bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction of an Ionic Liquid into the Micropores of a Metal–Organic Framework and Its Anomalous Phase Behavior
Authors: Fujie Kazuyuki , Yamada Teppei , Ikeda Ryuichi , Kitagawa Hiroshi
Published: August 2014

Controlling the dynamics of ionic liquids (ILs) is a significant issue for widespread use. Metal–organic frameworks (MOFs) are ideal host materials for ILs because of their small micropores and tunable host–guest interactions. Herein, we demonstrate the first example of an IL incorporated within the micropores of a MOF. The system studied consisted of EMI‐TFSA (1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)amide) and ZIF‐8 (composed of Zn(MeIM)2; H(MeIM)=2‐methylimidazole) as the IL and MOF, respectively. Construction of the EMI‐TFSA in ZIF‐8 was confirmed by X‐ray powder diffraction, nitrogen gas adsorption, and infrared absorption spectroscopy. Differential scanning calorimetry and solid‐state NMR measurements showed that the EMI‐TFSA inside the micropores demonstrated no freezing transition down to 123 K, whereas bulk EMI‐TFSA froze at 231 K. Such anomalous phase behavior originates from the nanosize effect of the MOF on the IL. This result provides a novel strategy for stabilizing the liquid phase of the ILs down to a lower temperature region.
Experimental and Computational Studies on the Reactivity of a Terminal Thorium Imidometallocene towards Organic Azides and Diazoalkanes
Authors: Ren Wenshan , Zhou Enwei , Fang Bo , Hou Guohua , Zi Guofu , Fang De‐Cai , Walter Marc D.
Published: August 2014

The reaction of the base‐free terminal thorium imido complex [{η5‐1,2,4‐(Me3C)3C5H2}2ThN(p‐tolyl)] (1) with p‐azidotoluene yielded irreversibly the tetraazametallacyclopentene [{η5‐1,2,4‐(Me3C)3C5H2}2Th{N(p‐tolyl)NNN(p‐tolyl)}] (2), whereas the bridging imido complex [{[η5‐1,2,4‐(Me3C)3C5H2]Th(N3)2}2{μ‐N(p‐tolyl)}2][(n‐C4H9)4N]2 (3) was isolated from the reaction of 1 with [(n‐C4H9)4N]N3. Unexpectedly, upon the treatment of 1 with 9‐diazofluorene, the NN bond was cleaved, an N atom was transferred, and the η2‐diazenido iminato complex [{η5‐1,2,4‐(Me3C)3C5H2}2Th{η2‐[NN(p‐tolyl)]}{N(9‐C13H8)}] (4) was formed. In contrast, the reaction of 1 with Me3SiCHN2 gave the nitrilimido complex [{η5‐1,2,4‐(Me3C)3C5H2}2Th{NH(p‐tolyl)}{N2CSiMe3}] (5), which slowly converted into [{η5‐1,2,4‐(Me3C)3C5H2}{η5:κ‐N‐1,2‐(Me3C)2‐4‐CMe2(CH2NNCHSiMe3)C5H2}Th{NH(p‐tolyl)}] (6) by intramolecular CH bond activation. The experimental results are complemented by density functional theory (DFT) studies.
Unravelling the Correlation between the Aspect Ratio of Nanotubular Structures and Their Electrochemical Performance To Achieve High‐Rate and Long‐Life Lithium‐Ion Batteries
Authors: Tang Yuxin , Zhang Yanyan , Deng Jiyang , Qi Dianpeng , Leow Wan Ru , Wei Jiaqi , Yin Shengyan , Dong Zhili , Yazami Rachid , Chen Zhong , Chen Xiaodong
Published: August 2014

The fundamental understanding of the relationship between the nanostructure of an electrode and its electrochemical performance is crucial for achieving high‐performance lithium‐ion batteries (LIBs). In this work, the relationship between the nanotubular aspect ratio and electrochemical performance of LIBs is elucidated for the first time. The stirring hydrothermal method was used to control the aspect ratio of viscous titanate nanotubes, which were used to fabricate additive‐free TiO2‐based electrode materials. We found that the battery performance at high charging/discharging rates is dramatically boosted when the aspect ratio is increased, due to the optimization of electronic/ionic transport properties within the electrode materials. The proof‐of‐concept LIBs comprising nanotubes with an aspect ratio of 265 can retain more than 86 % of their initial capacity over 6000 cycles at a high rate of 30 C. Such devices with supercapacitor‐like rate performance and battery‐like capacity herald a new paradigm for energy storage systems.
Anion–π and Cation–π Interactions on the Same Surface
Authors: Fujisawa Kaori , Beuchat César , Humbert‐Droz Marie , Wilson Adam , Wesolowski Tomasz A. , Mareda Jiri , Sakai Naomi , Matile Stefan
Published: August 2014

Herein, we address the question whether anion–π and cation–π interactions can take place simultaneously on the same aromatic surface. Covalently positioned carboxylate–guanidinium pairs on the surface of 4‐amino‐1,8‐naphthalimides are used as an example to explore push–pull chromophores as privileged platforms for such “ion pair–π” interactions. In antiparallel orientation with respect to the push–pull dipole, a bathochromic effect is observed. A red shift of 41 nm found in the least polar solvent is in good agreement with the 70 nm expected from theoretical calculations of ground and excited states. Decreasing shifts with solvent polarity, protonation, aggregation, and parallel carboxylate–guanidinium pairs imply that the intramolecular Stark effect from antiparallel ion pair–π interactions exceeds solvatochromic effects by far. Theoretical studies indicate that carboxylate–guanidinium pairs can also interact with the surfaces of π‐acidic naphthalenediimides and π‐basic pyrenes.
Palladium‐Catalyzed Asymmetric Decarboxylative Cycloaddition of Vinylethylene Carbonates with Michael Acceptors: Construction of Vicinal Quaternary Stereocenters
Authors: Khan Ajmal , Yang Lei , Xu Jing , Jin Long Yi , Zhang Yong Jian
Published: August 2014

