bluuebunny/crossref_metadata_2025_split huggingface dataset:
Importance of the Reducing Agent in Direct Reductive Heck Reactions
Authors: Raoufmoghaddam Saeed , Mannathan Subramaniyan , Minnaard Adriaan J. , de Vries Johannes G. , de Bruin Bas , Reek Joost N. H. 
Published: September 2017

AbstractThe role of the reductant in the palladium N‐heterocyclic carbene (NHC) catalyzed reductive Heck reaction and its effect on the mechanism of the reaction is reported. For the first time in this type of transformation, the palladium‐NHC‐catalyzed reductive Heck reaction was shown to proceed in the presence of LiOMe and iPrOH even at 10 °C to give the products very efficiently in excellent yields and with exceptional chemoselectivities. This study shows that the reaction proceeds through two distinct mechanisms that depend on the nature of the reducing agent. In the presence of a protic solvent or acidic medium the reaction undergoes protonation to yield the reduced product, whereas in the absence of proton source, it proceeds through the insertion of the reductant followed by reductive elimination. The kinetic data reveal that the oxidative addition is the rate‐determining step in the reaction. The reaction profiles show first‐order kinetics in aryl iodide and Pd and zero‐order kinetics in LiOMe, benzylideneacetone, and the excess amount of NHC ligand. In addition, the reaction progress kinetic analysis shows that neither catalyst decomposition nor product inhibition occurs during the reaction. DFT calculations of the key steps confirm that the oxidative addition step is the rate‐determining step in the reaction. Deuterium‐labeling experiments indicate that the product is formed by the protonation of the Pd−Calkyl bond of the intermediate formed after enone insertion into the Pd−CAr bond. Application of chiral NHC ligands in the asymmetric reductive Heck reaction only results in poor enantioselectivities (enantiomeric excess up to 20 %) and is also substrate specific. DFT calculations suggest that the migration of the aryl group to the alkene of the substrate is the enantioselectivity‐determining step of the reaction. It is further shown that if the steric bulk at the enone is small (a methyl group), the two transition state barriers from [PdII(L2)(ArI)(enone)] species Cre and Csi, which have the re and si face of the enone substrate coordinated to Pd, are very similar, in line with the experimental results. With a slightly larger group (an isopropyl substituent) a significant difference in energy barriers is calculated (2.6 kcal mol−1), and in the experiment this product is formed with a modest enantiomeric excess (up to 20 %).
Support Interaction Effect of Platinum Nanoparticles on Non‐, Y‐, Ce‐Doped Anatase and Its Implication on the ORR in Acid and Alkaline Media
Authors: Estudillo‐Wong Luis Alberto , Ramos‐Sanchez Guadalupe , Calvillo Laura , Granozzi Gaetano , Alonso‐Vante Nicolas 
Published: September 2017

AbstractPlatinum nanoparticles (Pt NPs) were prepared by using the photo‐assisted method and supported onto oxide‐carbon composites synthesized through a modified sol‐gel route (M : TiO2‐C, with M=Y and Ce). The physicochemical properties of these materials were investigated by transmission electron microscopy (TEM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). Rietveld refinement was used to identify existing phases of electrocatalysts and to determine the crystallite size. Micro‐strain and intrinsic stacking fault increased and decreased, respectively, as a function of crystallite size. Molecular probing via CO‐stripping analyses assessed the selectively deposition of Pt NPs onto oxide domains of M : TiO2‐C (M=Y and Ce) supports. This phenomenon can be associated with the formation of the covalent bond at the heterojunction interface between Pt and oxide sites. As confirmed by DFT simulation, this phenomenon was related to the adsorption energy between Pt NPs and Y‐ or Ce‐doped TiO2. Turnover frequency evaluation revealed that, in acid medium, the strong Pt/oxide interaction promotes the oxygen reduction reaction activity by 1.7‐fold, as compared to alkaline medium.
Cooperative Adsorption by Porous Frameworks: Diffraction Experiment and Phenomenological Theory
Authors: Dovgaliuk Iurii , Nouar Farid , Serre Christian , Filinchuk Yaroslav , Chernyshov Dmitry 
Published: September 2017

