bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Seebeck Coefficient in Mixtures of Conjugated Polymers
Authors: Zuo Guangzheng , Liu Xianjie , Fahlman Mats , Kemerink Martijn 
Published: November 2017

AbstractA universal method to obtain record‐high electronic Seebeck coefficients is demonstrated while preserving reasonable conductivities in doped blends of organic semiconductors through rational design of the density of states (DOSs). A polymer semiconductor with a shallow highest occupied molecular orbital (HOMO) level‐poly(3‐hexylthiophene) (P3HT) is mixed with materials with a deeper HOMO (PTB7, TQ1) to form binary blends of the type P3HTx:B1‐x (0 ≤ x ≤ 1) that is p‐type doped by F4TCNQ. For B = PTB7, a Seebeck coefficient S = 1100 µV K−1 with conductivity σ = 0.3 S m−1 at x = 0.10 is achieved, while for B = TQ1, S = 2000 µV K−1 and σ = 0.03 S m−1 at x = 0.05 is found. Kinetic Monte Carlo simulations with parameters based on experiments show good agreement with the experimental results, confirming the intended mechanism. The simulations are used to derive a design rule for parameter tuning. These results can become relevant for low‐power, low‐cost applications like (providing power to) autonomous sensors, in which a high Seebeck coefficient translates directly to a proportionally reduced number of legs in the thermogenerator, and hence in reduced fabrication cost and complexity.
Liquid‐Tin‐Assisted Molten Salt Electrodeposition of Photoresponsive n‐Type Silicon Films
Authors: Peng Junjun , Yin Huayi , Zhao Ji , Yang Xiao , Bard Allen J. , Sadoway Donald R. 
Published: November 2017

AbstractProduction of silicon film directly by electrodeposition from molten salt would have utility in the manufacturing of photovoltaic and optoelectronic devices owing to the simplicity of the process and the attendant low capital and operating costs. Here, dense and uniform polycrystalline silicon films (thickness up to 60 µm) are electrodeposited on graphite sheet substrates at 650 °C from molten KCl–KF‐1 mol% K2SiF6 salt containing 0.020–0.035 wt% tin. The growth of such high‐quality tin‐doped silicon films is attributable to the mediation effect of tin in the molten salt electrolyte. A four‐step mechanism is proposed for the generation of the films: nucleation, island formation, island aggregation, and film formation. The electrodeposited tin‐doped silicon film exhibits n‐type semiconductor behavior. In liquid junction photoelectrochemical measurement, this material generates a photocurrent about 38–44% that of a commercial n‐type Si wafer.
Investigation of the High Electron Affinity Molecular Dopant F6‐TCNNQ for Hole‐Transport Materials
Authors: Zhang Fengyu , Kahn Antoine 
Published: November 2017

Abstract2,2′‐(perfluoronaphthalene‐2,6‐diylidene)dimalononitrile (F6‐TCNNQ) is investigated as a molecular p‐type dopant in two hole‐transport materials, 2,2′,7,7′‐tetrakis(N,N‐diphenylamino)‐9,9‐spirobifluorene (Spiro‐TAD) and tris(4‐carbazoyl‐9‐ylphenyl)amine (TCTA). The electron affinity of F6‐TCNNQ is determined to be 5.60 eV, one of the strongest organic molecular oxidizing agents used to date in organic electronics. p‐Doping is found to be effective in Spiro‐TAD (ionization energy = 5.46 eV) but not in TCTA (ionization energy = 5.85 eV). Optical absorption measurements demonstrate that charge transfer is the predominant doping mechanism in Spiro‐TAD:F6‐TCNNQ. The host–dopant interaction also leads to a significant alteration of the host film morphology. Finally, transport measurements done on Spiro‐TAD:F6‐TCNNQ as a function of dopant concentration and temperature, and using a highly doped contact layer to ensure negligible hole injection barrier, lead to an accurate measurement of the film conductivity and hole‐hopping activation energy.
Photoswitchable Nanomaterials Based on Hierarchically Organized Siloxane Oligomers
Authors: Zha R. Helen , Vantomme Ghislaine , Berrocal José Augusto , Gosens Ronald , de Waal Bas , Meskers Stefan , Meijer E. W. 
Published: November 2017

