bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asphalt‐Derived Hierarchically Porous Carbon with Superior Electrode Properties for Capacitive Storage Devices
Authors: Song Xinyu , Ma Xinlong , Yu Zhiqing , Ning Guoqing , Li Yun , Sun Yuzhen 
Published: March 2018

AbstractActive carbon with hierarchical pore structure (HPC) is prepared in mass using asphalt as carbon precursor by a template‐directed method. The as‐prepared HPC exhibits excellent capacitive energy‐storage capacities on a symmetric supercapacitor (140 F g−1 at 0.5 A g−1) and Li‐ion capacitor (LIC) using HPC as both cathode and anode (340 F g−1 at 0.5 A g−1), as well as long cyclability for a supercapacitor (no capacity loss after 15000 cycles) and LIC (91.3 % capacitance retention after 10000 cycles). The superior energy and power densities are 202 W kg−1 and 15398 Wh kg−1, respectively. The hierarchical pore structure in combination with the existence of heteroatoms originated from the carbon precursor ensure the conductivity for the delivery of electrolyte ions and electrons, greatly contributing to the high capacitance and the excellent cycle performance. This work provides a very promising opportunity for high‐capacitive energy storage devices by means of the high value‐added utilization of asphalt.
One‐Step Electrodeposition Method to Prepare Robust Flexible PEDOT‐Based Films for Ultra‐Stable Supercapacitors
Authors: Ye Guo , Zhu Danhua , Zhou Qianjie , Li Danqin , Zuo Yinxiu , Duan Xuemin , Zhou Weiqiang , Xu Jingkun 
Published: March 2018

AbstractThe front cover artwork is provided by Jiangxi Provincial Key Laboratory of Drug Design and Evaluation, School of Pharmacy Jiangxi Science and Technology Normal University (China). The image shows a robust flexible P(EDOT‐co‐BEDTH) film with an ultra‐stable cyclic life, demonstrating 99% retention after 30 000 cycles, which makes it suitable for practical application in all‐solid‐state supercapacitors. Read the full text of the Article at 10.1002/celc.201800099.
Hierarchical Porous Carbons Derived from Renewable Poplar Anthers for High‐Performance Supercapacitors
Authors: Song Jian , Shen Wenzhong , Wang Jianguo , Fan Weibin 
Published: March 2018

AbstractHierarchical porous carbons with granular shape were prepared from waste biomass poplar anthers (PA) by pre‐carbonization and following KOH activation. The pore structure and surface chemistry of PA‐derived carbon can be controlled by adjusting the activation temperature. The material activated at 800 °C possesses a high surface area of 3639 m2 g−1, abundant mesopores, and appropriate amounts of oxygen‐ and nitrogen‐containing species. As a result, it exhibits excellent electrochemical performances as a supercapacitor electrode. The specific capacitance reaches 361.5 F g−1 at a current density of 0.5 A g−1 in 6 M KOH aqueous solution. In addition, it shows an impressive energy density of 60.8 Wh kg−1 at a power density of 10416.7 W kg−1 in the ionic liquid BMIMBF4. Particularly, a high electrochemical stability and an excellent reversibility were observed in both aqueous and non‐aqueous electrolytes.
Ruthenium‐Catalyzed Selective C−C Coupling of Allylic Alcohols with Free Indoles: Influence of the Metal Catalyst
Authors: Xia Ying‐Qi , Li Chao , Liu Man , Dong Lin 
Published: March 2018

AbstractVersatile reactive activities of allyl alcohols with free indoles in C−H functionalization reactions were investigated. Direct alkylation or cascade cyclization reactions could be selectively controlled based on the catalyst system: Ru(PPh3)3Cl2 provided C3‐substituted β‐ketone indoles whereas [Ru(p‐cymene)Cl2]2 yielded cyclized indoles.
Surface‐Doped Polystyrene Microsensors Containing Lipophilic Solvatochromic Dye Transducers
Authors: Wang Lu , Xie Xiaojiang , Cao Tianchi , Bosset Jérôme , Bakker Eric 
Published: March 2018

