bluuebunny/crossref_metadata_2025_split huggingface dataset:
MCM‐41 Derivatised with Pyridyl Groups and Its Use as a Support for Luminescent Europium(III) Complexes
Authors: Bruno Sofia M. , Coelho Ana C. , Ferreira Rute A. S. , Carlos Luís D. , Pillinger Martyn , Valente Anabela A. , Ribeiro‐Claro Paulo , Gonçalves Isabel S. 
Published: July 2008

AbstractAn organic–inorganic hybrid ligand silica was prepared by reaction of the ordered mesoporous silica MCM‐41 with 3‐triethoxysilylpropyl 4‐pyridylacetamide. Elemental analysis indicated that a pyridyl group loading of 0.93 mmol g–1 was achieved. The derivatised material was further characterised by powder X‐ray diffraction, N2 adsorption, thermogravimetric analysis, FTIR and Raman spectroscopy, and 13C and 29Si CP MAS NMR spectroscopy. Pyridyl‐functionalised MCM‐41 (L″) was treated with chloroform solutions of lanthanide tris‐β‐diketonate complexes Ln(nta)3(H2O)2 [Ln = Eu, Gd; nta = 1‐(2‐naphthoyl)‐3,3,3‐trifluoroacetonate] to give the surface‐bound monosubstituted species Ln(nta)3(H2O)(L″). The residual coordinated water molecules were subsequently replaced by pyridine (py) or methyl phenyl sulfoxide (mpso) to give immobilised Ln(nta)3(py)(L″) and Ln(nta)3(mpso)(L″) species. Photoluminescence studies were carried out at room temperature and 14 K. The emission spectra of the Eu‐modified materials were dominated by the typical Eu3+ red lines ascribed to transitions between the 5D0 excited state and the ground multiplet (7F0–4), and only very weak or negligible emission from the organic ligands are observed. Variation of the excitation wavelength confirmed that all of the Eu3+ ions occupied the same average local environment within each sample. By comparison with the photoluminescence data for the nonsupported Eu(nta)3(py)2 and Eu(nta)3(mpso)2 complexes, it is shown that the interaction between the host and guest has a strong effect on the excited states of the organic ligands; Eu3+ sensitisation occurs exclusively through the ligands rather than by direct intra‐4f6 excitation.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Magnetic Coupling and Anisotropy in a Series of Mixed Chain Charge‐Transfer Salts [M(Cp*)2][M′(tds)2] (M = Fe, Mn, Cr; M′ = Ni, Pt)
Authors: Rabaça Sandra , Vieira Bruno J. C. , Meira Rui , Santos Isabel C. , Pereira Laura C. J. , Duarte M. Teresa , da Gama Vasco 
Published: July 2008

AbstractThe preparation of new charge‐transfer (CT) salts based on the decamethylmetallocenium donors (D), [M(Cp*)2] (M = Mn, Cr), and on the bis[bis(trifluoromethyl)ethylene diselenolato]metalate(III) acceptors (A), [M′(tds)2] (M = Ni, Pt), yielded four new members of the family of CT salts [M(Cp*)2][M′(tds)2] {M/M′ = Fe/Ni (1), Fe/Pt (2), Mn/Ni (3), Mn/Pt (4), Cr/Ni (5), Cr/Pt (6)}. Their crystal structures consist of anarrangement of parallel mixed chains, DADADA, with short D–A contacts and large interchain separations. The CT salts 1–5 are isostructural and 6 shows minor differences in the interchain arrangements. The analysis of the intermolecular contacts, in the framework of the McConnell I model, provides a fair interpretation of the magnetic coupling. The behavior of these salts is dominated by the ferromagnetic (FM) D–A intrachain interactions. Coexisting weaker antiferromagnetic (AF) interchain couplings induce AF transitions in 2, 3, 4, and 6, with TN = 3.3, 2.1, 5.8, and 5.2 K, respectively. The intrachain coupling and the TN values of the CT salts based on the [M(Cp*)2] (M = Fe, Mn) donors (1, 2, 3, and 4) were found to be in good agreement with those predicted by the mean field model. Compounds 5 and 6 exhibit weaker intrachain coupling and lower critical temperatures than those predicted by that model, which is attributed to weaker D–A interactions. The study of the low temperature behavior of the salts 3, 4, and 6 allowed the disclosure of the effect of the magnetic anisotropy of the donors. The CT salts based on highly anisotropic donors, such as 3 and 4, show metamagnetic (MM) behavior, with phase diagrams that include a paramagnetic (PM) and an AF phase, as previously observed for 2. In the phase diagram of 6, where the [Cr(Cp*)2] donor does not show magnetic anisotropy, a spin‐flop (SF) phase is present in addition to the PM and AF phases. This is the first time an SF phase was observed in [M(Cp*)2]‐based CT salts. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Checking the Route to Cluster Helicates
Authors: Bermejo Manuel R. , González‐Noya Ana M. , Martínez‐Calvo Miguel , Pedrido Rosa , Romero María J. , Vázquez López Miguel 
Published: July 2008

