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Takahiro Ichikawa, Akiyoshi Okafuji, Takashi Kato, Hiroyuki Ohno
The Back Cover picture illustrates the attachment of iodine atoms onto the headgroup of an amphiphilic zwitterion, which leads to the formation of a bicontinuous cubic liquid-crystalline assembly with a primitive-type infinite periodic minimal surface. More information can be found in the Communication by T. Ichikawa, H. Ohno and co-workers on page 439 in Issue 5, 2016 (DOI: 10.1002/open.201600054).
October 2016: ChemistryOpen
Zhen Wang, Yuzhou Deng, Genli Shen, Sadia Akram, Ning Han, Yunfa Chen, Qi Wang
A Ce-Mn composite oxide possessing a rod-like morphology (with a fixed molar ratio of Ce/Mn=3:7) was synthesized through a hydrothermal method. Mn ions were doped into a CeO2 framework to replace Ce ions, thereby increasing the concentration of oxygen vacancies. The formation energies of O vacancies for the Ce-Mn composite oxide were calculated by applying density functional theory (DFT). The data showed that it was easier to form an O vacancy in the composite. The catalytic behavior of the Ce-Mn composite oxide for benzene degradation was researched in detail, which exhibited a higher activity than the pure phases...
October 2016: ChemistryOpen
Maria Garrido, Miriam Corredor, Mar Orzáez, Ignacio Alfonso, Angel Messeguer
Apoptosis is a biological process important to several human diseases; it is strongly regulated through protein-protein interactions and complex formation. We previously reported the synthesis of apoptosis inhibitors bearing an exocyclic triazole amide isoster by using an Ugi four-component coupling reaction (Ugi-4CC), followed by a base-promoted intramolecular cyclization. Depending on the substitution patterns and the reaction conditions, this cyclization forms the six- or four-membered ring. Two compounds bearing the β-lactam scaffold turned out to be the most potent inhibitors...
October 2016: ChemistryOpen
Gour Chand Daskhan, Carlo Pifferi, Olivier Renaudet
The synthesis of heteroglycoclusters (hGCs) is being subjected to rising interest, owing to their potential applications in glycobiology. In this paper, we report an efficient and straightforward convergent protocol based on orthogonal chemoselective ligations to prepare structurally well-defined cyclopeptide-based homo- and heterovalent glycoconjugates displaying 5-N-acetyl-neuraminic acid (Neu5Ac), galactose (Gal), and/or N-acetyl glucosamine (GlcNAc). We first used copper-catalyzed azide-alkyne cycloaddition and/or thiol-ene coupling to conjugate propargylated α-sialic acid 3, β-GlcNAc thiol 5, and β-Gal thiol 6 onto cyclopeptide scaffolds 7-9 to prepare tetravalent homoglycoclusters (10-12) and hGCs (13-14) with 2:2 combinations of sugars...
October 2016: ChemistryOpen
Chenggang Ci, Hongsheng Liu, Likai Yan, Zhongmin Su
Aqua-coordinated sandwich-type polyoxometalates (POMs), {[WZnTM2(H2O)2](ZnW9O34)2} (n-) (TM=Rh(III), Pd(II), and Pt(II)), catalyze olefin epoxidation with hydrogen peroxide and have been well established, and they present an advance toward the utilization of olefins. To elucidate the epoxidation mechanism, we systematically performed density functional calculations. The reaction proceeds through a two-step mechanism: activation of H2O2 and oxygen transfer. The aqua-coordinated complexes show two distinct H2O2 activation pathways: "two-step" and "concerted"...
October 2016: ChemistryOpen
Yusif Abdullayev, Vagif Abbasov, Lucas C Ducati, Avtandil Talybov, Jochen Autschbach
The mechanisms of a tetrasubstituted imidazole [2-(2,4,5-triphenyl-1 H-imidazol-1-yl)ethan-1-ol] synthesis from benzil, benzaldehyde, ammonium acetate, and ethanolamine in [Et2NH2][HSO4] ionic liquid (IL) are studied computationally. The effects of the presence of the cationic and anionic components of the IL on transition states and intermediate structures, acting as a solvent versus as a catalyst, are determined. In IL-free medium, carbonyl hydroxylation when using a nucleophile (ammonia) proceeds with a Gibbs free energy (ΔG(≠)) barrier of 49...
