bluuebunny/crossref_metadata_2025_split huggingface dataset:
EPR Studies of the Binding Properties, Guest Dynamics, and Inner‐Space Dimensions of a Water‐Soluble Resorcinarene Capsule
Authors: Ayhan Mehmet Menaf , Casano Gilles , Karoui Hakim , Rockenbauer Antal , Monnier Valérie , Hardy Micaël , Tordo Paul , Bardelang David , Ouari Olivier 
Published: September 2015

AbstractNitroxide free radicals have been used to study the inner space of one of Rebek’s water‐soluble capsules. EPR and 1H NMR spectroscopy, ESI‐MS, and DFT calculations showed a preference for the formation of 1:2 complexes. EPR titrations allowed us to determine binding constants (Ka) in the order of 107 M−2. EPR spectral‐shape analysis provided information on the guest rotational dynamics within the capsule. The interplay between optimum hydrogen bonding upon capsule formation and steric strain for guest accommodation highlights some degree of flexibility for guest inclusion, particularly at the center of the capsule where the hydrogen bond seam can be barely distorted or slightly disturbed.
Molecular Cobalt Clusters as Precursors of Distinct Active Species in Electrochemical, Photochemical, and Photoelectrochemical Water Oxidation Reactions in Phosphate Electrolytes
Authors: Li Xiaobo , Clatworthy Edwin B. , Masters Anthony F. , Maschmeyer Thomas 
Published: September 2015

AbstractThree cobalt model molecular compounds, Co‐cubane ([Co4(µ3‐O)4(µ‐OAc)4py4]), Co‐trimer ([Co3(μ3‐O)(µ‐OAc)6py3]PF6), and Co‐dimer ([Co2(μ‐OH)2(µ‐OAc)(OAc)2py4]PF6), are investigated as water oxidation reaction (WOR) catalysts, using electrochemical, photochemical, and photoelectrochemical methodologies in phosphate electrolyte. The actual species contributing to the catalytic activity observed in the WOR are derived from the transformation of these cobalt compounds. The catalytic activity observed is highly dependent on the initial compound structure and on the particular WOR methodology used. Co‐cubane shows no activity in the electrochemical WOR and negligible activity in the photochemical WOR, but is active in the photoelectrochemical WOR, in which it behaves as a precursor to catalytically active species. Co‐dimer also shows no activity in the electrochemical WOR, but behaves as a precursor to catalytically active species in both the photochemical and photoelectrochemical WOR experiments. Co‐trimer behaves as a precursor to catalytically active species in all three of the WOR methodologies.
Synthesis, Properties, and π‐Dimer Formation of Oligothiophenes Partially Bearing Orthogonally Fused Fluorene Units
Authors: Ie Yutaka , Okamoto Yuji , Tone Saori , Aso Yoshio 
Published: September 2015

AbstractA series of oligothiophenes that incorporate cyclopenta[c]thiophene‐based units bearing spiro‐substituted dialkylfluorene was synthesized. Photophysical measurements indicated that there was no interruption in the conjugation along the oligothiophene backbones, irrespective of the number or position of this unit. Electrochemical measurements showed that the thiophene 7‐mers and 11‐mer exhibit reversible multi‐oxidation waves. The formation of cationic species was clearly observed from UV/Vis/NIR measurements. Furthermore, the UV/Vis/NIR spectra at 223 K under one‐electron oxidation conditions revealed that the unsubstituted thiophene or bithiophene units remained in the absence of intermolecular π–π interactions, whereas the formation of π‐dimeric species was observed for the thiophene 7‐mer containing an unsubstituted terthiophene (U3) unit. Theoretical calculations indicated that the combination of the U3 unit and the all‐trans conformation decreased the intermolecular steric repulsion between the fused cyclopentene ring and its facing thiophene, which may contribute to the formation of the dimeric structure.
Human Serum Albumin Conjugated Nanoparticles for pH and Redox‐Responsive Delivery of a Prodrug of Cisplatin
Authors: Shi Hongdong , Cheng Qinqin , Yuan Siming , Ding Xin , Liu Yangzhong 
Published: September 2015