AbstractThe aim of the work described here was to test the general applicability of our recently reported route to cluster helicates and to carry out a systematic study to relate the structural and coordinative properties of the organic strands with the microarchitectures of the resulting cluster helicates. Nine new ZnII, CuI and AgI complexes were prepared from three Schiff base ligands [H2La: bis(4‐methyl‐3‐thiosemicarbazone)‐2,6‐diacetylpyridine; H2Lb: bis(4‐methyl‐3‐thiosemicarbazone)‐2,6‐diacetylbenzene; H2Lc: bis(4‐ethyl‐3‐thiosemicarbazone)‐2,6‐diacetylbenzene]. The experimental data confirm that AgI and CuI tetranuclear cluster helicates were obtained with a [M4(Lx)2] stoichiometry, and this finding demonstrates the general applicability of the synthetic route. The cluster helicates presented in this work were characterized for the first time in solution by NMR spectroscopy. In addition, six of the nine complexes were characterized by X‐ray diffraction studies, and three of them were found to be tetranuclear cluster helicates. A detailed study of these three crystal structures leads us to state that the changes introduced in the organic strands do not prevent the assembly of the tetranuclear cluster dihelicates, but they do affect the microarchitectures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Structure and Properties of NaBH4·2H2O and NaBH4 (Eur. J. Inorg. Chem. 20/2008)
Authors: Filinchuk Yaroslav , Hagemann Hans 
Published: July 2008

AbstractThe cover picture shows the crystal structure of sodium borohydride dihydrate, NaBH4·2H2O, determined from synchrotron diffraction on a single crystal. The European Synchrotron Radiation Facility (ESRF), shown in the lower left corner, provided the source of X‐rays. The BH4– anion has a nearly ideal tetrahedral geometry. By applying the systematic correction to the positions of hydrogen atoms seen by X‐rays, the geometry of the dihydrogen O–Hδ+···δ–H–B bonding was accurately characterized. The structure of anhydrous NaBH4 was also investigated by X‐ray diffraction on a single crystal. Vibrational properties of NaBH4·2H2O and related substances were studied by IR and Raman spectroscopy. Details are discussed in the article by Y. Filinchuk and H. Hagemann on p. 3127 ff.
The quality and volatile‐profile changes of camellia oil (Camellia oleifera Abel) following bleaching
Authors: Qizhi Long , Yonghui Huang , Haiyan Zhong , Bedgood Danny R. , Prenzler Paul D. , Robards Kevin 
Published: July 2008

AbstractBleaching is a necessary step in the production of refined camellia oil (Camellia oleifera Abel) since crude oil has a dark brown color, due to pigments extracted from the seed coat during pressing, which is unacceptable to consumers. In order to understand the quality change and oxidative state of camellia oil in the bleaching step, measurements of various quality parameters, i.e. peroxide value (POV), free fatty acids (FFA), UV absorbance, and the volatile profiles of crude and bleached oils, were carried out. The results showed that FFA, K270, and K232 increased, whereas POV decreased, with increase of the activated earth dosage of 0–4% and of bleaching time from 0 to 40 min at 110 °C. As the amount of activated earth was increased from 0 to 4% with bleaching at 110 °C for 30 min, various classes of volatile compounds increased in concentration: aldehydes (23.7 µg/g), alcohols (13.2 µg/g), esters (8.0 µg/g), alkenes (2.0 µg/g) and ketones (1.9 µg/g). Likewise, when bleaching was carried out at 110 °C with 3% activated earth and the bleaching time varied between 0 and 40 min, the concentrations of volatile compounds also increased: aldehydes (27.7 µg/g), alcohols (18.2 µg/g), esters (7.3 µg/g), ketones (3.2 µg/g) and alkenes (0.6 µg/g). These findings indicate that hydroperoxides in the oil were decomposed into lower‐molecular‐weight products in the process of bleaching and that the extent of this decomposition can be controlled by time and amount of activated earth.
The effect of malaxation temperature on the virgin olive oil phenolic profile under laboratory‐scale conditions
Authors: Parenti Alessandro , Spugnoli Paolo , Masella Piernicola , Calamai Luca 
Published: July 2008

