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https://www.readbyqxmd.com/read/28335484/energy-of-intramolecular-hydrogen-bonding-in-ortho-hydroxybenzaldehydes-phenones-and-quinones-transfer-of-aromaticity-from-ipso-benzene-ring-to-the-enol-system-s
#1
Danuta Rusinska-Roszak
Intramolecular hydrogen bonding (HB) is one of the most studied noncovalent interactions of molecules. Many physical, spectral, and topological properties of compounds are under the influence of HB, and there are many parameters used to notice and to describe these changes. Hitherto, no general method of measurement of the energy of intramolecular hydrogen bond (EHB) has been put into effect. We propose the molecular tailoring approach (MTA) for EHB calculation, modified to apply it to Ar-O-H∙∙∙O=C systems...
March 18, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28333118/synthesis-of-novel-saccharin-derivatives
#2
Gregory M Rankin, Sally-Ann Poulsen
The synthesis of saccharin (1,2-benzisothiazol-3-one-1,1-dioxide) derivatives substituted on the benzene ring has seen limited development despite the longevity of this compound's use as an artificial sweetener. This type of saccharin derivative would however present attractive properties for the development of new bioactive, drug-like small molecule compounds. Here we report the derivatisation of the benzene ring of saccharin using Cu(I)-catalyzed azide alkyne cycloaddition (CuAAC) to synthesise a diverse library of novel saccharin-1,2,3-triazole conjugates...
March 23, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28333065/preparation-of-mesoporous-tio2-with-enhanced-photocatalytic-activity-towards-tannery-wastewater-degradation
#3
Weiwei Zhao, Xiu He, Yu Peng, Hongfeng Zhang, Donglan Sun, Xiaocong Wang
Ordered mesoporous TiO2 materials are successfully synthesized via a sol-gel route using butyl titanate as a precursor and sodium dodecyl benzene sulfonate surfactants as soft templates. The as-prepared TiO2 samples possess a relatively high surface area of 40.03 m(2)/g and the center of pore diameter distribution of 13.04 nm. They exhibit excellent photocatalytic activity towards degradation of organic pollutants in tannery wastewater under UV-light and natural sunlight irradiation. The effect of the catalyst dosage, the pH value of the solution and the concentration of H2O2 are discussed in detail...
March 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28333050/oxidative-treatment-of-diclofenac-via-ferrate-vi-in-aqueous-media-effect-of-surfactant-additives
#4
Yingling Wang, Tianjun Ni, Jianmei Yuan, Chunfeng Wang, Guoguang Liu
The potential reaction of diclofenac (DCF) with ferrate(VI) and influences of coexisting surfactants have not been investigated in depth, and are the focus of this study. The results demonstrated that DCF reacted effectively and rapidly with Fe(VI) and approximately 75% of DCF (0.03 mM) was removed by excess Fe(VI) (0.45 mM) within 10 min. All of the reactions followed pseudo first-order kinetics with respect to DCF and Fe(VI), where the apparent second-order rate constant (kapp) was 5.07 M(-1) s(-1) at pH 9...
March 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
https://www.readbyqxmd.com/read/28332743/nitrene-radical-approach-to-saturated-heterocycles-cobalt-porphyrin-catalysed-intramolecular-ring-closing-c-h-amination-of-aliphatic-azides
#5
Bas de Bruin, Petrus F Kuijpers, Martijn J Tiekink, Willem B Breukelaar, Daniël L J Broere, Nicolaas P van Leest, Jarl Ivar van der Vlugt, Joost N H Reek
Cobalt porphyrin catalysed intramolecular ring-closing C-H bond amination enables direct synthesis of various N-heterocycles from aliphatic azides. Pyrrolidines, oxazolidines imidazolidines, isoindolines and tetrahydroisoquinoline can be obtained in good to excellent yields in a single reaction step with an air and moisture stable catalyst. Kinetic studies of the reaction in combination with DFT calculations reveal a metallo-radical-type mechanism involving rate limiting azide activation to form the key cobalt(III)-nitrene radical intermediate...
March 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28332232/paper-based-colorimetric-sensor-system-for-high-throughput-screening-of-c-h-borylation
#6
Han-Sung Kim, Min Sik Eom, Min Su Han, Sunwoo Lee
A paper-based colorimetric sensor system (PBCSS) was developed to detect the amount of bis(pinacolato)diboron (B2Pin2) and applied as a high-throughput screening protocol in Ir-catalyzed C-H borylation. First, 96 ligands were screened for the borylation of benzene, and then 12 of them were selected and tested for five substrates. These reaction mixtures were spotted in the PBCSS, showing a blue-violet color. The value of the gray scale of each reaction was obtained from these colored spots and converted to the extent of conversion of B2Pin2...