An efficient method for the diastereo‐ and enantioselective construction of vicinal all‐carbon quaternary stereocenters through palladium‐catalyzed decarboxylative cycloaddition of vinylethylene carbonates with activated Michael acceptors was developed. By using a palladium complex generated in situ from [Pd2(dab)3]⋅CHCl3 and a phosphoramidite ligand as a catalyst under mild reaction conditions, the process provides multifunctionalized tetrahydrofurans bearing vicinal all‐carbon quaternary stereocenters in high yields with a high level of absolute and relative stereocontrol.
Toughening epoxy resin with blocked isocyanate containing soft chain
Authors: Lou Chunhua , Zhang Xiao , Wang Yuwei , Chen Zhaohui , Li Hongshuang
Published: August 2014

A series of imidazole (MI) blocked 2,4‐toluene diisocyanate (TDI) with polyethylene glycol (PEG‐400) as soft segment (PEG‐MI‐b‐TDI) were synthesized for toughening and curing the bisphenol A type epoxy resin (E‐44). Fourier transform infrared (FTIR) spectrum indicates that the NCO groups of the isocyanate molecule are blocked with MI. For curing epoxy systems, elimination of epoxy group and the formation of urethane bonds were studied by FTIR spectroscopy. The results of mechanical property were shown that the tensile shear and impact strengths of neat MI and MI‐b‐TDI cured E‐44 are lower than those of PEG‐MI‐b‐TDI cured E‐44. Based on the scanning electron microscope studies, microstructure evolutions of the E‐44 cured by different curing agents were imaged. The mechanical, thermal, and dynamic mechanical properties were measured by universal testing machine, differential scanning calorimeter and dynamic mechanical analyzer (DMA). The toughness of E‐44 cured by PEG‐MI‐b‐TDI was effectively improved without sacrificing the tensile shear strength. Based on the DMA studies, the long soft chain of PEG brought in a noticeable lowering in the glass transition temperature (Tg). The glass transition temperature is near 165°C for the neat MI cured E‐44, which is higher than the Tgs of the other curing agents cured epoxy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41345.
Interfacial damage on fatigue‐loaded textile–rubber composites
Authors: Valantin Chloé , Lacroix Florian , Deffarges Marie‐Pierre , Morcel Julie , Aït Hocine Nourredine
Published: August 2014

To reach admissible lifetime expectancy, unidirectional textile–rubber composites must show a strong interface. Usually, it is achieved by coating the textile with Resorcinol–Formaldehyde–Latex (RFL). To evaluate fatigue impact on interfacial properties, composites with or without RFL are tested at different numbers of loading cycles and characterized through peel tests, dynamic mechanical analysis (DMA), scanning electron microscopy and energy‐dispersive X‐rays, and nanoindentation. For composites with RFL, the results indicate two main mechanisms for damaging: propagation of pre‐existing fibrillar microcracks at the rubber/RFL interface completed by adhesive debondings at the RFL/textile interface. At first, the propagation of fibrillar microcracks is correlated with decrease of global composite peeling resistance and contribution of interphase to DMA damping. Then, RFL/textile debondings become critical. They are highlighted with a change of peeling failure surface and could be explained by RFL hardening, highlighted by nanoindentation. This questions the choice for RFL as a sustainable adhesive for composites under fatigue loading. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41346.
Deoxygenation performance of polydimethylsiloxane mixed‐matrix membranes for dissolved oxygen removal from water
Authors: Li Ting , Yu Ping , Luo Yunbai
Published: August 2014

The removal of dissolved oxygen (DO) from water is an essential and important step in many industrial applications. The membrane technique offers much potential superiority over conventional physical and chemical processes. The development of a high‐performance membrane is the core of the membrane separation technique. In this study, a crosslinked matrix composed of a polydimethylsiloxane (PDMS) membrane with incorporated silica networks by the sol–gel method was manufactured. The application of the membrane method for the removal of DO from water on the laboratory scale was studied. The membrane properties and morphological structure were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, crosslinking density, and mechanical measurements. The PDMS hybrid membranes on the deoxygenation experiment by a vacuum degassing process were investigated. The results show that the crosslinked PDMS hybrid membranes effectively improved the oxygen‐removal efficiency with increasing tetraethoxysilane (TEOS) content, and the best performance was obtained when the weight ratio of PDMS–TEOS concentrations was 10:5. The optimal conditions for the deoxygenation performance were also investigated, and the results indicate that the degassing performances were related to the operating temperature, vacuum level, and feed flow rate. The PDMS nonporous composite membranes showed superior performances and have good potential for applications in industry for the removal of DO from water. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41350.
Association Between Experimental Pain Biomarkers and Serologic Markers in Patients With Different Degrees of Painful Knee Osteoarthritis
Authors: Arendt‐Nielsen Lars , Eskehave Thomas N. , Egsgaard Line L. , Petersen Kristian K. , Graven‐Nielsen Thomas , Hoeck Hans C. , Simonsen Ole , Siebuhr Anne S. , Karsdal Morten , Bay‐Jensen Anne C.
Published: August 2014

Objective

To assess the association between pain mechanisms (sensitization) and biochemical markers for cartilage, bone, and inflammation in patients with knee pain.

Methods

The study group comprised 281 patients with different degrees of knee pain intensity and radiographic findings (using the Kellgren/Lawrence [K/L] scale). The following structurally related serologic biomarkers were measured in serum: high‐sensitivity C‐reactive protein (hsCRP), matrix metalloproteinase (MMP)–mediated breakdown of CRP (CRPM), MMP‐mediated degradation of type I collagen (C1M), C2M, and C3M. Pressure–pain thresholds (PPT) (peripheral and spreading sensitization), temporal summation of pain, and conditioning pain modulation (CPM) (with the latter 2 biomarkers representing generalized sensitization) were assessed. For each pain parameter, the patients were categorized as most sensitized or least sensitized.

