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https://www.readbyqxmd.com/read/28511010/%C3%AF-extended-and-curved-anti-aromatic-polycyclic-hydrocarbons
#1
Junzhi Liu, Ji Ma, Ke Zhang, Prince Ravat, Peter Machata, Stanislav M Avdoshenko, Felix Hennersdorf, Hartmut Komber, Wojciech Pisula, Jan J Weigand, Alexey A Popov, Reinhard Berger, Klaus Müllen, Xinliang Feng
Synthesis of anti-aromatic polycyclic hydrocarbons (PHs) is challenging because the high energy of their highest occupied molecular orbital (HOMO) and low energy of their lowest unoccupied molecular orbital (LUMO) cause them to be reactive and unstable. In this work, two large anti-aromatic acene analogues, namely cyclopenta[pqr]indeno[2,1,7-ijk]tetraphene (CIT, 1a) and cyclopenta[pqr]indeno[7,1,2-cde]picene (CIP, 1b), as well as a curved anti-aromatic molecule with 48 π-electrons, dibenzo[a,c]diindeno[7,1,2-fgh:7',1',2'-mno]phenanthro[9,10-k]tetraphene (DPT, 1c), are synthesized based on the corona of indeno[1,2-b]fluorene...
May 16, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28503205/substitution-of-fluorine-in-m-c6f5bf3-with-organolithium-compounds-distinctions-between-o-and-n-nucleophiles
#2
Anton Yu Shabalin, Nicolay Yu Adonin, Vadim V Bardin
Borates M[C6F5BF3] (M = K, Li, Bu4N) react with organolithium compounds, RLi (R = Me, Bu, Ph), in 1,2-dimethoxyethane or diglyme to give M[4-RC6F4BF3] and M[2-RC6F4BF3]. When R is Me or Bu, the nucleophilic substitution of the fluorine atom at the para position to boron is the predominant route. When R = Ph, the ratio M[4-RC6F4BF3]/M[2-RC6F4BF3] is ca. 1:1. Substitution of the fluorine atom at the ortho position to boron is solely caused by the coordination of RLi via the lithium atom with the fluorine atoms of the BF3 group...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28485602/metal-free-sequential-c-sp-2-h-oh-and-c-sp-3-h-aminations-of-nitrosoarenes-and-n-heterocycles-to-ring-fused-imidazoles
#3
Anisha Purkait, Subhra Kanti Roy, Hemant Kumar Srivastava, Chandan K Jana
Hydrogen bond assisted ortho-selective C(sp(2))-H amination of nitrosoarenes and subsequent α-C(sp(3))-H functionalization of aliphatic amines is achieved under metal-free conditions. The annulation of nitrosoarenes and 2-hydroxy-C-nitroso compounds with N-heterocycles provides a facile excess to a wide range of biologically relevant ring-fused benzimidazoles and structurally novel polycyclic imidazoles, respectively. Nucleophilic aromatic hydrogen substitution (SNArH) was found to be preferred over classical SNAr reaction during the C(sp(2))-H amination of halogenated nitrosoarenes...
May 9, 2017: Organic Letters
https://www.readbyqxmd.com/read/28443910/spin-state-variability-in-fe-2-complexes-of-substituted-2-pyridin-2-yl-1-10-phenanthroline-ligands-as-versatile-terpyridine-analogues
#4
Holm Petzold, Paul Djomgoue, Gerald Hörner, Silvio Heider, Charles Lochenie, Birgit Weber, Tobias Rüffer, Dieter Schaarschmidt
Fe(2+) spin crossover complexes [Fe(L)2](2+) (L = 2-(6-R(1)-pyridin-2-yl)-1,10-phenanthroline with R(1) = H, methoxy, bromo, -(1H-pyrazol-1-yl) or L = 2-(3-methoxy-pyridin-2-yl)-1,10-phenanthroline) were prepared. These air stable and durable complexes show SCO behaviour with very different transition temperatures T1/2 ranging from 130 K to 600 K depending on the substitution pattern. The use of (1)H NMR spectroscopy to elucidate the thermodynamics and kinetics of SCO in a solution of this series is described in detail...
May 16, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28441011/synthesis-characterization-and-dft-analysis-of-bis-terpyridyl-based-molecular-cobalt-complexes
#5
Safwan Aroua, Tanya K Todorova, Paul Hommes, Lise-Marie Chamoreau, Hans-Ulrich Reissig, Victor Mougel, Marc Fontecave
Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions...