October 2016: ChemistryOpen
Ayat Allah Al-Massaedh, Manuel Schmidt, Ute Pyell, Uwe M Reinscheid
Enantiodiscrimination and enantioseparation are two highly important processes in chemistry, often performed by using NMR spectroscopy and chromatography. For a better understanding of the mechanistic details, the same system should be studied by both methods. In addition, isotropic and anisotropic NMR parameters should be obtained, the latter using alignment media so that residual dipolar couplings and chemical-shift anisotropies can be measured. Consequently, a chiral alignment medium was used for the first time in chiral gel-based capillary electrochromatography with the four stereoisomers of the antimalaria drug mefloquine as test compounds...
October 2016: ChemistryOpen
Giorgio Mirri, Daniël C Schoenmakers, Paul H J Kouwer, Peter Veranič, Igor Muševič, Bogdan Štefane
Fluorescent materials are widely used in biological and material applications as probes for imaging or sensing; however, their customization is usually complicated without the support of an organic chemistry laboratory. Here, we present a straightforward method for the customization of BODIPY cores, which are among the most commonly used fluorescent probes. The method is based on the formation of a new C-C bond through Friedel-Crafts electrophilic aromatic substitution carried out at room temperature. The method presented can be used to obtain completely customized fluorescent materials in one or two steps from commercially available compounds...
October 2016: ChemistryOpen
Anders Gunnarsson, Lisa Simonsson Nyström, Sabina Burazerovic, Jenny Gunnarsson, Arjan Snijder, Stefan Geschwindner, Fredrik Höök
Investigations of ligand-binding kinetics to membrane proteins are hampered by their poor stability and low expression levels, which often translates into sensitivity-related limitations impaired by low signal-to-noise ratios. Inspired by affinity capturing of water-soluble proteins, which utilizes water as the mobile phase, we demonstrate affinity capturing and local enrichment of membrane proteins by using a fluid lipid bilayer as the mobile phase. Specific membrane-protein capturing and enrichment in a microfluidic channel was accomplished by immobilizing a synthesized trivalent nitrilotriacetic acid (tris-NTA)-biotin conjugate...
October 2016: ChemistryOpen
Takahiro Ichikawa, Akiyoshi Okafuji, Takashi Kato, Hiroyuki Ohno
We have designed an amphiphilic zwitterion with an iodine-substituted imidazolium cation. Although it forms a layered assembly with flat interfaces, the addition of an equimolar amount of bis(trifluoromethane)sulfonimide results in the formation of a bicontinuous cubic liquid-crystalline assembly with a primitive-type infinite periodic minimal surface, where its zwitterionic headgroup sits regularly. IR measurements revealed that halogen bond between the iodine atoms on the imidazolium cation and the anions is involved in its molecular-assembly behavior...
October 2016: ChemistryOpen
Kirara Yamaguchi, Toshiaki Murai, Jing-Dong Guo, Takahiro Sasamori, Norihiro Tokitoh
Solutions of 5-N-arylaminothiazoles containing pyridyl groups exhibited clear halochromism and halofluorism upon addition of Brønsted and Lewis acids. The addition of triflic acid to solutions of 5-N-arylaminothiazoles in Et2O induced bathochromic shifts of the absorption and emission bands. DFT calculations suggested that the spectral changes arise from the protonation of the pyridyl group of the thiazoles in Et2O. Single-crystal X-ray diffraction analysis of a thiazole and its protonated form revealed the change of the conformation around the thiazole ring...
October 2016: ChemistryOpen
Rituparna Das, Balaram Mukhopadhyay
The development of glycobiology relies on the sources of particular oligosaccharides in their purest forms. As the isolation of the oligosaccharide structures from natural sources is not a reliable option for providing samples with homogeneity, chemical means become pertinent. The growing demand for diverse oligosaccharide structures has prompted the advancement of chemical strategies to stitch sugar molecules with precise stereo- and regioselectivity through the formation of glycosidic bonds. This Review will focus on the key developments towards chemical O-glycosylations in the current century...
October 2016: ChemistryOpen
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No abstract text is available yet for this article.
October 2016: ChemistryOpen
Kirara Yamaguchi, Toshiaki Murai, Jing-Dong Guo, Takahiro Sasamori, Norihiro Tokitoh
The front cover artwork is provided by the group of Toshiaki Murai at Gifu University (Japan). The image shows structures of the key compounds and the change of the fluorescence. Although electron-donating and -accepting groups are not in the same plane, they show relatively strong fluorescence from blue to orange. For more details, read the full text of the Communication at 10.1002/open.201600059.
