bluuebunny/crossref_metadata_2025 huggingface dataset:
Aliphatic Halogenase Enables Late‐Stage C−H Functionalization: Selective Synthesis of a Brominated Fischerindole Alkaloid with Enhanced Antibacterial Activity
Authors: Zhu Qin , Hillwig Matthew L. , Doi Yohei , Liu Xinyu
Published: January 2016

The anion promiscuity of a newly discovered standalone aliphatic halogenase WelO5 was probed and enabled the selective synthesis of 13R‐bromo‐12‐epi‐fischerindole U via late‐stage enzymatic functionalization of an unactivated sp3 C−H bond. Pre‐saturating the WelO5 active site with a non‐native bromide anion was found to be critical to the highly selective in vitro transfer of bromine, instead of chlorine, to the target carbon center and also allowed the relative binding affinity of bromide and chloride towards the WelO5 enzyme to be assessed. This study further revealed the critical importance of halogen substitution on modulating the antibiotic activity of fischerindole alkaloids and highlights the promise of WelO5‐type aliphatic halogenases as enzymatic tools to fine‐tune the bioactivity of complex natural products.
Phospha‐Michael Addition as a New Click Reaction for Protein Functionalization
Authors: Lee Yan‐Jiun , Kurra Yadagiri , Liu Wenshe R.
Published: January 2016

A new type of click reaction between an alkyl phosphine and acrylamide was developed and applied for site‐specific protein labeling in vitro and in live cells. Acrylamide is a small electrophilic olefin that readily undergoes phospha‐Michael addition with an alkyl phosphine. Our kinetic study indicated a second‐order rate constant of 0.07 m−1 s−1 for the reaction between tris(2‐carboxyethyl)phosphine and acrylamide at pH 7.4. To demonstrate its application in protein functionalization, we used a dansyl–phosphine conjugate to successfully label proteins that were site‐specifically installed with Nɛ‐acryloyl‐l‐lysine and employed a biotin–phosphine conjugate to selectively probe human proteins that were metabolically labeled with N‐acryloyl‐galactosamine.
Successful outcome following detection and removal of a very small ovarian teratoma associated with anti‐NMDA receptor encephalitis during pregnancy
Authors: Mizutamari Etsuko , Matsuo Yuji , Namimoto Tomohiro , Ohba Takashi , Yamashita Yasuyuki , Katabuchi Hidetaka
Published: January 2016

Key Clinical Message

An important part of anti–N‐methyl‐d‐aspartate (NMDA) receptor encephalitis treatment is prompt detection and removal of any associated ovarian teratoma, regardless of size. High‐resolution transvaginal ultrasonography followed by targeted CT with adaptive iterative dose reduction (AIDR) is a useful strategy for distinguishing small ovarian teratomas from luteal cysts during pregnancy.
A case of lethal giant inguinal hernia
Authors: Chida Yasuyuki , Inokuchi Ryota , Kumada Yoshibumi , Shinohara Kazuaki
Published: January 2016

Key Clinical Message

Several elective surgical managements have been reported regarding giant inguinal hernias (GIH), but no case of death. We here present a fatal case of bilateral GIHs in an extremely obese man with dyspnea. Bilateral GIHs are difficult to recognize in extreme obesity. Moreover, operation is recommended when GIH is diagnosed.
Design Strategies for a Denitrification Catalyst with Improved Resistance against Alkali Poisoning: The Significance of Nanoconfining Spaces and Acid–Base Balance
Authors: Wang Penglu , Wang Haiqiang , Chen Xiongbo , Wu Zhongbiao
Published: January 2016

Based on the ideas of the nanoconfining effect and the acid–base balance mechanism, a dual‐protection strategy was designed to solve the deactivation problem that occurs on ceria‐based deNOx catalysts. The nanoconfining spaces were provided by multilayer titanate nanotubes, and the acid–base balance was guaranteed by the modification of sulfuric acid pickling on titanate nanotubes. The ceria‐doped 0.1 mol L−1 sulfated titanate nanotubes catalyst exhibited an excellent selective catalytic reduction (SCR) catalytic activity and enhanced alkali resistance. It was found that the enhanced alkali resistance was relevant for the perfect hollow‐tubular structure, repeatable Ce4+/Ce3+ redox cycles, and increased surface acid sites. In situ diffuse reflectance infrared Fourier transform spectroscopy further identified that the balance of acidity and basicity on K‐Ce/0.1STNTs ensured the activity of adsorbed NH3 and NOx species. The SCR reaction was thus facilitated over the sulfated catalysts and both the Eley–Rideal and Langmuir–Hinshelwood mechanisms may occur during the reaction.
Application of Pd Nanoparticles Supported on Mesoporous Hollow Silica Nanospheres for the Efficient and Selective Semihydrogenation of Alkynes
Authors: Verho Oscar , Zheng Haoquan , Gustafson Karl P. J. , Nagendiran Anuja , Zou Xiaodong , Bäckvall Jan‐E.
Published: January 2016

Herein, the preparation of a heterogeneous catalyst consisting of 1–2 nm sized Pd nanoparticles supported on amino‐functionalized mesoporous hollow silica nanospheres and its use for the semihydrogenation of mono‐ and disubstituted alkynes is reported. By utilizing this Pd nanocatalyst together with the green poisoning agent DMSO, high yields of the desired alkenes could be achieved, while suppressing the degree of over‐reduction to alkanes. To our delight, the Pd nanocatalyst displayed remarkable chemoselectivity towards the alkyne moiety, allowing the transformation to be carried out in the presence of other reducible functionalities, such as halogens, carbonyl, and nitro groups.
Surface Reconstruction of Facet‐Functionalized SrTiO3 Nanocrystals for Photocatalytic Hydrogen Evolution
Authors: Wang Bin , Shen Shaohua , Guo Liejin
Published: January 2016

