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Chemistry, An Asian Journal

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https://www.readbyqxmd.com/read/28429413/vanadium-v-induced-oxidative-cross-coupling-of-various-boron-and-silyl-enolates
#1
Toru Amaya, Yuma Osafune, Yusuke Maegawa, Toshikazu Hirao
Intermolecular oxidative cross-coupling of two different enolates is one of the most useful reactions to synthesize unsymmetrical 1,4-dicarbonyl compounds. In this study, the oxovanadium(V)-induced intermolecular oxidative cross-coupling of enolates was achieved to give the corresponding unsymmetrical 1,4-dicarbonyl compounds, where combination of various boron and silyl enolates such as ketone-ester, ester-ketone, ester-ester, amide-ketone, and amide-ester enolates was adapted. These results clearly exhibit the versatility of the present oxidative cross-coupling protocol...
April 20, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28425208/nitrogenase-cofactor-inspiration-for-model-chemistry
#2
Ivana Djurdjevic, Oliver Einsle, Laure Decamps
The cofactor of nitrogenase is the largest and most intricate metal cluster known in nature. Its reactivity, mode of action and even the precise binding site of substrate remain a matter of debate. For decades, synthetic chemists have taken inspiration from the exceptional structural, electronic and catalytic features of the cofactor and have tried to either mimic the unique topology of the entire site, or to extract its functional principles and build them into novel catalysts that achieve the same - or very similar - astounding transformations...
April 20, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28422433/rigid-non-fullerene-acceptors-based-on-triptycene-perylene-dye-for-organic-solar-cells
#3
Dong Meng, Huiting Fu, Bingbing Fan, Jianqi Zhang, Yan Li, Yanming Sun, Zhaohui Wang
Three kinds of non-conjugated rigid perylene bisimide (PBI) derivatives based on a triptycene core were designed, synthesized and characterized. The unique three-dimensional (3D) conformation of triptycene could enable formation of polymer with the favorable morphology for organic polymer solar cells (PSCs) by relieving the self-aggregation of rigid PBI units. The low-lying LUMO energy levels of these compounds demonstrated that they are very suitable for using as acceptors in organic solar cells. A higher power conversion efficiency (PCE) of 6...
April 19, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28421668/effects-of-stoichiometry-on-the-h2-storage-properties-of-mg-nh2-2-lih-libh4-tri-component-system
#4
Han Wang, Hujun Cao, Claudio Pistidda, Sebastiano Garroni, Guotao Wu, Thomas Klassen, Martin Dorheim, Ping Chen
Hydrogen desorption pathways and storage properties of 2Mg(NH2)2-3LiH-xLiBH4 samples (x = 0, 1, 2 and 4) were investigated systematically by combination of Pressure-Composition-Isotherm (PCI), Differential scanning calorimetric (DSC) and volumetric release methods. Experimental results show that the desorption peak temperatures of 2Mg(NH2)2-3LiH-xLiBH4 samples are ca. 10-15 oC lower compared to that of 2Mg(NH2)2-3LiH. Especially the 2Mg(NH2)2-3LiH-4LiBH4 composite begins to release hydrogen at 90 oC, exhibiting a superior dehydrogenation performance...
April 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28418587/short-step-syntheses-of-4-deoxycarbazomycin-b-sorazolon-e-and-sorazolon-e2
#5
Makoto Sako, Kazuya Ichinose, Shinobu Takizawa, Hiroaki Sasai
Short-step syntheses of 4-deoxycarbazomycin B and sorazolon E were established through the condensation of cyclohexanone and commercially available 4-methoxy-2,3-dimethylaniline, followed by Pd(II)-catalyzed dehydrogenative aromatization/intramolecular C-C bond coupling and deprotection. A chiral dinuclear vanadium complex (Ra,S,S)-6 mediated the first enantioselective oxidative coupling of sorazolon E, affording (+)-sorazolon E2 in good enantioselectivity.
