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Chemistry: a European Journal

Xiaolei Zhu, Annamaria Quaranta, René Bensasson, Matthieu Sollogoub, Yongmin Zhang
DIBAL-H-mediated demethylation provides a novel entry to secondary rim functionalized γ-CD. 2A,3B-dihydroxyl-per-O-methylated-γ-cyclodextrin has been obtained, whose conjugation with C60 allows the access to the most water-soluble C60 conjugate described so far. The water-solubility 0.12 M (550 mg/mL) is 150 times higher than that of native γ-CD/ C60 complex. Its singlet oxygen (¹O₂) quantum yield is 0.39, an increase by one or two orders of magnitude compared to that of α(β)CD-C60 conjugates.
May 26, 2017: Chemistry: a European Journal
Yves Bleriot, Dimitri Alvarez-Dorta, Dustin T King, Thibaut Legigan, Daisuke Ide, Isao Adachi, David Deniaud, Jerome Desire, Atsushi Kato, David Vocadlo, Sebastien Gouin
A set of multivalent polyhydroxylated acetamidoazepanes based on ethylene glycol, glucoside or cyclodextrin scaffolds was prepared. The compounds were assessed against plant, mammalian and therapeutically relevant hexosaminidases. Multimerization was shown to improve the inhibitory potency with synergy, and to fine tune the selectivity profile between related hexosaminidases.
May 26, 2017: Chemistry: a European Journal
Lee Cronin, Jamie Purcell, Haralampos Miras, De-Liang Long, Panagiota Markopoulou
We report the preparation and characterization of a new family of four polyoxothiometalate (POTM) clusters, with varying size and complexity, based upon the dimeric [Mo2O2S2(H2O)6]2+ with the general formula (NMe4)aKb[(Mo2O2S2)c(TeO4)d(C4O4)e(OH)f] where a,b,c,d,e,f = {1,7,14,2,4,10} = 1, {Mo28Te2}; {2,26,36,4,10,48} = 2, {Mo72Te12}; {0,11,15,3,3,21} = 3, {Mo30Te3}; {2,6,12,2,4,16} = 4, {Mo24Te2}. The incorporation of tellurite anions allowed the fine tuning of the templation and bridging of the available building blocks leading to new topologies of increased complexity...
May 26, 2017: Chemistry: a European Journal
Marjan Firouzbakht, Shaodong Zhou, Patricio González-Navarrete, Maria Schlangen, Martin Kaupp, Helmut Schwarz
The thermal gas-phase reactions of methane with [OMoH]+ and [MoH]+ were investigated by using electrospray-ionization mass spectrometry (ESI-MS) complemented by quantum-chemical calculations. In contrast to the inertness of [MoH]+ towards methane, [OMoH]+ activates the C-H bond to form the ionic product [OMo(CH₃)]+ concomitantly with the liberation of H2. The origin of the varying reactivities is traced back to a different influence of the oxo ligand on the Mo-C and Mo-H bonds. While the presence of this ligand weakens both the Ti-H and the Ti-CH₃ bonds, both the Mo-H and Mo-CH₃ bonds are strengthened...
May 26, 2017: Chemistry: a European Journal
Xihe Bi, Yang Yang, Zhaohong Liu, Alessio Porta, Giuseppe Zanoni
The dissociation of N-tosylhydrazones is a safe and convenient method for the generation of donor carbenes. However, alkynyl carbenes cannot be isolated by this route because they readily undergo intramolecular cyclization to pyrazoles as soon as formed from alkynyl N-tosylhydrazones. Herein we report the use of alkynyl N-nosylhydrazones for the in situ generation of alkynyl carbenes and their coupling reaction with boronic acids under metal-free conditions, giving rise to a wide array of di- and trisubstituted allenes...
May 26, 2017: Chemistry: a European Journal
Binghe Wang, Zhixiang Pan, Xingyue Ji, Vayou Chittavong, Wei Li, Kaili Ji, Mengyuan Zhu, Jun Zhang
Carbon monoxide (CO) is an endogenously produced gasotransmitter in mammals, and may have signaling roles in bacteria as well. It has many recognized therapeutic effects. A significant challenge in this field is the development of pharmaceutically acceptable forms of CO delivery with controllable and tunable release rates. Herein, we describe the structure-release rate studies of the first class of organic CO-prodrugs that release CO in aqueous solution at neutral pH.
May 25, 2017: Chemistry: a European Journal
Sergio Navalon, Jose Raul Herance, Mercedes Alvaro, Hermenegildo García
Ideal graphene is a one-atom thick single layer of carbon atoms having sp2 hybridation in hexagonal arrangement. Due to their large surface area and good dispersability in common solvents, graphenes are suitable platforms to anchor covalently units. The appended unit can introduce additional functionality to graphene. Although the field of covalently modified graphene is still starting compared to the development of other carbon nanoforms, there is alrady many examples describing the use of modified graphenes as recoverable photo-, electro- and catalysts as well as in non-linear optics and to improve mechanical resistance and solubility of graphenes...