April 25, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28435723/formamidinium-iodide-crystal-structure-and-phase-transitions
#6
Andrey A Petrov, Eugene A Goodilin, Alexey B Tarasov, Vladimir A Lazarenko, Pavel V Dorovatovskii, Victor N Khrustalev
At a temperature of 100 K, CH5N2(+)·I(-) (I), crystallizes in the monoclinic space group P21/c. The formamidinium cation adopts a planar symmetrical structure [the r.m.s. deviation is 0.002 Å, and the C-N bond lengths are 1.301 (7) and 1.309 (8) Å]. The iodide anion does not lie within the cation plane, but deviates from it by 0.643 (10) Å. The cation and anion of I form a tight ionic pair by a strong N-H⋯I hydrogen bond. In the crystal of I, the tight ionic pairs form hydrogen-bonded zigzag-like chains propagating toward [20-1] via strong N-H⋯I hydrogen bonds...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28426213/role-of-mediator-and-effects-of-temperature-on-ortho-c-n-bond-fusion-reactions-of-aniline-using-ruthenium-templates-isolation-and-characterization-of-new-ruthenium-complexes-of-the-in-situ-generated-ligands
#7
Suman K Roy, Debabrata Sengupta, Santi Prasad Rath, Tanushri Saha, Subhas Samanta, Sreebrata Goswami
In this work, ortho-C-N bond fusion reactions of aniline are followed by the use of two different ruthenium mediators. Reaction of aniline with [Ru(III)(terpy)Cl3] (terpy = 2,2':6',2″-terpyridine) resulted in a trans bis-aniline ruthenium(II) complex [1](+) which upon oxidation with H2O2 produced compound [2](+) of a bidentate ligand, N-phenyl-1,2-benzoquinonediimine, due to an oxidative ortho-C-N bond fusion reaction. Complex [1](+) and aniline (neat) at 185 °C produced a bis-chelated ruthenium complex (3)...
April 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28406298/reaction-of-aniline-with-singlet-oxygen-o2-1-%C3%AE-g
#8
Jomana Al-Nu'airat, Mohammednoor Altarawneh, Xiangpeng Gao, Phillip R Westmoreland, Bogdan Z Dlugogorski
Dissolved organic matter (DOM) acts as an effective photochemical sensitizer that produces the singlet delta state of molecular oxygen (O2(1)Δg), a powerful oxidizer that removes aniline from aqueous solutions. However, the exact mode of this reaction, the p- to o-iminobenzoquinone ratio, and the selectivity of one over the other remain largely speculative. This contribution resolves these uncertainties. We report, for the first time, a comprehensive mechanistic and kinetic account of the oxidation of aniline with the singlet delta oxygen using B3LYP and M06 functionals in both gas and aqueous phases...
May 4, 2017: Journal of Physical Chemistry. A
https://www.readbyqxmd.com/read/28358500/molecular-mechanism-of-dioxin-formation-from-chlorophenol-based-on-electron-paramagnetic-resonance-spectroscopy
#9
Lili Yang, Guorui Liu, Minghui Zheng, Yuyang Zhao, Rong Jin, Xiaolin Wu, Yang Xu
Few studies have investigated the free radical intermediates involved in the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) from chlorophenol. This study clarified the reaction pathways during thermochemical formation of PCDDs from 2,3,6-trichlorophenol (TCP) over a Cu(II)O/silica matrix, which was used to simulate fly ash, at 298-523 K. The reaction was studied using electron paramagnetic resonance (EPR) spectroscopy and theoretical calculations. In situ EPR indicated the TCP radical (TCPR) formed by hydrogen abstraction of TCP...
April 12, 2017: Environmental Science & Technology
https://www.readbyqxmd.com/read/28346278/effects-of-myopic-orthokeratology-on-visual-performance-and-optical-quality
#10
Guihua Liu, Zhi Chen, Feng Xue, Jing Li, Mi Tian, Xingtao Zhou, Ruihua Wei
OBJECTIVES: To analyze the changes in visual performance and optical quality after orthokeratology (ortho-k) treatment and its correlation with the magnitude of lens decentration and the diameter of treatment zone (TxZ). METHODS: A prospective study was conducted in 27 eyes of 27 patients wearing ortho-k contact lens. Area under log contrast sensitivity function (AULCSF), modulation transfer function cutoff values (MTFcutoff), Strehl ratio (SR), and objective scattering index (OSI) were measured and compared before and 1 month after ortho-k lens treatment...
