bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benzotrithiophene‐Based Hole‐Transporting Materials for 18.2 % Perovskite Solar Cells
Authors: Molina‐Ontoria Agustín , Zimmermann Iwan , Garcia‐Benito Inés , Gratia Paul , Roldán‐Carmona Cristina , Aghazada Sadig , Graetzel Michael , Nazeeruddin Mohammad Khaja , Martín Nazario 
Published: April 2016

AbstractNew star‐shaped benzotrithiophene (BTT)‐based hole‐transporting materials (HTM) BTT‐1, BTT‐2 and BTT‐3 have been obtained through a facile synthetic route by crosslinking triarylamine‐based donor groups with a benzotrithiophene (BTT) core. The BTT HTMs were tested on solution‐processed lead trihalide perovskite‐based solar cells. Power conversion efficiencies in the range of 16 % to 18.2 % were achieved under AM 1.5 sun with the three derivatives. These values are comparable to those obtained with today's most commonly used HTM spiro‐OMeTAD, which point them out as promising candidates to be used as readily available and cost‐effective alternatives in perovskite solar cells (PSCs).
Surface‐Guided Formation of an Organocobalt Complex
Authors: Weber Peter B. , Hellwig Raphael , Paintner Tobias , Lattelais Marie , Paszkiewicz Mateusz , Casado Aguilar Pablo , Deimel Peter S. , Guo Yuanyuan , Zhang Yi‐Qi , Allegretti Francesco , Papageorgiou Anthoula C. , Reichert Joachim , Klyatskaya Svetlana , Ruben Mario , Barth Johannes V. , Bocquet Marie‐Laure , Klappenberger Florian 
Published: April 2016

AbstractOrganocobalt complexes represent a versatile tool in organic synthesis as they are important intermediates in Pauson–Khand, Friedel–Crafts, and Nicholas reactions. Herein, a single‐molecule‐level investigation addressing the formation of an organocobalt complex at a solid–vacuum interface is reported. Deposition of 4,4′‐(ethyne‐1,2‐diyl)dibenzonitrile and Co atoms on the Ag(111) surface followed by annealing resulted in genuine complexes in which single Co atoms laterally coordinated to two carbonitrile groups undergo organometallic bonding with the internal alkyne moiety of adjacent molecules. Alternative complexation scenarios involving fragmentation of the precursor were ruled out by complementary X‐ray photoelectron spectroscopy. According to density functional theory analysis, the complexation with the alkyne moiety follows the Dewar–Chatt–Duncanson model for a two‐electron‐donor ligand where an alkyne‐to‐Co donation occurs together with a strong metal‐to‐alkyne back‐donation.
Tailoring Copper Nanocrystals towards C2 Products in Electrochemical CO2 Reduction
Authors: Loiudice Anna , Lobaccaro Peter , Kamali Esmail A. , Thao Timothy , Huang Brandon H. , Ager Joel W. , Buonsanti Raffaella 
Published: April 2016

AbstractFavoring the CO2 reduction reaction (CO2RR) over the hydrogen evolution reaction and controlling the selectivity towards multicarbon products are currently major scientific challenges in sustainable energy research. It is known that the morphology of the catalyst can modulate catalytic activity and selectivity, yet this remains a relatively underexplored area in electrochemical CO2 reduction. Here, we exploit the material tunability afforded by colloidal chemistry to establish unambiguous structure/property relations between Cu nanocrystals and their behavior as electrocatalysts for CO2 reduction. Our study reveals a non‐monotonic size‐dependence of the selectivity in cube‐shaped copper nanocrystals. Among 24 nm, 44 nm and 63 nm cubes tested, the cubes with 44 nm edge length exhibited the highest selectivity towards CO2RR (80 %) and faradaic efficiency for ethylene (41 %). Statistical analysis of the surface atom density suggests the key role played by edge sites in CO2RR.
Covalent Self‐Assembly and One‐Step Photocrosslinking of Tyrosine‐Rich Oligopeptides to Form Diverse Nanostructures
Authors: Min Kyoung‐Ik , Yun Gyeongwon , Jang Yoonjung , Kim Kyung‐Rok , Ko Young Ho , Jang Hyung‐Seok , Lee Yoon‐Sik , Kim Kimoon , Kim Dong‐Pyo 
Published: April 2016