May 25, 2017: Chemistry: a European Journal
Yusuke Asakura, Naoki Kawaura, Yoshiyuki Kuroda, Masakazu Koike, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda
A single-crystalline macroporous layered silicate was obtained for the first time. Firstly, UTL-type zeolite with macropores was prepared hydrothermally under the presence of acetylene black as a macropore template and the subsequent calcination to remove the template. Double four-membered ring (d4r) units in the UTL framework were selectively dissolved to yield a layered silicate with macropores. Intercalation of tetrabutylammonium ions into the macroporous layered silicate is accelerated if compared with that into the same silicate without macropores, indicating the effectiveness of macropores due to easy diffusion...
May 25, 2017: Chemistry: a European Journal
John M Kelly, Paraic Keane, James Hall, Fergus Poynton, Bjorn Poulsen, Sarah Gurung, Ian Clark, Igor Sazanovich, Michael Towrie, Thorfinnur Gunnlaugsson, Susan Quinn, Christine Cardin
Key to the development of DNA-targeting phototherapeutic drugs is determining the interplay between the photoactivity of the drug and its binding preference for a target sequence. For the photo-oxidising lambda-[Ru(TAP)2(dppz)]2+ (Ʌ-1) complex bound to either d{T1C2G3G4C5G6C7C8G9A10}2 (G9) or d{TCGGCGCCIA}2 (I9), the X-ray crystal structures shows the dppz intercalated at the terminal T1C2;G9A10 step or T1C2;I9A10 step. Thus substitution of the G9 nucleobase by inosine does not affect intercalation in the solid state although with I9 the dppz is more deeply inserted...
May 25, 2017: Chemistry: a European Journal
Yao Fu, Rui Shang, Ming-Chen Fu, Wan-Min Cheng
Formic acid is efficiently used as a C1 source to directly carboxylate allylic alcohols in the presence of a low loading of palladium catalyst and acetic anhydride as additive to afford β,γ-unsaturated carboxylic acids with excellent chemo-, regio-, and stereoselectivity. The reaction proceeds through a carbonylation process with in situ-generated carbon monoxide (CO) under mild conditions, avoiding the use of high-pressure gaseous CO. A bisphosphine ligand that has a large bite angle (4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) was found to be uniquely effective for this transformation...
May 25, 2017: Chemistry: a European Journal
Andrew King, Kimberley Gallagher, Mary F Mahon, Ruth L Webster
The ability to tune between different regioselectivities using a common pre-catalyst is an unusual yet highly desirable process. Herein, we report the use of an iron(II) pre-catalyst that can be used to synthesize vinyl phosphines in a Markovnikov selective manner in benzene, whereas a simple change to dichloromethane as the reaction solvent leads to the Z-selective anti-Markovnikov functionalization. Preliminary mechanistic that studies suggest Markovnikov selectivity is a radical mediated process whereas the anti-Markovnikov selectivity is not radical in nature, and is due to a change in oxidation state, are reported...
May 24, 2017: Chemistry: a European Journal
Yan-Hong Ding, Jun Peng, Shifa-Ullah Khan, Yue Yuan
Organic substrates are indispensable to fabricate multi-functional polyoxometalate (POM)-based composites for various application fields. A new Molybdovanadophosphoric heteropolyacid (PMo10V2)-based polydopamine (PDA) composite (PMo10V2/PDA) has been firstly synthesized through a facile in-situ polymerization method under hydrothermal conditions without adding extra buffer solution. The obtained PMo10V2/PDA composite shows homogeneous microsphere morphology. By utilizing the adhesive ability of PDA, the composite can be used as an anode material without additional binder for rechargeable lithium ion batteries...
May 24, 2017: Chemistry: a European Journal
Manuel Petroselli, Lucio Melone, Massimo Cametti, Carlo Punta
A new class of lipophilic N-hydroxyphthalimides catalysts designed for the aerobic oxidation of cumene in solvent-free conditions were synthesized and tested. The specific strategy proposed for the introduction of lipophilic tails on the NHPI moiety leads to lipophilic catalysts which, while completely preserving the activity of the precursor, allow to conduct the catalytic oxidation in neat cumene for the very first time. The corresponding cumyl hydroperoxide is obtained in good yields (28-52%) and high selectivity (95-97%), under mild conditions...