The surface structure determines the surface electronic and chemical properties of semiconducting nanocrystals for efficient photocatalysis. Herein, SrTiO3 nanocrystals enclosed by {0 0 1} and {0 2 3} facets functionalized for photoreduction and photooxidation, respectively, were surface‐reconstructed with a disordered overlayer created by a thermal hydrogenation process. These surface‐reconstructed SrTiO3 nanocrystals showed much higher photocatalytic activities than the pristine SrTiO3, which was attributed to the enhanced charge transfer ability and accelerated oxidative reaction kinetics induced by the oxygen vacancies in disordered overlayer. Given the maintained {0 0 1} and {0 2 3} facets ensuring spatial charge separation and functioning for reduction and oxidation reactions, respectively, the surface‐reconstructed SrTiO3 nanocrystals enclosed with {0 2 3} and {0 0 1} facets in appropriate ratio showed the highest photocatalytic activity for hydrogen evolution.
Electrochemical Reduction of Carbon Dioxide at Gold‐Palladium Core–Shell Nanoparticles: Product Distribution versus Shell Thickness
Authors: Humphrey Jo J. L. , Plana Daniela , Celorrio Verónica , Sadasivan Sajanikumari , Tooze Robert P. , Rodríguez Paramaconi , Fermín David J.
Published: January 2016

The electrocatalytic reduction of CO2 at carbon‐supported Au‐Pd core–shell nanoparticles is investigated systematically as a function of the Pd shell thickness. Liquid‐ and gas‐phase products were determined by off‐line 1H NMR spectroscopy and on‐line electrochemical mass spectrometry. Our results uncover the relationship between the nature of the products generated and the Pd shell thickness. CO and H2 are the only products generated at 1 nm thick shells, whereas shells of 5 and 10 nm produced HCOO−, CH4 and C2H6. The concentration of HCOO− detected in the electrolyte was dependent on the applied potential and reached a maximum Faradaic efficiency of 27 % at −0.5 V versus the reversible hydrogen electrode for 10 nm thick shells. We conclude that collisions between absorbed hydrogen at relaxed Pd lattices and strongly bound “CO‐like” intermediates promote the complete hydrogenation to C1 and C2 alkanes without the generation of other products, such as alcohols and aldehydes.
Electrodeposition of Stoichiometric Indium Antimonide from Room‐Temperature Ionic Liquid 1‐Butyl‐1‐Methylpyrrolidinium Dicyanamide
Authors: Hsieh Yi‐Ting , Chen Yu‐Chen , Sun I‐Wen
Published: January 2016

A stoichiometric InSb film was electrodeposited on a nickel (Ni) substrate in a room‐temperature ionic liquid, 1‐butyl‐1‐methylpyrrolidinium dicyanamide (BMP‐DCA), containing anhydrous InCl3 and SbCl3 with a molar concentration ratio of 1:1. The composition of the deposited InSb film was found to depend on both the applied potential and the deposition charge. Crystalline deposits can be directly obtained at low temperature (60 °C) without any post‐heat treatment. The optical band gap of the InSb film analyzed by using FTIR spectroscopy measurements was approximately 0.17 eV. Results from photocurrent experiments indicate that the electrodeposited InSb film was a p‐type semiconductor.
Principles of Bipolar Electrochemistry
Authors: Crooks Richard M.
Published: January 2016

This is a tutorial on the basic concepts underlying bipolar electrochemistry. It is intended as an accompaniment to ChemElectroChem’s special issue on this topic. The guest editors of this special issue think it is worthwhile to introduce bipolar electrochemistry to a broader (electrochemistry) audience by explaining the similarities and differences between bipolar electrochemistry and normal electrochemical methods. The work presented herein has been adapted from: S. E. Fosdick, K. N. Knust; K. Scida; R. M. Crooks “Bipolar Electrochemistry” Angew. Chem. Int. Ed. 2013, 52, 10438–10456 (DOI: 10.1002/anie.201300947); “Bipolare Elektrochemie” Angew. Chem. 2013, 125, 10632–10651 (DOI: 10.1002/ange.201300947).
Comparison of using regression modeling and an artificial neural network for herbage dry matter yield forecasting
Authors: Majkovič Darja , O'Kiely Padraig , Kramberger Branko , Vračko Marjan , Turk Jernej , Pažek Karmen , Rozman Črtomir
Published: January 2016

This study presents an application of artificial neural network and regression modeling techniques for forecasting grassland dry matter yield. Using data from a field plot experiment on semi‐natural grassland in Maribor (Slovenia), the multiple regression and artificial neural network methodologies were employed to explain the patterns of dry matter yield during a 6‐year period. On the basis of the two proposed approaches forecasts were conducted for the independent, validation year (6). The results in terms of Theil inequality coefficient, mean absolute error, and correlation coefficient show a better forecasting performance for the artificial neural network (likely due to the non‐linear relationships prevailing among regressors and regressand) while relationships between observables can be better explained by regression modeling results. Copyright © 2016 John Wiley & Sons, Ltd.
Analytical investigation of secondary metabolites extracted from Camellia sinensis L. leaves using a HPLC‐DAD‐ESI/MS data fusion strategy and chemometric methods
Authors: Pauli Elis Daiane , Scarminio Ieda Spacino , Tauler Romà
Published: January 2016