AbstractPlatinum anticancer drugs are particularly in need of controlled drug delivery because of their severe side effects. Platinum(IV) agents are designed as prodrugs to reduce the side effects of platinum(II) drugs; however, premature reduction could limit the effect as a prodrug. In this work, a highly biocompatible, pH and redox dual‐responsive delivery system is prepared by using hybrid nanoparticles of human serum albumin (HSA) and calcium phosphate (CaP) for the PtIV prodrug of cisplatin. This conjugate is very stable under extracellular conditions, so that it protects the platinum(IV) prodrug in HSA. Upon reaching the acidic and hypoxic environment, the platinum drug is released in its active form and is able to bind to the target DNA. The Pt–HSA/CaP hybrid inhibits the proliferation of various cancer cells more efficiently than cisplatin. Different cell cycle arrests suggest different cellular responses of the PtIV prodrug in the CaP nanocarrier. Interestingly, this delivery system demonstrates enhanced cytotoxicity to tumor cells, but not to normal cells.
Chiral Dawson‐Type Hybrid Polyoxometalate Catalyzes Enantioselective Diels–Alder Reactions
Authors: Xuan Wen‐Jing , Botuha Candice , Hasenknopf Bernold , Thorimbert Serge 
Published: September 2015

AbstractCan achiral organocatalysts linked to chiral polyanionic metal oxide clusters provide good selectivity in enantioselective CC bond formations? The answer to this question is investigated by developing a new active hybrid polyoxometalate‐based catalyst for asymmetric Diels–Alder reaction. Chirality transfer from the chiral anionic polyoxometalate to the covalently linked achiral imidazolidinone allows Diels–Alder cycloaddition products to be obtained with good yields and high enantioselectivities when using cyclopentadiene and acrylaldehydes as partners.
Mechanistic Study of a Photocatalyzed CS Bond Formation Involving Alkyl/Aryl Thiosulfate
Authors: Li Yiming , Xie Weisi , Jiang Xuefeng 
Published: September 2015

AbstractThis study presents thioether construction involving alkyl/aryl thiosulfates and diazonium salt catalyzed by visible‐light‐excited [Ru(bpy)3Cl2] at room temperature in 44–86 % yield. Electron paramagnetic resonance studies found that thiosulfate radical formation was promoted by K2CO3. Conversely, radicals generated from BnSH or BnSSBn (Bn=benzyl) were clearly suppressed, demonstrating the special property of thiosulfate in this system. Transient absorption spectra confirmed the electron‐transfer process between [Ru(bpy)3Cl2] and 4‐MeO‐phenyl diazonium salt, which occurred with a rate constant of 1.69×109 M−1 s−1. The corresponding radical trapping product was confirmed by X‐ray diffraction. The full reaction mechanism was determined together with emission quenching data. Furthermore, this system efficiently avoided the over‐oxidation of sulfide caused by H2O in the photoexcited system containing Ru2+. Both aryl and heteroaryl diazonium salts with various electronic properties were investigated for synthetic compatibility. Both alkyl‐ and aryl‐substituted thiosulfates could be used as substrates. Notably, pharmaceutical derivatives afforded late‐stage sulfuration smoothly under mild conditions.
Structurally Diverse π‐Extended Conjugated Polycarbo‐ and Heterocycles through Pd‐Catalyzed Autotandem Cascades
Authors: Barroso Raquel , Cabal María‐Paz , Badía‐Laiño Rosana , Valdés Carlos 
Published: September 2015

AbstractThe Pd‐catalyzed reaction between 2,2′‐dibromobiphenyls and related systems with tosylhydrazones gives rise to new π‐extended conjugated polycarbo‐ and heterocycles through an autotandem process involving a cross‐coupling reaction followed by an intramolecular Heck cyclization. The reaction shows wide scope regarding both coupling partners. Cyclic and acyclic tosylhydrazones can participate in the process. Additionally, a variety of aromatic and heteroaromatic dibromoderivatives have been employed, leading to an array of diverse scaffolds featuring a fluorene or acridine central nucleus, and containing binaphthyl, thiophene, benzothiophene and indole moieties. The application to appropriate tetrabrominated systems led to greater structural complexity through two consecutive autotandem cascades. The photophysical properties of selected compounds were studied through their absorption and emission spectra. Fluorescence molecules featuring very high quantum yields were identified, showing the potential of this methodology in the development of molecules with interesting optoelectronic properties.
Native Mannose‐Dominant Extraction by Pyridine–Phenol Alternating Oligomers Having an Extremely Efficient Repeating Motif of Hydrogen‐Bonding Acceptors and Donors
Authors: Ohishi Yuki , Abe Hajime , Inouye Masahiko 
Published: September 2015