Results

Correlations were observed between the pain biomarkers PPT, temporal summation, and CPM and maximal pain intensity during the last 24 hours. Significant associations between most of the serologic biomarkers were observed. A high CRPM level was associated with centralized sensitization (temporal summation and CPM). None of the serologic markers correlated with the intensity or duration of knee pain, and only hsCRP correlated with the K/L grade. The most‐sensitized group contained more women than men, and the least‐sensitized group contained more men than women.

Conclusion

A platform of mechanistic pain biomarkers in combination with structure‐related serologic biomarkers provides new possibilities for understanding how osteoarthritis‐related structural features may be associated with pain and pain sensitization. This study showed significant correlations between central pain sensitization and CRPM as a possible measure for chronic inflammation. Future pain association studies should include biomarkers representing the local joint environment more specifically.
Oligopeptide‐Assisted Self‐Assembly of Oligothiophenes: Co‐Assembly and Chirality Transfer
Authors: Guo Zongxia , Gong Ruiying , Mu Youbing , Wang Xiao , Wan Xiaobo
Published: August 2014

The biomolecule‐assisted self‐assembly of semiconductive molecules has been developed recently for the formation of potential bio‐based functional materials. Oligopeptide‐assisted self‐assembly of oligothiophene through weak intermolecular interactions was investigated; specifically the self‐assembly and chirality‐transfer behavior of achiral oligothiophenes in the presence of an oligopeptide with a strong tendency to form β‐sheets. Two kinds of oligothiophenes without (QT) or with (QTDA) carboxylic groups were selected to explore the effect of the end functional group on self‐assembly and chirality transfer. In both cases, organogels were formed. However, the assembly behavior of QT was quite different from that of QTDA. It was found that QT formed an organogel with the oligopeptide and co‐assembled into chiral nanostructures. Conversely, although QTDA also formed a gel with the oligopeptide, it has a strong tendency to self‐assemble independently. However, during the formation of the xerogel, the chirality of the oligopeptide can also be transferred to the QTDA assemblies. Different assembly models were proposed to explain the assembly behavior.
Converting Ag2SCdS and Ag2SZnS into AgCdS and AgZnS Nanoheterostructures by Selective Extraction of Sulfur
Authors: Zhou Jiangcong , Huang Feng , Xu Ju , Wang Yuansheng
Published: August 2014

A mild three‐step solution strategy is developed to prepare AgMS (M=Zn, Cd) nanoheterostructures composed of MS nanorods with silver tips. First, Ag2SMS heterostructures are synthesized by following a solution–liquid–solid mechanism with Ag2S nanoparticles as catalysts, then the Ag2S sections of the heterostructures are converted into silver nanoparticles by selective extraction of sulfur. Notably, for the prepared AgCdS heterostructures, the localized surface plasmon resonance of silver remarkably intensifies the photoluminescence of CdS by enhancing the excitation light absorption, which is beneficial for potential applications of CdS nanoparticles in the fields of biolabeling, light‐emitting diodes, and so forth. The strategy reported herein would be useful for designing and fabricating other metal–semiconductor hybrid nanostructures with desirable performances.
Core–Shell α‐Fe2O3@α‐MoO3 Nanorods as Lithium‐Ion Battery Anodes with Extremely High Capacity and Cyclability
Authors: Wang Qiang , Wang Qi , Zhang De‐An , Sun Jing , Xing Li‐Li , Xue Xin‐Yu
Published: August 2014

α‐Fe2O3 nanoparticles are uniformly coated on the surface of α‐MoO3 nanorods through a two‐step hydrothermal synthesis method. As the anode of a lithium‐ion battery, α‐Fe2O3@α‐MoO3 core–shell nanorods exhibit extremely high lithium‐storage performance. At a rate of 0.1 C (10 h per half cycle), the reversible capacity of α‐Fe2O3@α‐MoO3 core–shell nanorods is 1481 mA h g−1 and a value of 1281 mA h g−1 is retained after 50 cycles, which is much higher than that retained by bare α‐MoO3 and α‐Fe2O3 and higher than traditional theoretical results. Such a good performance can be attributed to the synergistic effect between α‐Fe2O3 and α‐MoO3, the small size effect, one‐dimensional nanostructures, short paths for lithium diffusion, and interface spaces. Our results reveal that core–shell nanocomposites have potential applications as high‐performance lithium‐ion batteries.
Synthesis of Di‐ and Trixanthones that Display High Stability and a Visual Fluorescence Response to Strong Acid
Authors: Wang Baolin , Shao Jiafeng , Xu Taoshan , Chen Lichuan , Zhao Jinlian , Shao Yongliang , Zhang Hao‐Li , Shao Xiangfeng
Published: August 2014

Three dixanthones (1–3) and an unprecedented C3h‐symmetric trixanthone (4) were synthesized through a three‐step approach in overall yields above 63 %. These compounds possessed a planar π‐conjugated system and formed tight face‐to‐face columnar stacks, as confirmed by single‐crystal structural analysis. In comparison with xanthone, the fluorescence emissions of compounds 1–4 showed significant red‐shifts, with improved quantum yields. Moreover, the fluorescence emissions of compounds 1–4 could be modulated in a strongly acidic environment without decomposition, which led to a further red‐shift of the emissions, as well as enhancement of the emission intensities. These compounds have potential applications as optoelectronic materials and/or chemosensors.
Structures of Chlorinated Fullerenes, IPR C96Cl20 and Non‐classical C94Cl28 and C92Cl32: Evidence of the Existence of Three New Isomers of C96
Authors: Yang Shangfeng , Wei Tao , Wang Song , Ioffe Ilya N. , Kemnitz Erhard , Troyanov Sergey I.
Published: August 2014