Considerable attention has been paid to the study of green tea leaves because of their high consume and beneficial effects on human health. In this work, an appropriate strategy is proposed to investigate and resolve the major metabolites extracted from Camellia sinensis tea leaves. Statistical design mixtures of ethanol, ethyl acetate, dichloromethane, and chloroform were used to study the effects of different solvents and their mixtures on the extraction of the secondary metabolites of C. sinensis tea leaves from two different harvest seasons. Extracted samples were analyzed by high performance liquid chromatography‐diode array detection‐electrospray ionization mass spectrometer allowing the resolution of a large amount of tea metabolites with high relative abundances, especially when their extraction was performed in pure ethanol and with solvent mixtures with ethanol. Resolution of the more relevant metabolites was achieved by the simultaneous analysis of the fused diode array detection and mass spectrometer detectors data from the same samples using the multivariate curve resolution‐alternating least squares chemometric method. Peak areas finally resolved were further analyzed by orthogonal signal correction and partial least squares‐discrimination analysis to discriminate among C. sinensis tea samples. Using the Variable Importance in Projection variable selection method, epigallocatechin and caffeine were finally selected as the two more important chemical constituents of tea leaves that were discriminating more between the tea samples from two different harvest seasons. Copyright © 2016 John Wiley & Sons, Ltd.
Molecularly Dispersed Donors in Acceptor Molecular Crystals for Photon Upconversion under Low Excitation Intensity
Authors: Hosoyamada Masanori , Yanai Nobuhiro , Ogawa Taku , Kimizuka Nobuo
Published: January 2016

For real‐world applications of photon upconversion based on the triplet–triplet annihilation (TTA‐UC), it is imperative to develop solid‐state TTA‐UC systems that work effectively under low excitation power comparable to solar irradiance. As an approach in this direction, aromatic crystals showing high triplet diffusivity are expected to serve as a useful platform. However, donor molecules inevitably tend to segregate from the host acceptor crystals, and this inhomogeneity results in the disappointing performance of crystalline state TTA‐UC. In this work, a series of cast‐film‐forming acceptors was developed, which provide both regular acceptor alignment and soft domains of alkyl chains that accommodate donor molecules without segregation. A typical triplet sensitizer, PtII octaethylporphyrin (PtOEP), was dispersed in these acceptor crystals without aggregation. As a result, efficient triplet energy transfer from the donor to the acceptor and diffusion of triplet excitons among regularly aligned anthracene chromophores occurred. It resulted in TTA‐UC emission at low excitation intensities, comparable to solar irradiance.
Studies of a Large Odd‐Numbered Odd‐Electron Metal Ring: Inelastic Neutron Scattering and Muon Spin Relaxation Spectroscopy of Cr8Mn
Authors: Baker Michael L. , Lancaster Tom , Chiesa Alessandro , Amoretti Giuseppe , Baker Peter J. , Barker Claire , Blundell Stephen J. , Carretta Stefano , Collison David , Güdel Hans U. , Guidi Tatiana , McInnes Eric J. L. , Möller Johannes S. , Mutka Hannu , Ollivier Jacques , Pratt Francis L. , Santini Paolo , Tuna Floriana , Tregenna‐Piggott Philip L. W. , Vitorica‐Yrezabal Iñigo J. , Timco Grigore A. , Winpenny Richard E. P.
Published: January 2016

The spin dynamics of Cr8Mn, a nine‐membered antiferromagnetic (AF) molecular nanomagnet, are investigated. Cr8Mn is a rare example of a large odd‐membered AF ring, and has an odd‐number of 3d‐electrons present. Odd‐membered AF rings are unusual and of interest due to the presence of competing exchange interactions that result in frustrated‐spin ground states. The chemical synthesis and structures of two Cr8Mn variants that differ only in their crystal packing are reported. Evidence of spin frustration is investigated by inelastic neutron scattering (INS) and muon spin relaxation spectroscopy (μSR). From INS studies we accurately determine an appropriate microscopic spin Hamiltonian and we show that μSR is sensitive to the ground‐spin‐state crossing from S=1/2 to S=3/2 in Cr8Mn. The estimated width of the muon asymmetry resonance is consistent with the presence of an avoided crossing. The investigation of the internal spin structure of the ground state, through the analysis of spin‐pair correlations and scalar‐spin chirality, shows a non‐collinear spin structure that fluctuates between non‐planar states of opposite chiralities.
A Study on the Photoreaction of 2(5H)‐Furanones with Substituted Acetylenes: Evidence for a Mechanistic Reformulation
Authors: Flores Ramon , Font Josep , Alibés Ramon , Figueredo Marta
Published: January 2016

The photoreaction of 2(5H)‐furanones with alkynes has been investigated. The complexity of this process is evidenced by the variety of isolated products, which have allowed disclosing interesting mechanistic aspects. When the reaction is performed in acetonitrile under direct excitation, in addition to the primary [2+2] cycloadducts, products derived from an 1,3‐acyl shift rearrangement are also formed. For unsymmetrical alkynes, the rearrangement of the head‐to‐tail primary adducts produces new regioisomers and, when the starting furanone is chiral, this rearrangement inverts the relative anti/syn geometry of the primary cycloadducts. In the reactions performed in acetone under photosensitized conditions, rearranged products were never detected, supporting that the 1,3‐acyl shift takes place from the singlet excited state S1 of the β,γ‐unsaturated lactone. When bis(trimethylsilyl)acetylene is used as the alkyne partner, the major photoproducts are monocyclic bis(trimethylsilyl)lactones.
Ring Opening of a meso‐Triaryl 25‐Oxasmaragdyrin Macrocycle by m‐Chloroperoxybenzoic Acid
Authors: Kalita Hemanta , Ghosh Avijit , Lee Way‐Zen , Ravikanth Mangalampalli
Published: January 2016

Smaragdyrin, a class of expanded porphyrin macrocycles, upon treatment with meta‐chloroperoxybenzoic acid (mCPBA) underwent oxidative ring opening to form an unprecedented linear pentaheterocyclic compound. The linear pentaheterocyclic compound was freely soluble in common organic solvents and characterized in detail by HRMS, 1D and 2D NMR spectroscopy, and X‐ray crystallography. Our preliminary studies indicated that the linear pentaheterocyclic compound can specifically sense anions such as H2PO4− and CN− ions, which was corroborated by absorption and fluorescence studies.
Metal‐Ligand Cooperativity in a Methandiide‐Derived Iridium Carbene Complex
Authors: Weismann Julia , Waterman Rory , Gessner Viktoria H.
Published: January 2016