AbstractMaterials with highly ordered molecular arrangements have the capacity to display unique properties derived from their nanoscale structure. Here, the synthesis and characterization of azobenzene (AZO)‐functionalized siloxane oligomers of discrete length that form photoswitchable supramolecular materials are described. Specifically, synergy between phase segregation and azobenzene crystallization leads to the self‐assembly of an exfoliated 2D crystal that becomes isotropic upon photoisomerization with UV light. Consequently, the material undergoes a rapid athermal solid‐to‐liquid transition which can be reversed using blue light due to the unexpectedly fast 2D crystallization that is facilitated by phase segregation. In contrast, enabling telechelic supramolecular polymerization through hydrogen bonding inhibits azobenzene crystallization, and nanostructured pastes with well‐ordered morphologies are obtained based on phase segregation alone, thus demonstrating block copolymer‐like behavior. Therefore, by tailoring the balance of self‐assembly forces in the azobenzene‐functionalized siloxane oligomers, fast and reversible phase‐changing materials can be engineered with various mechanical properties for applications in photolithography or switchable adhesion to lubricant properties.
Highly Condensed Boron Cage Cluster Anions in 2D Carrier and Its Enhanced Antitumor Efficiency for Boron Neutron Capture Therapy
Authors: Choi Goeun , Jeon Ie‐Rang , Piao Huiyan , Choy Jin‐Ho 
Published: November 2017

AbstractAn attempt is made to apply layered double hydroxide (LDH) as a boron delivery carrier for boron neutron capture therapy (BNCT), which needs a sufficient amount of boron in tumor cells for its successful administration. To meet this requirement, a nanohybrid (BSH‐LDH), mercaptoundecahydro‐closo‐dodecaborate (BSH) anionic molecules in LDH, is developed as a boron delivery system. The cellular boron content upon permeation of BSH‐LDH nanoparticles (42.4 µg 10B 10−6 cells) in U87 glioblastoma cell line is found to be ≈2000 times larger than the minimum boron requirement (≈0.02 µg 10B 10−6 cells) for BNCT and also orders of magnitude higher than the previous results (0.2–1.5 µg 10B 10−6 cells) by those applied with other targeting strategies, and eventually results in excellent neutron capture efficiency even under such low dose (30 µg 10B mL−1) and weak irradiation (1 × 1012 n cm−2 corresponding to 20 min) condition. According to the biodistribution studies in xenograft mice model, the tumor‐to‐blood ratio of BSH in the BSH‐LDH‐treated‐group is found to be 4.4‐fold higher than that in the intact BSH treated one in 2 h after drug treatment. The present BNCT combined with boron delivery system provides a promising integrative therapeutic platform for cancer treatment.
Probing the Dynamic Nature of Self‐Assembling Cyclic Peptide–Polymer Nanotubes in Solution and in Mammalian Cells
Authors: Rho Julia Y. , Brendel Johannes C. , MacFarlane Liam R. , Mansfield Edward D. H. , Peltier Raoul , Rogers Sarah , Hartlieb Matthias , Perrier Sébastien 
Published: November 2017

