bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accessing Ambiphilic Phosphine Boronates through C−H Borylation by an Unforeseen Cationic Iridium Complex
Authors: Wright Shawn E. , Richardson‐Solorzano Stephanie , Stewart Tiffany N. , Miller Christopher D. , Morris Kelsey C. , Daley Christopher J. A. , Clark Timothy B. 
Published: January 2019

AbstractAmbiphilic molecules, which contain a Lewis base and Lewis acid, are of great interest based on their unique ability to activate small molecules. Phosphine boronates are one class of these substrates that have interesting catalytic activity. Direct access to these phosphine boronates is described through the iridium‐catalyzed C−H borylation of phosphines. An unconventional cationic iridium catalyst was identified as optimal for a range of phosphines, providing good yields and selectivity across a diverse class of phosphine boronates (isolated as the borane‐protected phosphine). A complimentary catalyst system (quinoline‐based silane ligand with [(COD)IrOMe]2) was optimal for biphenyl‐based phosphines. Selective polyborylation was also shown providing bis‐ and tris‐borylated phosphines. Deprotection of the phosphine boronate provided free ambiphilic phosphine boronates, which do not have detectable interactions between the phosphorus and boron atoms in solution or the solid state.
Aluminum(I)/Boron(III) Redox Reactions
Authors: Hofmann Alexander , Pranckevicius Conor , Tröster Tobias , Braunschweig Holger 
Published: January 2019

AbstractReactions between BIII species and the novel nucleophilic cyclopentadienyl‐stabilized AlI reagent (1) result in a diversity of complexes bearing different Al/B oxidation states and coordination geometries. With the triarylborane B(C6F5)3, a simple AlI→BIII adduct is formed. In contrast, a bulky aryldihaloborane undergoes oxidative addition with the formation of a covalent bora‐alane species. With an N‐heterocyclic carbene‐stabilized amino(bromo)borenium ion, a redox reaction was observed, where the product is a borylene‐alane BI→AlIII complex. Additionally, reaction of 1 with BI3 results in complete scrambling of all of the Al/B‐bound substituents, and the formation of a cyclopentadienylboron(I)→AlI3 complex. These latter reactions are the first examples of the reduction of a boron(III) compound to a borylene by a p‐block reagent, and illustrate how subtle changes in the nature of the borane can result in highly divergent reaction outcomes.
Hydrogen‐Bond‐Enabled Dynamic Kinetic Resolution of Axially Chiral Amides Mediated by a Chiral Counterion
Authors: Fugard Alison J. , Lahdenperä Antti S. K. , Tan Jaqueline S. J. , Mekareeya Aroonroj , Paton Robert S. , Smith Martin D. 
Published: January 2019

AbstractNon‐biaryl atropisomers are valuable in medicine, materials, and catalysis, but their enantioselective synthesis remains a challenge. Herein, a counterion‐mediated O‐alkylation method for the generation of atropisomeric amides with an er up to 99:1 is outlined. This dynamic kinetic resolution is enabled by the observation that the rate of racemization of atropisomeric naphthamides is significantly increased by the presence of an intramolecular O−H⋅⋅⋅NCO hydrogen bond. Upon O‐alkylation of the H‐bond donor, the barrier to rotation is significantly increased. Quantum calculations demonstrate that the intramolecular H‐bond reduces the rotational barrier about the aryl–amide bond, stabilizing the planar transition state for racemization by approximately 40 kJ mol−1, thereby facilitating the observed dynamic kinetic resolution.
Chlorine‐resistant and internal‐concentration‐polarization‐mitigated polyamide membrane via tethering poly(ethylene glycol) methacrylate
Authors: Chen Qing , Sun Fei , Zhou Jin , Lu Yao , Li Yuan‐Yuan , Yu Hai‐Yin , Gu Jia‐Shan 
Published: January 2019

ABSTRACTTo improve chlorine resistance and mitigate the internal concentration polarization (ICP), a membrane surface was tethered with poly(ethylene glycol) methacrylate (PEGMA). Characterization by attenuated total reflection–Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy analysis, and field emission scanning electron microscopy indicated the successful tethering of PEGMA onto the membrane. The antifouling and antichlorine characteristics were assessed in reverse osmosis (RO) and forward osmosis (FO) processes. The water flux increased obviously to 85.00 from 60.00 L m−2 h−1 (LMH) in the RO process; the chlorine stability of the modified membrane was improved. The greatly reduced structural parameters indicated that the ICP of the FO membrane was successfully alleviated; the water flux decreased greatly for the original membrane from 3.40 to 0.01 LMH, whereas it fell only slightly from 10.99 to 9.32 LMH for the modified membrane during synthetic sewage treatment. The ICP was greatly mitigated; the antichlorine performances and the antifouling characteristics drastically improved after grafting with PEGMA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47406.
Low‐dielectric‐constant benzocyclobutene–organosilicon resins constructed from cyclotetrasiloxane
Authors: Huang Yawen , Zhang Quanli , Peng Qiuxia , Hu Huan , Yu Hongtao , Yang Junxiao , Liu Lili 
Published: January 2019