The synthesis, electronic structure, and reactivity of the first Group 9 carbene complex, [Cp*IrL] [L=C(Ph2PS)(SO2Ph)] (2), based on a dilithio methandiide are reported. Spectroscopic as well as computational studies have shown that, despite using a late transition‐metal precursor, sufficient charge transfer occurred from the methandiide to the metal, resulting in a stable, nucleophilic carbene species with pronounced metal‐carbon double‐bond character. The potential of this iridium complex in the activation of a series of E−H bonds by means of metal‐ligand cooperation has been tested. These studies have revealed distinct differences in the reactivity of 2 compared to a previously reported ruthenium analogue. Whereas attempts to activate the O−H bond in different phenol derivatives resulted in ligand cleavage, H−H and Si−H activation as well as dehydrogenation of isopropanol have been accomplished. These reactions are driven by the transformation of the carbene to an alkyl ligand. Contrary to a previously reported ruthenium carbene system, the dihydrogen activation has been found to proceed by a stepwise mechanism, with the activation first taking place solely at the metal. The activated products further reacted to afford a cyclometalated complex through liberation of the activated substrates. In the case of triphenylsilane, cyclometalation could thus be induced by a substoichiometric (i.e., catalytic) amount of silane.
An Aromatic Hydroxyamide Attenuates Multiresistant Staphylococcus aureus Toxin Expression
Authors: Vomacka Jan , Korotkov Vadim S. , Bauer Bianca , Weinandy Franziska , Kunzmann Martin H. , Krysiak Joanna , Baron Oliver , Böttcher Thomas , Lorenz‐Baath Katrin , Sieber Stephan A.
Published: January 2016

Methicillin‐resistant Staphylococcus aureus (MRSA) causes severe infections with only few effective antibiotic therapies currently available. To approach this challenge, chemical entities with a novel and resistance‐free mode of action are desperately needed. Here, we introduce a new hydroxyamide compound that effectively reduces the expression of devastating toxins in various S. aureus and MRSA strains. The molecular mechanism was investigated by transcriptome analysis as well as by affinity‐based protein profiling. Down‐regulation of several pathogenesis associated genes suggested the inhibition of a central virulence‐related pathway. Mass spectrometry‐based chemical proteomics revealed putative molecular targets. Systemic treatment with the hydroxyamide showed significant reduction of abscess sizes in a MRSA mouse skin infection model. The absence of resistance development in vitro further underlines the finding that targeting virulence could lead to prolonged therapeutic options in comparison to antibiotics that directly address bacterial survival.
Synthesis and Characterization of 6,13‐Diamino‐Substituted Pentacenes
Authors: Ito Akihiro , Uebe Masashi , Takahashi Kazuki , Ishikawa Hiroshi , Sakamaki Daisuke , Sato Hiroyasu , Matsumoto Takashi , Tanaka Kazuyoshi
Published: January 2016

A series of 6,13‐diamino‐substituted pentacenes 1 a–d has been prepared and characterized as a new class of pentacene derivatives with strong donor ability and enhanced solubility in common organic solvents. The spectroelectrochemical and DFT studies revealed that the two‐electron oxidation process was accompanied by the substantial structural change into a butterfly‐like conformation of the pentacene moiety. More importantly, the extent of deformation from the planar pentacene moiety in the dications of 6,13‐diaminopentacene is tunable by varying the N‐substituents.
Mechano‐fluorochromic PtII Luminogen and Its Cysteine Recognition
Authors: Chowdhury Aniket , Howlader Prodip , Mukherjee Partha Sarathi
Published: January 2016

A new triphenylamine‐based organometallic PtII luminogen (1) and its analogous organic compound (2) are reported. The molecules are decorated with aldehyde functionality to improve their photophysical properties by utilising donor–acceptor interactions. The single crystal X‐ray structure analysis of PtII analogue 1 revealed that the neighbouring molecules were loosely organised by weak intermolecular C−H⋅⋅⋅π interactions. Because of the twisted nature of the triphenylamine backbone the compounds showed aggregation‐induced emission enhancement in THF/water mixture. Due to their loose crystal packing, upon application of external stimuli these luminogens exhibited mechano‐fluorochromic behaviour. The crystalline forms of the compounds displayed a more superior emission efficiency than the grinded samples. Moreover, the compounds showed crystallization‐induced emission enhancement (CIEE) and exhibited chemodosimetric response towards cysteine under physiological condition.
Tilting and Tumbling in Transmembrane Anion Carriers: Activity Tuning through n‐Alkyl Substitution
Authors: Edwards Sophie J. , Marques Igor , Dias Christopher M. , Tromans Robert A. , Lees Nicholas R. , Félix Vítor , Valkenier Hennie , Davis Anthony P.
Published: January 2016

Anion transport by synthetic carriers (anionophores) holds promise for medical applications, especially the treatment of cystic fibrosis. Among the factors which determine carrier activity, the size and disposition of alkyl groups is proving remarkably important. Herein we describe a series of dithioureidodecalin anionophores, in which alkyl substituents on one face are varied from C0 to C10 in two‐carbon steps. Activities increase then decrease as the chain length grows, peaking quite sharply at C6. Molecular dynamics simulations showed the transporter chloride complexes releasing chloride as they approach the membrane‐aqueous interface. The free transporter then stays at the interface, adopting an orientation that depends on the alkyl substituent. If chloride release is prevented, the complex is positioned similarly. Longer chains tilt the binding site away from the interface, potentially freeing the transporter or complex to move through the membrane. However, chains which are too long can also slow transport by inhibiting movement, and especially reorientation, within the phospholipid bilayer.
Large‐Scale Synthesis of Enantiopure Molecular Cages: Chiroptical and Recognition Properties
Authors: Lefevre Sara , Zhang Dawei , Godart Estelle , Jean Marion , Vanthuyne Nicolas , Mulatier Jean‐Christophe , Dutasta Jean‐Pierre , Guy Laure , Martinez Alexandre
Published: January 2016