Chlorination of various HPLC fractions of C96 with a mixture of VCl4 and SbCl5 at 340–360 °C and single‐crystal X‐ray diffraction study of the products led to the identification of three new IPR isomers of C96. The C96(175) isomer forms a stable chloride, C96(175)Cl20, while chlorides of two other new isomers, C96(114) and C96(80), undergo cage shrinkage yielding C94(NC1)Cl28 and C96(NC2)Cl32 with non‐classical (NC) cages. These two NC chlorides contain, respectively, one and two heptagons flanked by pairs of fused pentagons and are stabilized by chlorine attachment to the emerging pentagon–pentagon junctions. Thus, the number of the experimentally confirmed C96 isomers has reached nine, which corroborates the empirical rule that the C6n fullerenes exhibit particularly rich isomerism.
Metabolic engineering of 3‐hydroxypropionic acid biosynthesis in Escherichia coli
Authors: Chu Hun Su , Kim Young Soo , Lee Chan Mu , Lee Ju Hee , Jung Won Seok , Ahn Jin‐Ho , Song Seung Hoon , Choi In Suk , Cho Kwang Myung
Published: August 2014

3‐Hydroxypropionic acid (3‐HP) can be produced in microorganisms as a versatile platform chemical. However, owing to the toxicity of the intermediate product 3‐hydroxypropionaldehyde (3‐HPA), the minimization of 3‐HPA accumulation is critical for enhancing the productivity of 3‐HP. In this study, we identified a novel aldehyde dehydrogenase, GabD4 from Cupriavidus necator, and found that it possessed the highest enzyme activity toward 3‐HPA reported to date. To augment the activity of GabD4, several variants were obtained by site‐directed and saturation mutagenesis based on homology modeling. Escherichia coli transformed with the mutant GabD4_E209Q/E269Q showed the highest enzyme activity, which was 1.4‐fold higher than that of wild type GabD4, and produced up to 71.9 g L−1 of 3‐HP with a productivity of 1.8 g L−1 h−1. To the best of our knowledge, these are the highest 3‐HP titer and productivity values among those reported in the literature. Additionally, our study demonstrates that GabD4 can be a key enzyme for the development of industrial 3‐HP‐producing microbial strains, and provides further insight into the mechanism of aldehyde dehydrogenase activity. Biotechnol. Bioeng. 2015;112: 356–364. © 2014 Wiley Periodicals, Inc.
Effects of aeration on growth, ethanol and polyol accumulation by Spathaspora passalidarum NRRL Y‐27907 and Scheffersomyces stipitis NRRL Y‐7124
Authors: Su Yi‐Kai , Willis Laura B. , Jeffries Thomas W.
Published: August 2014

Spathaspora passalidarum NN245 (NRRL‐Y27907) is an ascomycetous yeast that displays a higher specific fermentation rate with xylose than with glucose. Previous studies have shown that its capacity for xylose fermentation increases while cell yield decreases with decreasing aeration. Aeration optimization plays a crucial role in maximizing bioethanol production from lignocellulosic hydrolysates. Here, we compared the kinetics of S. passalidarum NN245 and Scheffersomyces (Pichia) stipitis NRRL Y‐7124 fermenting 15% glucose, 15% xylose, or 12% xylose plus 3% glucose under four different aeration conditions. The maximum specific fermentation rate for S. passalidarum was 0.153 g ethanol/g CDW · h with a yield of 0.448 g/g from 150 g/L xylose at an oxygen transfer rate of 2.47 mmol O2/L h. Increasing the OTR to 4.27 mmol O2/L h. decreased the ethanol yield from 0.46 to 0.42 g/g xylose while increasing volumetric ethanol productivity from 0.52 to 0.8 g/L h. Both yeasts had lower cells yields and higher ethanol yields when growing on xylose than when growing on glucose. Acetic acid accretions of both strains correlated positively with increasing aeration. S. passalidarum secreted lower amounts of polyols compared to S. stipitis under most circumstances. In addition, the composition of polyols differed: S. passalidarum accumulated mostly xylitol and R,R‐2,3‐butanediol (BD) whereas S. stipitis accumulated mostly xylitol and ribitol when cultivated in xylose or a mixture of 12% xylose and 3% glucose. R,R‐2,3‐BD accumulation by S. passalidarum during xylose fermentation can be as much as four times of that by S. stipitis, and R,R‐2,3‐BD is also the most abundant byproduct after xylitol. The ratios of polyols accumulated by the two species under different aeration conditions and the implications of these observations for strain and process engineering are discussed. Biotechnol. Bioeng. 2015;112: 457–469. © 2014 Wiley Periodicals, Inc.
Quantitative determination of metformin, glyburide and its metabolites in plasma and urine of pregnant patients by LC‐MS/MS
Authors: Zhang Xing , Wang Xiaoming , Vernikovskaya Daria I. , Fokina Valentina M. , Nanovskaya Tatiana N. , Hankins Gary D. V. , Ahmed Mahmoud S.
Published: August 2014

This report describes the development and validation of an LC‐MS/MS method for the quantitative determination of glyburide (GLB), its five metabolites (M1, M2a, M2b, M3 and M4) and metformin (MET) in plasma and urine of pregnant patients under treatment with a combination of the two medications. The extraction recovery of the analytes from plasma samples was 87–99%, and that from urine samples was 85–95%. The differences in retention times among the analytes and the wide range of the concentrations of the medications and their metabolites in plasma and urine patient samples required the development of three LC methods. The lower limit of quantitation (LLOQ) of the analytes in plasma samples was as follows: GLB, 1.02 ng/mL; its five metabolites, 0.100–0.113 ng/mL; and MET, 4.95 ng/mL. The LLOQ in urine samples was 0.0594 ng/mL for GLB, 0.984–1.02 ng/mL for its five metabolites and 30.0 µg/mL for MET. The relative deviation of this method was <14% for intra‐day and inter‐day assays in plasma and urine samples, and the accuracy was 86–114% in plasma, and 94–105% in urine. The method described in this report was successfully utilized for determining the concentrations of the two medications in patient plasma and urine. Copyright © 2014 John Wiley & Sons, Ltd.
Determination of proline in human serum by a robust LC‐MS/MS method: application to identification of human metabolites as candidate biomarkers for esophageal cancer early detection and risk stratification
Authors: Liang Su , Sanchez‐Espiridion Beatriz , Xie Huan , Ma Jing , Wu Xifeng , Liang Dong
Published: August 2014

