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https://www.readbyqxmd.com/read/28644918/heterogeneous-microtesla-sabre-enhancement-of-15n-nmr-signals
#1
Kirill V Kovtunov, Larisa M Kovtunova, Max E Gemeinhardt, Andrey V Bukhtiyarov, Jonathan Gesiorski, Valerii I Bukhtiyarov, Eduard Y Chekmenev, Igor V Koptyug, Boyd Goodson
The hyperpolarization of heteronuclei via Signal Amplification by Reversible Exchange (SABRE) was investigated under conditions of heterogeneous catalysis and microtesla magnetic fields. Immobilization of [IrCl(COD)(IMes)], [IMes = 1,3-bis(2,4,6-trimethylphenyl), imidazole-2-ylidene; COD = cyclooctadiene] catalyst onto silica particles modified with NH2(CH2)3- linkers engenders an effective heterogeneous SABRE (HET-SABRE) catalyst that was used to demonstrate ~102-fold enhancement of 15N NMR signals in pyridine at 9...
June 23, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28644915/mechanistic-insights-on-the-reduction-of-co2-to-silylformates-catalyzed-by-ir-nsin-species
#2
Luis A Oro, Alejandro Julián, Jefferson Guzmán, E A Jaseer, Francisco Fernández-Alvarez, Raquel Royo, Victor Polo, María Pilar García Orduña, Fernando Lahoz
The hydrosilylation of CO2 with different silanes such as HSiEt3, HSiMe2Ph, HSiMePh2, HSiMe(OSiMe3)2 and HSi(OSiMe3)3 in presence of catalytic ammounts of the iridium(III) complex [Ir(H)(CF3CO2)(NSiN*)(coe)] (1; NSiN* = fac-bis-(4-methylpyridine-2-yloxy); coe = cis-cyclooctene) has been comparatively studied. The activity of the hydrosilylation catalytic system based on 1 depends on the nature of the reducing agent, where HSiMe(OSiMe3)2 has proven to be the most active. The aforementioned reactions were found to be highly selective to the formation of the corresponding silylformate...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28643874/2-6-bis-diazaboryl-pyridine-a-superbasic-sterically-demanding-pyridine-ligand
#3
Tobias Böttcher, Daniel Himmel, Jan Schröder
Herein we present a convenient one-pot route to a sterically demanding superbasic pyridine. Functionalization of the 2,6-positions with the highly sigma-donating boryl-groups shifts the calculated gas phase basicity of the pyridine's nitrogen atom to 1012 kJ mol-1, which outperforms the 'proton sponge' 1,8-bis(dimethylamino)naphthalene (996 kJ mol-1). The diazaboryl groups are oriented orthogonal to the pyridine ring and do not block the N-position, resembling the geometry of commonly used N-heterocyclic carbenes...
June 23, 2017: Chemistry: a European Journal
https://www.readbyqxmd.com/read/28643838/organics-filled-one-dimensional-tio2-nanowires-array-ultraviolet-detector-with-enhanced-photo-conductivity-and-dark-resistivity
#4
Dezhong Zhang, Chunyu Liu, Bo Yin, Ruiliang Xu, Jingran Zhou, Xindong Zhang, Shengping Ruan
A heterojunction photo-conductive ultraviolet (UV) detector was developed based on TiO2 nanowires array (NWA) surrounded by N,N'-bis-(1-naphthalenyl)-N,N'-bis-phenyl-(1,1'-biphenyl)-4,4'-diamine (NPB). The novel and effective two-step method of static infusion and dynamic solution-cleaning was employed to fill NPB into TiO2 NWA gaps and simultaneously remove the unwelcomed top NPB layer. The device fabricated via the two-step method exhibited optimal performance compared to TiO2/NPB device with top NPB layer and TiO2 NWA device...
June 23, 2017: Nanoscale
https://www.readbyqxmd.com/read/28642970/abilities-of-co-cultures-of-brown-rot-fungus-fomitopsis-pinicola-and-bacillus-subtilis-on-biodegradation-of-ddt
#5
Atmira Sariwati, Adi Setyo Purnomo, Ichiro Kamei
DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane) is one of the pesticides that are hazardous for the environment and human health. Effective environmental-friendly treatment using co-cultures of fungi and bacteria is needed. In this study, the bacteria Bacillus subtilis at various volumes of 1, 3, 5, 7, and 10 mL (1 mL ≈ 6.7 × 10(8) CFU) were mixed into 10 mL of the brown-rot fungus Fomitopsis pinicola culture for degrading DDT during a 7-days incubation period. DDT was degraded by approximately 42% by F...
