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Selected AbstractsEffect of temperature and isomorphic atom substitution on optical absorption edge of TlInS2xSe2(1-x) mixed crystals (0.25 , x , 1)CRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2010N. M. Gasanly Abstract The optical properties of the TlInS2xSe2(1-x)mixed crystals (0.25 , x , 1) have been investigated through the transmission and reflection measurements in the wavelength range of 400,1100 nm. The optical indirect band gap energies were determined by means of the analysis of the absorption data. It was found that the energy band gaps decrease with the increase of selenium atoms content in the TlInS2xSe2(1-x)mixed crystals. The transmission measurements carried out in the temperature range of 10,300 K revealed that the rates of change of the indirect band gaps with temperature are , = ,9.2×10,4 eV/K, ,6.1×10,4 eV/K, ,4.7×10,4 eV/K and ,5.6×10,4 eV/K for TlInS2, TlInS1.5Se0.5, TlInSSe and TlInS0.5Se1.5 crystals, respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of substrate temperature on the properties of electron beam evaporated ZnSe filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2010M. G. Syed Basheer Ahamed Abstract ZnSe films were deposited on glass substrates keeping the substrate temperatures, at room temperature (RT), 75, 150 and 250 °C. The films have exhibited cubic structure oriented along the (111) direction. Both the crystallinity and the grain size increased with increasing deposition temperature. A very high value of absorption co-efficient (104 cm -1) is observed. The band gap values decrease from a value of 2.94 eV to 2.69 eV with increasing substrate temperature. The average refractive index value is in the range of 2.39 , 2.41 for the films deposited at different substrate temperatures. The conductivity values increases continuously with temperature. Laser Raman spectra showed peaks at 140.8 cm -1, 246.7 cm -1and 204.5 cm -1which are attributable to 2TA LO phonon and TO phonon respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of single-grain GdBa2Cu3O7-x superconductors by top seeded infiltration and growth techniqueCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2010Guo-Zheng Li Abstract The top seeded infiltration and growth technique (TSIG) is an effective way for the preparation of bulk REBa2Cu3O7-x (RE-123, where RE denotes rare earth) with finely dispersed RE2BaCuO5 (RE-211) particles compared to the conventional melt growth (MG) method. The nucleation temperature and the ending growth temperature are the most important parameters need to be optimized during the preparation of RE-123 bulks by the TSIG process. In this paper, the effects of these parameters on the growth of single-grain GdBa2Cu3O7-x (GdBCO) superconductors have been investigated experimentally. It is found that the temperature for the growth of single-grain GdBCO is in the region between 1040 °C and 1015 °C. In addition, the relation between growth rate and supercooling has been investigated in detail. The combined techniques of SEM and EDS were used to study the microstructure of the samples grown at different temperatures. Based on this, a two-step slow cooling method during the crystallization process is proposed for the fabrication of RE-123 bulks. Finally, the single-grain GdBCO samples of the diameters 20 mm and 30 mm were fabricated successfully by the TSIG technique, with the slow-cooling process in the temperature window 1030 °C,1020 °C for 60 h and 100 h respectively. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Temperature-tuned band gap energy and oscillator parameters of Tl2InGaSe4 semiconducting layered single crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2009N. M. Gasanly Abstract The optical properties of Tl2InGaSe4 layered single crystals have been studied through the transmission and reflection measurements in the wavelength range of 500-1100 nm. The analysis of room temperature absorption data revealed the presence of both optical indirect and direct transitions with band gap energies of 1.86 and 2.05 eV, respectively. Transmission measurements carried out in the temperature range of 10-300 K revealed that the rate of change of the indirect band gap with temperature is , = , 4.4 × 10 -4 eV/K. The absolute zero value of the band gap energy was obtained as Egi(0) = 1.95 eV. The dispersion of the refractive index is discussed in terms of the single oscillator model. The refractive index dispersion parameters: oscillator wavelength and strength were found to be 2.53 × 10,7 m and 9.64 × 1013 m,2, respectively. