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https://www.readbyqxmd.com/read/28432923/triterpenoid-saponins-from-the-roots-of-spergularia-marginata
#1
David Pertuit, Mustafa Larshini, Malika Aitsidi Brahim, Mohamed Markouk, Anne-Claire Mitaine-Offer, Thomas Paululat, Stéphanie Delemasure, Patrick Dutartre, Marie-Aleth Lacaille-Dubois
Phytochemical investigations of the roots of Spergularia marginata had led to the isolation of four previously undescribed triterpenoid saponins, a known one and one spinasterol glycoside. Their structures were established by extensive NMR and mass spectroscopic techniques as 3-O-β-D-glucuronopyranosyl echinocystic acid 28-O-α-L-arabinopyranosyl-(1 → 2)-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-α-L- arabinopyranosyl ester, 3-O-β-D-glucopyranosyl-(1 → 3)-β-D-glucuronopyranosyl echinocystic acid 28-O-α-L-arabinopyranosyl-(1 → 2)-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)- α-L-arabinopyranosyl ester, 3-O-β-D-glucopyranosyl-(1 → 4)-3-O-sulfate-β-D-glucuronopyranosyl echinocystic acid 28-O-α-L-arabinopyranosyl-(1 → 2)-α-L-rhamnopyranosyl-(1 → 3)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl ester, and 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucuronopyranosyl 21-O-acetyl acacic acid...
April 19, 2017: Phytochemistry
https://www.readbyqxmd.com/read/28430438/controllable-synthesis-of-lindqvist-alkoxopolyoxovanadate-clusters-as-heterogeneous-catalysts-for-sulfoxidation-of-sulfides
#2
Ji-Kun Li, Jing Dong, Chuan-Ping Wei, Song Yang, Ying-Nan Chi, Yan-Qing Xu, Chang-Wen Hu
Six alkoxohexavanadate-based Cu- or Co-POVs [Cu(dpa)(acac)(H2O)]2[V6O13(OMe)6] (1), [Cu(phen)(acac)(MeOH)]2[V6O13(OMe)6] (2), [Co(dpa)(acac)2]2[V6O13(OMe)6]·2MeOH (3), [Co(phen)(acac)2]2[V6O13(OMe)6] (4), [Cu(dpa)(acac)]2[V(IV)2V(V)4O12(OMe)7] (5), and [Cu(dpa)(acac)(MeOH)]2[V(IV)2V(V)4O11(OMe)8] (6) (POV = polyoxovanadate; dpa = 2,2'-dipyridine amine; phen = 1,10-phenanthroline; acac = acetylacetone anion) have been synthesized by controlling the reaction conditions and characterized by single-crystal X-ray diffraction and powder X-ray diffraction analyses, FT-IR spectroscopy, element analyses, and X-ray photoelectron spectroscopy...
April 21, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28424495/significance-of-genetic-polymorphisms-in-long-non-coding-rna-ac079767-4-in-tuberculosis-susceptibility-and-clinical-phenotype-in-western-chinese-han-population
#3
Zhenzhen Zhao, Mei Zhang, Jun Ying, Xuejiao Hu, Jingya Zhang, Yanhong Zhou, Yi Zhou, Xingbo Song, Binwu Ying
Recent studies have implicated long non-coding RNA, AC079767.4, as a highly susceptible gene in tuberculosis. The aim of the study was to preliminarily explore the possible association of single nucleotide polymorphisms (SNPs) in AC079767.4 gene with clinical phenotypes and TB susceptibility in Western Chinese Han population. The improved multiplex ligation detection reaction (iMLDR) method was employed to genotype 4 SNPs in AC079767.4 in 554 tuberculosis patients and 561 healthy individuals. In subgroup analysis, only the C allele for rs12477677 was associated with the decreased susceptibility to pulmonary TB with a p-value of 0...