Altered serum proline levels are related to cancer metabolism. This study developed and validated a LC‐MS/MS method to analyze proline in human serum. Surrogate blank serum, coupled with stable isotope l‐proline‐13C5,15 N as internal standard, was used for generating standard curves ranging from 2.5 to 100 μg/mL. Proline was extracted from serum samples using methanol. A Phenomenex Lux 5u Cellulose‐1 column (250 × 4.6 mm) was used for chromatographic separation with 40% methanol in 0.05% formic acid aqueous solution as a mobile phase. Mass detection was performed under positive ionization electrospray. Intra‐ and inter‐day accuracy and precision were <10%. The extraction recovery and matrix factor were 99.17 and 1.47%, respectively. Our study showed that the chiral column had high specificity and selectivity for separating proline from serum components. The assay was successfully applied for the quantification of human serum proline levels from 30 esophageal cancer patients and 30 healthy volunteers. Statistical analyses showed significantly lower levels of serum proline in the patients as compared with the healthy volunteers (p‐value = 0.011). We report here a simple, specific and reproducible LC‐MS/MS method for the quantification of proline in human serum as a potential screening biomarker for esophageal cancer. Copyright © 2014 John Wiley & Sons, Ltd.
Survival of melanoma patients with brain metastases treated with ipilimumab and stereotactic radiosurgery
Authors: Tazi Karim , Hathaway Amanda , Chiuzan Cody , Shirai Keisuke
Published: August 2014

Historically, melanoma with brain metastases has a poor prognosis. In this retrospective medical record review, we report the outcome of patients with stage IV melanoma with brain metastases treated with ipilimumab and brain stereotactic radiosurgery (SRS). All patients with metastatic melanoma treated with ipilimumab from June 2010 to September 2012 were identified and stratified by presence (A) or absence (B) of brain metastases at the time of ipilimumab administration. All patients with brain metastases received SRS. Overall survival (OS) was defined as time from the date of stage IV diagnosis and the time of ipilimumab administration to death or last follow‐up. Survival curves were estimated using the Kaplan–Meier method, and Cox proportional hazards model was employed to compute the hazard ratios (HR). Results: Five out of 10 patients in Cohort A and 10 out of 21 patients in Cohort B died as of last follow‐up. In Cohort A, median number of lesions treated with SRS was 3. Median survivals from date of stage IV for Cohorts A and B were 29.3 and 33.1 months, respectively (HR = 0.93, P = 0.896). Median survival from cycle 1 ipilimumab was 16.5 and 24.5 months for Cohort A and B, respectively (HR = 1.05, P = 0.931). The 3‐year survival rates from the date of cycle one of ipilimumab administration for Cohort A and B were 50% (95% CI: 27–93%) and 39% (95% CI: 19–81%), respectively. Eight of 10 patients in Cohort A maintained a good PS. Survival of patients with melanoma brain metastases treated with ipilimumab combined with SRS may be comparable to patients without brain metastases.
Selective Dissociation of Dihydrogen over Dioxygen on a Hindered Platinum Surface for the Direct Synthesis of Hydrogen Peroxide
Authors: Yook Sunwoo , Shin Hyeyoung , Kim Hyungjun , Choi Minkee
Published: August 2014

To achieve high catalytic selectivity towards H2O2 from a H2/O2 mixture, HH bonds should be dissociated and OO bonds should be kept intact in the course of the reaction. A major dilemma in catalyst design, however, is that the metal catalysts that dissociate HH bonds have a thermodynamic preference for the dissociation of OO bonds. In this work, the selective dissociation of H2 over O2 was realized by the deposition of H2‐selective carbon diffusion layers on a Pt catalyst. Because O2 cannot access the carbon‐coated Pt surface, O2 hydrogenation occurs at the carbon surface from spilt‐over hydrogen rather than at the Pt surface on which OO dissociation is likely. This leads to the great suppression of OO dissociation, which allows the highly selective synthesis of H2O2. Notably, N‐doping of the carbon diffusion layer could increase the selectivity towards H2O2 significantly because of the stabilization of the hydroperoxy radical on the carbon surface.
NH4PF6 as a Structural Modifier for Building a Robust Carbon‐Coated Natural Graphite Anode for Lithium‐Ion Batteries
Authors: Lee Jaewoo , Park Min‐Sik , Park Yoon‐Soo , Jung Kyu‐Nam , Lee Jong‐Won , Kim So Yeun , Jo Yong Nam , Yim Taeeun , Lee Sung‐Man , Kim Young‐Jun
Published: August 2014

To improve the electrochemical performance of natural graphite anodes, we have designed a facile, scalable carbon‐coating process using coal‐tar pitch and ammonium hexafluorophosphate (NH4PF6) as a structural modifier. NH4PF6 effectively modifies the microstructure of amorphous carbon, coated on the surface of the natural graphite, leading to better, reversible Li+‐storage characteristics within a wide operating‐temperature range (from −20 to 60 °C). The COP linkage introduced as a result of the thermal decomposition of NH4PF6 assists the formation of open nanopores in the amorphous carbon layer. The integrated nanopores act as additional reversible Li+‐storage sites, which minimize the reversible capacity loss and improve the cycle performance of natural graphite. Moreover, the thermal stability of natural graphite can also be improved while maintaining the improved electrochemical performance. Thus, this approach is a step toward the practical use of natural graphite anodes for lithium‐ion batteries for electric‐vehicle applications.
Experimental and Theoretical Studies of Quadrupolar Oligothiophene‐Cored Chromophores Containing Dimesitylboryl Moieties as π‐Accepting End‐Groups: Syntheses, Structures, Fluorescence, and One‐ and Two‐Photon Absorption
Authors: Ji Lei , Edkins Robert M. , Sewell Laura J. , Beeby Andrew , Batsanov Andrei S. , Fucke Katharina , Drafz Martin , Howard Judith A. K. , Moutounet Odile , Ibersiene Fatima , Boucekkine Abdou , Furet Eric , Liu Zhiqiang , Halet Jean‐François , Katan Claudine , Marder Todd B.
Published: August 2014