AbstractPyridine–phenol alternating oligomers in which pyridine and phenol moieties are alternatingly linked through acetylene bonds at the 2,6‐positions of the aromatic rings were designed and synthesized. The pyridine nitrogen atom and the neighboring phenolic hydroxyl group were oriented so that they do not form an intramolecular hydrogen bond but cooperatively act as hydrogen‐bonding acceptor and donor in a push–pull fashion for the hydroxyl group of saccharides. The longer oligomer strongly bound to lipophilic glycosides in 1,2‐dichloroethane, and association constants approached 108 M−1. Moreover, the oligomer extracted native saccharides from a solid phase to apolar organic solvents up to the extent of an equal amount of the oligomer and showed mannose‐dominant extraction among naturally abundant hexoses. The oligomer bound to native saccharides even in 20 % DMSO‐containing 1,2‐dichloroethane and exhibited association constants of greater than 10 M−1 for D‐mannose and D‐glucose.
Stereo‐ and Chemodivergent NHC‐Promoted Functionalisation of Arylalkylketenes with Chloral
Authors: Douglas James J. , Churchill Gwydion , Slawin Alexandra M. Z. , Fox David J. , Smith Andrew D. 
Published: September 2015

AbstractStereo‐ and chemodivergent enantioselective reaction pathways are observed upon treatment of alkylarylketenes and trichloroacetaldehyde (chloral) with N‐heterocyclic carbenes, giving selectively either β‐lactones (up to 88:12 dr, up to 94 % ee) or α‐chloroesters (up to 94 % ee). Either 2‐arylsubstitution or an α‐branched iPr alkyl substituent within the ketene favours the chlorination pathway, allowing chloral to be used as an electrophilic chlorinating reagent in asymmetric catalysis.
Palladium‐Catalyzed Carbonylative Cyclization of Arenes by CH Bond Activation with DMF as the Carbonyl Source
Authors: Chen Jianbin , Feng Jian‐Bo , Natte Kishore , Wu Xiao‐Feng 
Published: September 2015

AbstractA novel palladium‐catalyzed CO‐gas‐ and autoclave‐free protocol for the synthesis of 11H‐pyrido[2,1‐b]quinazolin‐11‐ones has been developed. Quinazolinones, which are omnipresent motif in many pharmaceuticals and agrochemicals, were prepared in good yields by CH bond activation and annulation using DMF as the CO surrogate. A 13CO‐labelled DMF control experiment demonstrated that CO gas was released from the carbonyl of DMF with acid as the promotor. The kinetic isotope effect (KIE) value indicated that the CH activation step may not be involved in the rate‐determining step. This methodology is operationally simple and showed a broad substrate scope with good to excellent yields.
Facile, Catalytic Dehydrocoupling of Phosphines Using β‐Diketiminate Iron(II) Complexes
Authors: King Andrew K. , Buchard Antoine , Mahon Mary F. , Webster Ruth L. 
Published: September 2015

AbstractCatalytic dehydrocoupling of primary and secondary phosphines has been achieved for the first time using an iron pre‐catalyst. The reaction proceeds under mild reaction conditions and is successful with a range of diarylphosphines. A proton acceptor is not needed for the transformation to take place, but addition of 1‐hexene does allow for turnover at 50 °C. The catalytic system developed also facilitates the dehydrocoupling of phenylphosphane and dicyclohexylphosphane. A change in solvent switches off dehydrocoupling to allow hydrophosphination of alkenes.
Large Hexadecametallic {MnIII–LnIII} Wheels: Synthesis, Structural, Magnetic, and Theoretical Characterization
Authors: Vignesh Kuduva R. , Langley Stuart K. , Moubaraki Boujemaa , Murray Keith S. , Rajaraman Gopalan 
Published: September 2015

AbstractThe synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {MnIII8LnIII8} (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2, in the presence of ortho‐toluic or benzoic acid are reported. From the seven wheels studied the {Mn8Dy8} and {Mn8Y8} analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8Y8} complex due to weak ferromagnetic MnIII–MnIII interactions. Ab initio CASSCF+RASSI‐SO calculations on the {Mn8Dy8} wheel estimated the MnIII–DyIII exchange interaction as −0.1 cm−1. This weak exchange along with unfavorable single‐ion anisotropy of DyIII/MnIII ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g‐anisotropy of the DyIII ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8Ln8} clusters reported here are the largest heterometallic MnIIILnIII wheels and the largest {3d–4f} wheels to exhibit SMM behavior reported to date.
Cobalt(III)‐Catalyzed Dehydrative [4+2] Annulation of Oxime with Alkyne by CH and NOH Activation
Authors: Sen Malay , Kalsi Deepti , Sundararaju Basker 
Published: September 2015