April 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28400150/effects-of-acetylacetone-on-the-photoconversion-of-pharmaceuticals-in-natural-and-pure-waters
#4
Guoyang Zhang, Bingdang Wu, Shujuan Zhang
Acetylacetone (AcAc) has proven to be a potent photo-activator in the degradation of color compounds. The effects of AcAc on the photochemical conversion of five colorless pharmaceuticals were for the first time investigated in both pure and natural waters with the UV/H2O2 process as a reference. In most cases, AcAc played a similar role to H2O2. For example, AcAc accelerated the photodecomposition of carbamazepine, oxytetracycline, and tetracycline in pure water. Meanwhile, the toxicity of tetracyclines and carbamazepine were reduced to a similar extent to that in the UV/H2O2 process...
April 8, 2017: Environmental Pollution
https://www.readbyqxmd.com/read/28388072/tuning-the-excimer-emission-of-amphiphilic-platinum-ii-complexes-mediated-by-phospholipid-vesicles
#5
Marsel Z Shafikov, Alfiya F Suleymanova, Dmitry N Kozhevnikov, Burkhard König
Two new amphiphilic platinum(II) complexes, [Pt(2-(4-fluorophenyl)-5-(4-dodecyloxyphenyl)pyridine) (acac)] (Pt-1) and [Pt(2-(4-dodecyloxyphenyl)-5-(thien-2-yl)-c-cyclopentenepyridine) (acac)] (Pt-2), where acac is acetylacetonate, were synthesized and characterized. Apart from conventional phosphorescence of single molecules (ME-monomer emission), complexes Pt-1 and Pt-2 also exhibit excimer emission (EE) when embedded into phospholipid vesicles, that is assigned to emissive Pt-Pt excimers. The EE intensity in vesicular media appeared to depend on the viscosity of the vesicles and the concentration of the embedded complex...
April 7, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28352910/coordination-abilities-of-polycyano-anions-in-the-solid-state-coordination-geometries-and-d-d-transition-energies-of-mixed-ligand-solvatochromic-copper-ii-complexes-with-b-cn-4-c-cn-3-and-n-cn-2-anions
#6
Xue Lan, Takumi Tominaga, Tomoyuki Mochida
B(CN)4(-), C(CN)3(-), and N(CN)2(-) are highly versatile polycyano anions that produce various functional compounds. To investigate the coordination abilities of these anions in the solid state quantitatively, we synthesized mixed-ligand Cu(ii) complexes: [Cu(R-acac)(tmen)X] (X = polycyano anion, R-acac = acetylacetonate or butyl-acetylacetonate, tmen = tetramethylethylenediamine). The coordination abilities of the anions, increasing in the order B(CN)4(-) < C(CN)3(-) < N(CN)2(-), result in a decrease in the d-d transition energies of the complexes and the shortening of the axial coordination distance...
April 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28338686/an-iron-catalysed-c-c-bond-forming-spirocyclization-cascade-providing-sustainable-access-to-new-3d-heterocyclic-frameworks
#7
Kirsty Adams, Anthony K Ball, James Birkett, Lee Brown, Ben Chappell, Duncan M Gill, P K Tony Lo, Nathan J Patmore, Craig R Rice, James Ryan, Piotr Raubo, Joseph B Sweeney
Heterocyclic architectures offer powerful creative possibilities to a range of chemistry end-users. This is particularly true of heterocycles containing a high proportion of sp(3)-carbon atoms, which confer precise spatial definition upon chemical probes, drug substances, chiral monomers and the like. Nonetheless, simple catalytic routes to new heterocyclic cores are infrequently reported, and methods making use of biomass-accessible starting materials are also rare. Here, we demonstrate a new method allowing rapid entry to spirocyclic bis-heterocycles, in which inexpensive iron(III) catalysts mediate a highly stereoselective C-C bond-forming cyclization cascade reaction using (2-halo)aryl ethers and amines constructed using feedstock chemicals readily available from plant sources...
