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Chemistry: a European Journal

Iciar Uriarte, Cristóbal Pérez, Elena Caballero-Mancebo, Francisco J Basterretxea, Alberto Lesarri, José A Fernández, Emilio J Cocinero
Nicotinoids are agonists of the acetylcholine receptor (nAChR) and play important biochemical and pharmacological roles. Here we report on the structural and conformational landscape of cotinine, and compare its molecular properties with the nicotine prototype, from which it only differs in the addition of a carbonyl group. The investigation of cotinine included a theoretical survey of the effects of rotamerization of the pyridine moiety, the puckering of the pyrrolidinone ring and the internal rotation of the methyl group...
February 17, 2017: Chemistry: a European Journal
Guillaume Dagousset, Cédric Simon, Elsa Anselmi, Béatrice Tuccio, Thierry Billard, Emmanuel Magnier
We report herein the first use of N-trifluoromethylthiosaccharin as the source of SCF3 radical under photoredox catalysis. This allowed an efficient and general visible-light-mediated carbotrifluoromethylthiolation of alkenes. Under the optimized conditions using fac-Ir(ppy)3 as the photocatalyst, various N-aryl acrylamides as well as a wide range of substituted styrenes can readily be difunctionalized in an intra- or intermolecular fashion, affording the corresponding SCF3-containing products in good to excellent yield...
February 17, 2017: Chemistry: a European Journal
Dennis Barton, Hong-Ying Gao, Philipp Alexander Held, Armido Studer, Harald Fuchs, Nikos L Doltsinis, Johannes Neugebauer
Possible origins of the formation of organometallic intermediates in on-surface Ullmann couplings have been investigated by surface tunneling microscopy (STM) and density functional theory (DFT) calculations. We consider the case of iodobenzenes on the coinage metals Au, Ag and Cu. We found experimental evidence for the formation of surface vacancies and the presence of metal adatoms in these coupling reactions, which are taken as a hint for the reactive extraction of surface atoms by adsorbates. In a second step, we demonstrate by ab initio molecular dynamics calculations for aryl-iodides on copper that metal atoms can be pulled out of the surface to form metalorganic species...
February 17, 2017: Chemistry: a European Journal
Wanhe Wang, Chao Yang, Sheng Lin, Kasipandi Vellaisamy, Guodong Li, Weihong Tan, Chung-Hang Leung, Dik-Lung Ma
NF-κB is a critical transcription factor that plays an important role in mediating inflammation, the immune response, and cell proliferation. The activation of NF-κB leads to an enhancement of proinflammatory mediator expression, which is implicated in the pathogenesis of a variety of diseases. Therefore, methods that allow the intracellular tracking of NF-κB are particularly attractive as they can provide information regarding the pathways or stimulation responses that are involved in the activation of NF-κB...
February 17, 2017: Chemistry: a European Journal
Kimberly C Mullane, Patrick J Carroll, Eric J Schelter
Organic azides containing naphthyl functionalities were used to prepare uranium(V) imido complexes UV[=NC(2-naph)Ph2][N(SiMe3)2]3 (2), UV[=NC(2-naph)3][N(SiMe3)2]3 (3), and UV[=N(2-naph)][N(SiMe3)2]3 (4), and compared with UV[=NCPh3][N(SiMe3)2]3 (1). The electronic structures of these compounds were investigated by solution electrochemistry studies that revealed accessible U(V/VI), U(IV/V), and naphthalene0/naphthalene-1 couples. The uranium(V) naphthyl-imido complexes were reduced by potassium graphite to yield their uranium(IV) congeners K[UIV[=NC(2-naph)Ph2][N(SiMe3)2]3] (2-K), K[UIV[=NC(2-naph)3][N(SiMe3)2]3] (3-K), and K[UIV[=N(2-naph)][N(SiMe3)2]3] (4-K)...