A convenient and efficient gram‐scale synthesis for enantiopure hemicryptophane–tren (tren=tris(2‐aminoethyl)amine) derivatives has been developed. The four‐step synthesis is based on the optical resolution of a key intermediate, cyclotriveratrylene, for which the energy barrier for racemization has been measured to ensure that no racemization occurs during the two last steps of the synthetic pathway. The assignments of the absolute configurations have been performed by electronic circular dichroism and the enantiopurity was determined by NMR spectroscopy in the presence of enantiopure camphor sulfonic acid. To highlight the interest of such compounds, the recognition of norephedrine neurotransmitter was investigated and showed a remarkable enantioselectivity towards the C3 symmetrical hosts. Finally, this highly modular synthetic pathway was used to provide eight enantiopure hemicryptophanes with different sizes, shapes, and functionalities. These results underline the high potential of this approach, which could lead to many applications in chiral recognition or asymmetric supramolecular catalysis.
Structural Characteristics and Properties of a New Graphitic‐Based Material
Authors: Vishnyakova Elena , Brinson Bruce E. , Alemany Lawrence B. , Verma Manjusha , Billups W. Edward
Published: January 2016

The hydrogenation of commercial graphite using lithium/ammonia as the reducing agent and tert‐butyl alcohol as a proton source was investigated. Characterization of the products after successive reductions of the same material by high‐resolution transmission electron microscopy revealed a new material that was replete with edge and circular dislocations. Analysis by solid‐state 13C NMR spectroscopy indicates that after three reductions, the remaining aromatic rings appear to be interior benzene rings. NMR spectroscopy also offers strong evidence for the presence of small amounts of tert‐butyl alcohol and ethanol (workup solvent) that could not be removed in vacuo from the samples. These compounds could be observed to move freely between the layers of the hydrographene.
Microwave‐Assisted Solvothermal Synthesis of VO2 Hollow Spheres and Their Conversion into V2O5 Hollow Spheres with Improved Lithium Storage Capability
Authors: Pan Jing , Zhong Li , Li Ming , Luo Yuanyuan , Li Guanghai
Published: January 2016

Monodispersed hierarchically structured V2O5 hollow spheres were successfully obtained from orthorhombic VO2 hollow spheres, which are in turn synthesized by a simple template‐free microwave‐assisted solvothermal method. The structural evolution of VO2 hollow spheres has been studied and explained by a chemically induced self‐transformation process. The reaction time and water content in the reaction solution have a great influence on the morphology and phase structure of the resulting products in the solvothermal reaction. The diameter of the VO2 hollow spheres can be regulated simply by changing vanadium ion content in the reaction solution. The VO2 hollow spheres can be transformed into V2O5 hollow spheres with nearly no morphological change by annealing in air. The nanorods composed of V2O5 hollow spheres have an average length of about 70 nm and width of about 19 nm. When used as a cathode material for lithium‐ion batteries, the V2O5 hollow spheres display a diameter‐dependent electrochemical performance, and the 440 nm hollow spheres show the highest specific discharge capacity of 377.5 mAhg−1 at a current density of 50 mAg−1, and are better than the corresponding solid spheres and nanorod assemblies.
Metal‐Cation Recognition in Water by a Tetrapyrazinoporphyrazine‐Based Tweezer Receptor
Authors: Lochman Lukas , Svec Jan , Roh Jaroslav , Kirakci Kaplan , Lang Kamil , Zimcik Petr , Novakova Veronika
Published: January 2016

A series of zinc azaphthalocyanines with two azacrowns in a rigid tweezer arrangement were prepared and the fluorescence sensing properties were investigated. The size‐driven recognition of alkali and alkaline earth metal cations was significantly enhanced by the close cooperation of the two azacrown units, in which both donor nitrogen atoms need to be involved in analyte binding to switch the sensor on. The mono‐ or biphasic character of the binding isotherms, together with the binding stoichiometry and magnitude of association constants (KA), indicated specific complexation of particular analytes. Water solvation was shown to play an important role and resulted in a strong quenching of sensor fluorescence in the ON state. The lead compound was embedded into silica nanoparticles and advantageous sensing properties towards K+ were demonstrated in water (λF=671 nm, apparent KA=82 m−1, increase of 17×), even in the presence of (supra)physiological concentrations of Na+ and Ca2+.
Muon‐Substituted Malonaldehyde: Transforming a Transition State into a Stable Structure by Isotope Substitution
Authors: Goli Mohammad , Shahbazian Shant
Published: January 2016

Isotope substitutions are usually conceived to play a marginal role on the structure and bonding pattern of molecules. However, a recent study [Angew. Chem. Int. Ed.2014,53, 13706–13709;Angew. Chem. 2014, 126, 13925–13929] further demonstrates that upon replacing a proton with a positively charged muon, as the lightest radioisotope of hydrogen, radical changes in the nature of the structure and bonding of certain species may take place. The present report is a primary attempt to introduce another example of structural transformation on the basis of the malonaldehyde system. Accordingly, upon replacing the proton between the two oxygen atoms of malonaldehyde with the positively charged muon a serious structural transformation is observed. By using the ab initio nuclear‐electronic orbital non‐Born–Oppenheimer procedure, the nuclear configuration of the muon‐substituted species is derived. The resulting nuclear configuration is much more similar to the transition state of the proton transfer in malonaldehyde rather than to the stable configuration of malonaldehyde. The comparison of the “atoms in molecules” (AIM) structure of the muon‐substituted malonaldehyde and the AIM structure of the stable and the transition‐state configurations of malonaldehyde also unequivocally demonstrates substantial similarities of the muon‐substituted malonaldehyde to the transition state.
Highly Convergent Synthesis of Intensively Blue Emissive Furo[2,3‐c]isoquinolines by a Palladium‐Catalyzed Cyclization Cascade of Unsaturated Ugi Products
Authors: Moni Lisa , Gers‐Panther Charlotte F. , Anselmo Manuel , Müller Thomas J. J. , Riva Renata
Published: January 2016