April 2017: Nature Chemistry
https://www.readbyqxmd.com/read/28327758/a-dy4-single-molecule-magnet-and-its-gd-iii-tb-iii-ho-iii-and-er-iii-analogues-encapsulated-by-an-8-hydroxyquinoline-schiff-base-derivative-and-%C3%AE-diketonate-coligand
#8
Hong-Ling Gao, Xiao-Pu Zhou, Yan-Xia Bi, Hai-Yun Shen, Wen-Min Wang, Ni-Ni Wang, Yi-Xin Chang, Ru-Xia Zhang, Jian-Zhong Cui
Five new tetranuclear complexes based on an 8-hydroxyquinoline Schiff base derivative and the β-diketone coligand, [Ln4(acac)4L6(μ3-OH)2]·CH3CN·0.5CH2Cl2 (Ln = Gd (1), Tb (2), Dy (3), Ho (4) and Er (5); HL = 5-(benzylidene)amino-8-hydroxyquinoline; acac = acetylacetonate) have been synthesized, and structurally and magnetically characterized. Complexes 1-5 have similar tetranuclear structures. Each Ln(III) ion is eight coordinated and its coordination polyhedra can be described as being in a distorted square-antiprismatic geometry...
March 22, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28317955/prediction-of-strong-o-h-m-hydrogen-bonding-between-water-and-square-planar-ir-and-rh-complexes
#9
G V Janjić, M D Milosavljević, D Ž Veljković, S D Zarić
Intermolecular O-H/M interactions, between a water molecule and square-planar acac complexes ([M(acac)L2]), with different types of L ligands (en, H2O, CO, CN(-), and OH(-)) and different types of metal atoms (Ir(i), Rh(i), Pt(ii), and Pd(ii)) were studied by high level ab initio calculations. Among the studied neutral complexes, the [Pd(acac)(CN)(CO)] complex forms the weakest interaction, -0.62 kcal mol(-1), while the [Ir(acac)(en)] complex forms the strongest interaction, -9.83 kcal mol(-1), which is remarkably stronger than the conventional hydrogen bond between two water molecules (-4...
March 20, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28271707/highly-simplified-tandem-organic-light-emitting-devices-incorporating-a-green-phosphorescence-ultrathin-emitter-within-a-novel-interface-exciplex-for-high-efficiency
#10
Ting Xu, Jun-Gui Zhou, Chen-Chao Huang, Lei Zhang, Man-Keung Fung, Imran Murtaza, Hong Meng, Liang-Sheng Liao
Herein we report a novel design philosophy of tandem OLEDs incorporating a doping-free green phosphorescent bis[2-(2-pyridinyl-N)phenyl-C](acetylacetonato)iridium(III) (Ir(ppy)2(acac)) as an ultrathin emissive layer (UEML) into a novel interface-exciplex-forming structure of 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) and 1,3,5-tri(p-pyrid-3-yl-phenyl)benzene (TmPyPB). Particularly, relatively low working voltage and remarkable efficiency are achieved and the designed tandem OLEDs exhibit a peak current efficiency of 135...
March 29, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28254644/chemically-immobilized-and-physically-adsorbed-pan-acetylacetone-modified-mesoporous-silica-for-the-recovery-of-rare-earth-elements-from-the-waste-water-comparative-and-optimization-study
#11
Deepika Lakshmi Ramasamy, Eveliina Repo, Varsha Srivastava, Mika Sillanpää
This study was aimed at the investigation of Rare Earth Element (REE) recovery from aqueous solution by silica gels with 1-(2-Pyridylazo) 2-naphthol (PAN) and acetyl acetone (Acac) modifications. The two different methods of silica gel chelation, such as chemical immobilization with the help of silane coupling agents (3-aminopropyl triethoxysilane (APTES) and 3-aminopropyl trimethoxysilane (APTMS) in this study) and direct physical adsorption onto the silica surface, is compared in terms of their REE removal efficiency...