February 16, 2017: Chemistry: a European Journal
Lu Zheng, Chengyuan Yu, Yulin Zhan, Xuebing Deng, Ying Wang, Hua Jiang
A series of foldamers of 8-amino-2-quinolinecarboxylic acid were stapled by intramolecular ring-closing olefin metathesis to generate the constrained aromatic foldamers with varying lengths of hydrocarbon side-chains. Investigations clearly revealed that the side-chain crosslinkers are capable of completely locking the interconversions of the stapled aromatic foldamers over a wide range of temperature in CDCl3, even in C2D2Cl4. Hence, the stapled foldamers with the short hydrocarbon crosslinker can be easily separated by silica gel chromatography to generate foldamers with stable, absolute one-handed helicity...
February 16, 2017: Chemistry: a European Journal
Ramon Vilar, Chun-Qiong Zhou, Ting-Cong Liao, Zi-Qi Li, Jorge Gonzalez-Garcia, Matthew Reynolds, Min Zou
Three new polyether-tethered di-nickel-salphen complexes (2a-c) have been synthesized and fully characterized by NMR spectroscopy, mass spectrometry and elemental analyses. The binding affinity and selectivity of these complexes and of the parent mono-nickel complex (1) towards dimeric quadruplex DNA have been determined by UV-Vis titrations, fluorescence spectroscopy, CD spectroscopy and electrophoresis. These studies have shown that the di-nickel-salphen complex with the longest polyether linker (2c) has higher binding affinity and selectivity towards dimeric quadruplexes (over monomeric quadruplexes) than the di-nickel-salphen complexes with the shorter polyether linkers (2a and 2b)...
February 16, 2017: Chemistry: a European Journal
Ana M González-Noya, María J Romero, Vanesa Suárez, Sandra Fernández-Fariña, Marcelino Maneiro, Emilio Martínez-Núñez, Guillermo Zaragoza, Rosa Pedrido
The effect of the metal ion and ligand design on the enantioselectivity and linkage isomerization of neutral cobalt and zinc bisthiosemicarbazone metallohelicates has been investigated in this work. The electrochemical synthesis has afforded the enantioselective formation of chiral pure cobalt helicates, and the  isomer of a single enantiomer has been crystallized as only product for the cobalt methyl-substituted thiosemicarbazone helicate. Interestingly linkage isomers have been isolated from zinc ethyl-substituted thiosemicarbazone helicate enantiomers for the first time...
February 16, 2017: Chemistry: a European Journal
Ilda D'Annessa, Sara Sattin, Jiahui Tao, Marzia Pennati, Carlos Sànchez-Martìn, Elisabetta Moroni, Andrea Rasola, Nadia Zaffaroni, David A Agard, Anna Bernardi, Giorgio Colombo
We rationally designed allosteric compounds that stimulate Hsp90 ATPase activity and show anticancer potencies in the low micromolar to nanomolar range. In parallel, we clarify their mode of action and developed a quantitative model that links the dynamic ligand-protein cross-talk to observed cellular and in vitro activities. Our results support the potential of using dynamics-based approaches to develop original mechanism-based cancer therapeutics.
February 16, 2017: Chemistry: a European Journal
Vadapalli Chandrasekhar, Sourav Biswas, Sourav Das, Joydev Acharya, Vierandra Kumar, Jan Leusen, Juan Manuel Herrera, Paul Koegerler, Enrique Colacio
The synthesis, structure and magnetic properties of the four Dy(III) coordination compounds isolated as [Dy2(LH2)2(μ2-η1:η1-Piv)]Cl·2MeOH·H2O (1), [Dy4(LH)2(μ3-OH)2(Piv)4(MeOH)2]·4MeOH·2H2O(2), [Dy6(LH2)3(tfa)3(O3PtBu)(Cl)3]Cl4·15.5H2O·4MeOH· 5CHCl3 (3) and [Dy21(L)7(LH)7(tfa)7]Cl7·15H2O·7MeOH·12CHCl3 (4) are reported (Piv = pivalate, tfa = 1,1,1-trifluoro-acetylacetone, O3PtBu = tert-butylphosphonate). Some of these polynuclear coordination complexes exhibit aesthetic and unprecedented structural features...