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of material, thermal and laser conditioning on the damage threshold of type II tripler-cut DKDP crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2008Shao-Tao Sun Abstract By using the traditional temperature-reduction method, KD2PO4 (DKDP) crystals were grown from 85%-deuterated aqueous solution synthesized by different kind of KH2PO4 (KDP) raw materials. An experimental technique was employed to measure the variation of bulk damage threshold in plates of DKDP crystals. Bulk laser damage in unconditioned, thermal-conditioned and laser-conditioned type II tripler-cut DKDP crystals has been studied using 1064 nm (,) and 355 nm (3,) laser at pulse lengths of 5ns, 5ns respectively. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of ZnO single crystals by an induced nucleation from a high temperature solution of the ZnO-PbF2 systemCRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2007Xinhua Li Abstract To grow ZnO single crystals from a high temperature solution of the ZnO-PbF2 system, a gas cooling system was assembled at the bottom of the crucible to induce nucleation in the initial growth stage. The growth experiments were carried out in a homemade vertical Bridgman furnace and Pt crucible of 28 mm in diameter was used. The furnace temperature was set to 1100°C and the flow rate of the oxygen gas was optimized as 3.0 l/min. ZnO crystal up to 5,8mm in the thickness was obtained with the lowering rate of 0.3 mm/h. XRD patterns showed that the as-grown crystal was pure ZnO Wurtzite phase. The impurity ions were analyzed by the glow discharge mass spectroscopy (GDMS) as 390.0 ppm and 40.0 ppm for Pb2+ and F - , respectively. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Electrical and optical properties of CdS nanocrystalline semiconductorsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2006Shikha Tiwari Abstract II-VI semiconductor nanoparticles have recently attracted a lot of attention due to the possibility of their application in various devices. In the present study, chemical method has been used in synthesis of CdS nanoparticles and thiophenol was used as capping agent. X-ray diffraction studies of both samples were done. The dc conductivity of CdS increases at a lower rate or is approximately constant upto 500K and thereafter the conductivity increases at a rapid rate. Beyond Tc it is seen that the portion of the ,dc versus 1000/T is almost a straight line showing an Arrehenious behaviour. The dielectric constant of nanoparticles of CdS is found to be larger than the corresponding values of CdS crystals. It is clearly observed that at lower wavelengths nanocrystalline samples show a blue-shift. The three peaks of sample (S2), A, Band C can be ascribed to the transition from Cd-O complex donor formed by adsorbed oxygen to the valance band, Cd - excess acceptor and the surface states, respectively. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Convergence of multisensory inputs in Xenopus tadpole tectumDEVELOPMENTAL NEUROBIOLOGY, Issue 14 2009Masaki Hiramoto Abstract The integration of multisensory information takes place in the optic tectum where visual and auditory/mechanosensory inputs converge and regulate motor outputs. The circuits that integrate multisensory information are poorly understood. In an effort to identify the basic components of a multisensory integrative circuit, we determined the projections of the mechanosensory input from the periphery to the optic tectum and compared their distribution to the retinotectal inputs in Xenopus laevis tadpoles using dye-labeling methods. The peripheral ganglia of the lateral line system project to the ipsilateral hindbrain and the axons representing mechanosensory inputs along the anterior/posterior body axis are mapped along the ventrodorsal axis in the axon tract in the dorsal column of the hindbrain. Hindbrain neurons project axons to the contralateral optic tectum. The neurons from anterior and posterior hindbrain regions project axons to the dorsal and ventral tectum, respectively. While the retinotectal axons project to a superficial lamina in the tectal neuropil, the hindbrain axons project to a deep neuropil layer. Calcium imaging showed that multimodal inputs converge on tectal neurons. The layer-specific projections of the hindbrain and retinal axons suggest a functional segregation of sensory inputs to proximal and distal tectal cell dendrites, respectively. © 2009 Wiley Periodicals, Inc. Develop Neurobiol, 2009 [source] Complementary expression and heterophilic interactions between igLON family members neurotrimin and LAMPDEVELOPMENTAL NEUROBIOLOGY, Issue 3 2002Orlando D. Gil