bluuebunny/crossref_metadata_2025_split huggingface dataset:
Remarkable Solvent, Porphyrin Ligand, and Substrate Effects on Participation of Multiple Active Oxidants in Manganese(III) Porphyrin Catalyzed Oxidation Reactions
Authors: Hyun Min Young , Jo Young Dan , Lee Jun Ho , Lee Hong Gyu , Park Hyun Min , Hwang In Hong , Kim Kyeong Beom , Lee Suk Joong , Kim Cheal 
Published: November 2012

AbstractThe participation of multiple active oxidants generated from the reactions of two manganese(III) porphyrin complexes containing electron‐withdrawing and ‐donating substituents with peroxyphenylacetic acid (PPAA) as a mechanistic probe was studied by carrying out catalytic oxidations of cyclohexene, 1‐octene, and ethylbenzene in various solvent systems, namely, toluene, CH2Cl2, CH3CN, and H2O/CH3CN (1:4). With an increase in the concentration of the easy‐to‐oxidize substrate cyclohexene in the presence of [(TMP)MnCl] (1 a) with electron‐donating substituents, the ratio of heterolysis to homolysis increased gradually in all solvent systems, suggesting that [(TMP)MnOOC(O)R] species 2 a is the major active species. When the substrate was changed from the easy‐to‐oxidize one (cyclohexene) to difficult‐to‐oxidize ones (1‐octene and ethylbenzene), the ratio of heterolysis to homolysis increased a little or did not change. [(F20TPP)MnOOC(O)R] species 2 b generated from the reaction of [(F20TPP)MnCl] (1 b) with electron‐withdrawing substituents and PPAA also gradually becomes involved in olefin epoxidation (although to a much lesser degree than with [(TMP)MnOOR] 2 a) depending on the concentration of the easy‐to‐oxidize substrate cyclohexene in all aprotic solvent systems except for CH3CN, whereas MnVO species is the major active oxidant in the protic solvent system. With difficult‐to‐oxidize substrates, the ratio of heterolysis to homolysis did not vary except for 1‐octene in toluene, indicating that a MnVO intermediate generated from the heterolytic cleavage of 2 b becomes a major reactive species. We also studied the competitive epoxidations of cis‐2‐octene and trans‐2‐octene with two manganese(III) porphyrin complexes by meta‐chloroperbenzoic acid (MCPBA) in various solvents under catalytic reaction conditions. The ratios of cis‐ to trans‐2‐octene oxide formed in the reactions of MCPBA varied depending on the substrate concentration, further supporting the contention that the reactions of manganese porphyrin complexes with peracids generate multiple reactive oxidizing intermediates.
Comparative Electrochemical and Photophysical Studies of Tetrathiafulvalene‐Annulated Porphyrins and Their ZnII Complexes: The Effect of Metalation and Structural Variation
Authors: Jana Atanu , Ishida Masatoshi , Kwak Kyuju , Sung Young Mo , Kim Dong Sub , Lynch Vincent M. , Lee Dongil , Kim Dongho , Sessler Jonathan L. 
Published: November 2012

AbstractA series of tetrathiafulvalene (TTF)‐annulated porphyrins, and their corresponding ZnII complexes, have been synthesized. Detailed electrochemical, photophysical, and theoretical studies reveal the effects of intramolecular charge‐transfer transitions that originate from the TTF fragments to the macrocyclic core. The incremental synthetic addition of TTF moieties to the porphyrin core makes the species more susceptible to these charge‐transfer (CT) effects as evidenced by spectroscopic studies. On the other hand, regular positive shifts in the reduction signals are seen in the square‐wave voltammograms as the number of TTF subunits increases. Structural studies that involve the tetrakis‐substituted TTF–porphyrin (both free‐base and ZnII complex) reveal only modest deviations from planarity. The effect of TTF substitution is thus ascribed to electronic overlap between annulated TTF subunits rather than steric effects. The directly linked thiafulvalene subunits function as both π acceptors as well as σ donors. Whereas σ donation accounts for the substituent‐dependent charge‐transfer transitions, it is the π‐acceptor nature of the appended tetrathiafulvalene groups that dominates the redox chemistry. Interactions between the subunits are also reflected in the square‐wave voltammograms. In the case of the free‐base derivatives that bear multiple TTF subunits, the neighboring TTF units, as well as the TTF⋅+ generated through one‐electron oxidation, can interact with each other; this gives rise to multiple signals in the square‐wave voltammograms. On the other hand, after metalation, the electronic communication between the separate TTF moieties becomes restricted and they act as separate redox centers under conditions of oxidation. Thus only two signals, which correspond to TTF.+ and TTF2+, are observed. The reduction potentials are also seen to shift towards more negative values after metalation, a finding that is considered to reflect an increased HOMO–LUMO gap. To probe the excited‐state dynamics and internal CT character, transient absorption spectral studies were performed. These analyses revealed that all the TTF–porphyrins of this study display relatively short excited‐state lifetimes, which range from 1 to 20 ps. This reflects a very fast decay to the ground state and is consistent with the proposed intramolecular charge‐transfer effects inferred from the ground‐state studies. Complementary DFT calculations provide a mechanistic rationale for the electron flow within the TTF–porphyrins and support the proposed intramolecular charge‐transfer interactions and π‐acceptor effects.
Rapid, General Synthesis of PdPt Bimetallic Alloy Nanosponges and Their Enhanced Catalytic Performance for Ethanol/Methanol Electrooxidation in an Alkaline Medium
Authors: Zhu Chengzhou , Guo Shaojun , Dong Shaojun 
Published: November 2012