AbstractIon‐selective optical microsensors based on surface‐modified polystyrene (PS) beads with positively charged lipophilic solvatochromic dye (SD) on the surface were studied with K+ as model ion. Water‐soluble SDs are expelled into the aqueous phase by ion exchange with the cationic analyte of interest, resulting in a detectable color change. In contrast, lipophilic SDs are more attractive, as they appear to remain anchored to the surface after expulsion from the sensing phase. This transfers just the ionic chromophore functionality into the aqueous phase and allows the system to act as a reversible, truly self‐contained sensor. In this work this mechanism was evaluated with ζ‐potential measurements on microsensor suspensions. It indeed provides experimental evidence for the mechanism of SD transfer, as a reversal of the ζ‐potential of the PS microsensors was observed for higher potassium concentrations with valinomycin‐doped microspheres. For a discriminated ion such as sodium, the ζ‐potential change occurs at much higher electrolyte concentrations, in agreement with sensor selectivity. Undoped microspheres showed no apparent dependence of ζ‐potential on electrolyte concentration. The study also shows that the effective range of microsensor surface charge is tunable and depends on the concentration of the SD on the coating phase.
The Generation of Diazo Compounds in Continuous‐Flow
Authors: Hock Katharina J. , Koenigs Rene M. 
Published: March 2018

AbstractToxic, cancerogenic and explosive—these attributes are typically associated with diazo compounds. Nonetheless, diazo compounds are nowadays a highly demanded class of reagents for organic synthesis, yet the concerns with regards to safe and scalable transformations of these compounds are still exceptionally high. Lately, the research area of the continuous‐flow synthesis of diazo compounds attracted significant interest and a whole variety of protocols for their “on‐demand” preparation have been realized to date. This concept article focuses on the recent developments using continuous‐flow technologies to access diazo compounds; thus minimizing risks and hazards when working with this particular class of compounds. In this article we discuss these concepts and highlight different pre‐requisites to access and to perform downstream functionalization reaction.
Magnetic Interactions through a Nonconjugated Framework Observed in Back‐to‐Back Connected Triazinyl–Nitroxyl Biradical Derivatives
Authors: Takahashi Yusuke , Matsuhashi Ryo , Miura Youhei , Yoshioka Naoki 
Published: March 2018

AbstractThree hetero‐biradical derivatives, with the structure of a back‐to‐back connected benzotriazinyl and tetramethyl or tetraethylisoindoline N‐oxyl sharing a common benzo ring, 3‐tert‐butyl‐1‐phenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetramethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (1‐tBu), 1,3‐diphenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetramethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (1‐Ph), and 3‐tert‐butyl‐1‐phenyl‐1,4,6,8‐tetrahydro‐6,6,8,8‐tetraethyl‐pyrrolo[4,5‐g]‐1,2,4‐benzotriazin‐4‐yl‐7‐oxyl (2‐tBu), were synthesized and characterized by single‐crystal X‐ray analyses, variable‐temperature magnetic susceptibility studies, and DFT calculations. Temperature dependences of the magnetic susceptibilities of 1‐tBu, 1‐Ph, and 2‐tBu exhibit broad maxima at 70, 71, and 43 K, respectively. Although these radical derivatives form a columnar or chained assembly in the solid state, magnetic measurements of diluted samples in the polymer matrices and computational results imply that the magnetic properties of the polycrystalline sample can be explained by a two‐spin system with an intramolecular antiferromagnetic interaction. The magnetic behavior can be reproduced by using the Bleaney–Bowers model, with 2J=−80.0 cm−1 for 1‐tBu, 2J=−77.1 cm−1 for 1‐Ph, and 2J=−48.9 cm−1 for 2‐tBu. The moderately strong intramolecular antiferromagnetic interactions can be interpreted by a through‐bond interaction through the nonconjugated framework and/or through‐space interactions based on molecular orbital theory. The strong distance dependency between the N−O spin site and vinylic carbon atoms indicates that the orbital interaction plays an important role in the intramolecular magnetic interaction. The reduced magnetic interaction in 2‐tBu relative to those of 1‐tBu and 1‐Ph can be attributed to restricted rotation of the tetraethyl group.
3 D Porous CoS2 Hexadecahedron Derived from MOC toward Ultrafast and Long‐Lifespan Lithium Storage
Authors: Wang Han‐Chi , Cui Zheng , Fan Chao‐Ying , Liu Si‐Yu , Shi Yan‐Hong , Wu Xing‐Long , Zhang Jing‐Ping 
Published: March 2018