April 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28418182/cyclometalated-iridium-iii-bipyridine-phenylboronic-acid-complexes-as-luminescent-probes-for-sialic-acids-and-bioimaging-reagents
#6
Hua-Wei Liu, Wendell Ho-Tin Law, Lawrence Cho-Cheung Lee, Jonathan Chun-Wai Lau, Kenneth Kam-Wing Lo
Sialic acids play important roles in mammalian development, cell-cell attachment, and signaling. Since cancer cells utilize their overexpressed sialylated antigens to propagate metastases, the development of probes for sialic acids is of high importance. Herein, we report three luminescent cyclometalated iridium(III) bipyridine complexes bearing a phenylboronic acid (PBA) moiety. Spectrophotometric titrations revealed that the PBA complexes displayed higher binding affinity to the most common sialic acid N-acetylneuraminic acid (Neu5Ac) compared with simple sugars that are commonly found on glycoproteins...
April 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28417588/a-scalable-and-versatile-synthesis-of-oxime-based-hormone-dimers-and-gels-for-sustained-release
#7
Christopher W Bennett, Joe Collins, Zeyun Xiao, Daniel Klinger, Luke A Connal
Well-defined steroid hormone dimers and organogels were produced via a facile and scalable synthesis using oxime click chemistry. The versatile synthetic procedure extends to a wide range of hormones and linker groups exemplified here through the synthesis of cortisol- and progesterone-dimers linked via hydrophobic, hydrophilic or functional groups. This method was also extended to the synthesis of cortisone-based organogels. Owing to the dynamic nature of the oxime bond, the hormone-based materials are degradable via acidic hydrolysis and transoximination representing new materials for the controlled release of steroid hormones...
April 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28417555/a-novel-bat-shaped-dicyanomethylene-4h-pyran-functionalized-naphthalimidefor-highly-efficient-solution-processed-multilevel-memory-devices
#8
Jian-Mei Lu, Qi-Jian Zhang, Shi-Feng Miao, Hua Li, Jing-Hui He, Na-Jun Li, Qing-Feng Xu, Dong-Yun Chen
Small molecule based multilevel memory device has attracted increasing attentions since the advantages as super-high storage density, fast reading speed, light weight, low energy consumption, and shock resistance. However, the fabrication of small molecule-based device always needs expensive vacuum deposition techniques or high temperature for spin-coating. In this paper, through rationally tailoring of the previous molecule DPCNCANA, a novel bat-shaped A-D-A-type symmetric framework has been successfully synthesized, and can be dissolved in common solvents under room temperature...
April 18, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28409890/four-state-molecular-shuttling-of-2-rotaxanes-featuring-ammonium-aniline-anilinium-and-tetra-ethylene-glycol-stations-in-response-to-acid-base-and-alkali-metal-cation-stimuli
#9
Masaki Kimura, Takuma Mizuno, Masahiro Ueda, Shinobu Miyagawa, Tsuneomi Kawasaki, Yuji Tokunaga
In this study we synthesized [2]rotaxanes possessing three recognition sites-a dialkylammonium, an alkylarylamine, and a tetra(ethylene glycol) station-in their dumbbell-like axle component and dibenzo[24]crown-8 (DB24C8) as their macrocyclic component. These [2]rotaxanes behaved as four-state molecular shuttles: (i) under acidic conditions, the DB24C8 unit encircled both the dialkylammonium and alkylarylammonium stations; (ii) under neutral conditions, the dialkylammonium unit was the predominant station for the DB24C8 component; (iii) under basic conditions, when both ammonium centers were deprotonated, the alkylarylamine unit became a suitable station for the DB24C8 component; and (iv) under basic conditions in the presence of an alkali metal cation, the tetra(ethylene glycol) unit recognized the DB24C8 component through cooperative binding of the alkali metal ion...
April 13, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28407412/adsorption-and-desorption-of-single-stranded-dna-from-single-walled-carbon-nanotubes
#10
Cameron James Shearer, LePing Yu, Renzo Fenati, Alex Sibley, Jamie Scott Quinton, Christopher Thomas Gibson, Amanda Vera Ellis, Gunther Andersson, Joseph George Shapter
The chemical affinity of single stranded DNA (ssDNA) to adsorb to the surface of single walled carbon nanotubes (SWCNTs) is used for SWCNT purification, separation and in bio-devices. Despite the popularity of research on SWCNT-ssDNA conjugates, very little work has been dedicated to study the removal of adsorbed ssDNA on SWCNTs. This paper reports a comprehensive study of biological, physical and chemical treatments for the removal of ssDNA from SWCNT-ssDNA suspensions. These include enzymatic cleavage, heat treatment under vacuum up to 400 oC, chemical treatments with high or low pH, oxidising conditions, and high ionic strength solvents...