Quadrupolar oligothiophene chromophores composed of four to five thiophene rings with two terminal (E)‐dimesitylborylvinyl groups (4 V–5 V), and five thiophene rings with two terminal aryldimesitylboryl groups (5 B), as well as an analogue of 5 V with a central EDOT ring (5 VE), have been synthesized via Pd‐catalyzed cross‐coupling reactions in high yields (66–89 %). Crystal structures of 4 V, 5 B, bithiophene 2 V, and five thiophene‐derived intermediates are reported. Chromophores 4 V, 5 V, 5 B and 5 VE have photoluminescence quantum yields of 0.26–0.29, which are higher than those of the shorter analogues 1 V–3 V (0.01–0.20), and short fluorescence lifetimes (0.50–1.05 ns). Two‐photon absorption (TPA) spectra have been measured for 2 V–5 V, 5 B and 5 VE in the range 750–920 nm. The measured TPA cross‐sections for the series 2 V–5 V increase steadily with length up to a maximum of 1930 GM. We compare the TPA properties of 2 V–5 V with the related compounds 5 B and 5 VE, giving insight into the structure–property relationship for this class of chromophore. DFT and TD‐DFT results, including calculated TPA spectra, complement the experimental findings and contribute to their interpretation. A comparison to other related thiophene and dimesitylboryl compounds indicates that our design strategy is promising for the synthesis of efficient dyes for two‐photon‐excited fluorescence applications.
Light Harvesting and Directional Energy Transfer in Long‐Lived Homo‐ and Heterotrimetallic Complexes of FeII, RuII, and OsII
Authors: Maity Dinesh , Bhaumik Chanchal , Mardanya Sourav , Karmakar Srikanta , Baitalik Sujoy
Published: August 2014

A new family of trimetallic complexes of the form [(bpy)2M(phen‐Hbzim‐tpy)M′(tpy‐Hbzim‐phen)M(bpy)2]6+ (M=RuII, Os; M′=FeII, RuII, Os; bpy=2,2′‐bipyridine) derived from heteroditopic phenanthroline–terpyridine bridge 2‐{4‐[2,6‐di(pyridin‐2‐yl) pyridine‐4‐yl]phenyl}‐1H‐imidazole[4,5‐f][1,10]phenanthroline (phen‐Hbzim‐tpy) were prepared and fully characterized. Zn2+ was used to prepare mixed‐metal trimetallic complexes in situ by coordinating with the free tpy site of the monometallic precursors. The complexes show intense absorptions throughout the UV/Vis region and also exhibit luminescence at room temperature. The redox behavior of the compounds is characterized by several metal‐centered reversible oxidation and ligand‐centered reduction processes. Steady‐state and time‐resolved luminescence data show that the potentially luminescent RuII‐ and OsII‐based triplet metal‐to‐ligand charge‐transfer (3MLCT) excited states in the triads are quantitatively quenched, most likely by intercomponent energy transfer to the lower lying 3MLCT (for Ru and Os) or triplet metal‐centered (3MC) excited states of the FeII subunit (nonluminescent). Interestingly, iron did not adversely affect the photophysics of the respective systems. This suggests that the multicomponent molecular‐wire‐like complexes investigated here can behave as efficient light‐harvesting antennas, because all the light absorbed by the various subunits is efficiently channeled to the subunit(s) in which the lowest‐energy excited states are located.
Hetero‐tri‐spin [2p‐3d‐4f] Chain Compounds Based on Nitronyl Nitroxide Lanthanide Metallo‐Ligands: Synthesis, Structure, and Magnetic Properties
Authors: Zhu Mei , Hu Peng , Li Yungai , Wang Xiufeng , Li Licun , Liao Daizheng , Durga Prasad Goli V. M. L. , Ramasesha S. , Sutter Jean‐Pascal
Published: August 2014

Employing nitronyl nitroxide lanthanide(III) complexes as metallo‐ligands allowed the efficient and highly selective preparation of three series of unprecedented hetero‐tri‐spin (CuLn‐radical) one‐dimensional compounds. These 2p–3d–4f spin systems, namely [Ln3Cu(hfac)11(NitPhOAll)4] (LnIII=Gd 1Gd, Tb 1Tb, Dy 1Dy; NitPhOAll=2‐(4′‐allyloxyphenyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide), [Ln3Cu(hfac)11(NitPhOPr)4] (LnIII=Gd 2Gd, Tb 2Tb, Dy 2Dy, Ho 2Ho, Yb 2Yb; NitPhOPr=2‐(4′‐propoxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) and [Ln3Cu(hfac)11(NitPhOBz)4] (LnIII=Gd 3Gd, Tb 3Tb, Dy 3Dy; NitPhOBz=2‐(4′‐benzyloxyphenyl)‐4,4,5,5‐tetramethyl‐imidazoline‐1‐oxyl‐3‐oxide) involve O‐bound nitronyl nitroxide radicals as bridging ligands in chain structures with a [Cu‐Nit‐Ln‐Nit‐Ln‐Nit‐Ln‐Nit] repeating unit. The dc magnetic studies show that ferromagnetic metal–radical interactions take place in these hetero‐tri‐spin chain complexes, these and the next‐neighbor interactions have been quantified for the Gd derivatives. Complexes 1Tb and 2Tb exhibit frequency dependence of ac magnetic susceptibilities, indicating single‐chain magnet behavior.
One‐Pot Tandem Diastereoselective and Enantioselective Synthesis of Functionalized Oxindole‐Fused Spiropyrazolidine Frameworks
Authors: Mei Liang‐Yong , Tang Xiang‐Ying , Shi Min
Published: August 2014