February 16, 2017: Chemistry: a European Journal
Takashi Watanabe, Daisuke Hirose, Dennis P Curran, Tsuyoshi Taniguchi
Borylative radical cyclization of benzo[3,4]cyclodec-3-ene-1,5-diynes to provide 5-borylated 6,7,8,9-tetrahydrobenzo[a]azulenes has been developed. The experimental results suggest that the reaction proceeds by a radical chain mechanism, and di-tert-butyl hyponitrite (TBHN) works as a good radical initiator to form boryl radicals from N-heterocyclic carbene-boranes (NHC-boranes). The present reaction is a rare model to illustrate addition of boryl radicals to alkynes.
February 16, 2017: Chemistry: a European Journal
Yangyang Yang, Ryu Tashiro, Yuki Suzuki, Tomoko Emura, Kumi Hidaka, Hiroshi Sugiyama, Masayuki Endo
Various DNA-based nanodevices have been developed on the nanometer scale using light as regulation input. However, the programmed controllability is still a major challenge for these artificial nanodevices. Herein, we demonstrate a rotary DNA nanostructure in which the rotations are controlled by light. A bar-shaped DNA rotor, fabricated as a stiff double-crossover molecule, was placed on the top of a rectangular DNA tile. The photoresponsive oligonucleotides modified with azobenzenes were employed as switching motifs to release/trap the rotor at specific angular position on DNA tile by switching photoirradiations between ultraviolet and visible light...
February 15, 2017: Chemistry: a European Journal
Ljiljana Fruk, Antonina Kerbs, Patrick Mueller, Michael Kaupp, Ishtiaq Ahmed, Alexander S Quick, Doris Abt, Martin Wegener, Christof M Niemeyer, Christopher Barner-Kowollik
Oligonucleotides containing photo-caged dienes were prepared and shown to react quantitatively in a light-induced Diels-Alder cycloaddition with functional maleimides in aqueous solution within minutes. Due to its high yield and fast rate, the reaction was exploited for DNA surface patterning with sub-micrometer resolution employing direct laser writing (DLW). Functional DNA arrays were written via direct laser writing (DLW) in variable patterns, which were further encoded with fluorophores and proteins through DNA directed immobilisation...
February 15, 2017: Chemistry: a European Journal
Fenghua Zheng, Qichang Pan, Chenghao Yang, Xunhui Xiong, Xing Ou, Renzong Hu, Yu Chen, Meilin Liu
Sodium ion batteries (SIBs) have been regarded as a prime candidate for large-scale energy storage, and developing high performance anode material is one of the main challenges for advanced SIBs. Here, novel structured Sn-MoS2-C@C microspheres, in which Sn nanoparticles are evenly embedded in MoS2 nanosheets and a thin carbon film is homogenously engineered over the microspheres, have been fabricated by the hydrothermal method. The Sn-MoS2-C@C microspheres demonstrate an excellent Na-storage performance as an anode of SIBs, deliver a high reversible charge capacity (580...
February 15, 2017: Chemistry: a European Journal
Yusen Luo, Kevin Barthelmes, Maria Wächtler, Andreas Winter, Ulrich S Schubert, Benjamin Dietzek
The photochemistry of Ru(II) coordination compounds is generally discussed to originate from the lowest lying triplet metal-to-ligand charge-transfer state (3MLCT). However, when heteroleptic complexes are considered, e.g. in the design of molecular triads for efficient photoinduced charge separation, a complex structure of 1MLCT states, which can be populated in a rather narrow spectral window (typically around 450 nm) is to be considered. In this communication we show that the localization of MLCT excited states on different ligands can affect the following ps to ns decay pathways to an extend that by tuning the excitation wavelength intermolecular energy transfer from a Ru(II)-terpyridine unit to a fullerene acceptor can be favored over electron transfer within the molecular triad...