June 22, 2017: Current Microbiology
https://www.readbyqxmd.com/read/28642930/a-novel-etching-technique-for-surface-treatment-of-zirconia-ceramics-to-improve-adhesion-of-resin-based-luting-cements
#6
Eystein Ivar Ruyter, Nalini Vajeeston, Torbjørn Knarvang, Ketil Kvam
Objectives: Bonding of zirconia crowns and bridges to abutments is important, not only bonding of the thin resin layer to the abutment, but also bonding to the zirconia ceramic is crucial. Both mechanical and chemical adhesion are desired. Mechanical retention of dental porcelain achieved by etching with moderately concentrated hydrofluoric acid is not possible with zirconia ceramics. The purpose of this study was to show that etching is possible with relative low melting fluoride compounds such as ammonium hydrogen difluoride and potassium hydrogen difluoride...
January 2017: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642928/effect-of-curing-and-silanizing-on-composite-repair-bond-strength-using-an-improved-micro-tensile-test-method
#7
Sigfus Thor Eliasson, Jon E Dahl
Objectives: To evaluate the micro-tensile repair bond strength between aged and new composite, using silane and adhesives that were cured or left uncured when new composite was placed. Methods: Eighty Filtek Supreme XLT composite blocks and four control blocks were stored in water for two weeks and thermo-cycled. Sandpaper ground, etched and rinsed specimens were divided into two experimental groups: A, no further treatment and B, the surface was coated with bis-silane. Each group was divided into subgroups: (1) Adper Scotchbond Multi-Purpose, (2) Adper Scotchbond Multi-Purpose adhesive, (3) Adper Scotchbond Universal, (4) Clearfil SE Bond and (5) One Step Plus...
January 2017: Acta Biomaterialia Odontologica Scandinavica
https://www.readbyqxmd.com/read/28642874/combination-treatment-with-ppar%C3%AE-ligand-and-its-specific-inhibitor-gw9662-downregulates-bis-and-14-3-3-gamma-inhibiting-stem-like-properties-in-glioblastoma-cells
#8
Chang-Nim Im
PPARγ is a nuclear receptor that regulates differentiation and proliferation and is highly expressed in many cancer cells. Its synthetic ligands, such as rosiglitazone and ciglitazone, and its inhibitor GW9662, were shown to induce cellular differentiation, inhibit proliferation, and lead to apoptosis. Glioblastoma is a common brain tumor with poor survival prospects. Recently, glioblastoma stem cells (GSCs) have been examined as a potential target for anticancer therapy; however, little is known about the combined effect of various agents on GSCs...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28642435/a-catalytic-fluoride-rebound-mechanism-for-c-sp-3-cf3-bond-formation
#9
Mark D Levin, Tiffany Q Chen, Megan E Neubig, Cynthia M Hong, Cyril A Theulier, Ilia J Kobylianskii, Mustafa Janabi, James P O'Neil, F Dean Toste
The biological properties of trifluoromethyl compounds have led to their ubiquity in pharmaceuticals, yet their chemical properties have made their preparation a substantial challenge, necessitating innovative chemical solutions. We report the serendipitous discovery of a borane-catalyzed formal C(sp(3))-CF3 reductive elimination from Au(III) that accesses these compounds by a distinct mechanism proceeding via fluoride abstraction, migratory insertion, and C-F reductive elimination to achieve a net C-C bond construction...
June 23, 2017: Science
https://www.readbyqxmd.com/read/28641558/bis-2-aminoimidazolines-and-bisguanidines-synthetic-approaches-antiparasitic-activity-and-dna-binding-properties
#10
Christophe Dardonville, J Jonathan Nué Martínez
BACKGROUND: Parasitic diseases caused by protozoan parasites of the genus Trypanosoma and Plasmodium cause some of the deadliest and disabling human infections in tropical and subtropical areas. Diphenyl-based bis(2-phenylimino)imidazolidines and bisguanidines are extremely potent antiparasitic agents against Trypanosoma brucei (etiological agent of African trypanosomiasis) and Plasmodium falciparum (etiological agent of severe malaria). Many of these compounds are also curative in mouse models of stage 1 African trypanosomiasis representing promising leads for the development of antitrypanosomal drugs...
