bluuebunny/crossref_metadata_2025_split huggingface dataset:
ChemInform Abstract: Conformationally Locked Nucleoside Analogues Based on the Bridgehead Substituted 7‐Oxonorbornane and Their Antiviral Properties.
Authors: Dejmek Milan , Hrebabecky Hubert , Dracinsky Martin , Neyts Johan , Leyssen Pieter , Mertlikova‐Kaiserova Helena , Nencka Radim 
Published: May 2012

AbstractA series of novel conformationally‐constrained nucleoside analogues with an aromatic ring employed as the locking bridge is designed, synthesized and tested for antiviral properties.
ChemInform Abstract: First Synthesis of a Natural Isoxanthopterin Glycoside, Asperopterin‐A.
Authors: Hanaya Tadashi , Ejiri Kazumasa , Yamamoto Hiroshi 
Published: May 2012

AbstractAsperopterin‐A (VIII) is prepared via condensation of pyrimidine (I) with oxopropionate (II) and a SnCl4‐promoted glycosylation of xanthopterin (V) as key steps.
ChemInform Abstract: Synthesis and Antitumor Evaluation of B‐Ring Modified Caged Xanthone Analogues of Gambogic Acid.
Authors: Li Xiang , Zhang Xiaojin , Wang Xiaojian , Li Nianguang , Lin Changjun , Gao Yuan , Yu Zhuoqin , Guo Qinglong , You Qidong 
Published: May 2012

AbstractThe compounds (VIII) and (XI) are screened in vitro for their antitumor activities against the A549, MCF‐7, SMMC‐7721, and BGC‐823 cancer cell lines.
ChemInform Abstract: Modification of Quantum Dots with Nucleic Acids
Authors: Kocherginskaya P. B. , Romanova A. V. , Prokhorenko I. A. , Itkis D. M. , Korshun V. A. , Goodilin E. A. , Tretyakov Yu. D. 
Published: May 2012

AbstractReview: 80 refs.
Long‐Term Stability, Regeneration and Recycling of Imidazolium‐based Ionic Liquids
Authors: Keil Philipp , Kick Matthias , König Axel 
Published: May 2012

AbstractIonic liquids (ILs) are discussed in many current research papers extensively in terms of their potential use in the chemical industry, as process aids and novel materials. The long‐term stability of the IL is for industrial applications as important as to know which species arise during the degradation due to thermal, mechanical, chemical or electrochemical stress. The investigation of the long‐term stability of two selected ILs over several months under process‐like conditions is presented with a subsequent analysis by LC‐MS to identify the resulting decomposition products. Knowledge about the occurring species and their analytical quantification are basis for the selection of appropriate processes for the separation of the decomposition products and the development of recycling processes for ILs. Particularly melt crystallization processes are suitable for separating structurally similar decomposition products that typically occur in the IL degradation.
Batch and fixed‐bed column adsorption of Cu(II), Pb(II) and Cd(II) from aqueous solution onto functionalised SBA‐15 mesoporous silica
Authors: Shahbazi Afsaneh , Younesi Habibollah , Badiei Alireza 
Published: May 2012