Abstract Neurotrimin (Ntm) and the limbic system-associated membrane protein (LAMP) are members of the IgLON (LAMP, OBCAM, Ntm) family of glycorylphosphatidylinositol anchored neural cell adhesion molecules. We previously reported that LAMP and Ntm promote adhesion and neurite outgrowth via a homophilic mechanism, suggesting that these proteins promote the formation of specific neuronal circuits by homophilic interactions. In this report, we have further characterized the expression and binding specificity of Ntm. Using a newly generated monoclonal antibody to Ntm, we demonstrated that this protein is largely expressed in a complementary pattern to that of LAMP in the nervous system, with co-expression at a few sites. Ntm is expressed at high levels in sensory-motor cortex and, of particular note, is transiently expressed in neurons of cortical barrel fields and corresponding thalamic "barreloids." Binding of a recombinant, soluble form of Ntm to CHO cells expressing either Ntm or LAMP demonstrates that Ntm and LAMP interact both homophilically and heterophilically. In contrast to conventional growth-promoting activity of Ig superfamily members, LAMP strongly inhibits the outgrowth of Ntm-expressing dorsal root ganglion (DRG) neurons in a heterophilic manner. These anatomical and functional data support the concept that homophilic and heterophilic interactions between IgLON family members are likely to play a role in the specification of neuronal projections via growth promoting and inhibiting effects, respectively. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 190,204, 2002 [source] Development of 230,270 nm AlGaN-based deep-UV LEDsELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 3 2010Hideki Hirayama Abstract We demonstrated AlGaN multi-quantum well (MQW) deep-ultraviolet (UV) light-emitting diodes (LEDs) with wavelengths in the range of 227.5 to 273 nm fabricated on high-quality AlN buffers on sapphire substrates grown by metal-organic chemical vapor deposition (MOCVD). We realized crack-free, thick AlN buffers on sapphire with a low threading dislocation density (TDD) and an atomically flat surface by using the ammonia (NH3) pulse-flow multilayer (ML) growth technique. We obtained single-peaked operation of an AlGaN-MQW LED with a wavelength of 227.5 nm, which is the shortest wavelength of AlGaN-based LED on sapphire. The maximum output power and the external quantum efficiency (EQE) of the 261- and 227.5-nm LEDs were 1.65 mW and 0.23% in room-temperature (RT) continuous-wave (CW) operation, and 0.15 mW and 0.2% in RT pulsed operation, respectively. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(3): 24,33, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10197 [source] Comparison of air quality management strategies of PM10, SO2, and NOx by an industrial source complex model in BeijingENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2007Gaoxiang Ying Abstract The primary air pollutants in the Beijing urban area are fine particulate matter (PM10), sulfur dioxide (SO2), and nitrogen oxides (NOx). Using suitable emission factors for point, area, and line sources from 20 categories of industrial, commercial, domestic and traffic, total yearly mean emissions were estimated at 103.3 kton of PM10, 209.9 kton of SO2, and 225.4 kton of NOx in 1999. To abate this elevated air pollution, three air quality management schemes are adopted. After the implementation, the annual mean ground-level concentrations of air pollutants are predicted by an industrial source complex short term (ISCST3) dispersion model and compared by the geographic information system (GIS). The ISCST3 dispersion model is used by inputting emission inventory and meteorological data with 1 h temporal and 1 km × 1 km spatial resolution. The model validity is verified by its agreement with monitoring data from Beijing's Environmental Protection Bureau. Results indicate that the levels of PM10, SO2, and NOx in Beijing are improved gradually because of the adoption of these three control schemes. The predicted annual mean concentrations decreased from 90.63 to 67.28 ,g/m3 for PM10, 57.94 to 31.77 ,g/m3 for SO2, and 119.97 to 73.83 ,g/m3 for NOx, respectively. © 2007 American Institute of Chemical Engineers Environ Prog 26:33,42, 2007. [source] Reaction kinetics for the degradation of phenol and chlorinated phenols using Fenton's reagentENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 1 2006Asim K. De Abstract Fenton's reaction is an advanced treatment technology often used for the removal of hazardous and refractory organic compounds from industrial wastewaters. It can effectively be used