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Angewandte Chemie

Richard Hatley, Simon Macdonald, Robert Slack, Joelle Le, Steve Ludbrook, Pauline Lukey
There is a requirement for efficacious and safe medicines to treat diseases with high unmet need. The resurgence in av RGD integrin inhibitor drug discovery is poised to contribute to this requirement. However, drug discovery in the av integrin space is notoriously difficult due to the receptors being structurally very similar as well as the polar zwitterionic nature of the pharmacophore. This review aims to guide drug discovery research in this field through an av inhibitor toolbox, consisting of small molecules and antibodies...
September 25, 2017: Angewandte Chemie
Nema Hafezi, Wondimagegn T Shewa, James C Fettinger, Mark Mascal
A new concept in anionic 10 pi aromaticity is described by the embedding of a compensating charge within an aromatic cyclononatetraenide ring by the symmetric interposition of a methylammonium bridge. This is accomplished by the alkylation of azatriquinacene to give a quaternary ammonium salt, followed by oxidation to the tetraene and final deprotonation. The resulting zwitterion is a stable [9]annulene with strong aromaticity as shown by its degree of C-C bond equalization and a nucleus independent chemical shift value lower than that of benzene...
September 24, 2017: Angewandte Chemie
Xinrong Zhang, Jinyu Wang, Jie Xue, Zihe Yan, Sichun Zhang, Juan Qiao
Designing probes for real-time imaging of dynamic processes in living cells is a continual challenge. Herein, a novel near-infrared photoluminescence probe with long lifetime was exploited for photoluminescence lifetime imaging (PLIM) based on an Iridium-alkyne complex. This probe offers benefits of desirable deep-red to NIR emission, long stokes shift, excellent cell penetration, low cytotoxicity and good resistance to photobleaching. To the best of our knowledge this is the first PLIM probe applicable to click reaction of Cu(I)-catalysed azide-alkyne cycloaddition with remarkable lifetime shifts of 414 ns before and after click reaction...
September 23, 2017: Angewandte Chemie
Daniel T Chiu, Xu Wu, Quinn Degottardi, I-Che Wu, Jiangbo Yu, Li Wu, Fangmao Ye, Chun-Ting Kuo, William W Kwok
Simultaneous monitoring of biomarkers as well as single-cell analyses based on flow cytometry and mass cytometry are important for investigations of disease mechanisms, drug discovery, and signaling-network studies. Flow cytometry and mass cytometry are complementary to each other; however, probes that can satisfy all the requirements for these two advanced technologies are limited. In this study, we report a probe of lanthanide-coordinated semiconducting polymer dots (Pdots), which possess fluorescence and mass signals...
September 22, 2017: Angewandte Chemie
Nicolai Cramer, Yun-Suk Jang, Michael Dieckmann
An enantioselective C-H amidation of phosphine oxides by using an iridium(III) catalyst bearing an atropchiral cyclopentadienyl (Cpx) ligand is reported. A very strong cooperative effect between the chiral Cpx ligand and a phthaloyl tert-leucine enabled the transformation. Matched-mismatched cases of the different acid enantiomers are shown. The amidated P-chiral arylphosphine oxides are formed in yields of up to 95 % and with excellent enantioselectivities of up to 99:1 er. Enantiospecific reduction provides access to valuable P-chiral phosphorus(III) compounds...
September 22, 2017: Angewandte Chemie
Malay Pramanik, Satoshi Tominaka, Zhong-Li Wang, Toshiaki Takei, Yusuke Yamauchi
Mesoporous cobalt phosphide (meso-CoP) was prepared by the phosphorization of ordered mesoporous cobalt oxide (meso-Co3 O4 ). The electrical conductivity of meso-CoP is 37 times higher than that of nonporous CoP, and it displays semimetallic behavior with a negligibly small activation energy of 26 meV at temperatures below 296 K. Above this temperature, only materials with mesopores underwent a change in conductivity from semimetallic to semiconducting behavior. These properties were attributed to the coexistence of nanocrystalline Co2 P phases...
September 22, 2017: Angewandte Chemie
Wilbert J Smit, Huib J Bakker
The surface of ice has been reported to be disordered at temperatures well below the bulk melting point. However, the precise nature of this disorder has been a topic of intense debate. Here, we study the molecular properties of the surface of ice as a function of temperatures using heterodyne-detected sum-frequency generation spectroscopy. We observe that, down to 245 K, the spectral response of the surface of ice contains a component that is indistinguishable from supercooled liquid water.