AbstractFunctionalised SBA‐15 mesoporous silica with polyamidoamine groups (PAMAM‐SBA‐15) was successfully prepared with the structure characterised by X‐ray diffraction, nitrogen adsorption–desorption, Fourier transform infrared spectra and thermogravimetric analysis. PAMAM‐SBA‐15 was applied as adsorbent for Cu(II), Pb(II) and Cd(II) ions removal from aqueous solution. The effects of the solution pH, adsorbent dosage and metal ion concentration were studied under the batch mode. The Langmuir model was fitted favourably to the experimental data. The maximum sorptive capacities were determined to be 1.74 mmol g−1 for Cu(II), 1.16 mmol g−1 for Pb(II) and 0.97 mmol g−1 for Cd(II). The overall sorption process was fast and its kinetics was fitted well to a pseudo‐first‐order kinetic model. The mean free energy of sorption, calculated from the Dubinin–Radushkevich isotherm, indicated that the sorption of lead and copper, with E > 16 kJ mol−1, followed the sorption mechanism by particle diffusion. The adsorbent could be regenerated three times without significant varying its sorption capacity. A series of column tests were performed to determine the breakthrough curves with varying bed heights and flow rates. The breakthrough data gave a good fit to the Thomas model. Maximum sorption capacity of 1.6, 1.3 and 1.0 mmol g−1 were found for Cu(II), Pb(II) and Cd(II), respectively, at flow rate of 0.4 mL min−1 and bed height of 8 cm, which corresponds to 83%, 75% and 73% of metallic ion removal, respectively, which very close to the value determined in the batch process. Bed depth service time model could describe the breakthrough data from the column experiments properly. © 2012 Canadian Society for Chemical Engineering
Bromide Complexation by the EuIII Lanthanide Cation in Dry and Humid Ionic Liquids: A Molecular Dynamics PMF Study
Authors: Chaumont Alain , Wipff Georges 
Published: May 2012

AbstractWe report a molecular dynamics study on the EuBrn3‐n complexes (n=0 to 6) formed upon complexation of Br− by Eu3+ in the [BMI][PF6], [BMI][Tf2N] and [MeBu3N][Tf2N] ionic liquids (ILs), to compare the effect of the IL anion (PF6− versus Tf2N−), the IL cation (BMI+ versus MeBu3N+) and the “IL humidity” on their solvation and stability. In “dry” solutions all complexes remain stable and the first coordination shell of Eu3+ is purely anionic (Br− and IL anions), surrounded by IL cations (BMI+ or MeBu3N+ ions). Long range “onion type” solvation features (up to 20 Å from Eu3+), with alternating cation‐rich and anion‐rich solvent shells, are observed around the different complexes. The comparison of gas phase‐optimized structures of EuBrn3‐n complexes (that are unstable for n=5 and 6) with those observed in solution points to the importance of solvation forces on the nature of the complex, with a higher stabilization by imidazolium‐ than by ammonium‐based dry ILs. Adding water to the IL has different effects, depending on the IL. In the highly hygroscopic [BMI][PF6] IL, Br− ligands are displaced by water, to finally form Eu(H2O)93+. In the less “humid” [BMI][Tf2N], the EuBrn3‐n complexes do not dissociate and coordinate at most 1–2 H2O molecules. We also calculated the free‐energy profiles (Potential of Mean Force calculations) for the stepwise complexation of Br−, and found significant solvent effects. EuBr63− is predicted to form in both [BMI][PF6] and [BMI][Tf2N], but not in [MeBu3N][Tf2N], mainly due to weaker interactions with the cationic solvation shell. First steps are found to be more exergonic in the PF6−‐ than in the Tf2N−‐based IL. Molecular dynamics (MD) comparisons between ILs and classical solvents (acetonitrile and water) are also reported, affording good agreement with the experimental observations of Br− complexation by trivalent lanthanides in these classical solvents.
Ion‐Specific Aggregation of Hydrophobic Particles
Authors: López‐León Teresa , Ortega‐Vinuesa Juan Luis , Bastos‐González Delfina 
Published: May 2012