AbstractSelf‐assembling cyclic peptide–polymer nanotubes have emerged as a fascinating supramolecular system, well suited for a diverse range of biomedical applications. Due to their well‐defined diameter, tunable peptide anatomy, and ability to disassemble in situ, they have been investigated as promising materials for numerous applications including biosensors, antimicrobials, and drug delivery. Despite this continuous effort, the underlying mechanisms of assembly and disassembly are still not fully understood. In particular, the exchange of units between individual assembled nanotubes has been overlooked so far, despite its knowledge being essential for understanding their behavior in different environments. To investigate the dynamic nature of these systems, cyclic peptide–polymer nanotubes are synthesized, conjugated with complementary dyes, which undergo a Förster resonance energy transfer (FRET) in close proximity. Model conjugates enable to demonstrate not only that their self‐assembly is highly dynamic and not kinetically trapped, but also that the self‐assembly of the conjugates is strongly influenced by both solvent and concentration. Additionally, the versatility of the FRET system allows studying the dynamic exchange of these systems in mammalian cells in vitro using confocal microscopy, demonstrating the exchange of subunits between assembled nanotubes in the highly complex environment of a cell.
All‐Polymer Solar Cells Based on a Conjugated Polymer Containing Siloxane‐Functionalized Side Chains with Efficiency over 10%
Authors: Fan Baobing , Ying Lei , Zhu Peng , Pan Feilong , Liu Feng , Chen Junwu , Huang Fei , Cao Yong 
Published: November 2017

AbstractA novel wide‐bandgap conjugated copolymer based on an imide‐functionalized benzotriazole building block containing a siloxane‐terminated side‐chain is developed. This copolymer is successfully used to fabricate highly efficient all‐polymer solar cells (all‐PSCs) processed at room temperature with the green‐solvent 2‐methyl‐tetrahydrofuran. When paired with a naphthalene diimide‐based polymer electron‐acceptor, the all‐PSC exhibits a maximum power conversion efficiency (PCE) of 10.1%, which is the highest value so far reported for an all‐PSC. Of particular interest is that the PCE remains 9.4% after thermal annealing at 80 °C for 24 h. The resulting high efficiency is attributed to a combination of high and balanced bulky charge carrier mobility, favorable face‐on orientation, and high crystallinity. These observations indicate that the resulting copolymer can be a promising candidate toward high‐performance all‐PSCs for practical applications.
High Integration of Microfluidic Circuits Based on Hydrogel Valves for MEMS Control
Authors: Haefner Sebastian , Koerbitz Rene , Frank Philipp , Elstner Martin , Richter Andreas 
Published: November 2017

AbstractIntegrated circuits (ICs) are the key to powerful microarchitectures for lab on a chip applications. High actuator densities can enable the control of several thousand of reactions executed in parallel on a single chip. Hydrogels can act as self‐contained sensor–actuator materials, which control fluid flows depending on local physicochemical conditions. A concept is described for the preparation of highly integrated circuits based on stimuli‐sensitive hydrogels. The concept allows to adjust the working point and fulfill the free swelling condition of the hydrogels, which is favorable for the dynamic performance of the actuators. The components are polymerized on a glass substrate, which is also used to seal the microfluidic system. Therefore, the hydrogel integration is conducted within the standard microfluidic system set‐up procedure. For a first demonstration integration densities of microfluidic valves of up to 172 gels cm−2 in a single microfluidic circuit are realized. Furthermore, control of microfluidic valves fabricated by the demonstrated high integration procedure via an optoelectrothermic transducer setup is shown.
A Triphenylamine–Naphthalenediimide–Fullerene Triad: Synthesis, Photoinduced Charge Separation and Solution‐Processable Bulk Heterojunction Solar Cells
Authors: Srivani Doli , Gupta Akhil , Bhosale Sidhanath V. , Ohkubo Kei , Bhosale Rajesh S. , Fukuzumi Shunichi , Bilic Ante , Jones Lathe A. , Bhosale Sheshanath V. 
Published: November 2017