AbstractMaterials science of metal open frameworks is a state‐of‐the‐art field for numerous applications, such as gas storage, sensors, and medicine. Two nanoporous frameworks, γ‐Mg(BH4)2 and MIL‐91(Ti), with different levels of structural flexibility, were examined with in situ X‐ray diffraction guest adsorption–desorption experiments. Both frameworks exhibit a cooperative guest adsorption correlated with a lattice deformation. This cooperativity originates from the long‐range interactions between guest molecules, mediated by elastic response of the host porous structure. The observed experimental scenarios are rationalized with a mean field Gorsky–Bragg–Williams (GBW) approach for the lattice‐gas Ising model. The adjusted GBW model, in combination with in situ synchrotron powder diffraction, demonstrates an efficient experimental and phenomenological approach to characterize thermodynamics of the adsorption in MOFs not only for the total uptake but also for every specific guest site.
Ratiometric Fluorescence Detection of Phosphorylated Amino Acids Through Excited‐State Proton Transfer by Using Molecularly Imprinted Polymer (MIP) Recognition Nanolayers
Authors: Wan Wei , Descalzo Ana B. , Shinde Sudhirkumar , Weißhoff Hardy , Orellana Guillermo , Sellergren Börje , Rurack Knut 
Published: September 2017

AbstractA 2,3‐diaminophenazine bis‐urea fluorescent probe monomer (1) was developed. It responds to phenylphosphate and phosphorylated amino acids in a ratiometric fashion with enhanced fluorescence accompanied by the development of a redshifted emission band arising from an excited‐state proton transfer (ESPT) process in the hydrogen‐bonded probe/analyte complex. The two urea groups of 1 form a cleft‐like binding pocket (Kb>1010 L2 mol−2 for 1:2 complex). Imprinting of 1 in presence of ethyl ester‐ and fluorenylmethyloxycarbonyl (Fmoc)‐protected phosphorylated tyrosine (Fmoc‐pTyr‐OEt) as the template, methacrylamide as co‐monomer, and ethyleneglycol dimethacrylate as cross‐linker gave few‐nanometer‐thick molecularly imprinted polymer (MIP) shells on silica core microparticles with excellent selectivity for the template in a buffered biphasic assay. The supramolecular recognition features were established by spectroscopic and NMR studies. Rational screening of co‐monomers and cross‐linkers allowed to single out the best performing MIP components, giving significant imprinting factors (IF>3.5) while retaining ESPT emission and the ratiometric response in the thin polymer shell. Combination of the bead‐based detection scheme with the phase‐transfer assay dramatically improved the IF to 15.9, allowing sensitive determination of the analyte directly in aqueous media.
Synthesis and Magnetic Properties of Trioxytriphenylamine Dimers in their Di(radical cationic) States
Authors: Suzuki Shuichi , Tanaka Nobuaki , Kozaki Masatoshi , Shiomi Daisuke , Sato Kazunobu , Takui Takeji , Okada Keiji 
Published: September 2017

AbstractThree structural isomers of trioxytriphenylamine (TOT) dimers, 4,4′′′‐bis(2,2′:6′,2“:6”,6‐trioxytriphenylamine) (4), 3,3′′′‐bis(2,2′:6′,2“:6”,6‐trioxytriphenylamine) (5), and 3,4′′′‐bis(2,2′:6′,2“:6”,6‐trioxytriphenylamine) (6), have been prepared and their electronic and magnetic properties in their di(radical cationic) states have been investigated. These di(radical cationic) species can be handled under ambient conditions because of their high stability under aerated conditions even in solution. The X‐ray crystal structure analysis demonstrated that the TOT moieties of all the di(radical cation)s have planar structures similar to that of the parent TOT radical cation 3+. The UV/Vis spectra of the di(radical cation)s show characteristic absorptions depending on the connecting pattern. Thus, in the long‐wavelength region (600–900 nm), 42+ exhibits strong and broad characteristic absorptions, whereas compounds 52+ and 62+ exhibit weak absorptions. Notably, in the 450–600 nm region, 52+ displays very similar absorptions (with twice the intensity) to 3+, whereas small differences were observed for 62+. Finally, we investigated in detail the magnetic properties of the corresponding di(radical cation)s by electron spin resonance spectroscopy and magnetic susceptibility measurements, which indicated intramolecular exchange interactions with a singlet ground state and a large singlet–triplet (S–T) gap for 42+, a singlet ground state and a small S–T gap for 52+, and a triplet ground state for 62+.
Formation of Palladium η2‐Bound Chalcogenoketones across a Pd+−C− Bond
Authors: Rothstein Patrick E. , Comanescu Cezar C. , Iluc Vlad M. 
Published: September 2017