AbstractWe have demonstrated a rapid and general strategy to synthesize novel three‐dimensional PdPt bimetallic alloy nanosponges in the absence of a capping agent. Significantly, the as‐prepared PdPt bimetallic alloy nanosponges exhibited greatly enhanced activity and stability towards ethanol/methanol electrooxidation in an alkaline medium, which demonstrates the potential of applying these PdPt bimetallic alloy nanosponges as effective electrocatalysts for direct alcohol fuel cells. In addition, this simple method has also been applied for the synthesis of AuPt, AuPd bimetallic, and AuPtPd trimetallic alloy nanosponges. The as‐synthesized three‐dimensional bimetallic/trimetallic alloy nanosponges, because of their convenient preparation, well‐defined sponge‐like network, large‐scale production, and high electrocatalytic performance for ethanol/methanol electrooxidation, may find promising potential applications in various fields, such as formic acid oxidation or oxygen reduction reactions, electrochemical sensors, and hydrogen‐gas sensors.
Using Two Simple Methods of ArArF Self‐Assembly and Isolation Chromophores to Further Improve the Comprehensive Performance of NLO Dendrimers
Authors: Wu Wenbo , Yu Gui , Liu Yunqi , Ye Cheng , Qin Jingui , Li Zhen 
Published: November 2012

AbstractHerein, through a combination of divergent and convergent approaches, coupled with the utilization of the powerful Sharpless “click chemistry” reaction, two series of high‐generation nonlinear optical (NLO) dendrimers have been conveniently prepared in high purity and satisfactory yields. Perfluoroaromatic rings and isolation chromophores were introduced to further improve their comprehensive performance. Thanks to the effects of ArArF self‐assembly and the isolation chromophores, coupled with perfect 3D spatial isolation from the highly branched structure of the dendrimer, G5‐PFPh‐NS displayed very large NLO efficiency (up to 257 pm V−1), which is, to the best of our knowledge, the new record highest value reported so far for simple azo chromophore moieties. High‐quality wide optical transparency and good stability were also achieved.
Chemical Adaptability: The Integration of Different Kinds of Matter into Giant Molecular Metal Oxides
Authors: Müller Achim , Merca Alice , Al‐Karawi Ahmed Jasim M. , Garai Somenath , Bögge Hartmut , Hou Guangfeng , Wu Lixin , Haupt Erhard T. K. , Rehder Dieter , Haso Fadi , Liu Tianbo 
Published: November 2012