ABSTRACTOrganosilicon resins have been demonstrated to be promising materials for low‐dielectric‐constant (low‐k) related applications. In this study, we proposed a method to further reduce the dielectric constant (k) value of organosilicon resins with [1,1‐dimethyl,1‐(4′‐benzocyclobutenyl)silyl] cyclotetrasiloxane (BCB‐D4) as a building block. This building block was prepared by the hydrosilylation reaction of tetravinyl cyclotetrasiloxane with dimethyl–benzocyclobutene–silane. The reaction of benzocyclobutene on BCB‐D4 by bulk polymerization in modules directly produced a highly crosslinked resin (poly{[1,1‐dimethyl,1‐(4′‐benzocyclobutenyl)silyl] cyclotetrasiloxane) [poly(BCB‐D4)]). Poly(BCB‐D4) exhibited a low k of about 2.70; this value was greatly lower than the k (~3.0) of conventional benzocyclobutene–organosilicon resins obtained by the curing of linear polysiloxane. The low k was possibly due to the porous structure, which was constructed from multifunctionalized and cyclic building blocks. In addition, poly(BCB‐D4) also exhibited a relatively high modulus (5.0 GPa) without a sacrifice in the thermal resistance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47465.
Piezoelectric electrospun polyacrylonitrile with various tacticities
Authors: Street Reva M. , Minagawa Masatomo , Vengrenyuk Andriy , Schauer Caroline L. 
Published: January 2019

ABSTRACTElectrospinning of urea clathrate polymerized polyacrylonitrile (PAN) with isotacticity 25% and 52% was achieved in N,N‐dimethylformamide (DMF) at room temperature. Although the molecular weights of the 25% and 52% were found to be comparable by size exclusion chromatography, creation of uniform nanofibers with comparable diameters (average of ~450 nm) required concentrations of 5 % w/v and 3.5% w/v, respectively. X‐ray diffraction (XRD) analysis demonstrated that the polymer retained semicrystalline structure and suggested that crystallinity was correlated with increasing isotacticity. Fourier transform infrared spectroscopy (FTIR) also confirmed increased crystallinity as compared to commercially purchased free‐radical polymerized PAN due to a shift in the ~1250 cm−1 methine peak. Periodic semistatic normal load piezoelectric testing of the electrospun isotactic PAN samples also exhibited an average of ~30% of the piezoelectric response of electrospun (65:35) poly(vinylidene fluoride‐trifluoroethylene) (PVDF‐TrFE), a current gold standard for piezoelectric polymers, whereas commercially purchased free‐radical polymerized PAN exhibited no observable piezoelectric response. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47530.
Chemical Kinetic Strategies for High‐Throughput Screening of Protein Aggregation Modulators
Authors: Sárkány Zsuzsa , Rocha Fernando , Damas Ana M. , Macedo‐Ribeiro Sandra , Martins Pedro M. 
Published: January 2019

AbstractInsoluble aggregates staining positive to amyloid dyes are known histological hallmarks of different neurodegenerative disorders and of type II diabetes. Soluble oligomers are smaller assemblies whose formation prior to or concomitant with amyloid deposition has been associated to the processes of disease propagation and cell death. While the pathogenic mechanisms are complex and differ from disease to disease, both types of aggregates are important biological targets subject to intense investigation in academia and industry. Here we review recent advances in the fundamental understanding of protein aggregation that can be used on the development of anti‐amyloid and anti‐oligomerization drugs. Specifically, we pinpoint the chemical kinetic aspects that should be attended during the development of high‐throughput screening assays and in the hit validation phase. The strategies here devised are expected to establish a connection between basic research and pharmaceutical innovation.
Tertiary Amines Differentiated from Primary and Secondary Amines by Active Ester‐Functionalized Hexabenzoperylene in Field Effect Transistors
Authors: Li Changqing , Wang Yujing , Zhang Tiankai , Zheng Bo , Xu Jianbin , Miao Qian 
Published: January 2019