AbstractA series of chalcogen analogues encompassing a ketone and chalcogenoketones [{PC(=E)P}Pd(PMe3)] (E=O, S, Se, Te) was generated from a nucleophilic palladium carbene compound, [{PC(sp2)P}Pd(PMe3)] ([PC(sp3)HP]=bis[2‐(diisopropylphosphino)‐phenyl]methyl, iPr2P‐C6H4‐CH‐C6H4‐PiPr2). The thio‐, seleno‐, and telluroketone were all synthesized by means of an atom transfer from the respective chalcogens. The ketone analogue, however, required the use of nitrobenzene or nitrosobenzene as the oxygen‐atom transfer agent.
The 1,6,7,12‐Tetraazaperylene Bridging Ligand as an Electron Reservoir and Its Disulfonato Derivative as Redox Mediator in an Enzyme–Electrode Process
Authors: Brietzke Thomas , Dietz Thomas , Kelling Alexandra , Schilde Uwe , Bois Julianae , Kelm Harald , Reh Manuel , Schmitz Markus , Körzdörfer Thomas , Leimkühler Silke , Wollenberger Ulla , Krüger Hans‐Jörg , Holdt Hans‐Jürgen 
Published: September 2017

AbstractThe homodinuclear ruthenium(II) complex [{Ru(l‐N4Me2)}2(μ‐tape)](PF6)4 {[1](PF6)4} (l‐N4Me2=N,N′‐dimethyl‐2,11‐diaza[3.3](2,6)‐pyridinophane, tape=1,6,7,12‐tetraazaperylene) can store one or two electrons in the energetically low‐lying π* orbital of the bridging ligand tape. The corresponding singly and doubly reduced complexes [{Ru(l‐N4Me2)}2(μ‐tape.−)](PF6)3 {[2](PF6)3} and [{Ru(l‐N4Me2)}2(μ‐tape2−)](PF6)2 {[3](PF6)2}, respectively, were electrochemically generated, successfully isolated and fully characterized by single‐crystal X‐ray crystallography, spectroscopic methods and magnetic susceptibility measurements. The singly reduced complex [2](PF6)3 contains the π‐radical tape.− and the doubly reduced [3](PF6)2 the diamagnetic dianion tape2− as bridging ligand, respectively. Nucleophilic aromatic substitution at the bridging tape in [1]4+ by two sulfite units gave the complex [{Ru(l‐N4Me2)}2{μ‐tape‐(SO3)2}]2+ ([4]2+). Complex dication [4]2+ was exploited as a redox mediator between an anaerobic homogenous reaction solution of an enzyme system (sulfite/sulfite oxidase) and the electrode via participation of the low‐energy π*‐orbital of the disulfonato‐substituted bridging ligand tape–(SO3)22− (Ered1=−0.1 V versus Ag/AgCl/1 m KCl in water).
Multi‐wavelength excitation method for measuring FWA‐treated paper
Authors: Imura Kenji , Nagai Yoshiroh 
Published: September 2017

AbstractColorimetric properties of fluorescent materials depend on the SPD of the illumination. That is why most standards for evaluating them specify the illuminations, which are often hard‐to‐realize daylight illuminants. The presented method using commercially available LEDs enables accurate enough colorimetric measurements of FWA‐treated papers or prints on them illuminated by the specified illuminant. The total spectral radiance factor of a fluorescent specimen, from which most colorimetric values are derived, consists of the luminescent spectral radiance factor and the spectral reflectance factor. This method separately estimates those of FWA‐treated paper to add up to the total spectral radiance factor. The luminescent spectral radiance factor is obtained by estimating the SPD of luminescence excited by the specified illuminant as the weighted sum of the multiple SPDs of luminescence excited by the respective narrow band LED emissions at different wavelengths. The LEDs and their weights are determined optimally for generally used papers. The spectral reflectance factor is derived from the estimated SPD of the radiation with fluorescence excluded from the paper illuminated by visible illumination. The method was applied with five different illumination systems each using two or three narrow band LEDs in the excitation range. They were evaluated by measuring the total spectral radiance factors by D50 of seven FWA‐treated papers and CMYK prints on four papers. The derived colorimetric values were compared to the respective references by the ideal D50.
High Photoluminescence Quantum Yields in Organic Semiconductor–Perovskite Composite Thin Films
Authors: Longo Giulia , La‐Placa Maria‐Grazia , Sessolo Michele , Bolink Henk J. 
Published: September 2017