AbstractUnique properties of the two giant wheel‐shaped molybdenum‐oxides of the type {Mo154}≡[{Mo2}{Mo8}{Mo1}]14 (1) and {Mo176}≡[{Mo2}{Mo8}{Mo1}]16 (2) that have the same building blocks either 14 or 16 times, respectively, are considered and show a “chemical adaptability” as a new phenomenon regarding the integration of a large number of appropriate cations and anions, for example, in form of the large “salt‐like” {M(SO4)}16 rings (M=K+, NH4+), while the two resulting {Mo146 (K(SO4))16} (3) and {Mo146 (NH4(SO4))16} (4) type hybrid compounds have the same shape as the parent ring structures. The chemical adaptability, which also allows the integration of anions and cations even at the same positions in the {Mo4O6}‐type units of 1 and 2, is caused by easy changes in constitution by reorganisation and simultaneous release of (some) building blocks (one example: two opposite orientations of the same functional groups, that is, of H2O{MoO} (I) and O{Mo(H2O)} (II) are possible). Whereas Cu2+ in [(H4CuII5)MoV28MoVI114O432(H2O)58]26− (5 a) is simply coordinated to two parent O2− ions of {Mo4O6} and to two fragments of type II, the SO42− integration in 3 and 4 occurs through the substitution of two oxo ligands of {Mo4O6} as well as two H2O ligands of fragment I. Complexes 3 and now 4 were characterised by different physical methods, for example, solutions of 4 in DMSO with sophisticated NMR spectroscopy (EXSY, DOSY and HSQC). The NH4+ ions integrated in the cluster anion of 4 “communicate” with those in solution in the sense that the related H+ ion exchange is in equilibrium. The important message: the reported “chemical adaptability” has its formal counterpart in solutions of “molybdates”, which can form unique dynamic libraries containing constituents/building blocks that may form and break reversibly and can lead to the isolation of a variety of giant clusters with unusual properties.
Superacidic or Not…︁? Synthesis, Characterisation, and Acidity of the Room‐Temperature Ionic Liquid [C(CH3)3]+ [Al2Br7]−
Authors: Scholz Franziska , Himmel Daniel , Scherer Harald , Krossing Ingo 
Published: November 2012

AbstractThe room‐temperature ionic liquid (RT‐IL) [C(CH3)3]+ [Al2Br7]− (m.p. 2 °C) was generated by bromide abstraction from tert‐butyl bromide with the Lewis acid aluminum bromide in the absence of solvent. The crystal structure of the tert‐butyl cation salt was determined by X‐ray diffraction. NMR, IR, and Raman spectroscopy, as well as quantum‐chemical and thermodynamic calculations, confirm the composition of this RT‐IL. Thus, one may consider this RT‐IL to be a readily accessible (and on a large scale) cationic Brønsted acid (protonated isobutene) with the potential for further reactivity. Based on the new absolute Brønsted acidity scale, we calculated an absolute pHabs value of 171 for liquid bulk [C(CH3)3]+ [Al2Br7]−. This value is about as acidic as 100 % sulfuric acid (pHabs=171) and, thus, on the edge of superacidity.
Heteroleptic [n]Chromoarenophanes: ansa Complexes Derived from [Cr(η5‐C5H5)(η6‐C6H6)]
Authors: Braunschweig Holger , Breher Frank , Capper Sabrina , Dück Klaus , Fuß Marco , Jimenez‐Halla J. Oscar C. , Krummenacher Ivo , Kupfer Thomas , Nied Dominik , Radacki Krzysztof 
Published: November 2012

AbstractThe synthesis of ansa complexes has been studied intensively owing to their importance as homogeneous catalysts and as precursors of metal‐containing polymers. However, paramagnetic non‐metallocene derivatives are rare and have been limited to examples with vanadium and titanium. Herein, we report an efficient procedure for the selective dilithiation of paramagnetic sandwich complex [Cr(η5‐C5H5)(η6‐C6H6)], which allows the preparation of a series of [n]chromoarenophanes (n=1, 2, 3) that feature silicon, germanium, and tin atoms at the bridging positions. The electronic and structural properties of these complexes were probed by X‐ray diffraction analysis, cyclic voltammetry, and by UV/Vis and EPR spectroscopy. The spectroscopic parameters for the strained and less strained complexes (i.e., with multiple‐atom linkers) indicate that the unpaired electron resides primarily in a d orbital on chromium(I); this result was also supported by density functional theory (DFT) calculations. We did not observe a correlation between the experimental UV/Vis and EPR data and the degree of molecular distortion in these ansa complexes. The treatment of tin‐bridged complex [Cr(η5‐C5H4)(η6‐C6H5)SntBu2] with [Pt(PEt3)3] results in the non‐regioselective insertion of the low‐valent Pt0 fragment into the CipsoSn bonds in both the five‐ and six‐membered rings, thereby furnishing a bimetallic complex. This observed reactivity suggests that ansa complexes of this type are promising starting materials for the synthesis of bimetallic complexes in general and also underline their potential to undergo ring‐opening processes to yield new metal‐containing polymers.
Novel Electrochemical Method for the Characterization of the Degree of Chirality in Chiral Polyaniline
Authors: Feng Zhang , Li Ma , Yan Yang , Jihai Tang , Xiao Li , Wanglin Li 
Published: November 2012