A highly efficient palladium(0)‐catalyzed asymmetric [3+2] cycloaddition using 3‐diazooxindoles serving as dipolarophiles affords functionalized pyrazolidine derivatives in an atom‐economical way. In addition, by trapping the pyrazolidine derivatives with maleimides, the corresponding spiropyrazolidine oxindoles containing multiple stereogenic centers have been obtained in high yields along with moderate to good levels of diastereoselectivity and enantioselectivity under mild conditions. Thus, a novel three‐component one‐pot tandem reaction has been developed.
C‐2 Selective Arylation of Indoles with Heterogeneous Nanopalladium and Diaryliodonium Salts
Authors: Malmgren Joel , Nagendiran Anuja , Tai Cheuk‐Wai , Bäckvall Jan‐E. , Olofsson Berit
Published: August 2014

A simple and efficient method to prepare synthetically useful 2‐arylindoles is presented, using a heterogeneous Pd catalyst and diaryliodonium salts in water under mild conditions. A remarkably low leaching of metal catalyst was observed under the applied conditions. The developed protocol is highly C‐2 selective and tolerates structural variations both in the indole and in the diaryliodonium salt. Arylations of both NH indoles and N‐protected indoles with ortho‐substituted, electron‐rich, electron‐deficient, or halogenated diaryliodonium salts were achieved to give the desired products in high to excellent isolated yields within 6 to 15 h at room temperature or 40 °C.
A Cationic Ruthenium Complex for the Dynamic Kinetic Resolution of Secondary Alcohols
Authors: Fernández‐Salas José A. , Manzini Simone , Nolan Steven P.
Published: August 2014

A synthetic protocol making use of a well‐defined cationic ruthenium complex 2 enabling the racemization of enantiomerically pure secondary alcohols in the presence of a weak base (K2CO3) is described. The compatibility of 2 with Candida Antarctica lipase B (Novozym 435) allows the development of an efficient dynamic kinetic resolution of sec‐alcohols in the absence of an additional strong base. This procedure involves the first example of a dynamic kinetic resolution of alcohols in the presence of a cationic ruthenium catalyst. In addition, we describe the conversion of ketones to the enantioenriched acetates in a one‐pot reaction, probing the versatility of complex 2.
Cross‐Metathesis of Terminal Alkynes
Authors: Lhermet Rudy , Fürstner Alois
Published: August 2014

Terminal acetylenes are amongst the most problematic substrates for alkyne metathesis because they tend to undergo rapid polymerization on contact with a metal alkylidyne. The molybdenum complex 3 endowed with triphenylsilanolate ligands, however, is capable of inducing surprisingly effective cross‐metathesis reactions of terminal alkyl acetylenes with propynyl(trimethyl)silane to give products of type R1CCSiMe . This unconventional way of introducing a silyl substituent onto an alkyne terminus complements the conventional tactics of deprotonation/silylation and excels as an orthogonal way of alkyne protecting group chemistry for substrates bearing base‐sensitive functionalities. Moreover, it is shown that even terminal aryl acetylenes can be cross‐metathesized with internal alkyne partners. These unprecedented transformations are compatible with various functional groups. The need to suppress acetylene formation, which seems to be a particularly effective catalyst poison, is also discussed.
Total Synthesis of Five Lipoteichoic acids of Clostridium difficile
Authors: Hogendorf Wouter F. J. , Gisch Nicolas , Schwudke Dominik , Heine Holger , Bols Mikael , Pedersen Christian Marcus
Published: August 2014

The emergence of hypervirulent resistant strains have made Clostridium difficile a notorious nosocomial pathogen and has resulted in a renewed interest in preventive strategies, such as vaccines based on (synthetic) cell wall antigens. Recently, the structure of the lipoteichoic acid (LTA) of this species has been elucidated. Additionally, this LTA was found to induce the formation of protective antibodies against C. difficile in rabbits and mice. The LTA from C. difficile is isolated as a microheterogenous mixture, differing in size and composition, impeding any structure–activity relationship studies. To ensure reliable biological results, pure and well‐defined synthetic samples are required. In this work the total synthesis of LTAs from C. difficile with defined chain length is described and the initial biological results are presented.
Palladium‐Catalyzed Cross‐Coupling of Unactivated Aryl Sulfides with Arylzinc Reagents under Mild Conditions
Authors: Otsuka Shinya , Fujino Daishi , Murakami Kei , Yorimitsu Hideki , Osuka Atsuhiro
Published: August 2014

Cross‐coupling of general aryl alkyl sulfides with arylzinc reagents proceeds smoothly, even at room temperature or below, with a palladium–N‐heterocyclic carbene (NHC) catalyst. When combined with reactions that are unique to organosulfurs, that is, the SNAr sulfanylation or Pummerer reaction, the cross‐coupling offers interesting transformations that are otherwise difficult to achieve. An alkylsulfanyl group is preferentially converted whilst leaving the tosyloxy and chloro intact, which expands the variety of orthogonal cross‐coupling.
Complexation‐Induced Supramolecular Assembly Drives Metal‐Ion Extraction
Authors: Ellis Ross J. , Meridiano Yannick , Muller Julie , Berthon Laurence , Guilbaud Philippe , Zorz Nicole , Antonio Mark R. , Demars Thomas , Zemb Thomas
Published: August 2014

Invited for the cover of this issue is the Franco–American collaboration between Commissariat à l′énergie atomique et aux énergies alternatives ‐Marcoule and Argonne National Laboratory. The image (artwork from Sana Sandler, Argonne National Laboratory) depicts a malonamide amphiphile that extracts metal ions from water into oil through complexation interactions, which cause nanoscale ordering. This aggregation is induced by complexation as well as long‐range interactions and drives metal‐ion separation processes for nuclear fuel reprocessing and refining technologies. Read the full text of the article at 10.1002/chem.201403859.
Cucurbituril: Chiral Applications
Authors: Mandadapu Vijaybabu , Day Anthony I. , Ghanem Ashraf
Published: August 2014