AbstractWe present covalently self‐assembled peptide hollow nanocapsule and peptide lamella. These biomimetic dityrosine peptide nanostructures are synthesized by one‐step photopolymerization of a tyrosine‐rich short peptide without the aid of a template. This simple approach offers direct synthesis of fluorescent peptide nanocages and free‐standing thin films. The simple crosslinked peptide lamella films provide robust mechanical properties with an elastic modulus of approximately 30 GPa and a hardness of 740 MPa. These nanostructures also allow for the design of peptidosomes. The approach taken here represents a rare example of covalent self‐assembly of short peptides into nano‐objects, which may be useful as microcompartments and separation membranes.
Preparation and Reactivity of Acyclic Chiral Allylzinc Species by a Zinc‐Brook Rearrangement
Authors: Leibeling Markus , Shurrush Khriesto A. , Werner Veronika , Perrin Lionel , Marek Ilan 
Published: April 2016

AbstractThe zinc‐Brook rearrangement of enantiomerically enriched α‐hydroxy allylsilane produces a chiral allylzinc intermediate, which reacts with retention of configuration in the presence of an electrophile. Two remarkable features of this transformation are the stereochemical outcome during the formation of the allylzinc species and the complete stereocontrol in the organized six‐membered transition state, which leads to an overall and complete transfer of chirality within the reaction sequence.
Lewis Acid Assisted Nickel‐Catalyzed Cross‐Coupling of Aryl Methyl Ethers by C−O Bond‐Cleaving Alkylation: Prevention of Undesired β‐Hydride Elimination
Authors: Liu Xiangqian , Hsiao Chien‐Chi , Kalvet Indrek , Leiendecker Matthias , Guo Lin , Schoenebeck Franziska , Rueping Magnus 
Published: April 2016

AbstractIn the presence of trialkylaluminum reagents, diverse aryl methyl ethers can be transformed into valuable products by C−O bond‐cleaving alkylation, for the first time without the limiting β‐hydride elimination. This new nickel‐catalyzed dealkoxylative alkylation method enables powerful orthogonal synthetic strategies for the transformation of a variety of naturally occurring and easily accessible anisole derivatives. The directing and/or activating properties of aromatic methoxy groups are utilized first, before they are replaced by alkyl chains in a subsequent coupling process.
High‐Resolution Rotational Spectroscopy Study of the Smallest Sugar Dimer: Interplay of Hydrogen Bonds in the Glycolaldehyde Dimer
Authors: Zinn Sabrina , Medcraft Chris , Betz Thomas , Schnell Melanie 
Published: April 2016

AbstractMolecular recognition of carbohydrates plays an important role in nature. The aggregation of the smallest sugar, glycolaldehyde, was studied in a conformer‐selective manner using high‐resolution rotational spectroscopy. Two different dimer structures were observed. The most stable conformer reveals C2‐symmetry by forming two intermolecular hydrogen bonds, giving up the strong intramolecular hydrogen bonds of the monomers and thus showing high hydrogen bond selectivity. By analyzing the spectra of the 13C and 18O isotopologues of the dimer in natural abundance, we could precisely determine the heavy backbone structure of the dimer. Comparison to the monomer structure and the complex with water provides insight into intermolecular interactions. Despite hydrogen bonding being the dominant interaction, precise predictions from quantum‐chemical calculations highly rely on the consideration of dispersion.
Superior Electrical Conductivity in Hydrogenated Layered Ternary Chalcogenide Nanosheets for Flexible All‐Solid‐State Supercapacitors
Authors: Hu Xin , Shao Wei , Hang Xudong , Zhang Xiaodong , Zhu Wenguang , Xie Yi 
Published: April 2016

AbstractAs the properties of ultrathin two‐dimensional (2D) crystals are strongly related to their electronic structures, more and more attempts were carried out to tune their electronic structures to meet the high standards for the construction of next‐generation smart electronics. Herein, for the first time, we show that the conductive nature of layered ternary chalcogenide with formula of Cu2WS4 can be switched from semiconducting to metallic by hydrogen incorporation, accompanied by a high increase in electrical conductivity. In detail, the room‐temperature electrical conductivity of hydrogenated‐Cu2WS4 nanosheet film was almost 1010 times higher than that of pristine bulk sample with a value of about 2.9×104 S m−1, which is among the best values for conductive 2D nanosheets. In addition, the metallicity in the hydrogenated‐Cu2WS4 is robust and can be retained under high‐temperature treatment. The fabricated all‐solid‐state flexible supercapacitor based on the hydrogenated‐Cu2WS4 nanosheet film shows promising electrochemical performances with capacitance of 583.3 F cm−3 at a current density of 0.31 A cm−3. This work not only offers a prototype material for the study of electronic structure regulation in 2D crystals, but also paves the way in searching for highly conductive electrodes.
Dibenzo[a,j]phenazine‐Cored Donor–Acceptor–Donor Compounds as Green‐to‐Red/NIR Thermally Activated Delayed Fluorescence Organic Light Emitters
Authors: Data Przemyslaw , Pander Piotr , Okazaki Masato , Takeda Youhei , Minakata Satoshi , Monkman Andrew P. 
Published: April 2016