ABSTRACTA novel method to indicate the degree of chirality in polyaniline (PANI) was developed. The ( d‐camphorsulfonic acid)‐ and (HCl)‐PANI‐based electrodes exhibited significantly different electrochemical performances in d‐ and l‐Alanine (Ala) aqueous solution, respectively, which can be used for the characterization the optical activity of chiral PANI. Cyclic voltammogram, tafel, and open circuit potential of PANI‐based electrodes were measured within d‐ and l‐Ala electrolyte solution, respectively. The open circuit potentials under different reacting conditions were analyzed by Doblhofer model formula, in which [C+]poly1/[C+]poly2 was used as a parameter to characterize the degree of chirality in chiral PANI. The results showed that [C+]poly1/[C+]poly2 can be increased with increasing concentrations of (1S)‐(+)‐ and (1R)‐(−)‐10‐camphorsulfonic acid. In addition, we detected that appropriate response time and lower temperature are necessary to improve the degree of chirality. Chirality 25:39‐42, 2013.© 2012 Wiley Periodicals, Inc.
Coupling of Azomethine Ylides with Nitrilium Derivatives of closo‐Decaborate Clusters: A Synthetic and Theoretical Study
Authors: Mindich Aleksey L. , Bokach Nadezhda A. , Kuznetsov Maxim L. , Haukka Matti , Zhdanov Andrey P. , Zhizhin Konstantin Yu. , Miltsov Serguei A. , Kuznetsov Nikolay T. , Kukushkin Vadim Yu. 
Published: November 2012

AbstractThe azomethine ylides p‐R3C5H4N+CH−COC6H4R2‐p (3 a: R3=H, R2=H, X=Br; 3 b: R3=H, R2=Me, X=I; 3 c: R3=H, R2=OMe, X=I; 3 d: R3=H, R2=F, X=I; 3 e: R3=Me, R2=Me, X=Br) react with the nitrile functionality of the closo‐decaborate clusters [Bun4N][B10H9(NCR1)] (1 a: R1=Me; 1 b: R1=Et; 1 c: R1=Ph) in a CH3NO2 solution under mild conditions (20–25 °C, 2 min) to afford selectively products of the nucleophilic addition (ca. quantitative yields based on NMR analysis in [D6]DMSO, 71–87 % yield of isolated products). These products are the borylated enamino ketones as the salts bearing exclusively a tetrabutylammonium cation [Bun4N][B10H9{NCR1=C(N+C5H4R3‐p)COC6H4R2‐p}] (4 a–h,k–n) or the mixed salts [Bun4N]1‐x[p‐R3C5H4N+CH2COC6H4R2‐p]x[B10H9{NCR1=C(N+C5H4R3‐p)COC6H4R2‐p}] (4 i, 4 j, and 4 o). This reaction represents the first example of the selective nucleophilic addition of pyridinium azomethine ylides to the nitrile group and the first example of new CC bond formation in the reaction of nitrilium derivatives of boron clusters with any nucleophiles so far tested. Compounds 4 a–h,k–n were characterized by ICP‐MS, high resolution ESI‐MS, molar conductivity, and IR, 1H, 13C{1H}, and 11B{1H} NMR spectroscopy. The structures of 4 a and 4 b were determined by a single‐crystal X‐ray analysis. Theoretical calculations at the DFT level allowed the interpretation of the observed reaction selectivity, which is driven mostly by thermodynamic rather than kinetic factors, and steric repulsion between the boron cluster and the azomethine ylide molecule plays a crucial role. The activation of the nitrile group upon binding to the boron cluster is explained in terms of the electrostatic arguments. The mechanisms of the nucleophilic addition and the hypothetical cycloaddition between the azomethine ylide and nitriles were investigated in detail.
The challenges of statistical patterns of language: The case of Menzerath's law in genomes
Authors: Ferrer‐I‐Cancho Ramon , Forns Núria , Hernández‐Fernández Antoni , Bel‐enguix Gemma , Baixeries Jaume 
Published: November 2012

AbstractThe importance of statistical patterns of language has been debated over decades. Although Zipf's law is perhaps the most popular case, recently, Menzerath's law has begun to be involved. Menzerath's law manifests in language, music and genomes as a tendency of the mean size of the parts to decrease as the number of parts increases in many situations. This statistical regularity emerges also in the context of genomes, for instance, as a tendency of species with more chromosomes to have a smaller mean chromosome size. It has been argued that the instantiation of this law in genomes is not indicative of any parallel between language and genomes because (a) the law is inevitable and (b) noncoding DNA dominates genomes. Here mathematical, statistical, and conceptual challenges of these criticisms are discussed. Two major conclusions are drawn: the law is not inevitable and languages also have a correlate of noncoding DNA. However, the wide range of manifestations of the law in and outside genomes suggests that the striking similarities between noncoding DNA and certain linguistics units could be anecdotal for understanding the recurrence of that statistical law. © 2012 Wiley Periodicals, Inc. Complexity, 2012
A genetic‐based cognitive link decision algorithm for OFDM system
Authors: Tan Xiaobo , Zhang Hang , Liu Zhiwen , Hu Jian 
Published: November 2012