AbstractThis work shows that colloidal stability and aggregation kinetics of hydrophobic polystyrene (PS) nanospheres are extremely sensitive to the nature of the salt used to coagulate them. Three PS latices and four aggregating electrolytes, which all share the same cation (Na+) but have various anions located at different positions in the classical Hofmeister series depending on their kosmotropic or chaotropic character, are used. The present study focuses on analyzing different aggregating parameters, such as critical coagulation concentrations (CCC), cluster size distributions (CSD), initial kinetic constants K11, and fractal dimensions of the aggregates df. While aggregation induced by SO42− and Cl− behaved according to the predictions of the classical Derjaguin–Landau–Verwey–Overbeek theory, important discrepancies are found with NO3−, which become dramatic when using SCN−. These discrepancies among the anions were far more significant when they acted as counterions rather than as co‐ions. While SO42− and Cl− trigger fast diffusion‐limited aggregation, SCN− gives rise to a stationary cluster size distribution in a few aggregation times when working with cationic PS particles. Clear differences are found among all analyzed parameters (CCC, CSD, K11, and df), and the experimental findings show that particles aggregate in potential wells whose depth is controlled by the chaotropic character of the anion. This paper presents new experimental evidence that may help to understand the microscopic origin of Hofmeister effects, as the observations are consistent with appealing theoretical models developed in the last few years.
Decision‐making and planning in full recovery of anorexia nervosa
Authors: Lindner Susanne E. , Fichter Manfred M. , Quadflieg Norbert 
Published: May 2012

AbstractObjective:Based on findings of persisting neuropsychological impairments in women recovered from anorexia nervosa (rec AN), this study examined decision‐making and planning, for achieving a desired goal, as central executive functions in a large sample of rec AN. The definition of recovery included physiological, behavioral, and psychological variables.Method:A total of 100 rec AN women were compared to 100 healthy women, 1:1 matched for age and educational level. Decision‐making was assessed with the Iowa Gambling Task and planning with the Tower of London. Expert interviews and self‐ratings were used for assessing the inclusion/exclusion criteria and control variables.Results:Compared to healthy controls, rec AN women were better in decision‐making and worse in planning even after considering control variables.Discussion:This study does not support results from other studies showing that rec AN participants perform better in decision‐making. Results from this study show that planning is impaired even after full recovery from AN. © 2012 by Wiley Periodicals, Inc. (Int J Eat Disord 2011;45:866–875)
Copper Complexes of “Superpodal” Amine Ligands and Reactivity Studies towards Dioxygen
Authors: Jozwiuk Anna , Ünal E. Alper , Leopold Stefan , Boyd John P. , Haryono Marco , Kurowski Nadine , Escobar Francisco Velazquez , Hildebrandt Peter , Lach Jochen , Heinemann Frank W. , Wiedemann Dennis , Irran Elisabeth , Grohmann Andreas 
Published: May 2012

AbstractThe results of studies focussed on copper complexes of a variety of ligands with an NN4 donor set are reported. The permethylated tetrapodal ligand 2 forms a complex with copper(I) which, upon reaction with dioxygen at –90 °C, yields a product having a bis(μ‐oxido)dicopper(III) core (“O‐type” product, 10), as inferred from UV/Vis and resonance‐Raman spectroscopic data. The UV/Vis spectrum of 10 has two bands at 300 and 404 nm, with extinction coefficients of 9400 and 10400 L mol–1 cm–1, respectively. Resonance‐Raman spectra display two 16O/18O‐sensitive bands which, based on the isotopic shifts and the absolute frequencies, are attributed to the Cu–O stretching modes of the O‐type product. Complex 10 shows tyrosinase‐like activity, as its reaction with sodium p‐tert‐butylphenolate at –90 °C in THF yields p‐tert‐butylcatechol, in an ortho‐hydroxylation reaction (yield: 30 %). Two new rigid tetrapodal pentadentate ligands (the “superpods” 3 and 4) can be synthesized by condensation of the primary polyamine 1 with paraformaldehyde. Their copper(II) complexes (5 and 6) have been spectroscopically characterized. As ascertained by X‐ray crystallography, 5 has the CuII ion in a tetragonal‐pyramidal environment, with almost uniform Cu–N bond lengths (basal bonds: 2.052 Å and 2.070 Å; apical bond: 2.077 Å). No significant Jahn–Teller distortion is observed here. In 6, the ligand acts as a multinucleating donor, which leads to the formation of a ladder‐like cluster of [Cu(μ3‐OH)] units containing a total of two ligands, six copper(II) ions, four hydroxido ligands and eight trifluoroacetate ions. Two of the trifluoroacetate ions are non‐coordinating. Variable‐temperature magnetic susceptibility data are reported for this hexanuclear copper(II) cluster. Copper(I) complexes of 1 and 3 have been characterized and allowed to react with molecular oxygen, which caused the decomposition of the complexes. The IR spectra of the oxygenation products have bands at 1652 and 1632 cm–1, respectively, which are absent in the spectra of 1 and 3, suggesting that amine functions have been oxidized to imines.
Synthesis, Structure and Property of 5‐Aminotetrazolate Room‐Temperature Ionic Liquids
Authors: Tao Guo‐Hong , Tang Meng , He Ling , Ji Shun‐Ping , Nie Fu‐De , Huang Ming 
Published: May 2012