AbstractHerein, we report two novel derivatives of hexabenzoperylene (HBP) that are functionalized with ester groups. Methyl acetate functionalized HBP (1) in single crystals self‐assembles into a supramolecular nanosheet, which has a two‐dimensional π‐stack of HBP sandwiched between two layers of ester groups. With the same self‐assembly motif, active ester‐functionalized HBP (2) in field effect transistors has enabled differentiation of tertiary amines from primary and secondary amines, in agreement with the fact that active ester reacts with primary and secondary amines but not with tertiary amines to form amides.
Generation of “Sumanenylidene”: A Ground‐State Triplet Carbene on a Curved π‐Conjugated Periphery
Authors: Yakiyama Yumi , Wang Yufeng , Hatano Sayaka , Abe Manabu , Sakurai Hidehiro 
Published: January 2019

AbstractWe have observed the generation of sumanenylidene (2), a divalent, neutral‐carbon species at the benzylic position of sumanene (1). We also clarified both experimentally and theoretically that the ground state of compound 2 was a triplet state and that its singlet–triplet energy gap (ΔEST) was similar to that in fluorenylidene. The curved structure of compound 2 led to slightly better spin delocalization over the two adjacent aromatic rings than in planar systems, because of the unpaired spins on the σ and π orbitals. Synthetic application of the carbene precursor, diazosumanene (5), with a variety of thiocarbonyl compounds revealed its utility for the preparation of tetrasubstituted alkene compounds (e.g., that contain a strongly electron‐donating unit) that are directly conjugated to the sumanene (1) moiety.
A Series of Iodoargentates Directed by Solvated Metal Cations Featuring Uptake and Photocatalytic Degradation of Organic Dye Pollutants
Authors: Wei Qi , Wang Di , Pan Jie , Han Song‐De , Wang Guo‐Ming 
Published: January 2019

AbstractBy using solvated metal cations as structure‐directing agents, three new iodoargentates, namely, [Fe(DMSO)6][Ag6I9]⋅DMSO (1), [Fe(H2O)6][Ag15I18] (2) and [Cd(DMSO)6][Ag8I10] (3) (DMSO=dimethyl sulfoxide) have been solvothermally prepared and structurally characterized. The structures of compounds 1 and 2 can be described as 1D chains constructed from the linkage of [Ag6I9] and [Ag5I11] building units, respectively. For compound 3, the [Ag10I22] building blocks are directly interconnected to form a 2D [Ag8I10] layer, which are further interconnected via intermolecular forces to generate a 3D supramolecular framework with 1D large channels occupied by [Cd(DMSO)6]2+ cations. Interestingly, compounds 1–3 exhibit an ion‐exchange behavior for the adsorption of a specific dye (methylene blue, MB). Moreover, photocatalytic experiments indicate that these iodoargentates can be considered as promising photocatalysts for the degradation of organic dye pollutants.
St. Philips footbridge in Bristol
Authors: Beade‐Pereda Héctor , McElhinney John , Barbulescu Bogdan 
Published: January 2019

AbstractThe transformation of an area originally used for railway maintenance into a new neighbourhood in the city centre is one of the most important urban development projects being carried out in Bristol. The new St Philips footbridge spans the River Avon contributing to provide the needed accessibility for development to a site previously isolated by several infrastructures and the watercourse. The footbridge is an innovative solution to a complex crossing problem: the connection of two banks with a significant elevation and appearance difference and one of them being developed to high architectural standards faster than the other. The design should be appropriate for both immediate and medium‐term scenarios and to harmoniously coexist with the close existing bridges and the future buildings. The bridge is a 50m‐span and 4‐m wide steel beam with a forked geometry, hosting a ramp for disabled and cyclists and a staircase as part of its own structure to maximise functionality. The design approach to generate its shape was at the same time structural, aesthetical, and functional. Thanks to this holistic approach, the bridge is compact, simple, elegant and clearly legible for both footbridge and river path users.
Direct Imaging of Protein‐Specific Methylation in Mammalian Cells
Authors: Doll Franziska , Steimbach Raphael R. , Zumbusch Andreas 
Published: January 2019

AbstractAbundant post‐translational modification through methylation alters the function, stability, and/or localization of a protein. Malfunctions in post‐translational modification are associated with severe diseases. To unravel protein methylation sites and their biological functions, chemical methylation reporters have been developed. However, until now, their usage was limited to cell lysates. Herein, we present the first generally applicable approach for imaging methylation of individual proteins in human cells, which is based on a combination of chemical reporter strategies, bioorthogonal ligation reactions, and FRET detected by means of fluorescence lifetime imaging microscopy. Through this approach, methylation of histone 4 and the non‐histone proteins tumor suppressor p53, kinase Akt1, and transcription factor Foxo1 in two human cell lines has been successfully imaged. To further demonstrate its potential, the localization‐dependent methylation state of Foxo1 in the cellular context has been visualized.
Catalytic Conversion of 1‐butene over Modified Versions of Commercial ZSM‐5 to Produce Clean Fuels and Chemicals
Authors: Silva Andreia F. , Fernandes Auguste , Antunes Margarida M. , Ribeiro Maria F. , Silva Carlos M. , Valente Anabela A. 
Published: January 2019