March 24, 2017: Eye & Contact Lens
https://www.readbyqxmd.com/read/28337465/inflammatory-response-and-barrier-dysfunction-by-different-e-cigarette-flavoring-chemicals-identified-by-gas-chromatography-mass-spectrometry-in-e-liquids-and-e-vapors-on-human-lung-epithelial-cells-and-fibroblasts
#11
Janice Gerloff, Isaac K Sundar, Robert Freter, Emily R Sekera, Alan E Friedman, Risa Robinson, Todd Pagano, Irfan Rahman
Recent studies suggest that electronic cigarette (e-cig) flavors can be harmful to lung tissue by imposing oxidative stress and inflammatory responses. The potential inflammatory response by lung epithelial cells and fibroblasts exposed to e-cig flavoring chemicals in addition to other risk-anticipated flavor enhancers inhaled by e-cig users is not known. The goal of this study was to evaluate the release of the proinflammatory cytokine (interleukin-8 [IL-8]) and epithelial barrier function in response to different e-cig flavoring chemicals identified in various e-cig e-liquid flavorings and vapors by chemical characterization using gas chromatography-mass spectrometry analysis...
March 1, 2017: Applied in Vitro Toxicology
https://www.readbyqxmd.com/read/28330347/the-interaction-of-no-x-2-%C3%AE-with-h2-ab-initio-potential-energy-surfaces-and-bound-states
#12
Jacek Kłos, Qianli Ma, Millard H Alexander, Paul J Dagdigian
We determine from first principles two sets of four-dimensional diabatic potential energy surfaces (PES's) for the interaction of NO(X(2)Π) with H2, under the assumption of fixed NO and H2 bond distances. The first set of PES's was computed with the explicitly correlated multi-reference configuration interaction method [MRCISD-F12 + Q(Davidson)], and the second set with an explicitly correlated, coupled-cluster method [RCCSD(T)-F12a] with the geometry scan limited to geometries possessing a plane of symmetry...
March 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28316808/crystal-structure-of-the-monoclinic-phase-phase-iv-of-bis-tetra-methyl-ammonium-tetra-chlorido-cuprate-ii
#13
Gorgui Awa Seck, Libasse Diop, Allen G Oliver
The crystal structure of the low-temperature monoclinic phase of the title compound, [(CH3)4N]2[CuCl4], was determined at 120 K. The structure of the room-temperature phase has been determined in the ortho-rhom-bic space group Pmcm [Morosin & Lingafelter (1961 ▸). J. Phys. Chem. 50-51; Clay et al. (1975 ▸). Acta Cryst. B31 289-290]. The asymmetric unit consists of one discrete tetra-chlorido-cuprate anion with a distorted tetra-hedral geometry and two tetra-methyl-ammonium cations. In the crystal, the cations and the anions are linked via weak C-H⋯Cl hydrogen bonds...
March 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
https://www.readbyqxmd.com/read/28316195/-analysis-of-corneal-complications-in-children-wearing-orthokeratology-lenses-at-night
#14
C X Miao, X Y Xu, H Zhang
Objective: To explore the characteristics, prognoses and corneal complications of children wearing orthokeratology lenses (Ortho-K) at night. Methods: Retrospective case analysis. A total of 113 cases (219 eyes) wore Ortho-K for myopia at night, including 7 cases with unilateral glass wear. The average age was (11.5±2.0) years old. The myopia ranged from -1.00 D to -9.00 D in all eyes and from -2.00 D to -4.00 D in 157 of them. Examinations were performed before lens wearing, at 1 hour, the next morning, 2 days, 3 days, 1 week and 2 weeks after lens wearing, and thereafter once a month...
March 11, 2017: [Zhonghua Yan Ke za Zhi] Chinese Journal of Ophthalmology
https://www.readbyqxmd.com/read/28299841/fluorinated-unsymmetrical-n-n-diaryl-imidazolium-salts-new-functionalized-nhc-ligand-precursors
#15
Maxim A Topchiy, Maria A Zotova, Salekh M Masoud, Artur K Mailyan, Ivan V Ananyev, Sergey E Nefedov, Andrey F Asachenko, Sergey N Osipov
An efficient and scaled-up synthesis of the imidazol-2-ylidene-based unsymmetrical NHC precursors bearing the sterically demanding hexafluoroisopropylalkoxy group [(CF3 )2 (OR)C-] at the ortho position of the N-aryl substituent was developed. The key step of the method involved the transformation of a Mes-substituted oxazolinium tetrafluoroborate salt through the reaction with the corresponding binucleophilic fluoroalkyl-substituted aniline. The subsequent post-modification of the resulting hydroxyl-containing salt through a simple one-step O-alkylation protocol provided access to a new family of unsymmetrical fluorinated NHC precursors...