AbstractEight 5‐aminotetrazolate (AT) salts based on the 1,2,3‐trimethylimidazolium (1), 1,3‐dimethylimidazolium (2), 1‐ethyl‐3‐methylimidazolium (3), 1‐butyl‐3‐methylimidazolium (4), 1‐isobutyl‐3‐methylimidazolium (5), 1‐(3′‐methylbutyl)‐3‐methylimidazolium (6), 1‐hexyl‐3‐methylimidazolium (7) and 1‐methyl‐3‐octylimidazolium (8) cations have been synthesized in high yields and fully characterized by IR and NMR spectroscopy and elemental analysis. White plate crystals of 1 were isolated in methanol/diethyl ether and crystallized. Both the AT anion and the 1,2,3‐trimethylimidazolium cation in 1 were delocalized. Differential scanning calorimetry (DSC) combined with thermogravimetric analysis (TGA) tests were used to assess the thermal stabilities of the AT salts. These salts decomposed within the temperature range 230 °C–262 °C. Salts 3–8 are very fluent room‐temperature ionic liquids, whose glass transition temperatures are low. Their viscosities at 30 °C are in the range from 92 cP to 208 cP. A correlation between the viscosity and temperature was found, and the ionic liquids to do not display an Arrhenius temperature behaviour. In addition, the standard enthalpies of formation of salts 1–8 were investigated and analyzed by the theoretical methods. Salt 2 with the 1,3‐dimethylimidazolium cation gave the highest positive enthalpy of formation. For the assessment of the energetic character of the AT salts, impact sensitivities and friction sensitivities were recorded. These AT salts are insensitive to impact (>40 J) and friction (>360 N) confirmed by UN standards. The reactions of these AT salts with 100 % HNO3 were also determined.
Cobalt(II) Complexes Bearing a Bulky N‐Heterocyclic Carbene for Catalysis of Kumada–Tamao–Corriu Cross‐Coupling Reactions of Aryl Halides
Authors: Matsubara Kouki , Sueyasu Tsukasa , Esaki Mariko , Kumamoto Aya , Nagao Shinya , Yamamoto Hitomi , Koga Yuji , Kawata Satoshi , Matsumoto Taisuke 
Published: May 2012

AbstractCobalt(II) iodide, bromide, and chloride react with 1 equiv. of IPr [1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene] to form a series of tetrahedral dimeric (30e) complexes of cobalt(II) in good yields. These were transformed into the monomeric forms in the presence of pyridine. These complexes were characterized by SQUID, XPS, UV/Vis spectroscopy, elemental analysis, and X‐ray crystallography, and were found to have high catalytic activity for Kumada–Tamao–Corriu cross‐coupling reactions of aryl halides.
Gold(I) Complexes Incorporating Emissive Mercapto‐Pteridine Ligands: Syntheses, X‐ray Structure, Luminescence and Preliminary Cytotoxic Evaluation
Authors: Mullice Lucy A. , Mottram Huw J. , Hallett Andrew J. , Pope Simon J. A. 
Published: May 2012