February 20, 2017: Water Research
https://www.readbyqxmd.com/read/28207252/metal-metal-bridging-using-the-dppp-dye-system-electronic-configurations-within-multiple-redox-series
#12
Arijit Singha Hazari, Abhishek Mandal, Katharina Beyer, Alexa Paretzki, Wolfgang Kaim, Goutam Kumar Lahiri
Redox series [LnRu(μ-DPPP)RuLn](k), H2DPPP = 2,5-dihydro-3,6-di-2-pyridylpyrrolo(3,4-c)pyrrole-1,4-dione and L = 2,4-pentanedionato (acac(-)), 2,2'-bipyridine (bpy), and 2-phenylazopyridine (pap), have been studied by voltammetry (CV, DPV), EPR, and UV-vis-NIR spectroelectrochemistry, supported by TD-DFT calculations. Crystal structure analysis and (1)H NMR revealed oxidation states [(acac)2Ru(III)(μ-DPPP(2-))Ru(III)(acac)2] and [(bpy)2Ru(II)(μ-DPPP(2-))Ru(II)(bpy)2](2+) for the corresponding precursors, isolated as rac diastereomers...
February 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28207244/terminal-titanyl-complexes-of-tri-and-tetrametaphosphate-synthesis-structures-and-reactivity-with-hydrogen-peroxide
#13
Julia M Stauber, Christopher C Cummins
The synthesis and characterization of tri- and tetrametaphosphate titanium(IV) oxo and peroxo complexes is described. Addition of 0.5 equiv of [OTi(acac)2]2 to dihydrogen tetrametaphosphate ([P4O12H2](2-)) and monohydrogen trimetaphosphate ([P3O9H](2-)) provided a bis(μ2,κ(2),κ(2)) tetrametaphosphate titanyl dimer, [OTiP4O12]2(4-) (1; 70% yield), and a trimetaphosphate titanyl acetylacetonate complex, [OTiP3O9(acac)](2-) (2; 59% yield). Both 1 and 2 have been structurally characterized, crystallizing in the triclinic P1̅ and monoclinic P21 space groups, respectively...
February 16, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28198611/pdcu-pd-nanocube-with-pt-like-activity-for-hydrogen-evolution-reaction
#14
Jing Li, Feng Li, Si-Xuan Guo, Jie Zhang, Jiantai Ma
The electronic properties of metal surfaces can be modulated to weaken the binding energy of adsorbed H-intermediates on the catalyst surface, thus enhancing catalytic activity for the hydrogen evolution reaction (HER). Here we first prepare PdCu alloy nanocubes (NCs) by coreduction of Cu(acac)2 (acac = acetylacetonate) and Na2PdCl4 in the presence of oleylamine (OAm) and trioctylphosphine (TOP). The PdCu NC coated glassy carbon electrode is then anodized at a constant potential of 0.51 V vs Ag/AgCl at room temperature in 0...
February 27, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28186721/ionic-liquid-as-reaction-medium-for-synthesis-of-hierarchically-structured-one-dimensional-moo2-for-efficient-hydrogen-evolution
#15
Baohua Zhang, Yiguo Xue, Anning Jiang, Zhimin Xue, Zhonghao Li, Jingcheng Hao
Hierarchically structured one-dimensional (1D) MoO2 is synthesized for the first time in ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([BMIM][Tf2N]). The synthesis system is very simple (single [BMIM][Tf2N] solvent plus MoO2(acac)2 reactant). [BMIM][Tf2N] itself works as both the reaction medium and the template for the formation of these interesting 1D MoO2 particles with ultrathin nanosheet subunits. The as-synthesized hierarchically 1D MoO2_40 particles exhibit remarkable electrocatalytic activity with good long-term cycle stability for the hydrogen evolution reaction (HER) in acidic media...