AbstractOne of the obstacles towards efficient radiative recombination in hybrid perovskites is a low exciton binding energy, typically in the orders of tens of meV. It has been shown that the use of electron‐donor additives can lead to a substantial reduction of the non‐radiative recombination in perovskite films. Herein, the approach using small molecules with semiconducting properties, which are candidates to be implemented in future optoelectronic devices, is presented. In particular, highly luminescent perovskite–organic semiconductor composite thin films have been developed, which can be processed from solution in a simple coating step. By tuning the relative concentration of methylammonium lead bromide (MAPbBr3) and 9,9spirobifluoren‐2‐yl‐diphenyl‐phosphine oxide (SPPO1), it is possible to achieve photoluminescent quantum yields (PLQYs) as high as 85 %. This is attributed to the dual functions of SPPO1 that limit the grain growth while passivating the perovskite surface. The electroluminescence of these materials was investigated by fabricating multilayer LEDs, where charge injection and transport was found to be severely hindered for the perovskite/SPPO1 material. This was alleviated by partially substituting SPPO1 with a hole‐transporting material, 1,3‐bis(N‐carbazolyl)benzene (mCP), leading to bright electroluminescence. The potential of combining perovskite and organic semiconductors to prepare materials with improved properties opens new avenues for the preparation of simple lightemitting devices using perovskites as the emitter.
Modulating Crystallinity of Graphitic Carbon Nitride for Photocatalytic Oxidation of Alcohols
Authors: Zhou Min , Yang Pengju , Yuan Rusheng , Asiri Abdullah M. , Wakeel Muhammad , Wang Xinchen 
Published: September 2017

AbstractExploiting efficient photocatalysts with strengthened structure for solar‐driven alcohol oxidation is of great significance. The photocatalytic performance of graphitic carbon nitrides can be considerably promoted by modulating its crystallinity. Results confirmed that a high crystallinity accelerates the separation and transfer of photogenerated charge carriers, thus providing more free charges for photoredox reactions. More importantly, the high crystallinity facilitated the adsorption of benzyl alcohol and desorption of benzaldehyde and simultaneously lowered the energy barrier for O2 activation. As a result, the crystalline carbon nitride exhibited a roughly twelvefold promotion with respect to the normal carbon nitride. The remarkable enhancement of activity can be attributed to the synergistic effects of increased electron–hole separation and increased surface reaction kinetics. These findings will open up new opportunities to modulate the structure of polymers for a wide variety of organic reactions.
Climatically forced moisture supply, sediment flux and pedogenesis in Miocene mudflat deposits of south‐east Kazakhstan, Central Asia
Authors: Voigt Silke , Weber Yuki , Frisch Konstantin , Bartenstein Alexander , Hellwig Alexandra , Petschick Rainer , Bahr André , Pross Jörg , Koutsodendris Andreas , Voigt Thomas , Verestek Verena , Appel Erwin 
Published: September 2017

AbstractThe continental settings of Central Asia witnessed increased desertification during the Cenozoic as a result of mountain uplift and the Paratethys retreat. The interaction of these tectonic‐scale processes with orbitally forced climate change and their influence on Asia's atmospheric moisture distribution are poorly constrained. A Miocene succession of continental mudflat deposits, exposed in the Aktau Mountains (Ili Basin, south‐east Kazakhstan), has great potential as a terrestrial palaeoclimate archive. About 90 m of the 1700 m thick succession comprise alluvial mudflat deposits and appear as cyclic alternation of coarse sheet floods, mudflat fines and semi‐arid hydromorphic soils. In this study, bulk‐sediment mineralogy and geochemistry, magnetic susceptibility, sediment colour and palynology are used to reconstruct environmental conditions by determining changes and forcing mechanisms in the intensity of sediment discharge, weathering and pedogenesis. The results presented here indicate four major periods of arid soil formation and one palustrine interval characterized by higher evaporation rates under highly alkaline/saline conditions. A positive correlation between weathering indices and the Mg/Al ratio suggest that these horizons correspond to maximum rates of evapotranspiration and aridity. The formation of mudflat fines is, instead, interpreted as representing higher detrital sediment production by more intense alluvial fan activity during times of higher precipitation. Time series analysis of weathering indices, colour and magnetic susceptibility data yields cycle‐to‐frequency ratios with the potential to represent Milankovitch cyclicity with short and long eccentricity as dominant periodicities. Periods of pronounced aridity, paced by long eccentricity forcing, reflect changes in moisture availability. On longer tectonic timescales, the persistent appearance of gypsum indicates a shift towards more arid conditions. This trend in climate is considered to result from the closure of the eastern gateway of the Mediterranean to the Indian Ocean that restricted circulation and enhanced salinity within the Eastern Paratethys.
Genetic variation of a foundation rockweed species affects associated communities
Authors: Jormalainen Veijo , Danelli Maria , Gagnon Karine , Hillebrand Helmut , Rothäusler Eva , Salminen Juha‐Pekka , Sjöroos Joakim 
Published: September 2017