June 22, 2017: Current Medicinal Chemistry
https://www.readbyqxmd.com/read/28641143/spectroscopic-and-thermodynamic-studies-of-light-harvesting-perylenediimide-derivative-zinc-porphyrin-complex-in-aqueous-media
#11
Ahmed El-Refaey, Shaban Y Shaban, Maged El-Kemary, Mohamed E El-Khouly
Self-assembly of perylene derivative such as N,N'-bis(2(trimethylammonium iodide) ethylene)perylene-3,4,9,10-tetracarboxyldiimide (TAIPDI) can produce one-dimensional form (1D) in an aqueous media. The ability of one-dimensional TAIPDI to form light harvesting complex with water-soluble zinc porphyrin (ZnTPPS4) via the π-π and electrostatic interactions has been described. Owing to electronic interactions between the π-systems, the complex formation is accompanied by pronounced absorption spectral changes in the UV/Vis absorption bands...
June 15, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28641007/palladium-catalyzed-sn2-cyclization-of-ambivalent-bromoalkadienyl-malonates-preparation-of-medium-to-large-membered-endocyclic-allenes
#12
Hiroaki Ichio, Hidetoshi Murakami, Yen-Chou Chen, Tamotsu Takahashi, Masamichi Ogasawara
A palladium-catalyzed reaction of preparing various endocyclic allenes was developed. The substrates for the reaction were readily available ω-(pronucleophile-tethered)-3-bromo-1,3-alkadienes, and a palladium-catalyst facilitated their unimolecular SN2'-cyclization in the presence of potassium tert-butoxide to give the corresponding 9- to 16-membered endocyclic allenes in fair yields of up to 67% together with the dimeric 16- to 32-membered endocyclic bis-allenes and other oligomeric/polymeric intermolecular reaction products...
June 22, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28640291/a-ferrocene-based-switchable-molecular-folding-ruler
#13
Synøve Ø Scottwell, Jonathan E Barnsley, C John McAdam, Keith C Gordon, James D Crowley
A 2,2'-bipyridine-appended bis(ferrocene) three tiered molecular folding ruler, can be switched from a folded conformation to an extended conformation by the addition of [Cu(CH3CN)4](PF6) and 6,6'-dimesityl-2,2'-bipyridine. This extension and contraction process could be triggered either chemically or electrochemically and was reversible.
June 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28640168/degree-of-postictal-suppression-depends-on-seizure-induction-time-in-magnetic-seizure-therapy-and-electroconvulsive-therapy
#14
Sarah Kayser, Bettina H Bewernick, Martin Soehle, Christina Switala, Sabrina M Gippert, Nadine Dreimueller, Thomas E Schlaepfer
OBJECTIVES: Anesthesia is required for both magnetic seizure therapy (MST) and electroconvulsive therapy (ECT), although it has anticonvulsant properties. In this case, bispectral index (BIS) monitoring, a specific electroencephalogram-derived monitoring, can be used to find the optimal seizure induction time during anesthesia to elicit adequate seizures. A measurement of seizure adequacy in electroencephalogram is the postictal suppression. The purpose of this study was to investigate the influence of seizure induction time on the degree of postictal suppression by comparing BIS versus no-BIS monitoring in MST and ECT...
June 20, 2017: Journal of ECT
https://www.readbyqxmd.com/read/28639673/observing-the-real-time-formation-of-phosphine-ligated-gold-clusters-by-electrospray-ionization-mass-spectrometry
#15
Marshall R Ligare, Grant E Johnson, Julia Laskin
The early stages of reduction and nucleation of ligated gold clusters in solution are largely unknown due, in part, to high reaction rates and the inherent complexity of the process. This study demonstrates that the addition of a diphosphine ligand, 1-4-bis(diphenylphosphino)butane (L(4)) to a methanolic solution of the gold precursor, chloro(triphenylphosphine)gold(I) (Au(PPh3)Cl), results in the initial formation of organometallic complexes of the type [Au(L(4))x(L(4)O)y(PPh3)z](+). These initial complexes lower the rate of gold reduction so that the reaction can be directly monitored over time from 1 min to over an hour using on-line electrospray ionization mass spectrometry (ESI-MS)...