AbstractThe relationship between olive paste malaxation temperature and the concentration of olive oil hydrophilic phenols (HP), i.e. simple phenols, secoiridoids and lignans, was investigated. Malaxation experiments were performed at laboratory scale for 45 min at 21, 24, 27, 30, 33 and 36 °C. A significant (p <0.05) increment of total phenols concentration was found with a maximum at 27 °C, whereas for higher temperatures (30–36 °C) a progressive decrement was observed. A similar pattern was recorded approximately for all the secoiridoid compounds, i.e. a quasi‐linear increment of concentrations with increasing temperature until 30 °C, followed by a marked decrease in correspondence with the higher malaxation temperature (33 and 36 °C). The amount of simple phenols increased linearly with increasing temperature and no decrements were observed up to the maximal temperature investigated (36 °C), while no significant differences were found for lignans. A small increment of peroxide values and total chlorophyll was recorded as a function of the increasing malaxation temperature, whereas no differences were observed in the free acidity. The results highlight that there is not a univocal relationship between HP concentration and malaxation temperature. An equilibrium between degradation (chemical and biochemical oxidation and hydrolysis) and transfer (partitioning) phenomena was hypothesized.
Lipid adsorption capacities of magnesium silicate and activated carbon prepared from the same rice hull
Authors: Taspinar Ozgul O. , Ozgul‐Yucel Sevil 
Published: July 2008

AbstractThis study is a comparison of the lipid adsorption capacities of synthetic magnesium silicate and activated carbon produced from rice hulls of the same origin. The lipids examined were the free fatty acids, diacylglycerols and monoacylglycerols of frying oils. Pure oleic acid, an unused sunflower frying oil and a used sunflower frying oil were used in the experiments. The produced adsorbents, magnesium silicate and activated carbon, have surface areas of 680 and 43 m2/g, respectively. The lipid adsorption capacity of the produced magnesium silicate was found as 644 mg polar compounds/g adsorbent and it is higher than the capacities of the industrial adsorbents, Magnesol XL and activated carbon. This value is only 368 mg polar compounds/g adsorbent for the activated carbon produced from the same‐origin rice hull.
Undecylenic acid: A valuable renewable building block on route to Tyromycin A derivatives
Authors: Van der Steen Marijke , Stevens Christian V. , Eeckhout Yves , De Buyck Laurent , Ghelfi Franco , Roncaglia Fabrizio 
Published: July 2008

AbstractA key intermediate for the synthesis of Tyromycin A, a C‐20 tetrachlorodicarboxylic acid, was produced in six steps starting with the dimerization of methyl 10‐undecenoate which was obtained from a renewable resource, e.g. castor oil. The acyloin condensation product was then oxidized, transformed to the diene, followed by ozonization, chlorination and finally oxidation to the corresponding tetrachlorodicarboxylic acid.
Thermostability of genetically modified sunflower oils differing in fatty acid and tocopherol compositions
Authors: Marmesat Susana , Velasco Leonardo , Ruiz‐Méndez Maria Victoria , Fernández‐Martínez José María , Dobarganes Carmen 
Published: July 2008

AbstractThe objective of the study was to investigate the performance at frying temperature of a new sunflower oil with high content of oleic and palmitic acid (HOHPSO) and containing γ‐tocopherol as the most abundant natural antioxidant. HOHPSO either containing α‐ or γ‐tocopherol (HOHPSO‐α and HOHPSO‐γ, respectively) were obtained from genetically modified sunflower seeds and refined under identical conditions. The oil stability against oxidation, as measured by Rancimat at 120 °C, was much higher for the oil containing γ‐tocopherol, suggesting the higher effectiveness of γ‐tocopherol as compared to α‐tocopherol to delay oxidation. Experiments at high temperature (180 °C) simulating the conditions applied in the frying process clearly demonstrated that, for the same periods of heating, the oil degradation and the loss of natural tocopherol were significantly lower for the oil containing γ‐tocopherol. Comparison of different genetically modified sunflower oils with different fatty acid compositions confirmed that oil degradation depended on the fatty acid composition, being higher at a higher degree of unsaturation. However, the loss of tocopherol for a similar level of oil degradation was higher as the degree of unsaturation decreased. Overall, the results showed that HOHPSO‐γ had a very high stability at frying temperatures and that mixtures of HOHPSO‐α and HOHPSO‐γ would be an excellent alternative to fulfill the frying performance required by the processors and the vitamin E content claimed by the consumers.
J‐Based Analysis and DFT–NMR Assignments of Natural Complex Molecules: Application to 3β,7‐Dihydroxy‐5,6‐epoxycholestanes
Authors: Poza Jesús Javier , Jiménez Carlos , Rodríguez Jaime 
Published: July 2008