AbstractEfficient, scalable cobalt‐catalyzed redox‐neutral [4+2] annulation of readily available oximes and alkyne is reported. The developed synthetic methodology is widely applicable and tolerates various functional groups including heterocycles. A stable Cp*CoIII neutral complex is employed as the catalyst for this redox‐neutral [4+2] annulation reaction, which progresses smoothly by way of a reversible cyclometallation without any external oxidizing agent, and produces only water as the side product.
Enantioselective Degradation Mechanism of Beta‐Cypermethrin in Soil From the Perspective of Functional Genes
Authors: Yang Zhong‐Hua , Ji Guo‐Dong 
Published: September 2015

AbstractThe behavior and mechanisms of the enantioselective degradation of beta‐cypermethrin were studied in soil. The four isomers were degraded at different rates, and the enantiomer fractions of alpha‐cypermethrin and theta‐cypermethrin exceeded 0.5. Moreover, 3‐phenoxybenzoic acid, phenol, and protocatechuic acid were detected; based on the presence of these metabolites, we predicted the degradation pathway and identified the functional genes that are related to this degradation process. We established quantitative relationships between the data on degradation kinetics and functional genes; we found that the quantitative relationships between different enantiomers differed even under the same conditions, and the genes pobA and pytH played key roles in limiting the degradation rate. Data obtained using path analysis revealed that the same gene had different direct and indirect effects on the degradation of different isomers. A mechanism was successfully proposed to explain the selective degradation of chiral compounds based on the perspective of functional genes. Chirality 27:929–935, 2015. © 2015 Wiley Periodicals, Inc.
Specialized survivor clinic attendance is associated with decreased rates of emergency department visits in adult survivors of childhood cancer
Authors: Sutradhar Rinku , Agha Mohammad , Pole Jason D. , Greenberg Mark , Guttmann Astrid , Hodgson David , Nathan Paul C. 
Published: September 2015

BACKGROUNDSurvivors of childhood cancer are at considerable risk of experiencing treatment‐related adverse health outcomes. To provide survivors with specialized care focused on these risks during adulthood, the government of Ontario funded a provincial network of specialized survivor clinics in 1999. The aim of this study was to determine whether prior attendance at survivor clinics by adult survivors of childhood cancer was associated with rates of emergency department (ED) visits.METHODSThis was a population‐based, retrospective cohort study using multiple linked administrative health databases. The cohort consisted of all adult survivors of childhood cancer diagnosed between January 1, 1986 and December 31, 2005 in Ontario, Canada. A recurrent event regression model was used to evaluate the association between prior attendance at survivor clinics and the rate of ED visits; adjustments were made for individual, demographic, treatment, and provider characteristics.RESULTSThe study consisted of 3912 adult survivors of childhood cancer. Individuals who had at least 1 prior visit to a survivor clinic had a 19% decreased rate of ED visits in comparison with individuals who had not visited a survivor clinic (adjusted relative rate, 0.81; 95% confidence interval, 0.78‐0.85). Each additional prior visit to a survivor clinic was associated with a 5% decrease in the rate of ED visits (adjusted relative rate, 0.95; 95% confidence interval, 0.93‐0.96). These results were independent of whether or not survivors received care from a primary care physician.CONCLUSIONSAttendance at a specialized survivor clinic was significantly associated with decreased ED visits among adult survivors of childhood cancer. Cancer 2015;121:4389–97. © 2015 American Cancer Society.
Waste Tire Derived Carbon–Polymer Composite Paper as Pseudocapacitive Electrode with Long Cycle Life
Authors: Boota M. , Paranthaman M. Parans , Naskar Amit K. , Li Yunchao , Akato Kokouvi , Gogotsi Y. 
Published: September 2015

AbstractRecycling hazardous wastes to produce value‐added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2 g−1) is synthesized using waste tires as the precursor and used as a supercapacitor electrode material. The narrow pore‐size distribution and high surface area led to good charge storage capacity, especially when used as a three‐dimensional nanoscaffold to polymerize polyaniline (PANI). The composite paper was highly flexible, conductive, and exhibited a capacitance of 480 F g−1 at 1 mV s−1 with excellent capacitance retention of up to 98 % after 10 000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating, and tight confinement of the PANI in the inner pores of the tire‐derived carbon through π–π interactions, which minimized the degradation of the PANI upon cycling. We anticipate that the same strategy can be applied to deposit other pseudocapacitive materials to achieve even higher electrochemical performance and longer cycle life—a key challenge for redox active polymers.
Release from belowground enemies and shifts in root traits as interrelated drivers of alien plant invasion success: a hypothesis
Authors: Dawson Wayne 
Published: September 2015