October 2016: ChemistryOpen
Kirara Yamaguchi, Toshiaki Murai, Jing-Dong Guo, Takahiro Sasamori, Norihiro Tokitoh
The Front Cover picture shows structures of the key compounds and the change in the fluorescence. Although electron-donating and -accepting groups of monocyclic 5-N,N-diarylaminothiazoles are not in the same plane but highly deviated, they show relatively strong fluorescence from blue to orange. In particular, the addition of Brønsted and Lewis acids to 5-N,N-diaryl-2-(4-pyridyl)thiazoles shifts the absorption and emission to longer wavelengths. The thiazoles and acids form 1:1 complexes. Fine tuning of the amount of added B(C6F5)3 enables us to provide a white-light emission with a single fluorescent molecule...
October 2016: ChemistryOpen
Yu Chen, Zhiqiang Zhao, Zheng Bian, Rizhe Jin, Chuanqing Kang, Xuepeng Qiu, Haiquan Guo, Zhijun Du, Lianxun Gao
The motivation of foldamer chemistry is to identify novel building blocks that have the potential to imitate natural species. Peptides and peptide mimetics can form stable helical conformations and further self-assemble into diverse aggregates in water, where it is difficult to isolate a single helix. In contrast, most "abiotic" foldamers may fold into helical structures in solution, but are difficult to assemble into tertiary ones. It remains a challenge to obtain "abiotic" species similar to peptides. In this paper, a novel foldamer scaffold, in which p-phenyleneethynylene units are linked by chiral carbon atoms, was designed and prepared...
August 2016: ChemistryOpen
Joseph K-H Wong, Sandra Ast, Mingfeng Yu, Roman Flehr, Andrew J Counsell, Peter Turner, Patrick Crisologo, Matthew H Todd, Peter J Rutledge
Fluorescent molecular probes for metal ions have a raft of potential applications in chemistry and biomedicine. We report the synthesis and photophysical characterisation of 1,8-disubstituted-cyclam/naphthalimide conjugates and their zinc complexes. An efficient synthesis of 1,8-bis-(2-azidoethyl)cyclam has been developed and used to prepare 1,8-disubstituted triazolyl-cyclam systems, in which the pendant group is connected to triazole C4. UV/Vis and fluorescence emission spectra, zinc binding experiments, fluorescence quantum yield and lifetime measurements and pH titrations of the resultant bis-naphthalimide ligand elucidate a complex pattern of photophysical behaviour...
August 2016: ChemistryOpen
Masaki Fuchiwaki, Jose G Martinez, Toribio Fernandez Otero
Three bilayer muscles [polypyrrole-paraphenolsulfonic acid/polypyrrole-dodecylbenzensulfonic acid (PPy-HpPS/PPy-DBS) asymmetric bilayer, PPy-HpPS/tape, and PPy-DBS/tape] were characterized during potential cycling in NaPF6 aqueous solutions. In parallel, the angular displacement of the muscle was video-recorded. The dynamo-voltammetric (angle-potential) and coulo-dynamic (charge-potential) results give the reaction-driven ionic exchanges in each PPy film. Electrochemical reactions drive the exchange of anions from the PPy-HpPS layer and cations from the PPy-DBS layer...
August 2016: ChemistryOpen
Fei Mao, Qingya Kong, Wei Ni, Xiang Xu, Dazheng Ling, Zhengyu Lu, Jian Li
The melting point (MP), an easily accessible physical parameter, has considerable potential for the judgment of drug-like properties. However, to the best of our knowledge, there are no useful guidelines for understanding the relationship between the MP and drug-like properties. To this end, we have constructed the largest MP database (experimental value) of globally approved drugs (3164 organic small-molecule drugs) and discontinued drugs (417 organic small-molecule drugs) and subsequently extracted six subdatabases from the whole approved database and two subdatabases from the discontinued database...
August 2016: ChemistryOpen
Michael R Chapman, Susan E Henkelis, Nikil Kapur, Bao N Nguyen, Charlotte E Willans
Synthetic methods to prepare organometallic and coordination compounds such as Schiff-base complexes are diverse, with the route chosen being dependent upon many factors such as metal-ligand combination and metal oxidation state. In this work we have shown that electrochemical methodology can be employed to synthesize a variety of metal-salen/salan complexes which comprise diverse metal-ligand combinations and oxidation states. Broad application has been demonstrated through the preparation of 34 complexes under mild and ambient conditions...
August 2016: ChemistryOpen
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