AbstractA new naphthalenediimide (NDI) derivative linked to triphenylamine (TPA) and fullerene (TPA–NDI–C60 triad; S3) was designed, synthesized and characterized. Femtosecond laser transient absorption spectral measurements revealed that fast electron transfer from TPA to the singlet‐excited state of NDI occurred to form a charge‐separated state (TPA.+–NDI.−–C60) with a rate constant of approximately 1012 s−1, followed by the charge‐shift reaction from NDI.− to C60 to produce the charge‐separated state (TPA.+–NDI–C60.−) that decayed by back electron transfer with a rate constant of 4.4×109 s−1 (with a corresponding lifetime of 230 ps). Organic bulk heterojunction solar cells were fabricated using the triad S3 as an n‐type semiconductor along with the conventional donor polymer poly(3‐hexylthiophene). The power conversion efficiency reached 3.03 % before annealing and 4.85 % after annealing in the optimized devices. To rationalize the performance of these organic photovoltaic devices, atomic force microscopy was used to study the morphology of poly(3‐hexylthiophene):S3 blend surfaces, which were found to be well interlaced and free from projections, lumps, or indentations.
Room‐Temperature‐Phosphorescence‐Based Dissolved Oxygen Detection by Core‐Shell Polymer Nanoparticles Containing Metal‐Free Organic Phosphors
Authors: Yu Youngchang , Kwon Min Sang , Jung Jaehun , Zeng Yingying , Kim Mounggon , Chung Kyeongwoon , Gierschner Johannes , Youk Ji Ho , Borisov Sergey M. , Kim Jinsang 
Published: November 2017

AbstractThe highly sensitive optical detection of oxygen including dissolved oxygen (DO) is of great interest in various applications. We devised a novel room‐temperature‐phosphorescence (RTP)‐based oxygen detection platform by constructing core–shell nanoparticles with water‐soluble polymethyloxazoline shells and oxygen‐permeable polystyrene cores crosslinked with metal‐free purely organic phosphors. The resulting nanoparticles show a very high sensitivity for DO with a limit of detection (LOD) of 60 nm and can be readily used for oxygen quantification in aqueous environments as well as the gaseous phase.
Asymmetric Traceless Petasis Borono‐Mannich Reactions of Enals: Reductive Transposition of Allylic Diazenes
Authors: Jiang Yao , Thomson Regan J. , Schaus Scott E. 
Published: November 2017

AbstractThe traceless Petasis borono‐Mannich reaction of enals, sulfonylhydrazines, and allylboronates, catalyzed by chiral biphenols, results in an asymmetric reductive transposition of the in situ generated allylic diazene. Acyclic 1,4‐diene products bearing either alkyl‐ or aryl‐substituted benzylic stereocenters are afforded in excellent yields and enantiomeric ratios of up to 99:1. The use of crotylboronates in the reaction results in concomitant formation of two stereocenters in either a 1,4‐syn or anti relationship from the corresponding E‐ or Z‐crotylboronate used in the reaction. The use of β‐monosubstituted enals in the asymmetric traceless Petasis borono‐Mannich reaction of crotylboronates installs tertiary methyl‐bearing stereocenters in good yields and high enantioselectivities.
Toblerols: Cyclopropanol‐Containing Polyketide Modulators of Antibiosis in Methylobacteria
Authors: Ueoka Reiko , Bortfeld‐Miller Miriam , Morinaka Brandon I. , Vorholt Julia A. , Piel Jörn 
Published: November 2017

AbstractTrans‐AT polyketide synthases (PKSs) are a family of biosynthetically versatile modular type I PKSs that generate bioactive polyketides of impressive structural diversity. In this study, we detected, in the genome of several bacteria a cryptic, architecturally unusual trans‐AT PKS gene cluster which eluded automated PKS prediction. Genomic mining of one of these strains, the model methylotroph Methylobacterium extorquens AM1, revealed unique epoxide‐ and cyclopropanol‐containing polyketides named toblerols. Relative and absolute stereochemistry were determined by NMR experiments, chemical derivatization, and the comparison of CD data between the derivatized natural product and a synthesized model compound. Biosynthetic data suggest that the cyclopropanol moiety is generated by carbon–carbon shortening of a more extended precursor. Surprisingly, a knock‐out strain impaired in polyketide production showed strong inhibitory activity against other methylobacteria in contrast to the wild‐type producer. The activity was inhibited by complementation with toblerols, thus suggesting that these compounds modulate an as‐yet unknown methylobacterial antibiotic.
Reduction of Dioxygen by Radical/B(p‐C6F4X)3 Pairs to Give Isolable Bis(borane)superoxide Compounds
Authors: Tao Xin , Daniliuc Constantin G. , Janka Oliver , Pöttgen Rainer , Knitsch Robert , Hansen Michael Ryan , Eckert Hellmut , Lübbesmeyer Maximilian , Studer Armido , Kehr Gerald , Erker Gerhard 
Published: November 2017