AbstractA new family of thermally activated delayed fluorescence (TADF) emitters based on U‐shaped D‐A‐D architecture with a novel accepting unit has been developed. All investigated compounds have small singlet‐triplet energy splitting (ΔEST) ranging from 0.02 to 0.20 eV and showed efficient TADF properties. The lowest triplet state of the acceptor unit plays the key role in the TADF mechanism. OLEDs fabricated with these TADF emitters achieved excellent efficiencies up to 16 % external quantum efficiency (EQE).
Polymerization Initiated by Organic Electron Donors
Authors: Broggi Julie , Rollet Marion , Clément Jean‐Louis , Canard Gabriel , Terme Thierry , Gigmes Didier , Vanelle Patrice 
Published: April 2016

AbstractPolymerization reactions with organic electron donors (OED) as initiators are presented herein. The metal‐free polymerization of various activated alkene and cyclic ester monomers was performed in short reaction times, under mild conditions, with small amounts of organic reducing agents, and without the need for co‐initiators or activation by photochemical, electrochemical, or other methods. Hence, OED initiators enabled the development of an efficient, rapid, room‐temperature process that meets the technical standards expected for industrial processes, such as energy savings, cost‐effectiveness and safety. Mechanistic investigations support an electron‐transfer initiation pathway that leads to the reduction of the monomer.
Efficient Synthesis of Molecular Precursors for Para‐Hydrogen‐Induced Polarization of Ethyl Acetate‐1‐13C and Beyond
Authors: Shchepin Roman V. , Barskiy Danila A. , Coffey Aaron M. , Manzanera Esteve Isaac V. , Chekmenev Eduard Y. 
Published: April 2016

AbstractA scalable and versatile methodology for production of vinylated carboxylic compounds with 13C isotopic label in C1 position is described. It allowed synthesis of vinyl acetate‐1‐13C, which is a precursor for preparation of 13C hyperpolarized ethyl acetate‐1‐13C, which provides a convenient vehicle for potential in vivo delivery of hyperpolarized acetate to probe metabolism in living organisms. Kinetics of vinyl acetate molecular hydrogenation and polarization transfer from para‐hydrogen to 13C via magnetic field cycling were investigated. Nascent proton nuclear spin polarization (%PH) of ca. 3.3 % and carbon‐13 polarization (%P13C) of ca. 1.8 % were achieved in ethyl acetate utilizing 50 % para‐hydrogen corresponding to ca. 50 % polarization transfer efficiency. The use of nearly 100% para‐hydrogen and the improvements of %PH of para‐hydrogen‐nascent protons may enable production of 13C hyperpolarized contrast agents with %P13C of 20–50 % in seconds using this chemistry.
A Single‐Crystalline Mesoporous Quartz Superlattice
Authors: Matsuno Takamichi , Kuroda Yoshiyuki , Kitahara Masaki , Shimojima Atsushi , Wada Hiroaki , Kuroda Kazuyuki 
Published: April 2016

AbstractThere has been significant interest in the crystallization of nanostructured silica into α‐quartz because of its physicochemical properties. We demonstrate a single‐crystalline mesoporous quartz superlattice, a silica polymorph with unprecedentedly ordered hierarchical structures on both the several tens of nanometers scale and the atomic one. The mesoporous quartz superlattice consists of periodically arranged α‐quartz nanospheres whose crystalline axes are mostly oriented in an assembly. The superlattice is prepared by thermal crystallization of amorphous silica nanospheres constituting a colloidal crystal. We found that the deposition of a strong flux of Li+ only on the surface of silica nanospheres is effective for crystallization.
Readily Accessible Bulky Iron Catalysts exhibiting Site Selectivity in the Oxidation of Steroidal Substrates
Authors: Font David , Canta Mercè , Milan Michela , Cussó Olaf , Ribas Xavi , Klein Gebbink Robertus J. M. , Costas Miquel 
Published: April 2016

AbstractBulky iron complexes are described that catalyze the site‐selective oxidation of alkyl C−H bonds with hydrogen peroxide under mild conditions. Steric bulk at the iron center is introduced by appending trialkylsilyl groups at the meta‐position of the pyridines in tetradentate aminopyridine ligands, and this effect translates into high product yields, an enhanced preferential oxidation of secondary over tertiary C−H bonds, and the ability to perform site‐selective oxidation of methylenic sites in terpenoid and steroidal substrates. Unprecedented site selective oxidation at C6 and C12 methylenic sites in steroidal substrates is shown to be governed by the chirality of the catalysts.
Dysprosium(III)‐Catalyzed Ring‐Opening of meso‐Epoxides: Desymmetrization by Remote Stereocontrol in a Thiolysis/Elimination Sequence
Authors: Yao Lu , Zhu Qiao , Wei Liang , Wang Zuo‐Fei , Wang Chun‐Jiang 
Published: April 2016