A convergent and diversity‐oriented approach to the unusual furo[2,3‐c]isoquinoline scaffold is presented. This serendipity‐driven approach is characterized by an Ugi multicomponent reaction, which gives the substrate for a palladium‐catalyzed insertion–alkynylation–cycloisomerization cascade to provide the furo[2,3‐c]isoquinolines in moderate to high yield. Upon UV excitation, all representatives are intensively blue luminescent, as observed by the naked eye, and quantitative fluorescence spectroscopy reveals a considerable effect of the substitution pattern on the quantum yields. The electronic structure is semiquantitatively rationalized by DFT and time‐dependent DFT calculations.
Ln3+‐Mediated Self‐Assembly of a Collagen Peptide into Luminescent Banded Helical Nanoropes
Authors: He Manman , Wang Lang , Wu Jiang , Xiao Jianxi
Published: January 2016

Design of biomimetic peptides to achieve the desired properties of natural collagen has much potential to build functional biomaterials. A collagen‐peptide/Ln3+ system has been constructed and self‐assembled to form helical nanoropes with a distinct periodic banding pattern characteristic of natural collagen. The fully reversible self‐assembly is specifically mediated by lanthanide ions, but not by other commonly used divalent metal ions. Lanthanide ions not only provide an external biocompatible stimulus of the assembly, but also play as a functional unit to endow the assembled materials with easily tunable photoluminescence. To our knowledge, this is the first report of collagen‐peptide‐based materials with exquisite nanorope structure and excellent photoluminescent features. These novel luminescent nanomaterials may have great potential in cell imaging, medical diagnostics, and luminescent scaffolds for cell cultivation.
Molecular‐Level Understanding of Structural Changes of Organic Crystals Induced by Macroscopic Mechanical Stimulation
Authors: Seki Tomohiro , Ito Hajime
Published: January 2016

Structural changes to molecular crystals upon mechanical stimulation have attracted attention for sensing, recording, and microactuation. Comprehensive structure information is required to understand relationships between the mechanical force applied, the crystal structure, and the bulk property changes in order to develop general design concepts for mechanoresponsive compounds. Unfortunately, mechanical stimulation of organic crystals typically deteriorates their integrity, preventing detailed structure analyses by single‐crystal X‐ray diffraction (XRD) methods. However, in the past three years, several interesting studies have been reported in which molecular crystals retain their integrity even after a mechanically induced crystalline structure change. These materials have allowed us to investigate how macroscopic mechanical forces affect the microscopic structures of molecular crystals by single‐crystal XRD analyses. This Minireview summarizes current knowledge of mechanically induced structure changes in molecular crystals, which will facilitate research in this field.
Co‐Adsorption of O2 and CO on Au2−: Infrared Photodissociation Spectroscopy and Theoretical Study of [Au2O2(CO)n]− (n=2–6)
Authors: Liu Hao , Xing Xiaopeng , Wang Xuefeng , Qu Hui , Wang Guan‐jun , Zhou Ming‐fei
Published: January 2016

The co‐adsorption of O2 and CO on anionic sites of gold species is considered as a crucial step in the catalytic CO oxidation on gold catalysts. In this regard, the [Au2O2(CO)n]− (n=2–6) complexes were prepared by using a laser vaporization supersonic ion source and were studied by using infrared photodissociation spectroscopy in the gas phase. All the [Au2O2(CO)n]− (n=2–6) complexes were characterized to have a core structure involving one CO and one O2 molecule co‐adsorbed on Au2− with the other CO molecules physically tagged around. The CO stretching frequency of the [Au2O2(CO)]− core ion is observed around
=2032–2042 cm−1, which is about 200 cm−1 higher than that in [Au2(CO)2]−. This frequency difference and the analyses based on density functional calculations provide direct evidence for the synergy effect of the chemically adsorbed O2 and CO. The low lying structures with carbonate group were not observed experimentally because of high formation barriers. The structures and the stability (i.e., the inertness in a sense) of the co‐adsorbed O2 and CO on Au2− may have relevance to the elementary reaction steps on real gold catalysts.
Polyelectrolyte Complexes Formed from Conjugated Polymers: Array‐Based Sensing of Organic Acids
Authors: Han Jinsong , Bender Markus , Hahn Sebastian , Seehafer Kai , Bunz Uwe H. F.
Published: January 2016

One fluorescent, positively charged poly(para‐phenyleneethynylene) (PAE 1) forms electrostatic complexes with five negatively charged pyridine‐ or benzothiadiazole‐containing poly(para‐aryleneethynylene)s (PAE 2–PAE 6). The PAE 2–PAE 6 are less fluorescent in water and act as quenchers for PAE 1 in their electrostatic complexes C 1–C 5; the PAE‐complexes (2 μm) were exposed to thirteen different carboxylic acids (50 mm) in buffered aqueous solution. The fluorescence responses of the small library of electrostatic PAE–complexes towards the acids was analyzed; discrimination of all of the thirteen acids was achieved. The investigated acids include acetic, butyric, tartaric, maleic, lactic, sorbic, oxalic, aspartic, and citric acids. A random, simple, ad‐hoc library of electrostatic polymer complexes, C 1–C 5, therefore discerns the thirteen carboxylic acids in water.
Polymerizable Molecular Silsesquioxane Cage Armored Hybrid Microcapsules with In Situ Shell Functionalization
Authors: Xing Yuxiu , Peng Jun , Xu Kai , Lin Weihong , Gao Shuxi , Ren Yuanyuan , Gui Xuefeng , Liang Shengyuan , Chen Mingcai
Published: January 2016