AbstractThe oligomerisation of light olefins, obtainable from fossil/renewable sources and refinery streams, is an attractive route to produce clean synthetic fuels and added‐value chemicals. ZSM‐5 is a type of catalyst used in commercial olefin oligomerisation processes. Using appropriate modification procedures, it was possible to prepare catalysts with improved performances. Various modified versions of commercially available ZSM‐5 were prepared and investigated for 1‐butene oligomerisation under high‐pressure, continuous‐flow operation (30 bar, 200 °C). Simple, up‐scalable top‐down strategies involving base‐acid treatments of ZSM‐5 led to catalysts possessing enlarged pores and the required acidity for converting 1‐butene to higher molar mass products. In targeting diesel type products, the modified catalysts led to up to 86 % butenes conversion, space time yield of 852 mg gcat−1 h−1 and mass ratio diesel:naphtha cuts of 2.2. Characterisation studies and multivariate/principal component analysis helped categorise the differently prepared catalysts, and gain insights into complex interplay of material properties influencing the catalytic reaction.
Synthesis of Nickel‐Doped Ceria Catalysts for Selective Acetylene Hydrogenation
Authors: Riley Christopher , De La Riva Andrew , Zhou Shulan , Wan Qiang , Peterson Eric , Artyushkova Kateryna , Farahani Majid D. , Friedrich Holger B. , Burkemper Laura , Atudorei Nicu‐Viorel , Lin Sen , Guo Hua , Datye Abhaya 
Published: January 2019

AbstractMetallic nickel is known to be an active, but not a selective hydrogenation catalyst for conversion of alkynes to alkenes. On the other hand, nickel oxide is not active. Recently, we have demonstrated that nickel doped into ceria provides an inexpensive catalyst for selective hydrogenation of acetylene in the presence of ethylene. Here, we evaluate various synthesis methods to achieve optimal selective hydrogenation performance. We examined incipient wetness impregnation, coprecipitation, solution combustion, and sol‐gel synthesis to study how the method of preparation affects catalytic structure and behavior. Sol‐gel synthesis, coprecipitation, and solution combustion synthesis methods favor nickel incorporation into the ceria lattice, while incipient wetness impregnation creates segregated nickel species on the ceria surface. For hydrogenation of acetylene, these nickel surface species lead to poor ethylene selectivity due to ethane and oligomer formation. However, when nickel is incorporated into the ceria lattice, ethane formation is prevented even while achieving 100 % conversion of acetylene. Coke formation is also significantly reduced on these catalysts compared to conventional nanoparticle counterparts. We conclude that sol‐gel synthesis provides the optimal method for creating a uniform dopant distribution within the high surface area ceria.
Oxygen Vacancy Induced Structural Distortions in Black Titania: A Unique Approach using Soft X‐ray EXAFS at the O–K Edge
Authors: Leedahl Brett , de Boer Tristan , Yuan Xiaotao , Moewes Alexander 
Published: January 2019

AbstractUnknown changes in the crystalline order of regular TiO2 result in the formation of black titania, which has garnered significant interest as a photocatalytic material due to the accompanying electronic changes. Herein, the nature of the lattice distortion caused by an oxygen vacancy was determined that in turn results in the formation of mid‐band‐gap states found in previous studies of black titania. An innovative technique is introduced using a state‐of‐the‐art silicon drift detector, which can be used in conjunction with extended X‐ray absorption fine structure (EXAFS) to measure bulk interatomic distances. Also discussed is how the energy dispersive nature of such a detector can allow for an unimpeded signal, indefinitely in energy space, thereby sidestepping the hurdles of more conventional EXAFS, which is often impeded by other absorption edges.
Exohedral Addition Chemistry of the Fullerenide Anions C602− and C60⋅−
Authors: Wabra Isabell , Holzwarth Johannes , Hauke Frank , Hirsch Andreas 
Published: January 2019