AbstractAn unprecedented asymmetric desymmetrization of meso‐epoxides, derived from cyclopentene‐1,3‐diones, with 2‐mercaptobenzothiazoles has been realized. It was efficiently catalyzed by a chiral DyIII/N,N′‐dioxide complex through a thiolysis/elimination sequence. This remote stereocontrol strategy provides facile access to synthetically versatile cyclopentene derivatives bearing an all‐carbon quaternary stereogenic center in high yield and excellent enantioselectivity. Intriguingly, optically active thiophene could be readily generated from the obtained product through an efficient one‐pot protocol.
The Bis(pentafluoroethyl)germylene Trimethylphosphane Adduct (C2F5)2Ge⋅PMe3: Characterization, Ligand Properties, and Reactivity
Authors: Pelzer Stefanie , Neumann Beate , Stammler Hans‐Georg , Ignat'ev Nikolai , Hoge Berthold 
Published: April 2016

AbstractThe synthesis of the germylene phosphane adduct (C2F5)2Ge⋅PMe3 is described. Starting from (C2F5)3GeH in an excess of PMe3, heating was applied, whereupon reductive elimination of C2F5H occurred. The molecular structure was ascertained by X‐ray diffraction and compared with information obtained by quantum chemical methods. The ligand properties were derived by studying the IR spectrum of the nickel(0) complex [Ni(CO)3{Ge(C2F5)2(PMe3)}] in the CO region. (C2F5)2Ge⋅PMe3 turned out to be a π‐accepting ligand comparable to PMe3, in terms of Tolman's electronic parameter. Furthermore a [2+4] cycloaddition reaction with 2,3‐dimethyl‐1,3‐butadiene, and σ‐bond insertion reactions were recorded. Activation of the C−Cl bond in dichloromethane gives rise to the formation of the phosphonium ylide complex [(C2F5)2Cl2Ge‐CH2PMe3], which was fully characterized by X‐ray diffraction.
Broad‐Spectrum Liquid‐ and Gas‐Phase Decontamination of Chemical Warfare Agents by One‐Dimensional Heteropolyniobates
Authors: Guo Weiwei , Lv Hongjin , Sullivan Kevin P. , Gordon Wesley O. , Balboa Alex , Wagner George W. , Musaev Djamaladdin G. , Bacsa John , Hill Craig L. 
Published: April 2016

AbstractA wide range of chemical warfare agents and their simulants are catalytically decontaminated by a new one‐dimensional polymeric polyniobate (P‐PONb), K12[Ti2O2][GeNb12O40]⋅19 H2O (KGeNb) under mild conditions and in the dark. Uniquely, KGeNb facilitates hydrolysis of nerve agents Sarin (GB) and Soman (GD) (and their less reactive simulants, dimethyl methylphosphonate (DMMP)) as well as mustard (HD) in both liquid and gas phases at ambient temperature and in the absence of neutralizing bases or illumination. Three lines of evidence establish that KGeNb removes DMMP, and thus likely GB/GD, by general base catalysis: a) the k(H2O)/k(D2O) solvent isotope effect is 1.4; b) the rate law (hydrolysis at the same pH depends on the amount of P‐PONb present); and c) hydroxide is far less active against the above simulants at the same pH than the P‐PONbs themselves, a critical control experiment.
Well‐Defined Models for the Elusive Dinuclear Intermediates of the Pauson–Khand Reaction
Authors: Hartline Douglas R. , Zeller Matthias , Uyeda Christopher 
Published: April 2016

AbstractThe mechanism of the Pauson–Khand reaction has attracted significant interest due to the unusual dinuclear nature of the Co2(CO)x active site. Experimental and computational data have indicated that the intermediates following the initial Co2(CO)6(alkyne) complex are thermodynamically unstable and do not build up in appreciable concentrations during the course of the reaction. As a consequence, the key steps that control the scope of viable substrates and various aspects of selectivity have remained largely uncharacterized. Herein, a direct experimental investigation of the dinuclear metallacycle‐forming step of the Pauson–Khand reaction is reported. These studies capitalize on well‐defined d9–d9 dinickel complexes supported by a naphthyridine–diimine (NDI) pincer ligand as functional surrogates of Co2(CO)8.
Visible‐Light‐Driven Water Oxidation by a Molecular Manganese Vanadium Oxide Cluster
Authors: Schwarz Benjamin , Forster Johannes , Goetz McKenna K. , Yücel Duygu , Berger Claudia , Jacob Timo , Streb Carsten 
Published: April 2016