September 22, 2017: Angewandte Chemie
Rein V Ulijn, Chunqiu Zhang, Ramim Shafi, Ayala Lampel, Douglas MacPherson, Charalampas Pappas, Vishal Narang, Tong Wang, Charles Madarelli
The reversible regulation of catalytic activity is a feature found in natural enzymes which is not commonly observed in artificial catalytic systems. Here, we fabricate an artificial hydrolase with pH-switchable activity, achieved by introducing a catalytic histidine residue at the terminus of a pH-responsive peptide. The peptide exhibits a conformational transition from random coil to β-sheet by changing the pH from acidic to alkaline. The β-sheet self-assembles to form long fibrils with the hydrophobic edge and histidine residues extending in an ordered array as the catalytic microenvironment, which shows significant esterase activity...
September 22, 2017: Angewandte Chemie
Kai Johnsson, Julien Hiblot, Qiluiyang Yu, Marina Sabbadini, Luc Reymond, Lin Xue, Olivier Sallin, Alberto Schena, Rudolf Griss, Nicholas Hill
We introduce luciferases whose emission maxima can be tuned to different wavelengths by chemical labeling. These tunable luciferases are generated by inserting the small luciferase NanoLuc into the structures of the self-labeling proteins SNAP-tag or HaloTag7 near their active sites. Labeling of the tags with a fluorophore shifts the emission maximum of NanoLuc to that of the fluorophore. Luciferases with tunable colors have applications as reporter genes, for the construction of biosensors and in bioimaging...
September 22, 2017: Angewandte Chemie
Vladimir Gevorgyan, Daria Kurandina, Marvin Parasram
The first visible light-induced Pd-catalyzed Heck reaction of α-heteroatom substituted alkyl iodides and -bromides with vinyl arenes/heteroarenes has been developed. This transformation efficiently proceeds at room temperature and enables synthesis of valuable functionalized allylic systems, such as allylic silanes, -boronates, -germanes, -stannanes, -pivalates, -phosphonates, -phthalimides, and -tosylates from the corresponding α-substituted methyl iodides. Notably, synthesis of the latter substrates failed under existing thermally induced Pd-catalyzed conditions, which highlights the importance of visible light for this transformation...
September 22, 2017: Angewandte Chemie
Simon Aldridge, Andrey Protchenko, Juan Urbano, Joseph Abdalla, Jesus Campos, Dragoslav Vidovic, Andrew Schwarz, Matthew Blake, Philip Mountford, Cameron Jones
Reduction of indium boryl precursors to give two- and three-dimensional M-M bonded networks is influenced by the choice of supporting ligand. While the unprecedented nanoscale cluster [In68(boryl)12]- (with an In12@In44@In12(boryl)12 concentric structure), can be isolated from the potassium reduction of a bis(boryl)indium(III) chloride precursor, analogous reduction of the corresponding (benzamidinate)InIIIBr(boryl) system gives a near-planar (and weakly aromatic) tetranuclear [In4(boryl)4]2- system.
September 22, 2017: Angewandte Chemie
Haixing Li, Timothy Su, María Camarasa-Gómez, Daniel Hernangómez-Pérez, Simon Henn, Vladislav Pokorný, Caravaggio Dante Caniglia, Michael Inkpen, Richard Korytár, Michael Steigerwald, Colin Nuckolls, Ferdinand Evers, Latha Venkataraman
We report that the single molecule junction conductance of thiol-terminated silanes with Ag electrodes are higher than the conductance of those formed with Au electrodes. These results are in contrast to the trends in the metal work function Φ(Ag) < Φ(Au). As such, one would expect a better alignment of the Au Fermi level to the molecular orbital of silane that mediates charge transport. Additionally, this conductance trend is reversed when we replace the thiols with amines, highlighting the impact of metal-S covalent and metal-NH2 dative bonds in controlling the molecular conductance...
September 22, 2017: Angewandte Chemie
Nicholas Robert Vance, Michael Ashley Spies, Lokesh Gakhar
The caspase family of cysteine proteases are highly sought after drug targets due to their essential roles in apoptosis, proliferation and inflammation pathways. High throughput screening efforts to discover inhibitors have gained little traction. Fragment-based screening has emerged as a powerful tool for the discovery of innovative drug leads. This methodology has become a central facet of drug discovery campaigns in the pharmaceutical industry and academia. A fragment-based drug discovery campaign against human caspase-7 resulted in the discovery of a novel series of allosteric inhibitors...