AbstractGenetic variation in a foundation species may affect the composition of associated communities as well as modify ecosystem function. While the ecological consequences of genetic diversity of foundation species have been widely reported, the ability of individual genotypes to support dissimilar communities has been documented only in forest ecosystems. Here, for the first time in a marine ecosystem, we test whether the different genotypes of the rockweedFucus vesiculosusharbor distinct community phenotypes and whether the genetic similarity of individual genotypes or their defensive compound content can explain the variation of the associated communities. We reared replicated genotypes in a common garden in the sea and analyzed their associated communities of periphytic algae and invertebrates as well as determined their contents of defense compounds, phlorotannins, and genetic distance based on neutral molecular markers. The periphytic community was abundant in mid‐summer and its biovolume, diversity and community composition varied among the rockweed genotypes. The diversity of the periphytic community decreased with its increasing biovolume. In autumn, when grazers were abundant, periphytic community biomass was lower and less variable among rockweed genotypes, indicating different relative importance of bottom‐up regulation through heritable variation of the foundation species and top‐down regulation through grazing intensity. Similarly, composition of the invertebrate community varied among the rockweed genotypes. Although the genotype explained about 10–18% of the variation in associated communities, the variation was explained neither by the genetic distance nor the phlorotannin content. Thus, neither neutral genetic markers nor a single phenotypic trait could provide a mechanistic understanding of the genetic basis of community specificity. Therefore, a more comprehensive mapping of quantitative trait variation is needed to understand the underlying mechanisms. The community specificity implies that genetic variation within a foundation species is crucial for the biodiversity and assembly of associated organisms and, thus, for the functioning of associated communities. The result highlights the importance of ensuring the genetic variation of foundation species as a conservation target.
Validating the semantic misattribution procedure as an implicit measure of gender stereotyping
Authors: Ye Yang , Gawronski Bertram 
Published: September 2017

AbstractThe current research tested the validity of the semantic misattribution procedure (SMP)—a variant of the affect misattribution procedure—as an implicit measure of gender stereotyping. In three studies (N = 604), prime words of gender‐stereotypical occupations (e.g., nurse, doctor) influenced participants' guesses of whether unknown Chinese ideographs referred to male or female names in a stereotype‐congruent manner. Priming scores of gender stereotyping showed high internal consistency and construct‐valid correlations with explicit measures of sexism. Discriminant validity of gender stereotyping scores was tested by investigating relations with priming effects involving grammatical gender (e.g., mother, father). Evidence for discriminant validity was obtained when (1) trials from the two priming measures were presented in a blocked rather than interspersed manner and (2) the measure of stereotypical gender priming preceded the measure of grammatical gender priming. Overall, the SMP showed good psychometric properties and construct validity for the assessment of gender stereotyping.
Voltammetric Determination of Captopril on a Glassy Carbon Electrode Modified with Copper Metal‐organic Framework
Authors: Silva Vasconcelos Wellyton , da Silva Gilvaldo Gentil , Alves Junior Severino , dos Anjos Janaína Versiani , da Cunha Areias Madalena Carneiro 
Published: September 2017

AbstractWe report in this work, a new method for the determination of captopril by differential pulse voltammetry using a glassy carbon electrode modified with a copper metal‐organic framework (H‐Kust‐1 or Cu3(BTC)2 or Cu‐BTC), immobilized on the surface by a copolymer of acrylamide and sodium acrylate. This compound is detected by the formation of a copper(II)‐captopril complex that is observed in an oxidation potential at ca. +0.28 V vs. Ag/AgCl. A linear dynamic range is obtained for a captopril concentration of 0.5 μM to 7.0 μM and the voltammetric response is highly reproducible within 3.52 % error. The sensitivity of 9.71±0.37 nA μM−1 and the limit of detection of 0.20±0.01 μM make this methodology highly applicable for practical applications. The determination of captopril in a commercial pharmaceutical sample showed a recovery of 93.3 %.