to degrade phenol and chlorophenols. The initial contaminant concentrations as well as the concentration of hydrogen peroxide and ferrous ions in aqueous solution have a significant effect on the effective degradation of contaminants. For a particular concentration of initial substrate in solution there should be an optimum level of ferrous ion concentration in the reaction medium. Based on experimental observations, a probable mechanism for Fenton's degradation kinetics has been proposed and a rate equation developed. From the rate expression, OH· radical reaction rate constants for the degradation of three compounds,phenol and o- and p-chlorophenols,in Fenton reaction were calculated to have values of 2.53 × 107, 2.38 × 107, and 2.45 × 107 m3 mol,1 s,1, respectively. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Optimization of the simultaneous removal of nitrogen and organic matter from fishery wastewatersENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2005Estrella Aspé Abstract Anaerobic treatment of saline and protein-rich effluents reduces the organic concentration but forms ammonium that hinders nitrogen removal in a later aerobic treatment. The goal of this work was to optimize the design of a denitrifying,nitrifying system for the simultaneous removal of organic matter and nitrogenous compounds from fishery effluents to meet the Chilean legal standards and to compare pre- and postdenitrification processes in the biological treatment of high-strength effluents to minimize the total volume of biological reactors required. A predenitrifying system, that included three reactors,acidifying anaerobic filter, denitrifying (anoxic) filter, and aerobic-active sludge (nitrifying reactor) with recycle to the denitrifying reactor,reduced nitrogen to 0.33 g of total ammonia nitrogen (TAN) L,1, well above the allowed 0.05 g total nitrogen L,1. The predenitrifying system with a second denitrifying reactor, to which organic matter was added, met the legal organic matter and nitrogen emission concentrations (0.042 g TAN L,1). Conversions were 99.0, 92.5, 90.9, and 99.0% for the anaerobic digestion, first denitrification, nitrification, and second denitrification, respectively. © 2005 American Institute of Chemical Engineers Environ Prog, 2005 [source] Determination of chiral ratio of o,p -DDT and o,p -DDD pesticides on polysaccharides chiral stationary phases by HPLC under reversed-phase modeENVIRONMENTAL TOXICOLOGY, Issue 4 2002Imran Ali Abstract A simple and reliable HPLC method for the chiral resolution of o,p -DDT and o,p -DDD is described. The enantiomeric resolution of o,p -DDT and o,p -DDD has been achieved on Chiralpak AD-R, Chiralcel OD-R, and Chiralcel OJ-R chiral stationary phases. The mobile phases used were acetonitrile,water (50:50 [v/v]) and acetonitrile-2-propanol (50:50 [v/v]) at a flow rate of 1.0 mL/min. For both pesticides detection was done at 220 nm. The values for o,p -DDT of , and Rs varied from 1.24 to 2.52 and from 0.80 to 2.47, respectively. The values of , and Rs for o,p -DDD were 1.26 and 0.60, respectively. © 2002 Wiley Periodicals, Inc. Environ Toxicol 17: 329,333, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/tox.10069 [source] Cross-cultural assessment of eating disorders: psychometric properties of a Spanish version of the Bulimia Test-Revised,EUROPEAN EATING DISORDERS REVIEW, Issue 6 2007Mayra N. Berrios-Hernandez Abstract The purpose of this study was to examine the psychometric properties of a Spanish version of the Bulimia Test-Revised (BULIT-R). The goal was to test the factor-structure equivalence of the BULIT-R across two samples of college students from two different cultures, Spain and the US. Researchers using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) have reported different model solutions for the factor-structure of the BULIT-R: a one-factor model, a four-factor model, a five-factor model and a six-factor model. For the two samples, CFA did not support any of the models previously reported in the literature. EFA supported a six- and a four-factor models for the US and Spanish samples, respectively. © 2007 John Wiley & Sons, Ltd and Eating Disorders Association. [source] Synthesis and Cytotoxicity Studies of Fluorinated Derivatives of Vanadocene YEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 19 2009Brendan Gleeson Abstract From the reaction of 6-(2-fluoro-4-methoxyphenyl)fulvene (1a), 6-(3-fluoro-4-methoxyphenyl)fulvene (1b) and 6-[4-(trifluoromethoxy)phenyl]fulvene (1c) with LiBEt3H, lithiated cyclopentadienide intermediates (2a,c) were synthesised. These intermediates were then transmetallated to