September 22, 2017: Angewandte Chemie
Olivier Dalstein, Effrosyni Gkaniatsou, Clemence Sicard, Ozlem Sel, Hubert Perrot, Christian Serre, Cedric Boissiere, Marco Faustini
Herein, a straightforward crack-patterning method is reported allowing the direct formation of periodic cracks in Metal-Organic Framework nanoparticles films during dip-coating deposition. The crack propagation and periodicity can be easily tailored by controlling the evaporation front and the withdrawal speed. Several MOF patterned films can be fabricated on large surfaces and on several substrates (flat, curved or flexible) including the inner surface of a tube, not achievable by other lithographic techniques...
September 22, 2017: Angewandte Chemie
Thomas Friedrich Fässler, Kerstin Mayer, Jasmin Dums, Wilhelm Klein
The new [SnBi3]5- polyanion is obtained by the reaction of K3Bi2 with K4Sn9 or K12Sn17 in liquid ammonia. The anion is iso(valence)electronic with and structurally analogous to the carbonate ion. Despite the high negative charge of the anion, the Sn-Bi bond lengths range between single and double bonds. Quantum-chemical calculations at a DFT-PBE0/def2-TZVPP/COSMO level of theory reveal that the partial double bond character between the heavy main group atoms Bi and Sn originates from a delocalized π-electronic system...
September 22, 2017: Angewandte Chemie
Chuanle Zhu, Rui Zhu, Hao Zeng, Fulin Chen, Chi Liu, Wanqing Wu, Huanfeng Jiang
The first oxidative C(sp(3) )-H/C(sp(3) )-H cross-dehydrogenative coupling (CDC) reaction promoted by an internal oxidant is reported. This copper-catalyzed CDC reaction of oxime acetates and trifluoromethyl ketones provides a simple and efficient approach towards 2-trifluoromethyldihydropyrrol-2-ol derivatives in a highly diastereoselective manner by cascade C(sp(3) )-C(sp(3) ) bond formation and cyclization. These products were further transformed into various significant and useful trifluoromethylated heterocyclic compounds, such as trifluoromethylated furan, thiophene, pyrrole, dihydropyridazine, and pyridazine derivatives...
September 22, 2017: Angewandte Chemie
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No abstract text is available yet for this article.
September 22, 2017: Angewandte Chemie
Jürgen Kopitz, Qi Xiao, Anna-Kristin Ludwig, Antonio Romero, Malwina Michalak, Samuel E Sherman, Xuhao Zhou, Cody Dazen, Sabine Vértesy, Herbert Kaltner, Michael L Klein, Hans-Joachim Gabius, Virgil Percec
Chemical and biological tools are harnessed to investigate the impact of spatial factors for functional pairing of human lectins with counterreceptors. The homodimeric adhesion/growth-regulatory galectin-1 and a set of covalently linked homo-oligomers from di- to tetramers serve as proof-of-principle test cases. Glycodendrimersomes provide a versatile and sensitive diagnostic platform to reveal thresholds for ligand density and protein concentration in aggregation assays (trans-activity), irrespective of linker length between lectin domains...
September 22, 2017: Angewandte Chemie
Sabine Flitsch, Alexander Wood, Nicholas Weise, Joseph Frampton, Mark Dunstan, Michael Hollas, Sasha Derrington, Richard LLoyd, Daniela Quaglia, Fabio Parmeggiani, David Leys, Nicholas Turner
Carboxylic acid reductases (CARs) catalyze the reduction of a broad range of carboxylic acids to aldehydes using the co-factors ATP and NADPH, and have become attractive biocatalysts for organic synthesis. Here we exploit our mechanistic understanding of CARs to expand their reaction scope, generating biocatalysts for amide bond formation from carboxylic acid and amine. After reaction engineering, CARs were found to have amidation activity for various acids and amines. Optimization of reaction conditions with respect to pH and temperature allowed for the synthesis of the anticonvulsant ilepcimide with up to 96% conversion...
September 22, 2017: Angewandte Chemie
Qinfeng Rong, Wenwei Lei, Lie Chen, Yongai Yin, Jiajia Zhou, Mingjie Liu
Conductive hydrogels emerge as a fascinating class of stretchable conductive materials that are important for various applications. However, water-based conductive hydrogels inevitably lose elasticity and conductivity at subzero temperatures, which severely limits their practical applications at low temperatures. Here we report anti-freezing conductive organohydrogels by using an H2O/ethylene glycol binary solvent as dispersion medium. Owing to the freezing tolerance of the binary solvent, our organohydrogels exhibit stable flexibility and strain-sensitivity in the temperature range from -55...
September 22, 2017: Angewandte Chemie
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