This review brings together the past and current methods for synthesizing the classical cucurbit[n]uril (Q[n]), structural variants, and derivatives. Here we refer to the first family of Q[n] as " classical," where the cavity is spheroidal and carry no substituents at any of the equatorial methine carbons or the methylene bridging carbons. The synthetic background and general physical and chemical properties of the Q[n] as molecular hosts is discussed. Particular attention is drawn to the synthesis of structural variants that have significance for chiral recognition properties such as (±)‐bis‐nor‐seco‐Q[6] and (±)‐bis‐nor‐seco‐Q[10]. Furthermore, examples of chiral recognition, enantio‐ and stereoselectivity using the achiral Q[n] as supramolecular structures with a chiral function directly or indirectly via another chiral agent are also discussed. Chirality 26:712–723, 2014. © 2014 Wiley Periodicals, Inc.
Inkjet Printing of 2D Layered Materials
Authors: Li Jiantong , Lemme Max C. , Östling Mikael
Published: August 2014

Inkjet printing of 2D layered materials, such as graphene and MoS2, has attracted great interests for emerging electronics. However, incompatible rheology, low concentration, severe aggregation and toxicity of solvents constitute critical challenges which hamper the manufacturing efficiency and product quality. Here, we introduce a simple and general technology concept (distillation‐assisted solvent exchange) to efficiently overcome these challenges. By implementing the concept, we have demonstrated excellent jetting performance, ideal printing patterns and a variety of promising applications for inkjet printing of 2D layered materials.
Solvatochromic Study of Highly Fluorescent Alkylated Isocyanonaphthalenes, Their π‐Stacking, Hydrogen‐Bonding Complexation, and Quenching with Pyridine
Authors: Nagy Miklós , Rácz Dávid , Lázár László , Purgel Mihály , Ditrói Tamás , Zsuga Miklós , Kéki Sándor
Published: August 2014

Mono‐ and dialkylated derivatives of 1‐amino‐5‐isocyanonaphthalene (ICAN) were studied as new members of a multifunctional, easy‐to‐prepare fluorophore family, which showed excellent solvatochromic properties. The monoallyl derivative and the starting ICAN exhibited strong fluorescence quenching in the presence of small amounts of pyridine. The formation of a hydrogen‐bonded ground‐state pyridine complex was detected; however, analysis of quantum chemical calculations suggested the presence of an additional π‐stacked pyridine complex. The Stern–Volmer plot of the quenching process exhibited a downward curvature and after reaching a minimum the fluorescence intensity increased back to a significant level at high pyridine concentrations. Significant fluorescence was observed even in pure pyridine. A new mechanism and a simple mathematical equation were derived to explain the downward curvature and the remaining fluorescence by the formation of a fluorescent π‐stacked complex.
Doubly Renewable Cellulose Polymer for Water‐Based Coatings
Authors: Tristram Cameron J. , Mason Jennifer M. , Williams D. Bradley G. , Hinkley Simon F. R.
Published: August 2014

A levulinoyl ester‐containing cellulose polymer is introduced as a waterborne coating. Incorporation of the biomass‐derived levulinic acid proceeds via an unexpected intermediate and provides the unusual feature of a cellulose derivative that is readily chemically modified. The levulinoyl‐cellulose ester could be chemically manipulated, allowing it to be dispersed to generate a waterborne hydrocolloid latex. This was capable of film‐formation at room temperature, and was formulated for use as a coating of high‐renewable content.
Selective Hydrogenation of Furan‐Containing Condensation Products as a Source of Biomass‐Derived Diesel Additives
Authors: Balakrishnan Madhesan , Sacia Eric R. , Bell Alexis T.
Published: August 2014

In this study, we demonstrate that while the energy density and lubricity of the C15 and C16 products of furan condensation of biomass‐derived aldehydes with 2‐methylfuran are consistent with requirements for diesel, these products do not meet specifications for cetane number and pour point due to their aromatic furan rings. However, a novel class of products that fully meet or exceed most specifications for diesel can be produced by converting the furan rings in these compounds to cyclic ether moieties. Full hydrodeoxygenation of furan condensation products to alkanes would require 55–60 % higher hydrogen demand, starting from biomass, compared to the products of furan ring saturation, providing an additional incentive to support the saturated products. We also report here on a tunable class of catalysts that contain Pd nanoparticles supported on ionic liquid‐modified SiO2 that can achieve complete saturation of the furan rings in yields of 95 % without opening these rings.
Elevation‐dependent responses of tree mast seeding to climate change over 45 years
Authors: Allen Robert B. , Hurst Jennifer M. , Portier Jeanne , Richardson Sarah J.
Published: August 2014

We use seed count data from a New Zealand mono‐specific mountain beech forest to test for decadal trends in seed production along an elevation gradient in relation to changes in climate. Seedfall was collected (1965 to 2009) from seed trays located on transect lines at fixed elevations along an elevation gradient (1020 to 1370 m). We counted the number of seeds in the catch of each tray, for each year, and determined the number of viable seeds. Climate variables were obtained from a nearby (<2 km) climate station (914‐m elevation). Variables were the sum or mean of daily measurements, using periods within each year known to correlate with subsequent interannual variation in seed production. To determine trends in mean seed production, at each elevation, and climate variables, we used generalized least squares (GLS) regression. We demonstrate a trend of increasing total and viable seed production, particularly at higher elevations, which emerged from marked interannual variation. Significant changes in four seasonal climate variables had GLS regression coefficients consistent with predictions of increased seed production. These variables subsumed the effect of year in GLS regressions with a greater influence on seed production with increasing elevation. Regression models enforce a view that the sequence of climate variables was additive in their influence on seed production throughout a reproductive cycle spanning more than 2 years and including three summers. Models with the most support always included summer precipitation as the earliest variable in the sequence followed by summer maximum daily temperatures. We interpret this as reflecting precipitation driven increases in soil nutrient availability enhancing seed production at higher elevations rather than the direct effects of climate, stand development or rising atmospheric CO2 partial pressures. Greater sensitivity of tree seeding at higher elevations to changes in climate reveals how ecosystem responses to climate change will be spatially variable.