vanadium with VCl4 to yield the benzyl-substituted vanadocenes bis[(2-fluoro-4-methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3a), bis[(3-fluoro-4-methoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3b), and bis[(4-trifluoromethoxybenzyl)cyclopentadienyl]vanadium(IV) dichloride (3c). The three vanadocenes 3a,c were characterised by single-crystal X-ray diffraction. All three vanadocenes had their cytotoxicity investigated through MTT-based preliminary in-vitro testing on the LLC-PK and Caki-1 cell lines in order to determine their IC50 values. Vanadocenes 3a,c were found to have IC50 values of 6.0 (+/,4), 35 (+/,7) and 13 (+/,3) ,M on the LLC-PK cell line and IC50 values of 78 (+/,11), 18 (+/,16) and 2.2 (+/,0.5) ,M on the Caki-1 cell line respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis, Structure, Conductivity, and Calculated Nonlinear Optical Properties of Two Novel Bis(triphenylphosphane)copper(I) Dithiocarbamates,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2009Abhinav Kumar Abstract A centrosymmetric binuclear [{Cu(PPh3)2}2(piperzdtc)] (1) [piperzdtc2, = piperazinebis(dithiocarbamate)] and another mononuclear [{Cu(PPh3)2}(BzMedtc)] (2) (BzMedtc, = N -benzyl- N -methyldithiocarbamate) complex have been synthesized and characterized by elemental analyses, IR, 1H, 13C, and 31P NMR spectroscopy and by X-ray crystallography. The nonlinear optical properties of 2 have been investigated by density functional theory and its electronic absorption bands have been assigned by time-dependent density functional theory (TD-DFT). Both complexes are weakly conducting (,rt , 10,8 S,cm,1) because of the absence of M···S/S···S intermolecular stacking and exhibit semiconductivity with band gaps of 0.94 and 1.24 eV, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The Oriented Self-Assembly of Magnetic Fe3O4 Nanoparticles into Monodisperse Microspheres and Their Use as Substrates in the Formation of Fe3O4 NanorodsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Guangcheng Xi Abstract We describe a facile solvothermal route for the large-scale preparation of ferromagnetic Fe3O4 sub-micrometer spheres and nanorods by using FeCl3 as the iron source, oleic acid as the surfactant, and ethylene glycol as the reducing agent and solvent. The as-synthesized Fe3O4 microspheres are composed of a mess of Fe3O4 nanoparticles with a size of 10 nm and have nearly monodisperse diameters that can be controlled in the range 100,410 nm. HRTEM images and SAED patterns show that these microspheres present a "single-crystalline" nature, which can be attributed to the highly oriented assembly of the small Fe3O4 nanoparticles. Interestingly, by using the pre-synthesized Fe3O4 microspheres as the growth substrate, single-crystalline Fe3O4 nanorods can be formed on the surfaces of the microspheres. These nanorods are about 7,20 nm in diameter and 120,400 nm in length, and have smooth surfaces. The formation mechanisms of the Fe3O4 microspheres and nanorods have been investigated and discussed. Furthermore, the magnetic properties of the as-synthesized microspheres and nanorods have also been investigated and the magnetization saturation values are 74.6 and 92.3 emu/g, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] N -(Aryl)picolinamide Complexes of Ruthenium: Usual Coordination and Strategic CyclometalationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007Sumon Nag Abstract Reaction of five N -(4- R -phenyl)picolinamides (R = OCH3, CH3, H, Cl, and NO2) with [Ru(PPh3)2(CO)2Cl2] in refluxing 2-methoxyethanol in the presence of a base (NEt3) affords two geometrical isomers of a group of complexes (1-R and 2-R), each of which contains an amide ligand coordinated to the metal center as a monoanionic bidentate N,N donor along with two triphenylphosphanes, a carbonyl, and a hydride. Similar reaction of N -(naphthyl)picolinamide with [Ru(PPh3)2(CO)2Cl2] affords an organometallic complex, 3, in which the amide ligand is coordinated to the metal center, by C,H activation of the naphthyl ring at the 8-position, as a dianionic tridentate N,N,C donor along with two triphenylphosphanes and one carbonyl. Structures of the 1-OCH3, 2-CH3, and 3 complexes have been determined by X-ray crystallography. In all the complexes the two triphenylphosphanes are trans. In the 1-R complexes the hydride is trans to the pyridine nitrogen and in the 2-R complexes it is trans to the amide-nitrogen. All the complexes are diamagnetic, and show characteristic 1H NMR signals and intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a RuII,RuIII oxidation within 0.71,0.93 V versus SCE. An oxidation and