We prepared core–shell polymer–silsesquioxane hybrid microcapsules from cage‐like methacryloxypropyl silsesquioxanes (CMSQs) and styrene (St). The presence of CMSQ can moderately reduce the interfacial tension between St and water and help to emulsify the monomer prior to polymerization. Dynamic light scattering (DLS) and TEM analysis demonstrated that uniform core–shell latex particles were achieved. The polymer latex particles were subsequently transformed into well‐defined hollow nanospheres by removing the polystyrene (PS) core with 1:1 ethanol/cyclohexane. High‐resolution TEM and nitrogen adsorption–desorption analysis showed that the final nanospheres possessed hollow cavities and had porous shells; the pore size was approximately 2–3 nm. The nanospheres exhibited large surface areas (up to 486 m2 g−1) and preferential adsorption, and they demonstrated the highest reported methylene blue adsorption capacity (95.1 mg g−1). Moreover, the uniform distribution of the methacryloyl moiety on the hollow nanospheres endowed them with more potential properties. These results could provide a new benchmark for preparing hollow microspheres by a facile one‐step template‐free method for various applications.
Cisplatin Binding to Biological Ligands Revealed at the Encounter Complex Level by IR Action Spectroscopy
Authors: Corinti Davide , Coletti Cecilia , Re Nazzareno , Chiavarino Barbara , Crestoni Maria Elisa , Fornarini Simonetta
Published: January 2016

Cisplatin [cis‐diamminedichloroplatinum(II)] was the first platinum‐based antineoplastic agent and is still a cornerstone for the treatment of various solid tumors. Reactive events responsible for cisplatin activity are unveiled here at the molecular level. Simple ligands (L) representing ubiquitous functional groups in the biological environment likely to be encountered by administered cisplatin have been allowed to react with cis‐[PtCl(NH3)2(H2O)]+, the primary intermediate from cisplatin hydrolysis. The substitution reactions have been examined by a combined experimental and computational approach and the structural features of the substitution product, cis‐[PtCl(NH3)2(L)]+, have been probed by IR multiple‐photon dissociation (IRMPD) spectroscopy. Furthermore, IRMPD spectroscopy has been exploited to elucidate the structure of [PtCl(NH3)2(L)(H2O)]+ clusters, also obtained by electrospray ionization (ESI) from the aqueous solution and representing the major focus of this investigation. These ions conform to the encounter complex of cis‐[PtCl(NH3)2(H2O)]+ with the incoming ligand and represent the first direct evidence of a prototypical Eigen–Wilkins encounter complex in solution, lying on the reaction coordinate for ligand substitution and extracted by ESI for mass spectrometric analysis. Activated [PtCl(NH3)2(L)(H2O)]+ ions dissociate by the loss of either H2O or L, the former process implying a ligand substitution event. IRMPD spectroscopy has thus revealed both structural details and reaction dynamics at the level of the isolated encounter complex.
Binary Zinc Azides
Authors: Schulz Axel , Villinger Alexander
Published: January 2016

Pure, solvent‐free Zn(N3)2 was prepared by reaction of diethyl zinc and hydrazoic acid in aprotic solvents. The single‐crystal structure determination, along with the comprehensive characterization of α‐Zn(N3)2 and two metastable polymorphs, could be achieved for the first time. Since these data disagree in large parts with the known, previously reported values, all previous syntheses of Zn(N3)2, and for comparison Zn(N3)2⋅2.5 H2O and Zn(OH)N3 were reinvestigated, indicating that some of the earlier work has to be revised.
One‐Step Pyro‐Synthesis of a Nanostructured Mn3O4/C Electrode with Long Cycle Stability for Rechargeable Lithium‐Ion Batteries
Authors: Alfaruqi Muhammad Hilmy , Gim Jihyeon , Kim Sungjin , Song Jinju , Duong Pham Tung , Jo Jeonggeun , Baboo Joseph Paul , Xiu Zhiliang , Mathew Vinod , Kim Jaekook
Published: January 2016

A nanostructured Mn3O4/C electrode was prepared by a one‐step polyol‐assisted pyro‐synthesis without any post‐heat treatments. The as‐prepared Mn3O4/C revealed nanostructured morphology comprised of secondary aggregates formed from carbon‐coated primary particles of average diameters ranging between 20 and 40 nm, as evidenced from the electron microscopy studies. The N2 adsorption studies reveal a hierarchical porous feature in the nanostructured electrode. The nanostructured morphology appears to be related to the present rapid combustion strategy. The nanostructured porous Mn3O4/C electrode demonstrated impressive electrode properties with reversible capacities of 666 mAh g−1 at a current density of 33 mA g−1, good capacity retentions (1141 mAh g−1 with 100 % Coulombic efficiencies at the 100th cycle), and rate capabilities (307 and 202 mAh g−1 at 528 and 1056 mA g−1, respectively) when tested as an anode for lithium‐ion battery applications.
Evaluation of New Palladium Cages as Potential Delivery Systems for the Anticancer Drug Cisplatin
Authors: Schmidt Andrea , Molano Viviana , Hollering Manuela , Pöthig Alexander , Casini Angela , Kühn Fritz E.
Published: January 2016