May 24, 2017: Chemistry: a European Journal
Philippe Serp, Faqiang Leng, Iann C Gerber, Pierre Lecante, Ahmed Bentaleb, Antonio Muñoz, Beatriz M Illescas, Nazario Martín, Georgian Melinte, Ovidiu Ersen, Hervé Martinez, M Rosa Axet
The C66(COOH)12 hexa-adduct has been successfully used as a building block to construct, via carboxylate bridges, 3D networks with very homogeneous sub-1.8 nm ruthenium nanoparticles. This strategy allows the control of the interparticle distance. The obtained nanostructures are active in nitrobenzene selective hydrogenation.
May 24, 2017: Chemistry: a European Journal
Frederick Lewis, Ashutosh Kumar Mishra, Haim Weissman, Elisha Krieg, Kevin A Voltaw, Martin McCullagh, Boris Rybtchiinski
The self-assembly behavior of DNA conjugates possessing a perylenediimide (PDI) head group and a single N-oligonucleotide tail has been investigated using a combination of optical spectroscopy and cryogenic transmission electron microscopy (cryo-TEM) imaging. In order to obtain insight into the interplay between DNA base pairing and PDI hydrophobic interactions we employed systematic variation in the length and composition of the oligo tails. Conjugates with short (TA)n or (CG)n oligo tails (n ≤ 3) form fibers (helical or nonhelical) constructed from -stacked PDI head groups with pendent oligo tails at room temperature in aqueous solution...
May 24, 2017: Chemistry: a European Journal
Daniela E Ortega, Diego Cortés-Arriagada, Oleksandra S Trofymchuk, Diana Yepes, Soledad Gutierrez-Oliva, René S Rojas, Alejandro Toro-Labbe
It is presented a detailed quantum chemical study analyzing the mechanism of ethylene oligomerization and polymerization by means of a family of four neutral methallyl NiII catalysts. The role of the boron co-activators [BF₃ or B(C₆F₅)₃] and ligand functionalization (in ortho or para position of the N-arylcyano moiety of the catalysts) was investigated to explain the chain length of the obtained polymers. The chain initialization proceeds with higher activation barriers for the ortho functionalized complexes (19 kcal mol¯¹) compared to the para isomers (17-18 kcal mol¯¹)...
May 24, 2017: Chemistry: a European Journal
Lidija Barisic, Monika Kovacevic, Ivan Kodrin, Suncica Roca, Kresimir Molcanov, Yuning Shen, Bimalendu Adhikari, Heinz-Bernhard Kraatz
A series of peptides containing homo- and heterochiral Ala-Pro sequences attached to the turn inducing ferrocene-1,1'-diamine scaffold was synthesized. The effects of the backbone chirality and N-terminal group (Boc/Ac) on the conformational properties of the novel peptidomimetics were thoroughly explored by IR, NMR and CD spectroscopies as well as corroborated by DFT studies in solution. The most stable conformers of the homochiral peptides adopt the interstrand hydrogen bonding patterns, realized through ten- and thirteen-membered rings...
May 24, 2017: Chemistry: a European Journal
Libin Liu, Wenyuan Fang, Gailan Guo
Polymer-dominated membranes with switchable wettability are highly desired due to their on-demand applications for oil/water separation. Herein, we report a low-cost methodology to fabricate membranes consisting of hyperbranched polyurethane (HBPU) and fluorine-modified silica (F-SiO2) with tunable wettability by electrospinning. The HBPU/F-SiO2 composite membranes can be transformed from superhydrophobicity to superhydrophilicity via plasma treatment, which exhibit different wettability for effective separation of surfactant-stabilized water-in-oil and oil-in-water emulsions...
May 24, 2017: Chemistry: a European Journal
Clemens Richert, Pierre-Emmanuel Alexandre, Alexander Schwenger, Wolfgang Frey
Recently, a tetraphenyladamantane octamethylether was shown to encapsulate a wide range of small molecules in its crystals. Uptake and release from the liquid phase were demonstrated, and crystalline inclusion complexes were prepared that act as formulation for obnoxious reagents. Less than two equivalents of guest molecules were found in the crystal structures, though. Here we report the synthesis of 1,3,5,7-tetrakis(2,4-diethoxyphenyl)-adamantane (TEO) and twelve X-ray crystal structures that contain up to 3...
May 23, 2017: Chemistry: a European Journal
Yuquan Feng, Zhiguo Zhong, Hongwei Wang, Huitao Fan, Dongqin Bi, Lu Wang, Zhengzheng Xing, Dongfang Qiu
A novel open-framework copper borovanadate with 6-conected topological net and 1-D 8-MR channels has been obtained for the first time. The compound not only exhibits a unique -B3O7(OH)-Cu-B(OH)3 linkage and features the largest ratio between TM2+(Cu2+) and the borovanadate anion, but also possesses enhanced catalytic performance, high recyclability and stability during the oxidations of benzylic C-H bond.
May 23, 2017: Chemistry: a European Journal
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