SUMMARYTo solve the problem of cognitive link decision for OFDM system in a time‐varying environment, an improved genetic algorithm‐based decision‐making module is proposed. At first, the decision‐making module collects the environmental information and QoS requirements of the radio and then produces link configuration for the radio on the basis of the improved genetic algorithm. New crossover and mutation strategies are introduced to accelerate convergence rate of the genetic algorithm. A novel population initialization method is also proposed to reduce the time of achieving the optimal decision by the decision‐making module when the radio is operated in a slow changeable environment. Simulations and discussions demonstrate the effectiveness of the decision‐making module, and this research work exhibits its importance of enhancing the decision speed that is of crucial demand in cognitive decision‐making applications. Copyright © 2012 John Wiley & Sons, Ltd.
Multiple evolutionary processes drive the patterns of genetic differentiation in a forest tree species complex
Authors: Jones Rebecca C. , Steane Dorothy A. , Lavery Martyn , Vaillancourt René E. , Potts Brad M. 
Published: November 2012

AbstractForest trees frequently form species complexes, complicating taxonomic classification and gene pool management. This is certainly the case in Eucalyptus, and well exemplified by the Eucalyptus globulus complex. This ecologically and economically significant complex comprises four taxa (sspp. bicostata, globulus, maidenii, pseudoglobulus) that are geographically and morphologically distinct, but linked by extensive “intergrade” populations. To resolve their genetic affinities, nine microsatellites were used to genotype 1200 trees from throughout the natural range of the complex in Australia, representing 33 morphological core and intergrade populations. There was significant spatial genetic structure (FST = 0.10), but variation was continuous. High genetic diversity in southern ssp. maidenii indicates that this region is the center of origin. Genetic diversity decreases and population differentiation increases with distance from this area, suggesting that drift is a major evolutionary process. Many of the intergrade populations, along with other populations morphologically classified as ssp. pseudoglobulus or ssp. globulus, belong to a “cryptic genetic entity” that is genetically and geographically intermediate between core ssp. bicostata, ssp. maidenii, and ssp. globulus. Geography, rather than morphology, therefore, is the best predictor of overall genetic affinities within the complex and should be used to classify germplasm into management units for conservation and breeding purposes.
Resistin reduces mitochondria and induces hepatic steatosis in mice by the protein kinase C/protein kinase G/p65/PPAR gamma coactivator 1 alpha pathway
Authors: Zhou Lei , Yu Xiaolan , Meng Qingjie , Li Hongqiang , Niu Congcong , Jiang Yun , Cai Yuxi , Li Minghui , Li Qiang , An Chaoqiang , Shu Le , Chen Ao , Su Handong , Tang Yin , Yin Shen , Raschke Silja , Eckardt Kristin , Eckel Jürgen , Yang Zaiqing 
Published: November 2012

Abstract

Obesity is associated with many severe chronic diseases and deciphering its development and molecular mechanisms is necessary for promoting treatment. Previous studies have revealed that mitochondrial content is down-regulated in obesity, diabetes, and nonalcoholic fatty liver disease (NAFLD) and proposed that NAFLD and diabetes are mitochondrial diseases. However, the exact mechanisms underlying these processes remain unclear. In this study, we discovered that resistin down-regulated the content and activities of mitochondria, enhanced hepatic steatosis, and induced insulin resistance (IR) in mice. The time course indicated that the change in mitochondrial content was before the change in fat accumulation and development of insulin resistance. When the mitochondrial content was maintained, resistin did not stimulate hepatic fat accumulation. The present mutation study found that the residue Thr464 of the p65 subunit of nuclear factor kappa B was essential for regulating mitochondria. A proximity ligation assay revealed that resistin inactivated peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC-1α) and diminished the mitochondrial content by promoting the interaction of p65 and PGC-1α. Signaling-transduction analysis demonstrated that resistin down-regulated mitochondria by a novel protein kinase C/protein kinase G/p65/PGC-1α-signaling pathway.

Conclusion

: Resistin induces hepatic steatosis through diminishing mitochondrial content. This reveals a novel pathway for mitochondrial regulation, and suggests that the maintenance of normal mitochondrial content could be a new strategy for treatment of obesity-associated diseases.