AbstractOur understanding of the interrelated mechanisms driving plant invasions, such as the interplay between enemy release and resource‐acquisition traits, is biased by an aboveground perspective. To address this bias, I hypothesize that plant release from belowground enemies (especially fungal pathogens) will give invasive plant species a fitness advantage in the alien range, via shifts in root traits (e.g., increased specific root length and branching intensity) that increase resource uptake and competitive ability compared to native species in the alien range, and compared to plants of the invader in its native range. Such root‐trait changes could be ecological or evolutionary in nature. I explain how shifts in root traits could occur as a consequence of enemy release and contribute to invasion success of alien plants, and how they could be interrelated with other potential belowground drivers of invasion success (allelopathy, mutualist enhancement). Finally, I outline the approaches that could be taken to test whether belowground enemy release results in increased competitive ability and nutrient uptake by invasive alien plants, via changes in root traits in the alien range.
Quantitative Analysis of Active Pharmaceutical Ingredients (APIs) Using a Potentiometric Electronic Tongue in a SIA Flow System
Authors: Wesoły M. , Cetó X. , del Valle M. , Ciosek P. , Wróblewski W. 
Published: September 2015

AbstractAn advanced potentiometric electronic tongue and Sequential Injection Analysis (SIA) measurement system was applied for the quantitative analysis of mixtures containing three active pharmaceutical ingredients (APIs): acetaminophen, ascorbic acid and acetylsalicylic acid, in the presence of various amounts of caffeine as interferent. The flow‐through sensor array was composed of miniaturized classical ion‐selective electrodes based on plasticized PVC membranes containing only ion exchangers. Partial Least Squares (PLS) analysis of the steady‐state sensor array responses, measured in API mixtures prepared by the SIA system permitted a correct quantitative analysis of acetylsalicylic acid and ascorbic acid. Further optimization using multiway PLS fed by dynamic responses without additional feature extraction did not improve significantly the resolution of acetaminophen. Lastly, the chemometric treatment, involving the extraction of dynamic components of the transient response employing the Wavelet transform, the removal of less‐significant coefficients by means of Causal Index pruning and training of an Artificial Neural Network (ANN) with the selected coefficients, allowed the simultaneous determination of all the three studied APIs, while counterbalancing any interference due to caffeine.
Voltammetric Lead Determination in Aviation Fuel Samples Using a Screen‐Printed Gold Electrode and Batch‐Injection Analysis
Authors: Almeida Eduardo S. , Richter Eduardo M. , Munoz Rodrigo A. A. 
Published: September 2015

AbstractThis work presents the lead determination in aviation (bio)fuels using disposable screen‐printed gold electrodes (SPGEs) adapted on a batch‐injection cell associated with a micropipette for portable analysis. The method involves injections of 200 µL of sample or standard solutions at controlled dispensing rate (4.8 µL s−1) during deposition step (−550 mV for 90 s), followed by anodic‐stripping voltammetry. Either samples treated by sonication or dry‐ashing can be analyzed with detection limits of 0.0071 and 0.0008 µg g−1 Pb, respectively. A single SPGE can be applied for 60 consecutive measurements (or 120 for samples dry‐ashed). The ultrasound‐assisted treatment is faster, safer, and easily adapted for on‐site analyses, especially considering the portable characteristics of commercially‐available potentiostats and batch‐injection analysis cell using SPGEs.
High‐Performance Hydrazine Sensor Based on Graphene Nano Platelets Supported Metal Nanoparticles
Authors: Liu Yi , Qiu Zhipeng , Wan Qijin , Wang Zhaohao , Wu Kangbing , Yang Nianjun 
Published: September 2015

AbstractSurface coating of graphene nano platelets with gold‐palladium nanoparticles (AuPd NPs) was conducted via potentiostatic electrodeposition from a mixture of HAuCl4 and H2PdCl4. AuPd NPs were characterized using SEM, TEM, XRD and energy dispersive X‐ray spectroscopy. The AuPd NPs with the diameter of about 30–60 nm were alloyed and well‐dispersed on the graphene surface. Electrochemistry of hydrazine on AuPd NPs was investigated using cyclic voltammetry and chronoamperometry, indicating high electrocatalytic ability of AuPd NPs towards oxidation of hydrazine. Under the optimized conditions, the oxidation current was linear to the hydrazine concentration in the range of 0.02–166.6 µM. The calculated detection limit was 5 nM (S/N=3).