AbstractA new hexadecahedron assembled by core–shell CoS2 particles@N‐doped carbon (CoS2@NCH) is prepared successfully through the self‐templating method. The CoS2@NCH hybrid electrode delivers a high lithium‐storage capacity of 778 mA h g−1 after 1000 cycles at a high current density of 1 A g−1, which is the longest cycle lifespan among the reported CoS2 anode materials in lithium‐ion batteries. Furthermore, the CoS2@NCH hybrid electrode shows excellent rate capability with a discharge capacity of 220 mA h g−1 at an extremely high current density of 20 A g−1, and a charge capacity of 649 mA h g−1 is restored upon returning the current density back to 2 A g−1. The superior performance is attributed to the unique construction of CoS2@NCH. The N‐doped interconnected porous carbon shells form highly conductive skeletons for quick electron transfer and prevent the electrode from collapsing. Moreover, the porous characteristic of the materials plays a key role: as some effective channels, the mesopores on the porous carbon shells provide greater access for lithium, and the mesopores derived from the particle interspace enables the complete immersion of the electrodes in electrolyte, which alleviates the volume expansion and ensures the integrity of the electrode. In addition, the nanosized CoS2 particles, which shorten the ion‐transport path and provide extra electroactive sites, also improve the reaction kinetics.
Nitrogen‐Functionalized Hydrothermal Carbon Materials by Using Urotropine as the Nitrogen Precursor
Authors: Straten Jan Willem , Schleker Philipp , Krasowska Małgorzata , Veroutis Emmanouil , Granwehr Josef , Auer Alexander A. , Hetaba Walid , Becker Sylvia , Schlögl Robert , Heumann Saskia 
Published: March 2018

AbstractNitrogen‐containing hydrothermal carbon (N‐HTC) materials of spherical particle morphology were prepared by means of hydrothermal synthesis with glucose and urotropine as precursors. The molar ratio of glucose to urotropine has been varied to achieve a continuous increase in nitrogen content. By raising the ratio of urotropine to glucose, a maximal nitrogen fraction of about 19 wt % could be obtained. Decomposition products of both glucose and urotropine react with each other; this opens up a variety of possible reaction pathways. The pH has a pronounced effect on the reaction pathway of the corresponding reaction steps. For the first time, a comprehensive analytical investigation, comprising a multitude of analytical tools and instruments, of a series of nitrogen‐containing HTC materials was applied. Functional groups and structural motifs identified were analyzed by means of FTIR spectroscopy, thermogravimetric MS, and solid‐state NMR spectroscopy. Information on reaction mechanisms and structural details were obtained by electronic structure calculations that were compared with vibrational spectra of polyfuran or polypyrrole‐like groups, which represent structural motifs occurring in the present samples.
Diquats with Robust Chirality: Facile Resolution, Synthesis of Chiral Dyes, and Application as Selectors in Chiral Analysis
Authors: Talele Harish R. , Koval Dušan , Severa Lukáš , Reyes‐Gutiérrez Paul E. , Císařová Ivana , Sázelová Petra , Šaman David , Bednárová Lucie , Kašička Václav , Teplý Filip 
Published: March 2018