April 13, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28407369/reactivity-of-functionalized-ynamides-with-tetracyanoethylene-scope-limitations-and-optoelectronic-properties-of-the-adducts
#11
Marie Betou, Raphaël J Durand, Antoine Sallustrau, Claire Gousset, Erwann Le Coz, Yann R Leroux, Loïc Toupet, Elzbieta Trzop, Thierry Roisnel, Yann Trolez
The reactivity of functionalized ynamides and arylynamines with tetracyanoethylene at room temperature has been evaluated. In most cases, the corresponding 1,1,4,4-tetracyanobutadienes (TCBDs) have been obtained in good to excellent yields, following a sequence of [2+2]cycloaddition and [2+2]retroelectrocyclization. The influence of diverse functional groups on the yield of the reaction has been investigated, in particular concerning multiple ynamides. These TCBDs have been characterized by various spectroscopic techniques, electrochemistry and X-Ray diffraction for some of them...
April 13, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28406551/preparation-of-magnetically-recyclable-yolk-shell-fexoy-pdpt-ceo2-nanoreactors-with-enhanced-catalytic-activity
#12
Jie Wu, Chenchen Guan, Tongjie Yao, Junshuai Zhang, Xiao Zhang, Xin Huang
Noble metal nanoparticles (NPs) have received considerable attention in the field of catalysis. However, exploitation of their maximal catalytic properties is still a chanllenge. Nanoreactors could dramatically improve activity with the help of the intrinsic confinement effect. Herein, we designed a kind of yolk/shell FexOy/PdPt@CeO2 composites, in which FexOy NPs acted as movable core and allowed uniform distribution of PdPt alloys on the inner surface of the CeO2 shell. Due to the porosity of CeO2 shell and existence of hollow voids, FexOy/PdPt@CeO2 composites could be used as nanoreactors in catalytic reactions...
April 12, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28406550/unusual-assembly-and-conversion-of-graphene-quantum-dots-into-crystalline-graphite-nanocapsules
#13
Liangti Qu, Jian Gao, Chenyu Xu, Yue Hu, Fei Zhao, Changxiang Shao, Yang Zhao, Shilv Chen
The development of a facile strategy for conversion of graphene quantum dots (GQDs) into crystalline graphite is of great practical significance, which still remains challenging. Herein, a rationally assembled crystalline-intercrossed graphite nanocapsules (CI-GNCs) has been achieved by a one-step electrochemical-induced strategy with the assistant of soft template, in which the GQDs act as the initial building blocks. The as-prepared CI-GNCs exhibit high crystalline graphitic-like nanostructures. Moreover, it possesses a promising electrocatalytic activity for oxygen reaction reduction (ORR) in an alkaline medium...
April 12, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28406544/halogen-free-synthesis-of-carbamates-from-co2-and-amines-using-titanium-alkoxides
#14
Jun-Chul Choi, Hao-Yu Yuan, Norihisa Fukaya, Syun-Ya Onozawa, Qiao Zhang, Seong Jib Choi, Hiroyuki Yasuda
The direct synthesis of carbamates from amines and carbon dioxide in the presence of Ti(OR)4 (R = nBu (1), Me (2), Et (3), nPr (4)) was investigated. Aniline was reacted with the titanium n-butoxide (1) in the presence of carbon dioxide (5 MPa) to give the corresponding n-butyl N-phenylcarbamate (BPC) in nearly quantitative yield (99%) within 20 min. Furthermore, 1 could be regenerated upon reaction with n-butanol during water removal. The recovered 1 could then be reused in a subsequent reaction.
April 12, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28401668/stabilities-and-biological-activities-of-vanadium-drugs-what-is-the-nature-of-active-species
#15
Aviva Levina, Peter Andrew Lay
Diverse biological activities of vanadium(V) drugs mainly arise from their abilities to inhibit phosphate-dependent enzymes and to alter cell signaling. Initial interest focused on anti-diabetic activities but has shifted to anti-cancer and anti-parasitic drugs. V-based anti-diabetics are pro-drugs that release active components (e.g., H₂VO₄¯) in biological media. By contrast, V anti-cancer drugs are generally assumed to enter cells intact; however, speciation studies indicate that nearly all drugs are likely to react in cell culture media during in-vitro assays and the same would apply in vivo...