May 11, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28298110/near-infrared-overtone-voh-2-%C3%A2-0-spectroscopy-of-ne-h2o-clusters
#16
Michael P Ziemkiewicz, Christian Pluetzer, Michael Wojcik, Jérôme Loreau, Ad van der Avoird, David J Nesbitt
Vibrationally state selective overtone spectroscopy and dynamics of weakly bound Ne-H2O complexes (D0((para)) = 31.67 cm(-1), D0((ortho)) = 34.66 cm(-1)) are reported for the first time, based on near infrared excitation of van der Waals cluster bands correlating with vOH = 2 ← 0 overtone transitions (|02(-)⟩←|00(+)⟩ and |02(+)⟩←|00(+)⟩) out of the ortho (101) and para (000) internal rotor states of the H2O moiety. Quantum theoretical calculations for nuclear motion on a high level ab initio potential energy surface (CCSD(T)/VnZ-f12 (n = 3,4), corrected for basis set superposition error and extrapolated to the complete basis set limit) are employed for assignment of Σ←Σ,Π←Σ, and Σ←Π infrared bands in the overtone spectra, where Σ(K = 0) and Π (K = 1) represent approximate projections (K) of the body angular momentum along the Ne-H2O internuclear axis...
March 14, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28291200/-stabilizing-effect-of-orthokeratology-lenses-ten-year-follow-up-results
#17
E P Tarutta, T Yu Verzhanskaya
The global prevalence of myopia in adults varies between 20-50% in Europe and the US and 60-90% in Asian countries. According to WHO, myopia is one of the five leading causes of blindness and low vision in the world. Prevention or deceleration of myopia progression is an important public health problem. In recent years, orthokeratology (ortho-k) contact lenses worn at night have been found effective in slowing down the progression of myopia, however, the follow-up period in related studies is no longer than five years...
2017: Vestnik Oftalmologii
https://www.readbyqxmd.com/read/28287790/cocaine-self-administration-in-male-and-female-rats-perinatally-exposed-to-pcbs-evaluating-drug-use-in-an-animal-model-of-environmental-contaminant-exposure
#18
Mellessa M Miller, Abby E Meyer, Jenna L N Sprowles, Helen J K Sable
Polychlorinated biphenyls (PCBs) are ubiquitous environmental toxicants known to adversely impact human health. Ortho-substituted PCBs affect the nervous system, including the brain dopaminergic system. The reinforcing effects of psychostimulants are typically modulated via the dopaminergic system, so this study used a preclinical (i.e., rodent) model to evaluate whether developmental contaminant exposure altered intravenous self-administration (IV SA) for the psychostimulant cocaine. Long-Evans rats were perinatally exposed to 6 or 3 mg/kg/day of PCBs throughout gestation and lactation and compared with nonexposed controls...
April 2017: Experimental and Clinical Psychopharmacology
https://www.readbyqxmd.com/read/28287419/bimolecular-rate-constants-for-fad-dependent-glucose-dehydrogenase-from-aspergillus-terreus-and-organic-electron-acceptors
#19
Nozomu Tsuruoka, Takuya Sadakane, Rika Hayashi, Seiya Tsujimura
The flavin adenine dinucleotide-dependent glucose dehydrogenase (FAD-GDH) from Aspergillus species require suitable redox mediators to transfer electrons from the enzyme to the electrode surface for the application of bioelectrical devices. Although several mediators for FAD-GDH are already in use, they are still far from optimum in view of potential, kinetics, sustainability, and cost-effectiveness. Herein, we investigated the efficiency of various phenothiazines and quinones in the electrochemical oxidation of FAD-GDH from Aspergillus terreus...
March 10, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28278579/ph-activated-nano-amorphous-calcium-phosphate-based-cement-to-reduce-dental-enamel-demineralization
#20
Mary A S Melo, Michael D Weir, Vanara F Passos, Michael Powers, Hockin H K Xu
Enamel demineralization is destructive, esthetically compromised, and costly complications for orthodontic patients. Nano-sized amorphous calcium phosphate (NACP) has been explored to address this challenge. The 20% NACP-loaded ortho-cement notably exhibited favorable behavior on reducing demineralization of enamel around brackets in a caries model designed to simulate the carious attack. The 20% NACP-loaded ortho-cement markedly promotes higher calcium and phosphate release at a low pH, and the mineral loss was almost two fold lower and carious lesion depth decreased the by 1/3...
February 21, 2017: Artificial Cells, Nanomedicine, and Biotechnology
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