AbstractThe syntheses of six new mixed P/S‐donor two‐coordinate AuI complexes are described. The complexes incorporate a pteridinyl ligand coordinated through a thiolate donor, and an ancillary tertiary phosphane (PPh3 or PCy3). The mercapto‐pteridine ligands (L1–L3) differ in the nature of the substituents on the pteridine core. An X‐ray crystal structure was obtained for one of the examples, [(L1)Au(PPh3)], revealing weak intermolecular interactions between two molecules of the complex: π–π contacts between aromatic rings appear to support an intermolecular Au–Au contact of approximately 3.05 Å. All of the complexes are luminescent in solution, with emission arising from tuneable ligand‐based excited states, and characterised as a perturbed fluorescence in nature. In this context, complexes of L3 displayed useful visible absorption and emission. Preliminary cytotoxicity assessments were conducted using the MTT assay, and the complexes each displayed impressive anti‐proliferative activities (IC50 < 5 μM) with respect to four different adenocarcinoma cell lines (MCF7, A549, PC3 and LOVO). For a given pteridine moiety, triphenylphosphane appeared to be the co‐ligand of choice for enhancing biological activity.
Zn‐Mediated Synthesis of 3‐Substituted Indoles Using a Three‐Component Reaction Approach
Authors: Anselmo Daniele , Escudero‐Adán Eduardo C. , Martínez Belmonte Marta , Kleij Arjan W. 
Published: May 2012

AbstractThe synthesis of 3‐substituted indoles was investigated through a multicomponent reaction (MCR) approach by using aldehydes, indole and malononitrile as the reagents. The reaction was catalyzed by Lewis acidic Zn(salphen) complexes and their performance was compared with a number of other ZnII structures and M(salphen)s, which showed the Zn(salphen)s to be superior. However, the complex nature of this three‐component reaction (3‐CR) results in substantial byproduct formation that arises from the intermediate benzylidene malononitrile species. The 3‐CR was studied in detail that covered the influence of the base, solvent, reagent stoichiometry and also involved stability studies. The results led to a mechanistic proposal in which the benzylidene malononitrile intermediate plays a central role; it is one of the major species that is formed in most of the catalytic reactions studied. Furthermore, it provided a prelude for the in situ reaction with the malononitrile reagent, which most probably affords a complex mixture of N‐containing heterocycles.
Straightforward Synthesis of Poly(dimethylsiloxane) Phases with Immobilized (1R)‐3‐(Perfluoroalkanoyl)camphorate Metal Complexes and Their Application in Enantioselective Complexation Gas Chromatography
Authors: Spallek Markus J. , Storch Golo , Trapp Oliver 
Published: May 2012

AbstractA straightforward synthesis of novel chiral polysiloxane‐based metal stationary phases immobilized through a propylenoxy linker (Chirasil‐Metal‐OC3) to the polymeric backbone is presented. Synthesis was accomplished in six steps with high overall yields starting from commercially available, enantiopure (+)‐(1S)‐camphorsulfonic acid. Two different approaches towards Chirasil‐Metal phases featuring either a propylenoxy or propylenthio linker used for immobilization through hydrosilylation are presented. Furthermore, a new protocol for the fluoroacylation, which is one of the key steps in the synthesis of (1R)‐3‐(perfluoroalkanoyl)camphorate metal complexes, was developed to improve the isolation and overall yield. The immobilization of (1R,4S)‐10‐(allyloxy)‐3‐(heptafluorobutanoyl)camphor – 10‐(allyloxy)‐hfbc – onto polysiloxanes as well as the incorporation of nickel(II), oxovanadium(IV), europium(III), and lanthanum(III) was characterized by FT ATR IR and NMR spectroscopy. Overall, seven different Chirasil‐Metal‐OC3polymers with different separation properties were prepared by metal incorporation and variation of the amount of immobilized (1R,4S)‐10‐(allyloxy)‐3‐(heptafluorobutanoyl)camphor (10‐allyloxy‐hfbc: 3.5, 10.2, and 20.0 %). Their performance in enantioselective complexation gas chromatography was systematically studied and excellent enantioselectivity was found for Chirasil‐Nickel‐OC3. Separation of 29 small‐sized compounds, encompassing, among others, epoxides, substituted alkenes and alkynes as well as alcohols and amides, was achieved with high separation factorsα. The synthetic strategy, enantiomer separations and thermal stability (up to 160 °C) demonstrates the versatility of the newly derived Chirasil‐Metal‐OC3phases.
Application of L‐Erythrose‐Derived Nitrones in the Synthesis of Polyhydroxylated Compounds via 3,6‐Dihydro‐2H‐1,2‐oxazine Derivatives
Authors: Jasiński Marcin , Lentz Dieter , Moreno‐Clavijo Elena , Reissig Hans‐Ulrich 
Published: May 2012