March 1, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28165085/steric-effect-on-excimer-formation-in-planar-pt-ii-complexes
#16
Yang-Jin Cho, So-Yoen Kim, Ho-Jin Son, Dae Won Cho, Sang Ook Kang
In order to understand the steric influence on excimer formation in square planar metal complexes, three different Pt(ii) complexes were prepared by modifying the substituents in the main ligand: Pt(ii)(dfppy)(acac) (Pt-1, where dfppy is difluorophenylpyridine, acac is acetylacetonate); the bulky triphenyl silyl (Ph3Si-) group was substituted at the pyridine moiety (Pt-2) and at the phenyl moiety (Pt-3) of the main ligand of Pt-1. The Pt-complexes showed sky-blue emission at ∼460 nm. In addition, Pt-1 and Pt-3 showed excimer emission at ∼600 nm in the concentrated solution and the solid sample...
February 6, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28156109/long-range-intramolecular-electronic-communication-in-a-trinuclear-ruthenium-tropolonate-complex
#17
Jun Yoshida, Kyohei Kuwahara, Kota Suzuki, Hidetaka Yuge
Dinuclear and trinuclear ruthenium complexes, [Ru(trop)2(C2trop)Ru(dppe)Cp] [2b; trop = tropolonato, C2trop = ethynyltropolonato, dppe = 1,2-bis(diphenylphosphino)ethane] and [Ru(trop){(C2trop)Ru(dppe)Cp}2] (3), were synthesized, and their electronic and electrochemical properties were investigated in comparison with our previously reported complex [Ru(acac)2(C2trop)Ru(dppe)Cp] (2a). The electron-donating Ru(II)(dppe)Cp unit and electron-accepting Ru(III)O6 unit are connected by C2trop in these complexes. 2a incorporates acetylacetonate as an ancillary ligand, while 2b and 3 incorporate tropolonate as an ancillary ligand...
February 20, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28144673/heterometallic-molecular-precursors-for-a-lithium-iron-oxide-material-synthesis-solid-state-structure-solution-and-gas-phase-behaviour-and-thermal-decomposition
#18
Haixiang Han, Zheng Wei, Matthew C Barry, Alexander S Filatov, Evgeny V Dikarev
Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO2 oxide material are reported. Heterometallic compounds LiFeL3 (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac)3 (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents...
February 1, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28138791/effect-of-pulse-polarity-on-thresholds-and-on-non-monotonic-loudness-growth-in-cochlear-implant-users
#19
Olivier Macherey, Robert P Carlyon, Jacques Chatron, Stéphane Roman
Most cochlear implants (CIs) activate their electrodes non-simultaneously in order to eliminate electrical field interactions. However, the membrane of auditory nerve fibers needs time to return to its resting state, causing the probability of firing to a pulse to be affected by previous pulses. Here, we provide new evidence on the effect of pulse polarity and current level on these interactions. In experiment 1, detection thresholds and most comfortable levels (MCLs) were measured in CI users for 100-Hz pulse trains consisting of two consecutive biphasic pulses of the same or of opposite polarity...
January 30, 2017: Journal of the Association for Research in Otolaryngology: JARO
https://www.readbyqxmd.com/read/28103036/paramagnetic-enhancement-of-nuclear-spin-spin-coupling
#20
Peter John Cherry, Syed Awais Rouf, Juha Vaara
We present a derivation and computations of the paramagnetic enhancement of the nuclear magnetic resonance (NMR) spin-spin coupling, which may be expressed in terms of the hyperfine coupling (HFC) and (for systems with multiple unpaired electrons) zero-field splitting (ZFS) tensors. This enhancement is formally analogous to the hyperfine contributions to the NMR shielding tensor as formulated by Kurland and McGarvey. The significance of the spin-spin coupling enhancement is demonstrated by using a combination of density-functional theory and correlated ab initio calculations, to determine the HFC and ZFS tensors, respectively, for two paramagnetic 3d metallocenes, a Cr(II)(acac)2 complex, a Co(II) pyrazolylborate complex, and a lanthanide system, Gd-DOTA...
March 14, 2017: Journal of Chemical Theory and Computation
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