AbstractTriplet dioxygen was reduced by TEMPO or trityl radicals in the presence of two molar equivalents of the strong B(p‐C6F4X)3 (X: F or H) boron Lewis acids under mild conditions to give the bis(borane)superoxide systems 2. The sensitive radical anion species were isolated and characterized by methods including X‐ray crystal structure analysis and EPR spectroscopy.
A Supramolecular Capsule for Reversible Polysulfide Storage/Delivery in Lithium‐Sulfur Batteries
Authors: Xie Jin , Peng Hong‐Jie , Huang Jia‐Qi , Xu Wen‐Tao , Chen Xiang , Zhang Qiang 
Published: November 2017

AbstractSupramolecular materials, in which small organic molecules are assembled into regular structures by non‐covalent interactions, attract tremendous interests because of their highly tunable functional groups and porous structure. Supramolecular adsorbents are expected to fully expose their abundant adsorptive sites in a dynamic framework. In this contribution, we introduced cucurbit[6]uril as a supramolecular capsule for reversible storage/delivery of mobile polysulfides in lithium‐sulfur (Li‐S) batteries to control undesirable polysulfide shuttle. The Li‐S battery equipped with the supramolecular capsules retains a high Coulombic efficiency and shows a large increase in capacity from 300 to 900 mAh g−1 at a sulfur loading of 4.2 mg cm−2. The implementation of supramolecular capsules offers insights into intricate multi‐electron‐conversion reactions and manifests as an effective and efficient strategy to enhance Li‐S batteries and analogous applications that involve complex transport phenomena and intermediate manipulation.
Asymmetric Synthesis of Less Accessible α‐Tertiary Amines from Alkynyl Z‐Ketimines
Authors: Kano Taichi , Aota Yusuke , Maruoka Keiji 
Published: November 2017

AbstractA highly stereoselective synthesis of hitherto less accessible chiral α‐tertiary amines with multiple structurally similar linear carbon chains was achieved through chiral auxiliary mediated addition of organolithium reagents to the geometrically well‐controlled alkynyl Z‐ketimines. This stereoselective nucleophilic addition offers a general approach to the asymmetric synthesis of nitrogen‐containing chiral materials.
Enantioselective and Collective Total Syntheses of Xanthanolides
Authors: Feng Juan , Lei Xiaoqiang , Bao Ruiyang , Li Yuanhe , Xiao Chengqian , Hu Lihong , Tang Yefeng 
Published: November 2017

AbstractAn enantioselective synthesis of (+)‐8‐epi‐xanthatin hinging on a chiral phosphoric acid catalyzed tandem allylboration/lactonization reaction is reported. With (+)‐8‐epi‐xanthatin as the precursor, the collective synthesis of a series of synthetically challenging xanthanolides was also accomplished. Among them, xanthipungolide, one of the most complex xanthanolide monomers, was accessed through a bioinspired tandem double‐bond isomerization/6π electronic cyclization/intramolecular Diels–Alder reaction, and pungiolides A, B, D, E, and L–N, a group of xanthanolide dimers, were assembled through a bioinspired Diels–Alder dimerization followed by late‐stage diversification.
Enantiospecific sp2–sp3 Coupling of ortho‐ and para‐Phenols with Secondary and Tertiary Boronic Esters
Authors: Wilson Claire M. , Ganesh Venkataraman , Noble Adam , Aggarwal Varinder K. 
Published: November 2017

