bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractMethicillin‐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

AbstractA 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

AbstractA 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

AbstractAnion 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

AbstractA 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

AbstractThe 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

AbstractMonodispersed 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

AbstractA 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

AbstractIsotope 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

AbstractA 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

AbstractDesign 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

AbstractStructural 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

AbstractThe 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

AbstractOne 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

AbstractWe 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

AbstractCisplatin [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

AbstractPure, 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

AbstractA 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

AbstractSelf‐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

AbstractInvited 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.