March 22, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28330693/evaluation-of-sediment-contamination-by-monoaromatic-hydrocarbons-in-the-coastal-lagoons-of-gulf-of-saros-ne-aegean-sea
#7
Selma Ünlü, Bedri Alpar
The concentrations and distribution of monoaromatic hydrocarbons (benzene, toluene, ethyl benzene and the sum of m-, p- and o-, xylenes) were determined in the sediments of coastal lagoons of the Gulf of Saros, using a static headspace GC-MS. The total concentrations of BTEX compounds ranged from 368.5 to below detection limit 0.6μgkg(-1) dw, with a mean value of 61.5μgkg(-1) dw. The light aromatic fraction of m-, p-xylene was the most abundant compound (57.1% in average), and followed by toluene (38.1%)>ethylbenzene (4...
March 19, 2017: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/28330217/sulfitolytic-and-keratinolytic-potential-of-chryseobacterium-sp-rbt-revealed-hydrolysis-of-melanin-containing-feathers
#8
Ranjit G Gurav, Jingchun Tang, Jyoti P Jadhav
In black feathers, melanin is embedded in keratin matrix that makes feather more resistance to the microbial degradation. Chryseobacterium sp. RBT previously isolated from the poultry waste disposable site revealed strong sulfitolytic and keratinolytic activities. Maximum keratinase activity was observed at 48 h (89.12 U ml(-1)) showed 83 % of native black feather degradation. The concentration of free sulfhydryl groups released during degradation was 0.648 × 10(-4) M (12 h), 2.144 × 10(-4) M (96 h), and however, declined on prolong incubation to 1...
December 2016: 3 Biotech
https://www.readbyqxmd.com/read/28330095/potential-mosquito-repellent-compounds-of-ocimum-species-against-3n7h-and-3q8i-of-anopheles-gambiae
#9
Venugopal Gaddaguti, Talluri Venkateswara Rao, Allu Prasada Rao
Mosquitoes are exceptionally efficient in detecting their hosts for blood meal using odorant binding proteins, viz. 3N7H and 3Q8I and spread several dreadful diseases. DEET is a synthetic mosquito repellent widely used all over world for protection against mosquito bite. Reports reveal that, synthetic mosquito repellents may pose health problems in considerably large population. In view of the above fact, we made an attempt to discover efficient and novel natural mosquito repellent compounds with least impact on human health...
June 2016: 3 Biotech
https://www.readbyqxmd.com/read/28330077/diversity-and-antagonistic-potential-of-marine-microbes-collected-from-south-west-coast-of-india
#10
S Sinimol, A R Sarika, A Jayakumaran Nair
The diversity of some of the culturable microorganisms associated with marine flora and fauna collected off Vizhinjam and Mulloor coast of South India was evaluated and their bioactive production potential determined. From a total of 24 bacteria, 4 actinomycetes and 8 fungi isolated from diverse marine sources, five bacterial species-BLM3, BSP2, BCS1, BCS4 and BMA6 showed inhibitory activity against at least one of the tested pathogens viz., Klebsiella pneumonia KU1, Pseudomonas aeruginosa VL3, Salmonella enterica typhimurium MTCC 98, Escherichia coli MTCC 40, Micrococcus luteus MTCC 105, Staphylococcus simulans MTCC 3610, Proteus vulgaris MTCC 426, Vibrio fluvialis, Vibrio sp...
June 2016: 3 Biotech
https://www.readbyqxmd.com/read/28327357/the-ternary-complex-structure-of-d-mandelate-dehydrogenase-with-nadh-and-anilino-oxo-acetate
#11
Nayuta Furukawa, Akimasa Miyanaga, Masahiro Nakajima, Hayao Taguchi
Enterococcus faecium NAD-dependent d-mandelate dehydrogenase (D-ManDH) belongs to a ketopantoate reductase (KPR)-related D-2-hydroxyacid dehydrogenase family, and exhibits broad substrate specificity toward bulky hydrophobic 2-ketoacids, preferring C3-branched substrates. The ternary complex structure of D-ManDH with NADH and anilino(oxo)acetate (AOA) revealed that the substrate binding induces a shear motion of the N-terminal domain along the C-terminal domain, following the hinge motion induced by the NADH binding, and allows the bound NADH molecule to form favorable interactions with a 2-ketoacid substrate...