AbstractIn order to reproduce the stereochemical dispositions of the epoxy and hydroxy functionalities, four 3β,7‐hydroxy‐5,6‐epoxycholestanes were easily prepared from cholesterol, and their NMR spectroscopic data were experimentally obtained from 1D and 2D NMR experiments. An exhaustive QM‐J‐based analysis was then performed to replicate the experimental H–H and C–H coupling constants as well as the 13C NMR chemical shifts. The B3LYP GIAO methodology with the 6‐311‐G(d,p) basis set was chosen and showed that the data obtained from rings A and B were sufficient to calculate the correct stereochemistry of the 5,6‐epoxy and 7‐hydroxy groups. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of α,α‐Difluoro‐β‐amino Esters or gem‐Difluoro‐β‐lactams as Potential Metallocarboxypeptidase Inhibitors
Authors: Boyer Nicolas , Gloanec Philippe , De Nanteuil Guillaume , Jubault Philippe , Quirion Jean‐Charles 
Published: July 2008

AbstractThe synthesis of gem‐difluorinated β‐lactams and gem‐difluorinated β‐amino acids, each possessing a potential basic functional group, from ethyl bromodifluoroacetate and either imines (for β‐lactams) or N‐(α‐aminoalkyl)benzotriazoles (for β‐amino esters) was investigated. A series of these compounds were used for the design of novel metallocarboxypeptidase inhibitors. N‐Alkylation and N‐acylation of these two versatile scaffolds were carried out, leading to the expected targets in moderate to good yields.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Tuning the Chemoselectivity of the Metathesis Reactions of N‐Substituted 2‐Azabicyclo[2.2.1]hept‐5‐en‐3‐one
Authors: Aljarilla Ana , Plumet Joaquín 
Published: July 2008

AbstractBy using the second‐generation Hoveyda–Grubbs precatalyst, the metathesis transformations of N‐substituted 2‐azabicyclo[2.2.1]hept‐5‐en‐3‐one derivatives have been explored. In the absence of any external alkene (cross‐metathesis partner), substituted pyrrolizidin‐3‐one derivatives were obtained by ring‐opening metathesis/ring‐closing metathesis tandem reactions. In the presence of an external alkene, N‐substituted 2‐pyrrolidinones were isolated by ring‐opening metathesis/cross metathesis tandem reactions. In this case, and by using an alkene other than ethylene (allyltrimethylsilane), the reaction was totally chemo‐ and diastereoselective. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Electrochemistry of Mitochondria: A New Way to Understand Their Structure and Function
Authors: Zhao Jing , Meng Fanben , Zhu Xiaoli , Han Kun , Liu Shanli , Li Genxi 
Published: July 2008

AbstractIn this article, electrochemistry of mitochondria is achieved. Cyclic voltammograms of freshly prepared mitochondria were obtained by immobilizing mitochondria together with glutaraldehyde and bovine serum albumin on the surface of a pyrolytic graphite electrode. Two pairs of redox peaks could be observed which were ascribed to the electron transfer reactions of cytochrome c and FAD/FADH2. Study of submitochondrial particles was also conducted, which could confirm the results of the study of the entire mitochondria. The redox wave of NADH could be obtained due to the destruction of the membrane of mitochondria. We have also checked the function of succinate in mitochondria by employing the electrochemical method. This work is not only the first to be able to obtain the direct electrochemistry of mitochondria, but is also beneficial to the further understanding of the structure and function of mitochondria in vitro.
Underivatized cyclic olefin copolymer as substrate material and stationary phase for capillary and microchip electrochromatography
Authors: Gustafsson Omar , Mogensen Klaus B. , Kutter Jörg P. 
Published: July 2008