February 15, 2017: Chemistry: a European Journal
Lisa M Eytel, Annie K Gilbert, Paul Görner, Lev N Zakharov, Darren W Johnson, Michael Mark Haley
Selective tuning of arylethynyl urea scaffolds for anionic guests requires an understanding of preferred binding motifs of the host-guest interaction. To investigate the binding preference of receptors without a pre-organized binding pocket, two electron deficient phenylacetylene receptors with a single urea moiety have been prepared and are found to bind halides as 2-to-1 host-guest complexes that feature key CH-anion or anion-pi interactions. These supporting interactions also appear to influence the mechanism of the 2:1 binding event...
February 14, 2017: Chemistry: a European Journal
Farhana Aman, Muhammad Hanif, Mario Kubanik, Adnan Ashraf, Tilo Soehnel, Stephen Jamieson, Waseeq Siddiqui, Christian Hartinger
The nitrogen- and sulfur-containing 1,2-benzothiazines meloxicam and piroxicam are widely used as nonsteroidal antiinflammatory drugs. Intrigued by the presence of multiple donor atoms and therefore a potentially rich coordination chemistry, we prepared a series of organometallic Ru and Os compounds with meloxicam and piroxicam featuring either as mono- or bidentate ligand systems. The choice of the solvent and the pH value was identified as the critical parameter to achieve selectively mono- or bidentate coordination...
February 14, 2017: Chemistry: a European Journal
Maksymilian Karczewski, Michał Ociepa, Katarzyna Pluta, Keith óProinsias, Dorota Gryko
Vitamin B12 is a cofactor for many enzymes but it also functions as a catalyst in C-C bond forming reactions. In the present study, the impact of corrin structural modifications on their catalytic efficacy was examined. Derivatives with various substituents at c-, d-, and meso-positions were synthesized using traditional and new microwave methodologies and then tested in the model reaction of 1,1-diphenylethylene with EDA. To complement our experimental data, CV and DFT calculations were performed. Mainly alterations at the c- or d-positions influence both the reaction yield and selectivity...
February 14, 2017: Chemistry: a European Journal
Christina Rutz, Kai Schütte, Juri Barthel, Alexey Bushmelev, Annette Schmidt, Katharina Dilchert, Roland Fischer, Christoph Janiak
The microwave-induced decomposition of bis{N,N'-diisopropylacetamidinate}nickel(II) [Ni{MeC(NiPr)2}2] or bis(1,5-cyclooctadiene)nickel(0) [Ni(COD)2] in imidazolium-, pyridinium- or thiophenium-based ionic liquids with different anions (tetrafluoroborate, [BF4]-, hexafluorophosphate, [PF6]- and bis(trifluoromethylsulfonyl)imide, [NTf2]-) yields small, uniform nickel nanoparticles (Ni-NPs) which are stable in the absence of capping ligands (surfactants) for more than eight weeks. The soft wet-chemical synthesis yield the metastable Ni(hcp) and not the stable Ni(fcc) phase...
February 14, 2017: Chemistry: a European Journal
Wen-Yong Lai, Yi Jiang, Mei Fang, Si-Ju Chang, Jin-Jin Huang, Shuang-Quan Chu, Shan-Ming Hu, Cheng-Fang Liu, Wei Huang
A novel series of monodisperse star-shaped ladder-type oligo(p-phenylene)s, named as TrL-n (n = 1-3), have been explored. Their thermal and electrochemical properties, fluorescence transients, photoluminescence quantum yields, density functional theory calculations, electroluminescence (EL) and amplified spontaneous emission (ASE) properties have been systematically investigated to unravel the molecular design on optoelectronic properties. The resulting materials showed excellent structural perfection free of chemical defects, exhibiting great thermal stability (Td: 404-418°C and Tg:147-184°C) and amorphous glassy morphologies...
February 14, 2017: Chemistry: a European Journal
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