AbstractEnantiopure 3,6‐dihydro‐2H‐1,2‐oxazines were prepared by [3+3] cyclisations starting from lithiated methoxyallene and the L‐erythrose‐derived nitrones 1′ and 3. The role of the side‐chain protective group, which steers the highly selective formation of either anti‐ or syn‐configured products, was demonstrated. A hydroboration/oxidation protocol smoothly converted 1,2‐oxazine derivative syn‐5 into secondary alcohol 6. After deprotection, polyhydroxylated tetrahydro‐2H‐1,2‐oxazine 11, which can be regarded as an azasugar, was isolated. Analogous treatment of 1,2‐oxazine anti‐5 with the borane not only provided the expected secondary alcohol 7, but it also induced reduction of the C=C bond and ring opening. Treatment of syn‐5 and anti‐2 with hydrochloric acid in methanol induced deprotections and cyclisations leading to bicyclic tetrahydro‐2H‐1,2‐oxazine derivatives. The second ring can be either a furan or a pyran ring. In the syn series, furan derivative 12 was formed exclusively, and its hydrogenolysis led to enantiopure aminofuran derivative 14. Acid‐promoted rearrangement of unprotected anti‐2 led to a mixture of bicyclic compounds with furan or pyran rings fused to the 1,2‐oxazine core. However, when TBDPS‐protected compound 20 was used it cleanly led to 1,2‐oxazine 21 with a fused furan ring and then to aminofuran 22. Alternatively, the N–O bond in unprotected anti‐2 was chemoselectively reduced with samarium diiodide, efficiently generating highly functionalized allylic alcohol 23. Acid‐promoted cyclisation and deprotection furnished furan derivative 24. Mechanistic suggestions to explain the different outcomes of the acid‐induced transformations are provided. Overall, it is demonstrated that the stereodivergent addition of lithiated alkoxyallenes to L‐erythrose‐derived nitrones allow flexible access to a series of enantiopure amino polyols, including aminofuran derivatives.
Element profiles in hair and nails of children reflect the uptake from food and the environment
Authors: Oyoo-Okoth Elijah , Admiraal Wim , Osano Odipo , Kraak Michiel H.S. 
Published: May 2012

Abstract
The present study evaluated if the element profiles in hair and nails of children from the Lake Victoria region in Kenya reflect uptake from food and the environment. To this purpose, the element concentrations in hair and nails were related to element concentrations measured in food items, water, and soil. The highest intake of most elements occurred via ingestion of the fish Rastrineobola argentea, which is consumed in higher quantities than other fish and food items. Element concentrations in hair and nails were correlated to food and soil in element-specific patterns. Multivariate analysis combining principal component analysis and multidimensional scaling enabled us to cluster individuals from specific sites and to relate differences between sites to food-consumption patterns and environmental exposures. Site-specific differences in macroelement concentrations among the children were attributed to patterns of food consumption, while those in microelement concentrations reflected differences in geochemical background. It is concluded that the simultaneous analysis of elements in human hair and nails allows separation of populations based on food consumption and geochemical background. Environ. Toxicol. Chem. 2012; 31: 1461–1469. © 2012 SETAC