AbstractDiquats with extremely high racemization barriers with ΔG≠theor of 233 kJ mol−1 at 180 °C are described. Reported configurational robustness is due to a combination of two structural features: the rigid o‐xylylene tether connecting the nitrogen atoms and the presence of two substituents in the bay region of the bipyridinium scaffold. The straightforward synthesis of diquats, plus facile resolution and derivatization make them attractive for chiral application studies. This is demonstrated by: 1) synthesis of the first non‐racemic diquat dyes with pronounced chiroptical properties, and 2) capability of diquats to interact stereospecifically with chiral molecules. This suggests potential for diquat derivatives to be used as chiral selectors in separation methods.
Photocatalysis with Quantum Dots and Visible Light for Effective Organic Synthesis
Authors: Huang Cheng , Li Xu‐Bing , Tung Chen‐Ho , Wu Li‐Zhu 
Published: March 2018

AbstractColloidal semiconductor quantum dots (QDs) have recently attracted widespread interest for diverse applications. Owing to their quantum confinement effects, rich surface binding properties, high surface‐to‐volume ratios, broad and intense absorption spectra in the visible region, and low cost as well, QDs offer new and versatile ways to serve as photocatalysts for organic synthesis. Most recently, the use of QDs photocatalysts is springing up in organic synthesis. Herein, we highlight the recent advances of QDs used for smart and clean organic transformations.
A Multifaceted Study of Methane Adsorption in Metal–Organic Frameworks by Using Three Complementary Techniques
Authors: Zhang Yue , Lucier Bryan E. G. , Fischer Michael , Gan Zhehong , Boyle Paul D. , Desveaux Bligh , Huang Yining 
Published: March 2018

AbstractMethane is a promising clean and inexpensive energy alternative to traditional fossil fuels, however, its low volumetric energy density at ambient conditions has made devising viable, efficient methane storage systems very challenging. Metal–organic frameworks (MOFs) are promising candidates for methane storage. In order to improve the methane storage capacity of MOFs, a better understanding of the methane adsorption, mobility, and host–guest interactions within MOFs must be realized. In this study, methane adsorption within α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, SIFSIX‐3‐Zn, and M‐MOF‐74 (M=Mg, Zn, Ni, Co) has been comprehensively examined. Single‐crystal X‐ray diffraction (SCXRD) experiments and DFT calculations of the methane adsorption locations were performed for α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, and SIFSIX‐3‐Zn. The SCXRD thermal ellipsoids indicate that methane possesses significant mobility at the adsorption sites in each system. 2H solid‐state NMR (SSNMR) experiments targeting deuterated CH3D guests in α‐Mg3(HCO2)6, α‐Zn3(HCO2)6, SIFSIX‐3‐Zn, and MOF‐74 yield an interesting finding: the 2H SSNMR spectra of methane adsorbed in these MOFs are significantly influenced by the chemical shielding anisotropy in addition to the quadrupolar interaction. The chemical shielding anisotropy contribution is likely due mainly to the nuclear independent chemical shift effect on the MOF surfaces. In addition, the 2H SSNMR results and DFT calculations strongly indicate that the methane adsorption strength is linked to the MOF pore size and that dispersive forces are responsible for the methane adsorption in these systems. This work lays a very promising foundation for future studies of methane adsorption locations and dynamics within adsorbent MOF materials.
Enantioselective Synthesis of 5,5‐Disubstituted Hydantoins by Brønsted Base/H‐Bond Catalyst Assisted Michael Reactions of a Design Template
Authors: Izquierdo Joseba , Etxabe Julen , Duñabeitia Eider , Landa Aitor , Oiarbide Mikel , Palomo Claudio 
Published: March 2018