AbstractThe coupling of ortho‐ and para‐phenols with secondary and tertiary boronic esters has been explored. In the case of para‐substituted phenols, after reaction of a dilithio phenolate species with a boronic ester, treatment with Ph3BiF2 or Martin's sulfurane gave the coupled product with complete enantiospecificity. The methodology was applied to the synthesis of the broad spectrum antibacterial natural product (−)‐4‐(1,5‐dimethylhex‐4‐enyl)‐2‐methyl phenol. For ortho‐substituted phenols, initial incorporation of a benzotriazole on the phenol oxygen atom was required. Subsequent ortho‐lithiation and borylation gave the coupled product, again with complete stereospecificity.
Synthesis of a novel azaphosphorine flame retardant and its application in epoxy resins
Authors: Liu Chao , Huang Jiamei , Zhu Jihong , Yuan Conghui , Zeng Birong , Chen Guorong , Xu Yiting , Dai Lizong 
Published: November 2017

ABSTRACTA novel PCN bond containing azaphosphorine, 5‐(4‐hydroxy)anilinomethyl‐1,3‐di(4‐hydroxy)phenyl‐1,3,5‐diazaphosphorinane (ADDPP‐OH), which could be used as both a cocuring agent and a flame‐retarding agent for epoxy resins (EPs), was synthesized from tetrakis(hydroxymethyl)phosphonium sulfate and characterized by FTIR, 1H‐NMR, 13C‐NMR, 31P‐NMR, and so on. Compared with the pure EP, the ADDPP‐OH–EP composites showed increased decomposition temperatures and char yields. When the content of ADDPP‐OH was 10 wt %, the cured EP composite possessed a limiting oxygen index value of 33.7% and passed the V‐0 rating of the UL‐94 test. The mechanical properties of the ADDPP‐OH–EP composites was improved because of the increased crosslinking density. In addition, the morphology of the residual char indicated an intumescent and multiporous structure in the inner space and a compact and continual appearance in the outer layer; this was important in preventing the materials from burning further. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45721.
Enhancement of electrical and thermal conductivity of polypropylene by graphene nanoplatelets
Authors: Imran Kazi Al , Lou Jianzhong , Shivakumar Kunigal N. 
Published: November 2017

ABSTRACTOne of disadvantages of polymer composites is poor electrical and thermal conductivity. As a first step in this direction, graphene‐modified polypropylene polymer is being developed to improve its electrical and thermal conductivity. Two techniques were investigated: surface coating and extrusion. In the case of coating technique, the percolation threshold was found to be 0.5 wt % of graphene and electrical conductivity of polypropylene increased around 13 log cycles. Coating technique breaks the agglomerations due to magnetic stirring followed by sonication and gives homogeneous graphene‐coated polypropylene pellets. When polymer melts under compression molding, the graphene platelets network formed on the surface of polypropylene pellets as well as through‐the‐thickness of the molded disk, which provide continuous network of graphene. However, in extrusion technique, graphene segregated and did not disperse properly in polypropylene. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45833.
Effect of amide distribution in polyamide isomers on their melting points
Authors: Coussens Betty , Rulkens Rudy 
Published: November 2017

ABSTRACTA new insight has been obtained relating the different structures of linear aliphatic homopolyamides to their melting points. A new equation is derived for structures based on monomers with an even number of methylene units. In this equation, the amide distribution along the polymer chain is defined by a newly introduced parameter K which indicates the lowest number of methylene units between adjacent amide groups. For K ≥ 4 a generic empirical relation is defined, describing the observed melting points of these polyamides. The trend in H‐bond densities in the melt obtained by modeling corresponds well with the trend in observed melting points. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45837.