AbstractA systematic screening study of the exohedral reactivity of the reduced fullerenes (fullerenides) C602− and C60⋅− is reported. These doubly and singly negatively charged carbon cages were prepared by two‐fold reduction of C60 with potassium, leading to K2C60, or by in situ monoreduction with the radical anion of benzonitrile PhCN⋅−, respectively. Several series of electrophiles, including geminal and distant dihalides, benzyl bromides, and diazonium compounds, were employed as addition partners. In general, the investigated bromides proved to be the most suitable reaction partners. A series of fullerene adducts and cycloadducts involving either 1,2‐ or 1,4‐addition patterns, depending on the precise architecture and the steric demand of the addends, were synthesized and fully characterized. Some of the reaction products are unprecedented and inaccessible forms of neutral C60. The fullerenide chemistry presented here closely resembles related reactions of graphenides and carbon nanotubides, which are the most powerful methods for the functionalization of these macromolecular forms of synthetic carbon allotropes (SCAs). Activation of C60 by negative charging represents a little explored concept of fullerene chemistry, providing both new insights of fullerene reactivity itself and new types of exohedral derivatives.
Anthracene‐Based Cyclophanes with Selective Fluorescent Responses for TTP and GTP: Insights into Recognition and Sensing Mechanisms
Authors: Agafontsev Aleksandr M. , Shumilova Tatiana A. , Rüffer Tobias , Lang Heinrich , Kataev Evgeny A. 
Published: January 2019

AbstractThree anthracene‐based cyclophanes were synthesized and their binding properties towards nucleoside triphosphates were studied. A new polycyclic amine derived from dearomatized anthracene was identified as a major side product in the cyclization reaction between 9,10‐anthracenedicarboxaldehyde and diethylenetriamine. Its structure was determined by single‐crystal X‐ray analysis. The cyclophanes were found to form 1:1 complexes with all nucleoside triphosphates as well as with pyrophosphate in a buffered aqueous solution at pH 6.2. A turn‐on fluorescence response was observed for all nucleotides except for GTP, which demonstrated strong fluorescence quenching. The strongest turn‐on fluorescence was observed for the largest receptor 3 in the presence of thymidine triphosphate (TTP). Based on the NMR and fluorescence experiments, two major binding modes for nucleotide complexes were identified.
A Closed Metallomolecular Cage that can Open its Aperture by Disulfide Exchange
Authors: Akine Shigehisa , Miyashita Masato , Nabeshima Tatsuya 
Published: January 2019

AbstractInvited for the cover of this issue is the group of Shigehisa Akine at Kanazawa University and Tatsuya Nabeshima at the University of Tsukuba. The image, designed by Prof. Akine, depicts a visualization of the possible “open” intermediate molecule that allows a guest to enter and exit. Read the full text of the article at 10.1002/chem.201805359.
Nonmosaic somatic HIF2A mutations associated with late onset polycythemia‐paraganglioma syndrome: Newly recognized subclass of polycythemia‐paraganglioma syndrome
Authors: Pang Ying , Gupta Garima , Jha Abhishek , Yue Xupeng , Wang Herui , Huynh Thanh‐Truc , Li Aiguo , Li Liping , Baker Eva , Chew Emily , Feelders Richard A. , Korpershoek Esther , Zhuang Zhengping , Yang Chunzhang , Pacak Karel 
Published: January 2019

BackgroundSomatic mutations in hypoxia‐inducible factor 2α (HIF2A) are associated with polycythemia‐paraganglioma syndrome. Specifically, the classic presentation of female patients with recurrent paragangliomas (PGLs), polycythemia (at birth or in early childhood), and duodenal somatostatinomas has been described. Studies have demonstrated that somatic HIF2A mutations occur as postzygotic events and some to be associated with somatic mosaicism affecting hematopoietic and other tissue precursors. This phenomenon could explain the development of early onset of polycythemia in the absence of erythropoietin‐secreting tumors.MethodsCorrelation analysis was performed between mosaicism of HIF2A mutant patients and clinical presentations.ResultsSomatic HIF2A mutations (p.A530V, p.P531S, and p.D539N) were identified in DNA extracted from PGLs of 3 patients. No somatic mosaicism was detected through deep sequencing of blood genomic DNA. Compared with classic syndrome, both polycythemia and PGL in all 3 patients developed at an advanced age with polycythemia at age 30, 30, and 17 years and PGLs at age 34, 30, and 55 years, respectively. Somatostatinomas were not detected, and 2 patients had ophthalmic findings. The biochemical phenotype in all 3 patients was noradrenergic with 18F‐fluorodopa PET/CT as the most sensitive imaging modality. All patients demonstrated multiplicity, and none developed metastatic disease.ConclusionThese findings suggest that newer techniques need to be developed to detect somatic mosaicism in patients with this syndrome. Absence of HIF2A mosaicism in patients with somatic HIF2A mutations supports association with late onset of the disease, milder clinical phenotype, and an improved prognosis compared with patients who have HIF2A mosaicism.