June 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28639656/orthogonal-electronic-coupling-in-multicentre-arylamine-mixed-valence-compounds-based-on-a-dibenzofulvene-thiophene-conjugated-bridge
#16
A Beneduci, G A Corrente, E Fabiano, V Maltese, S Cospito, G Ciccarella, G Chidichimo, G Gigli, A-L Capodilupo
Herein we present organic mixed-valence compounds with an innovative H-shape design, where four redox centres are bridged "vertically" via a dibenzofulvene backbone and "horizontally" via a bis-(dibenzofulvene)-thiophene bridge. These compounds are easily oxidized to stable highly charged radical species which show intense intervalence charge transfer transitions in the near infrared region. Interestingly, depending on the position of the arylamine substituents on the bridge, both vertical and horizontal electron transfer pathways can be optically induced...
June 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28639632/an-nhc-phosphinidenyl-as-a-synthon-for-new-group-13-15-compounds
#17
Otfried Lemp, Markus Balmer, Kevin Reiter, Florian Weigend, Carsten von Hänisch
The parent phosphinidene SIMesPH (1) (SIMes = 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene) was treated with benzyl potassium to form the metalated species SIMesPK (2), which was used as a synthon for the new group 13/15 cycles and cage compounds [SIMesPGatBu2]2 (3), [SIMesP(GatBu2)2Cl] (4) and [K(SIMesP)3AltBu] (5).
June 22, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28638775/host-guest-complexes-of-c-ethyl-2-methylresorcinarene-and-aromatic-n-n-dioxides
#18
Rakesh Puttreddy, Ngong Kodiah Beyeh, Robin H A Ras, Kari Rissanen
The C-ethyl-2-methylresorcinarene (1) forms 1:1 in-cavity complexes with aromatic N,N'-dioxides, only if each of the aromatic rings has an N-O group. The structurally different C-shaped 2,2'-bipyridine N,N'-dioxide (2,2'-BiPyNO) and the linear rod-shaped 4,4'-bipyridine N,N'-dioxide (4,4'-BiPyNO) both form 1:1 in-cavity complexes with the host resorcinarene in C4v crown and C2v conformations, respectively. In the solid state, the host-guest interactions between the 1,3-bis(4-pyridyl)propane N,N'-dioxide (BiPyPNO) and the host 1 stabilize the unfavorable anti-gauche conformation...
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28638765/convenient-and-general-zinc-catalyzed-borylation-of-aryl-diazonium-salts-and-aryltriazenes-under-mild-conditions
#19
Xinxin Qi, Li-Bing Jiang, Chao Zhou, Jin-Bao Peng, Xiao-Feng Wu
A convenient and general zinc-catalyzed borylation of aryl diazonium salts and aryltriazenes has been developed. With bis- (pinacolato)diboron as the borylation reagent, aryldiazonium tetrafluoroborate salts and aryltriazenes were transformed into the corresponding arylboronates in moderate to excellent yields under mild conditions. As a convenient and practical methodology, no additional ligands, base, or any other additives are required here.
June 2017: ChemistryOpen
https://www.readbyqxmd.com/read/28638760/-bedt-ttf-2cu2-hcoo-5-an-organic-inorganic-hybrid-conducting-magnet
#20
Bin Zhang, Yan Zhang, Zheming Wang, Zengqiang Gao, Deliang Yang, Dongwei Wang, Yanjun Guo, Daoben Zhu
A dual-functional organic-inorganic hybrid (BEDT-TTF)2Cu2(HCOO)5 (1) (BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene) was obtained through the electrochemical oxidation of neutral BEDT-TTF in the presence of an ammonium salt of the one-dimensional copper-formate framework [(C2H5)3NH]2Cu2(HCOO)5 in a C6H5Cl-C2H5OH solution. Compound 1 was composed of organic donor BEDT-TTF(+0)⋅(5) in a θ-phase arrangement and Jahn-Teller distorted (4,4) grid anion sheets [Cu2(HCOO)5(-)] n with S=1/2. We identified the material as a semiconductor with values of σ300K=10(-1) S cm(-1)...
June 2017: ChemistryOpen
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