AbstractA new method for the enantioselective synthesis of 5,5‐disubstituted (quaternary) hydantoins was developed on the basis of an organocatalytic Michael reaction approach involving the use of 2‐benzylthio‐3,5‐dihydroimidazol‐4‐ones as key hydantoin surrogates. The method is general with respect to the substitution pattern at the hydantoin N1 (alkyl, aryl, acyl), N3 (aryl), and C5 (linear/branched alkyl, aryl) positions and affords essentially single diastereomeric products with enantioselectivities higher than 95 % ee in most cases. Among the bifunctional Brønsted base/H‐bond catalysts examined, a known squaramide–tertiary amine catalyst and a newly prepared squaramide–tertiary amine catalyst provide the highest selectivity so far with either nitroolefins or vinyl ketones as the acceptor components. Kinetic measurements support a first‐order rate dependence on both reaction partners, the donor template and the Michael acceptor, whereas competitive 1H NMR spectroscopy experiments reveal the high ability of the template for catalyst binding.
Polyacrylonitrile‐Derived Sponge‐Like Micro/Macroporous Carbon for Selective CO2 Separation
Authors: Guo Li‐Ping , Hu Qing‐Tao , Zhang Peng , Li Wen‐Cui , Lu An‐Hui 
Published: March 2018

AbstractCO2 capture under a dynamical flow situation requires adsorbents possessing balanced proportion of macropores as diffusion path and micropores as adsorption reservoir. However, the construction of interconnected micro‐/macropores structure coupled with abundant nitrogen species into one carbon skeleton remains a challenge. Here, we report a new approach to prepare sponge‐like carbon with a well‐developed micro‐/macroporous structure and enriched nitrogen species through aqueous phase polymerization of acrylonitrile in the presence of graphene oxide. The tension stress caused by the uniform thermal shrinkage of polyacrylonitrile during the pyrolysis together with the favorable flexibility of graphene oxide sheets are responsible for the formation of the sponge‐like morphology. The synergistic effect of micro‐/macroporous framework and rich CO2‐philic site enables such carbon to decrease resistance to mass transfer and show high CO2 dynamic selectivity over N2 (454) and CH4 (11), as well as good CO2 capacity at 298 K under low CO2 partial pressure (0.17 bar, a typical CO2 partial pressure in flue gas). The above attributes make this porous carbon a promising candidate for CO2 capture from flue gas, methane sources and other relevant applications.
Towards Useful Boronates through Atom‐Economical Catalyzed Cascade Reactions
Authors: Buñuel Elena , Cárdenas Diego J. 
Published: March 2018

AbstractMetal‐catalyzed borylative cyclization reactions of polyunsaturated compounds allow concomitant formation of C−C and C−B bonds to provide cyclic boronates, which constitute synthetically useful intermediates. Recent developments using first‐row transition metals as catalysts provide fully atom‐economical reactions that follow mechanisms involving σ‐bond metathesis.
The Expanding Utility of Rhodium‐Iminocarbenes: Recent Advances in the Synthesis of Natural Products and Related Scaffolds
Authors: Li Yun , Yang Hongjian , Zhai Hongbin 
Published: March 2018

AbstractRhodium‐iminocarbenes that are derived from N‐sulfonyl‐1,2,3‐triazoles have become an important class of reactive species and useful intermediates in organic synthesis. Over the last several years, many practical and versatile approaches involving rhodium‐iminocarbene intermediates to synthetically challenging molecules (scaffolds) have been developed. This Minireview mainly summarizes the recent advance of rhodium‐iminocarbene involved reactions in the synthesis of natural products and their related scaffolds by the end of 2017. Several applications in important pharmaceuticals are documented as well.
Optical Sensing of Aromatic Amino Acids and Dipeptides by a Crown‐Ether‐Functionalized Perylene Bisimide Fluorophore
Authors: Weißenstein Annike , Saha‐Möller Chantu R. , Würthner Frank 
Published: March 2018