March 18, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28325450/classification-of-nervous-system-withdrawn-and-approved-drugs-with-toxprint-features-via-machine-learning-strategies
#12
Aytun Onay, Melih Onay, Osman Abul
BACKGROUND AND OBJECTIVES: Early-phase virtual screening of candidate drug molecules plays a key role in pharmaceutical industry from data mining and machine learning to prevent adverse effects of the drugs. Computational classification methods can distinguish approved drugs from withdrawn ones. We focused on 6 data sets including maximum 110 approved and 110 withdrawn drugs for all and nervous system diseases to distinguish approved drugs from withdrawn ones. METHODS: In this study, we used support vector machines (SVMs) and ensemble methods (EMs) such as boosted and bagged trees to classify drugs into approved and withdrawn categories...
April 2017: Computer Methods and Programs in Biomedicine
https://www.readbyqxmd.com/read/28323375/synthesis-and-optoelectronic-properties-of-hexa-peri-hexabenzoborazinocoronene
#13
Jacopo Dosso, Jonathan Tasseroul, Francesco Fasano, Davide Marinelli, Nicolas Biot, Andrea Fermi, Davide Bonifazi
The first rational synthesis of a BN-doped coronene derivative in which the central benzene ring has been replaced by a borazine core is described. This includes six C-C ring-closure steps that, through intramolecular Friedel-Crafts-type reactions, allow the stepwise planarization of the hexaarylborazine precursor. UV/Vis absorption, emission, and electrochemical investigations show that the introduction of the central BN core induces a dramatic widening of the HOMO-LUMO gap and an enhancement of the blue-shifted emissive properties with respect to its all-carbon congener...
March 21, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28322368/alkaline-earth-metal-mg-polynitrides-at-high-pressure-as-possible-high-energy-materials
#14
Shuli Wei, Da Li, Zhao Liu, Xin Li, Fubo Tian, Defang Duan, Bingbing Liu, Tian Cui
The high-pressure structural evolutionary behaviors of magnesium polynitrides were studied up to 100 GPa using first-principles calculations. Using the unbiased structure searching method, five stable chemical stoichiometries of magnesium polynitrides (MgN, Mg2N3, MgN2, MgN3, and MgN4) were theoretically predicted at high pressures. The predicted MgNx compounds contain a rich variety of polynitrogen forms ranging from charged molecules (one-dimensional bent molecules N3, planar triangle N4 to benzene-like rings N6) to extended polymeric chains (N∞)...
March 21, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28321487/benzene-degradation-in-a-denitrifying-biofilm-reactor-activity-and-microbial-community-composition
#15
Marcelle J van der Waals, Siavash Atashgahi, Ulisses Nunes da Rocha, Bas M van der Zaan, Hauke Smidt, Jan Gerritse
Benzene is an aromatic compound and harmful for the environment. Biodegradation of benzene can reduce the toxicological risk after accidental or controlled release of this chemical in the environment. In this study, we further characterized an anaerobic continuous biofilm culture grown for more than 14 years on benzene with nitrate as electron acceptor. We determined steady state degradation rates, microbial community composition dynamics in the biofilm, and the initial anaerobic benzene degradation reactions...
March 20, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28320639/exposure-to-polycyclic-aromatic-hydrocarbons-and-volatile-organic-compounds-among-recently-pregnant-rural-guatemalan-women-cooking-and-heating-with-solid-fuels
#16
John R Weinstein, Renée Asteria-Peñaloza, Anaité Diaz-Artiga, Gilberto Davila, S Katharine Hammond, Ian T Ryde, Joel N Meyer, Neal Benowitz, Lisa M Thompson
BACKGROUND: Household air pollution is a major contributor to death and disability worldwide. Over 95% of rural Guatemalan households use woodstoves for cooking or heating. Woodsmoke contains carcinogenic or fetotoxic polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Increased PAHs and VOCs have been shown to increase levels of oxidative stress. OBJECTIVE: We examined PAH and VOC exposures among recently pregnant rural Guatemalan women exposed to woodsmoke and compared exposures to levels seen occupationally or among smokers...