AbstractWe report, for the first time, the use of underivatized cyclic olefin copolymer (COC, more specifically: Topas) as the substrate material and the stationary phase for capillary and microchip electrochromatography (CEC), and demonstrate chromatographic separations without the need of coating procedures. Electroosmotic mobility measurements in a 25 μm id Topas capillary showed a significant cathodic EOF that is pH‐dependent. The magnitude of the electroosmotic mobility is comparable to that found in glass substrates and other polymeric materials. Open‐tubular CEC was employed to baseline‐separate three neutral compounds in an underivatized Topas capillary with plate heights ranging from 5.3 to 12.7 μm. The analytes were detected using UV absorbance at 254 nm, thus taking advantage of the optical transparency of Topas at short wavelengths. The fabrication of a Topas‐based electrochromatography microchip by nanoimprint lithography is also presented. The microchip has an array of pillars in the separation column to increase the surface area. The smallest features that were successfully imprinted were around 2 μm wide and 5 μm high. No plasma treatment was used during the bonding, thus keeping the surface properties of the native material. An RP microchip electrochromatography separation of three fluorescently labeled amines is demonstrated on the underivatized microchip with plate heights ranging from 3.4 to 22 μm.
Optimization of Two‐Step Cotton Scouring with β‐Cyclodextrin and Alkaline Pectinase
Authors: Wang Q. , Fan X. , Yuan J. , Wang P. , Cui L. , Chen J. 
Published: July 2008

AbstractThe hydrophobic cuticle of cotton fibers has formed a natural barrier for individual pectinases to catalyze its substrates (pectins beneath the cuticle), thus resulting in an insufficient bio‐scouring. β‐Cyclodextrin with a special non‐polar cavity is accommodating some organic compounds (dyestuffs, functional finishes, etc.) to form stable inclusion complexes. It has been demonstrated that β‐cyclodextrin can be used as a scouring agent of cotton fabric because this special inclusion helps to remove hydrophobic waxes in the cuticle of cotton. Considering possible synergetic effects between pectinase and β‐cyclodextrin which might lead to better cotton scouring effects, two reverse cases of scouring processing, β‐CD treatment followed by pectinase treatment and pectinase treatment followed by β‐cyclodextrin treatment, were put forward. For each scouring processing, optimal scouring parameter dosages of pectinase and β‐cyclodextrin as well as incubation time were determined by means of wettability. β‐CD treatment followed by pectinase treatment produced a better scouring effect than β‐CD treatment following pectinase treatment because the partially elimination of hydrophobic waxes and fats in the cotton cuticle could increase the accessibility of the subsequent pectinase to the substrates. Finally, the whiteness and strength of the bleached cotton fabrics and the K/S values (color depth) of the dyed cotton fabrics were measured and compared with those of conventionally alkali‐treated ones.
Combined Bio‐carbonization and Dyeing of Wool: A Possibility Using Cell Wall‐Degrading Enzymes and 1:1 Metal–Complex Dyes
Authors: Gouveia I. C. , Fiadeiro J. M. , Queiroz J. A. 
Published: July 2008

AbstractThis study was undertaken to investigate the possibility of a new process to remove plant residues from wool, using enzymes as biocatalysts together with a dyeing process in a two‐step exhaustion process, performed in a single bath. The enzymes were selected in order to hydrolyze the polysaccharides in primary plant cell walls and middle lamella, resulting in more fragile residues easier to be removed. Commercial enzymatic preparations of Trichoderma reesei and Aspergillus aculeatus were used, after appropriate optimization. A total enzyme loading of 1.0 mL/L of each enzymatic preparation yielded an equivalent amount of 241.2 mg of glucose per gram of plant residue, under the optimal conditions: 40.5 °C, pH 4.0, and 0.75 mL/L of a non‐ionic wetting agent. Reducing groups of the total released sugars were determined with the Miller reactive 3,5‐dinitrosalicilic acid (DNS), which has been used for the indirect measurement of the efficiency of the process. Furthermore, to enhance the degradation of the plant residues, dyeing processes using the incubation bath and several acid and metal–complex dyes, usually applied on wool dyeing, were tested. The dyeing procedure with 1:1 metal–complex dyes adjusted to pH 1.9 with sulfuric acid has promoted a higher degradation of the plant residues without damaging wool fibers. Accordingly, higher concentration of glucose was detected by the DNS reagent and higher weight losses of the plant residues were obtained when compared to enzymatic treatment without dyeing. The low pH used in the dyeing procedure increases the degradation of the cell wall polysaccharides, by acid catalysis. Also, scanning electron microscopy was used to show the plant cell wall degradation.