AbstractThe host–guest binding properties of a fluorescent perylene bisimide (PBI) receptor equipped with crown ether were studied in detail with a series of aromatic amino acids and dipeptides by UV/Vis, fluorescence and NMR spectroscopy. Fluorescence titration experiments showed that electron‐rich aromatic amino acids and dipeptides strongly quench the fluorescence of the electron‐poor PBI host molecule. Benesi–Hildebrand plots of fluorescence titration data confirmed the formation of host–guest complexes with 1:2 stoichiometry. Binding constants determined by global analysis of UV/Vis and fluorescence titration experiments revealed values between 103 m−1 and 105 m−1 in acetonitrile/methanol (9:1) at 23 °C. These data showed that amino acid l‐Trp having an indole group and dipeptides containing this amino acid bind to the PBI receptor more strongly than other amino acids and dipeptides investigated here. For dipeptides containing l‐Trp or l‐Tyr, the binding strength is dependent on the distance between the ammonium group and the aromatic unit of the amino acids and dipeptides leading to a strong sensitivity for Ala‐Trp dipeptide. 1D and 2D NMR experiments also corroborated 1:2 host–guest complexation and indicated formation of two diastereomeric species of host–guest complexes. The studies have shown that a properly functionalized PBI fluorophore functions as a molecular probe for the optical sensing of aromatic amino acids and dipeptides.
Sr[BeSi2N4]:Eu2+/Ce3+ and Eu[BeSi2N4]: Nontypical Luminescence in Highly Condensed Nitridoberyllosilicates
Authors: Strobel Philipp , Weiler Volker , Schmidt Peter J. , Schnick Wolfgang 
Published: March 2018

AbstractM[BeSi2N4] (M=Sr,Eu), crystallizing in the hexagonal space group P
2c, was synthesized from Sr(NH2)2, Be3N2, and “Si(NH)2” in W crucibles under a N2 atmosphere in a radio‐frequency furnace. The crystal structure was solved from powder X‐ray diffraction data by the charge‐flipping method (Sr[BeSi2N4]: a=4.86082(2), c=9.42264(4) Å, Z=2; Eu[BeSi2N4]: a=4.85848(1), c=9.41615(4) Å). M[BeSi2N4] contains a highly condensed rigid network of trigonal planar [BeN3] units that are connected to Si2N7 double tetrahedra by common vertices. M[BeSi2N4] (M=Sr,Eu) are the first examples of nitridoberyllosilicates and are isotypic to the oxoberyllate Sr[Be3O4]. Eu2+‐doped Sr[BeSi2N4] and Eu[BeSi2N4] show orange‐trapped exciton emission (λem=605 nm, fwhm ≈126 nm), whereas Ce3+‐doped samples of Sr[BeSi2N4] show nontypical yellowish‐orange luminescence. Sr[BeSi2N4] has a large band gap of ≈4.4 eV and shows high chemical and thermal stability. Eu2+‐doped beryllates with regular 4f65d1→4f7‐emission could be interesting for future application in LEDs upon doping with Eu2+ or Ce3+ due to large band gaps, rigid networks, and chemical and thermal stability.
Coumarin/BODIPY Hybridisation for Ratiometric Sensing of Intracellular Polarity Oscillation
Authors: Bai Yang , Shi Xiangchao , Chen Yuncong , Zhu Chengcheng , Jiao Yang , Han Zhong , He Weijiang , Guo Zijian 
Published: March 2018

AbstractWith different polarity responses, coumarin and 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) were hybridised to construct polarity fluorescent sensors, CBDP and iso‐CBDP, to overcome the disadvantages of solvatochromic sensors in ratiometric polarity sensing. Only CBDP displayed an emission ratio (ICou/IBDP, coumarin to BODIPY emissions) that increased with an exponential dependence on medium relative permittivity over a wide polarity range (ϵr<57.9). This sensing ability of CBDP was not affected by medium pH; viscosity; and most intracellular species, especially reactive oxygen, nitrogen, and sulfur species. Apart from local cytoplasmic polarity quantification through lambda imaging, CBDP enables real‐time ratiometric imaging for intracellular polarity oscillation induced by oxidative stimulation. Ratiometric polarity flow cytometry was developed, for the first time, with CBDP, which demonstrated that a high concentration H2O2 induced cytoplasmic polarity enhancement, whereas pre‐incubation with N‐acetyl‐l‐cysteine inhibited this effect.