azar, Seda Keskin
Efficient separation of acetylene (C2 H2 ) from CO2 and CH4 is important to meet the requirement of high-purity acetylene in various industrial applications. Metal organic frameworks (MOFs) are great candidates for adsorption-based C2 H2 /CO2 and C2 H2 /CH4 separations due to their unique properties such as wide range of pore sizes and tunable chemistries. Experimental studies on the limited number of MOFs revealed that MOFs offer remarkable C2 H2 /CO2 and C2 H2 /CH4 selectivities based on single-component adsorption data...
2018: Frontiers in Chemistry
Detlef Ulrich, Steffen Kecke, Klaus Olbricht
The strawberry, with its unique aroma, is one of the most popular fruits worldwide. The demand for specific knowledge of metabolism in strawberries is increasing. This knowledge is applicable for genetic studies, plant breeding, resistance research, nutritional science, and the processing industry. The molecular basis of strawberry aroma has been studied for more than 80 years. Thus far, hundreds of volatile organic compounds (VOC) have been identified. The qualitative composition of the strawberry volatilome remains controversial though considerable progress has been made during the past several decades...
March 13, 2018: Journal of Agricultural and Food Chemistry
Ralph Freund, Ulrich Lächelt, Tobias Gruber, Bastian Rühle, Stefan Wuttke
Green chemistry, in particular, the principle of atom economy, has defined new criteria for the efficient and sustainable production of synthetic compounds. In complex nanomaterials, the number of embedded functional entities and the energy expenditure of the assembly process represent additional compound-associated parameters that can be evaluated from an economic viewpoint. In this Perspective, we extend the principle of atom economy to the study and characterization of multifunctionality in nanocarriers, which we define as "multifunctional efficiency"...
March 13, 2018: ACS Nano
Heiko Sommer, Francisco Juliá-Hernández, Ruben Martin, Ilan Marek
The distant and selective activation of unreactive C-H and C-C bonds remains one of the biggest challenges in organic chemistry. In recent years, the development of remote functionalization has received growing interest as it allows for the activation of rather challenging C-H and C-C bonds distant from the initiation point by means of a "metal-walk". A "metal-walk" or "chain-walk" is defined by an iterative series of consecutive 1,2- or 1,3-hydride shifts of a metal complex along a single hydrocarbon chain...
February 28, 2018: ACS Central Science
Karen M Lammers, Maria G Herrera, Veronica I Dodero
Gluten-related disorders are a complex group of diseases that involve the activation of the immune system triggered by the ingestion of gluten. Among these, celiac disease, with a prevalence of 1 %, is the most investigated, but recently, a new pathology, named nonceliac gluten sensitivity, was reported with a general prevalence of 7 %. Finally, there other less-prevalent gluten-related diseases such as wheat allergy, gluten ataxia, and dermatitis herpetiformis (with an overall prevalence of less than 0...
March 2018: ChemistryOpen
Megan Suzanne Claflin, Paul J Ziemann
Substantial amounts of gas- and particle-phase organic nitrates have been reported in field studies of atmospheric chemistry conducted around the world, and it has been proposed that a significant fraction of these may be formed from the nighttime reaction of monoterpenes with NO3 radicals. In the study presented here, β-pinene (a major global monoterpene emission) was reacted with NO3 radicals in an environmental chamber and the molecular and functional group composition of the resulting secondary organic aerosol (SOA) was determined using a variety of methods...
March 12, 2018: Journal of Physical Chemistry. A
Andrew Johnston, Keith Rogers
A compositionally simplified analogue of a latent fingermark was created by combining single representatives of each major component of a natural fingermark. Further modified analogues were also produced each having one component removed. The aim of this study was to investigate the intermolecular interactions that occurred within these analogue samples using Fourier Transform Infrared (FT-IR) Microspectroscopy. FT-IR microspectroscopy showed that the absence of squalene and cholesterol significantly restricted the interactions between the other organic constituents within the analogue samples...
March 2018: Science & Justice: Journal of the Forensic Science Society
Kelsey Craig
Sulfur dioxide (SO2 ) is an atmospheric pollutant that is moderately persistent in the atmosphere and highly water soluble. When applied as a pesticide, SO2 may be transported, deposited, or transformed in various chemical reactions. SO2 participates in the sulfur biogeochemical cycle, which involves complex reactions of sulfur-containing compounds between abiotic and biotic components of ecosystems. The main degradation route of SO2 is atmospheric oxidation, and sulfur oxides may undergo long-distance transport prior to removal from the atmosphere by wet or dry deposition...
March 11, 2018: Reviews of Environmental Contamination and Toxicology
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