March 10, 2017: International Journal of Hygiene and Environmental Health
https://www.readbyqxmd.com/read/28320536/retention-models-and-interaction-mechanisms-of-benzene-and-other-aromatic-molecules-with-an-amylose-based-sorbent
#17
Han-Yu Hsieh, Shyuan-Guey Wu, Hung-Wei Tsui
Stoichiometric displacement models have been widely used for understanding the adsorption mechanisms of solutes in chromatography systems. Such models are used for interpreting plots of solute retention factor versus concentrations of polar modifier in an inert solvent. However, these models often assume that dispersion forces are negligible and they are unable to account for solutes with significant aromatic interactions. In this study, a systematic investigation of the relationship between retention behavior and aromatic groups was performed using five simple aromatic molecules-benzene, naphthalene, mesitylene, durene, and toluene-with a commercially available amylose tris(3,5-dimethylphenylcarbamate)-based sorbent...
March 8, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28320234/gelidiella-acerosa-protects-against-a%C3%AE-25-35-induced-toxicity-and-memory-impairment-in-swiss-albino-mice-an-in-vivo-report
#18
Syad Arif Nisha, Kasi Pandima Devi
CONTEXT: Alzheimer's disease (AD) is believed to develop due to deposition of β-amyloid (Aβ) peptide. Hence, efforts are being made to develop potent drug that target amyloid hypothesis. OBJECTIVE: The present study explores the effect of the seaweed Gelidiella acerosa (Forsskål) Feldmann & Hamel (Gelidiellaceae) against Aβ 25-35 peptide in Swiss albino mice. MATERIALS AND METHODS: The animals were administered through intracerebroventricular (ICV) injection with the Aβ 25-35 peptide (10 μg/10 μL/ICV site) on 21st day of the pretreatment of G...
December 2017: Pharmaceutical Biology
https://www.readbyqxmd.com/read/28320204/coordination-nanosheets-based-on-terpyridine-zinc-ii-complexes-as-photoactive-host-materials
#19
Takamasa Tsukamoto, Kenji Takada, Ryota Sakamoto, Ryota Matsuoka, Ryojun Toyoda, Hiroaki Maeda, Toshiki Yagi, Michihiro Nishikawa, Naoaki Shinjo, Shuntaro Amano, Tadashi Iokawa, Narutaka Ishibashi, Tsugumi Oi, Koshiro Kanayama, Rina Kinugawa, Yoichiro Koda, Toshiyuki Komura, Shuhei Nakajima, Ryota Fukuyama, Nobuyuki Fuse, Makoto Mizui, Masashi Miyasaki, Yutaro Yamashita, Kuni Yamada, Wenxuan Zhang, Ruo-Cheng Han, Wenyu Liu, Taro Tsubomura, Hiroshi Nishihara
Photoluminescent coordination nanosheets (CONASHs) comprising three-way terpyridine (tpy) ligands and zinc(II) ions are created by allowing the two constitutive components to react with each other at a liquid/liquid interface. Taking advantage of bottom-up CONASHs, or flexibility in organic ligand design and coordination modes, we demonstrate the diversity of the tpy-zinc(II) CONASH in structures and photofunctions. A combination of 1,3,5-tris[4-(2,2':6',2″-terpyridyl)phenyl]benzene (1) and Zn(BF4)2 affords a cationic CONASH featuring the bis(tpy)Zn complex motif (1-Zn), while substitution of the zinc source with ZnSO4 realizes a charge-neutral CONASH with the [Zn2(μ-O2SO2)2(tpy)2] motif [1-Zn2(SO4)2]...
March 21, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28319744/kinetics-and-mechanism-of-17%C3%AE-estradiol-chlorination-in-a-pilot-scale-water-distribution-systems
#20
Cong Li, Feilong Dong, John C Crittenden, Feng Luo, Xinbo Chen, Taotao Zhao
The kinetics and mechanisms of 17β-estradiol (E2) chlorination in water distribution systems (WDS) were studied. We examined the impacts of different factors, including pH, temperature, humic acid concentration and type, and flow velocity. The experimental results showed that the rate constants in beaker tests and WDS were described by a pseudo-first-order model. pH had the greatest impact on E2 chlorination in the beaker tests. However, temperature had the greatest impact on E2 chlorination in WDS. Mechanistic analysis of E2 chlorination showed that chlorine attacked E2 in three stages: 1) halogenation of the aromatic ring, 2) cleavage of the benzene moiety and chlorine or bromine substitution formation, and 3) formation of trihalomethanes (THMs) and halogenated acetic acids (HAAs) from phenolic intermediates through benzene ring opening with chlorine and/or bromine substitution of hydrogen on the carbon atoms...
March 14, 2017: Chemosphere
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