AbstractPhotosynthetic water oxidation in plants occurs at an inorganic calcium manganese oxo cluster, which is known as the oxygen evolving complex (OEC), in photosystem II. Herein, we report a synthetic OEC model based on a molecular manganese vanadium oxide cluster, [Mn4V4O17(OAc)3]3−. The compound is based on a [Mn4O4]6+ cubane core, which catalyzes the homogeneous, visible‐light‐driven oxidation of water to molecular oxygen and is stabilized by a tripodal [V4O13]6− polyoxovanadate and three acetate ligands. When combined with the photosensitizer [Ru(bpy)3]2+ and the oxidant persulfate, visible‐light‐driven water oxidation with turnover numbers of approximately 1150 and turnover frequencies of about 1.75 s−1 is observed. Electrochemical, mass‐spectrometric, and spectroscopic studies provide insight into the cluster stability and reactivity. This compound could serve as a model for the molecular structure and reactivity of the OEC and for heterogeneous metal oxide water‐oxidation catalysts.
Predicting and Screening Dielectric Transitions in a Series of Hybrid Organic–Inorganic Double Perovskites via an Extended Tolerance Factor Approach
Authors: Shi Chao , Yu Chun‐Hua , Zhang Wen 
Published: April 2016

AbstractExtended Goldschmidt tolerance factor t is applied to the hybrid double perovskites (MA)2[B′B′′(CN)6] (MA=methylammonium cation) to predict and screen dielectric transitions in 121 compounds through the correlations among t, the radius of the B component rB and the transition temperature Tc, based on experimental results from model compounds. For (MA)2[B′Co(CN)6], it is concluded that: i) when t>0.873, the cubic phase would be stable below 298 K; ii) when 0.873>t>0.805, the cubic phase would be stable between 298 and 523 K; iii) the larger the rB, the higher the Tc of the perovskite (Tc1/2∝rB); and iv) the Tc of the hybrid perovskites can be well tuned by doping the B components.
Are biofuels sustainable? An LCA/multivariate perspective on feedstocks and processes
Authors: Russo Valentina , Paola Luisa Di , Piemonte Vincenzo , Basile Angelo , Falco Marcello De , Giuliani Alessandro 
Published: April 2016

AbstractLiquid biofuels represent a valid option for traditional fossil liquid fuels, but their sustainability is still under enquiry. In this work, we merge the Life‐Cycle‐Assessment methods with the Multivariate Statistic Analysis (MVA), to define a general methodology to compare biofuels derived from different feedstocks and fossil fuels. We tried to assess in an unambiguous way whether the biofuels are more sustainable than liquid fuels, in terms of both emissions and depletion of non‐renewable sources. Whereas first generation products present even higher environmental impacts than fossil fuels, which in turn rely on consolidated, optimized processes, whose environmental footprint and yields have been improved over the years. Our results trace a good sustainability profile for second generation biofuels, especially for biogas that seems to be the best trade‐off both from a LCA perspective and as a single dimensionless score derived from the MVA. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.
Experimental study on film thickness and the problem of free surface film flow in dip coating
Authors: Chen Meng Meng , Zhang Xian Ming , Ma Jian Ping , Chen Shi Chang , Chen Wen Xing , Feng Lian Fang 
Published: April 2016

AbstractDip coating is widely applied in industries for coating a solid substrate with a fluid because of its simplicity and applicability to substrates with different shapes. An experimental study was reported with dip coater on the film coating of solid plates by withdrawal from a tank filled with silicone oil fluids or polyacrylic acid (PAA) solutions with different rheological properties, the liquid film thickness deposited on the plate substrate was measured using capacitance method, and the evolution of free surface morphology was recorded with photographs. The purpose was to investigate the effects of plate substrate roughness, withdrawal speed, rest time, and fluid viscosity on the liquid film thickness and free surface morphology in detail. Results showed that the increases in coating fluid viscosity, withdrawal speed, and substrate roughness are beneficial to film thickening. The influence of rest time on liquid film thickness could be neglected when it was greater than 3 min. For silicone oil fluids, the free surface exhibited a depression, which gradually deepened, with the increasing in withdrawal speed and viscosities. By contrast, PAA solutions showed a bump on the free surface, exhibiting a curvature that increased with the increasing in withdrawal speed and concentrations. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.