April 11, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28398672/symmetry-breaking-in-pyrrolo-3-2-b-pyrroles-synthesis-solvatofluorochromism-and-two-photon-absorption
#16
Daniel T Gryko, Aleksander Mikhaylov, Łukasz Łukasiewicz, Hye Gun Ryu, Aleksander Rebane, Kyo Han Ahn, Marzena Banasiewicz, Bolesław Kozankiewicz, Denis Jacquemin, Cloe Azarias
Five centrosymmetric and one dipolar pyrrolo[3,2-b]pyrroles, possessing, respectively, either two- or one strongly electron-withdrawing nitro groups have been synthesized in a straightforward manner from simple building blocks. In the symmetric compounds the nitroaryl groups induced spontaneous breaking of inversion symmetry in the excited-state, leading to large solvatofluorochromism. To study the origin of this effect, the series employed peripheral structural motifs that control the degree of conjugation via altering of dihedral angle between the 4-nitrophenyl moiety and the electron-rich core...
April 11, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28397391/simple-nanodroplet-templating-functional-surfaces-with-tailored-wettability-and-microstructures
#17
Shuhua Peng, Xuehua Zhang
Recently, solvent exchange has been demonstrated as a simple, solution based approach for the controlled formation of surface nanodroplets over large areas. The as-formed surface nanodroplets provide new opportunities for a wide range of droplet based applications. In this work, we demonstrate that surface nanodroplets can be used as versatile structural templates for fabrication of functional surfaces with tailored wettability and morphology. Guided by the microstructural and wetting properties of desert beetle back and cactus spine, we prepared two types of functional surfaces...
April 10, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28395122/cu-%C3%B0-mediated-denitrogenative-macrocyclization-for-the-synthesis-of-cyclic-%C3%AE-3%C3%AE-tetrapeptide-analogs
#18
Chun-Chi Chen, Sheng-Fu Wang, Yung-Yu Su, Yuya A Lin, Po-Chiao Lin
A copper(I)-mediated denitrogenative reaction has been successfully developed in the preparation of cyclic tetrapeptides. A key reactive intermediate, ketenimine, triggers the key intramolecular cyclization by the terminal amine group and therefore generates an internal β-amino acid with an amidine linkage. The chemistry developed here provides a new synthetic route for the preparation of cyclic α3β-tetrapeptide analogs which are rich in information to the conformational study of macrocycles as well as important biologically active peptides...
April 10, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28394453/catalytic-systems-for-the-cross-linking-of-organosilicon-polymers
#19
Esteban Mejía, Dengxu Wang, Johann Klein
Silicones and silicone rubbers are omnipresent in household and industrial products like lubricants, coatings, sealants, insulators, medical devices, etc. This plethora of applications arises from their unparalleled properties like hydrophobicity, low surface energy, chemical inertness, extreme temperature stability, elasticity and biocompatibility. Even though silicones are known since more than five decades, they are still ill-characterized and their chemistry is still far from fully understood. Industrially, the vast majority of processes for their synthesis, transformation and use are based in rather well established, alas outdated technologies, which are frequently empirical and poorly investigated...
April 10, 2017: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/28393490/cimicifoetones-a-and-b-dimeric-prenylindole-alkaloids-as-black-pigments-of-cimicifuga-foetida
#20
Chang-Xin Zhou, Yu-E Yu, Rong Sheng, Jian-Xia Mo, Min Huang, Liang Ouyang, Lishe Gan
Two dimeric prenylindole alkaloids with an unique indole-benzoindolequinone skeleton, cimicifoetones A (1) and B (2), were isolated as black pigments from the rhizomes of Cimicifuga foetida. The structures were elucidated by spectroscopic methods including HRMS and 2D NMR, as well as single crystal X-ray diffraction and computational chemical modeling techniques. Cimicifoetones A and B represented the first examples of dimeric indole alkaloids generated through [4+2] Diels-Alder cycloaddition between the prenyl side chain in one 3-prenylindole and the aromatic ring in another...
April 9, 2017: Chemistry, An Asian Journal
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