Self‐assembled metallocages are very promising drug‐delivery systems among supramolecular complexes. Thus, exo‐functionalized Pd2L4 (L=ligand) cages were synthesized and characterized, and the encapsulation of the anticancer drug cisplatin in their cavity has been documented. The antiproliferative effects of the metallocages and their combination with cisplatin were examined in vitro in cancer cell lines, while fluorescence microscopy was used to monitor their uptake. Notably, the hydroxymethyl‐functionalized PdII cage encapsulating cisplatin showed improved cytotoxic effect against human ovarian cancer cells compared to free cisplatin. The toxicity of Pd2L4 cages was evaluated for the first time ex vivo in healthy rat‐liver tissues using the precision cut‐tissue slices technology, demonstrating in some cases scarce effects on liver viability. These results further highlight the potential of self‐assembled Pd2L4 cages for biological applications.
Synthesis of Optically Active, X‐Shaped, Conjugated Compounds and Dendrimers Based on Planar Chiral [2.2]Paracyclophane, Leading to Highly Emissive Circularly Polarized Luminescence
Authors: Gon Masayuki , Morisaki Yasuhiro , Sawada Risa , Chujo Yoshiki
Published: January 2016

Invited for the cover of this issue is Yasuhiro Morisaki at Kwansei Gakuin University together with the group of Yoshiki Chujo at Kyoto University. The image depicts the circularly polarized luminescence of the dendrimer films described in their Full Paper. Read the full text of the article at 10.1002/chem.201504270.
Free‐Standing Silver Nanocube/Graphene Oxide Hybrid Paper for Surface‐Enhanced Raman Scattering
Authors: Fan Wei , Yue‐E Miao , Ling Xingyi , Liu Tianxi
Published: January 2016

Surface‐enhanced Raman spectroscopy (SERS) as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a great challenge for creating a universal substrate with long‐term stability and reproducible SERS signals. In this work, Ag nanocubes and graphene oxide (GO) suspension were mixed to form a stable solution and further vacuum filtrated to obtain a free‐standing hybrid paper. The Ag/GO hybrid papers exhibit excellent SERS activity because of the synergistic effect of Ag nanocubes and GO sheets. GO sheets can act as both SERS enhancement substrate and framework for supporting Ag nanocubes. Moreover, GO sheets can protect Ag nanoparticles from oxidation under ambient condition for prolonged life time SERS substrate. Furthermore, we demonstrate the use of the free‐standing and flexible Ag/GO hybrid paper to enable direct, real‐time and reliable detection of trace amounts of analytes in aqueous systems. This novel SERS substrate is expected to be applied in real‐time analysis and expands the flexibility of SERS for useful applications in the materials and life science.
Graphene‐Based Sulfur Composites for Energy Storage and Conversion in Li‐S Batteries
Authors: Gu Xingxing , Zhang Shanqing , Hou Yanglong
Published: January 2016

There are growing research interests in developing high‐performance energy storage systems to meet the demands for large‐scale and sustainable energy storage. The lithium‐sulfur (Li‐S) batteries have drawn numerous attentions due to their exceptionally high energy density compared with other batteries. However, achieving the high capacities with long‐term cycle stability and retaining an essentially high sulfur loading remains a tremendous challenge for the designs of Li‐S batteries. Graphene is regarded as a very suitable and promising addition to the compositions for Li‐S batteries due to its unique two dimensional (2D) structure, high conductivity and superior mechanical flexibility. Besides, the functional groups of graphene surface can be tuned flexibly to immobilize the S/Li2Sx on the graphene surface during the cycling process. In this review, the development of graphene‐sulfur composites and their applications in Li‐S batteries are discussed. The attempts are also devoted to the synthesis approaches of various graphene‐based sulfur composites, the graphene‐sulfur interaction and the impacts on the electrochemical performances as well as the major issues of Li‐S batteries.
Design, Synthesis, and Evaluation of 3‐((4‐(t‐Butyl)‐2‐(2‐benzylidenehydrazinyl)thiazol‐5‐yl)methyl)quinolin‐2(1H)‐ones as Neuraminidase Inhibitors
Authors: Fang Yilin , Xiao Mengwu , Hu Aixi , Ye Jiao , Lian Wenwen , Liu Ailin
Published: January 2016

A series of novel 3‐((4‐(t‐butyl)‐2‐(2‐benzylidenehydrazinyl)thiazol‐5‐yl)methyl)quinolin‐2(1H)‐ones (7a–7z) were designed, synthesized and evaluated for their ability of inhibiting neuraminidase (NA) of in?uenza H1N1 virus. Some compounds displayed moderate influenza NA inhibitory activity. Compound 7l with the scaffold of 2‐(2‐(2‐methoxybenzylidene)hydrazinyl)thiazole was the best one, exhibiting moderate NA inhibitory activity with IC50 of 44.66 µmol/L. Structure‐activity relationship showed that compounds with methoxy or hydroxy groups at the ortho position, fluorine and nitro groups at the meta position and chlorine and bromine groups at the para position of phenyl ring were more active. Docking study indicated that compound 7l has important interactions with some key residues (including Asp151, Glu119, Arg292, Tyr406, and Asn347) and binds to 430‐cavity adjacent to NA active site.
Cytidine Mediated AuAg Nanoclusters as Bright Fluorescent Probe for Tumor Imaging in vivo
Authors: Chen Leifeng , Zhang Yuanyuan , Jiang Hui , Wang Xuemei , Liu Chongyang
Published: January 2016

Noble metal clusters is an emerging class of fluorescent probes, avoiding most of the drawbacks of common fluorescent compounds, and they are simple to prepare and have good water solubility, good biocompatibility and excellent fluorescence properties. In this study, we have explored the synthesis of the cytidine mediated gold‐silver nanoclusters (AuAg NCs) and applied it for both in vitro cellular imaging and tumor in vivo detection. Experimental results show that the as‐prepared AuAg NCs can be used as a sensitive fluorescent probe for cancer cells/tissue detection. Especially, it is evident that under the relevant light irradiation with the wavelength of 488 nm, obviously bright fluorescence signal could be readily detected from focus location of inoculating tumor mouse, implying its possible application for the effective in vivo tumor bioimaging.