a reduction of the coordinated amide ligand are also observed within 1.29,1.69 V versus SCE and ,1.02 to ,1.21 V versus SCE respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Crystal Structure, Solid-State NMR Spectroscopic and Photoluminescence Studies of Organic-Inorganic Hybrid Materials (HL)6[Ge6(OH)6(hedp)6]·2(L)·nH2O, L = hqn or phen,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2006Luís Mafra Abstract Two germanium,hedp4, solids with heteroaromatic amines 8-hydroxyquinoline (hqn) and 1,10-phenanthroline (phen), (HL)6[Ge6(OH)6(hedp)6]·2(L)·nH2O (L = hqn or phen), in I and II respectively, have been prepared and characterised by single-crystal XRD, thermogravimetry, FTIR and UV/Vis spectroscopy. The complex hydrogen-bond networks, particularly in compound I, have been studied by advanced high-resolution solid-state NMR spectroscopy that combines homonuclear recoupling techniques (two-dimensional 1H- 1H DQF and 1H- 1H RFDR MAS NMR) and combined rotation and multiple-pulse spectroscopy (two-dimensional 1H- 1H FS-LG, 1H- 31P FS-LG). The fine details of the crystal structure of I have been elucidated, mainly those involving the ,,, stacking of 8-hydroxyquinoline and the relative orientation of adjacent such molecules. Compound II exhibits an emission from the lowest triplet-state energy (,,,* 0-phonon transition) of the aromatic rings at 320 nm (31250 cm,1) from 14 K to room temperature. In contrast, the triplet emission of I at 530 nm (18868 cm,1) is only detected at low temperature, because of thermally activated non-radiative mechanisms. The emission spectra of I and II display a lower-energy component with a larger life time, which results from the formation of an excimer state that originated from the ,,, phenanthroline and hydroxyquinoline interactions, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A Theoretical Investigation of Substituent Effects on the Absorption and Emission Properties of a Series of Terpyridylplatinum(II) Acetylide ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2005Xiao-Juan Liu Abstract A comprehensive calculational investigation has been carried out on a series of complexes of the type [(terpyridyl-R1)Pt(C,C-R2)], where terpyridyl-R1 is a series of substituted 2,2':6',2"-terpyridyl ligands and C,C-R2 is a series of substituted acetylide ligands. In one series of complexes (I), the energy of the electronic excited state is varied by changing the substituents on the terpyridyl ligand (R1). In a second series of complexes (II), this electronic structure variation is obtained by changing the para substituents (R2) of the acetylide ligand. The effect of varying the substituents on the lowest-energy excited states of the complexes has been assessed by calculating their electronic structures and excitation energies. We anticipated that introduction of electron-withdrawing substituents on the terpyridyl ligand will benefit the LLCT (or MLCT) and prohibit the nonradiative pathways via d-d transitions in these complexes; introduction of electron-donating substituents on the acetylide ligand can also prohibit the nonradiative pathways by increasing the energy gaps between the HOMO,LUMO and d-d transitions. The results also reveal that the lowest-energy excitations of all complexes of series I and IIa,b complexes are dominated by a ,(C,C),,,,*(terp) (LLCT) transition mixed with some energetically d,(Pt),,,terpyridyl (MLCT) transition. However, for the complexes IIc,IId, in which phenyl rings are introduced on the acetylide ligand, the lowest-lying absorptions of IIc and IId are predominately LLCT in character, with less MLCT mixture, due to a lower contribution of the Pt(d) orbital to the HOMO, while for IIe, with a stronger donor on the acetylide, the lowest-lying absorption is completely LLCT in character. The absorption and emission calculations using the TDDFT method are based on the optimized geometries obtained at the B3LYP/LanL2DZ and CIS/LanL2DZ levels, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Lithium and Potassium Amides of Sterically Demanding AminopyridinesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2004Natalie M. Scott Abstract The reaction of Grignard compounds of 1-bromo-2,4,6-diisopropylbenzene (1) or 1-bromo-2,6-dimethylbenzene (2), formed in situ, with 2,6-dibromopyridine in the presence of a catalytic amount of [(dme)NiBr2] (dme = 1,2-dimethoxyethane) and tricyclohexylphosphane (1:2 ratio) leads to the corresponding monoarylated bromopyridines. These bromopyridines undergo Pd-catalysed aryl amination (Buchwald,Hartwig amination) with 2,6-diisopropylaniline giving rise to (2,6-diisopropylphenyl)[6-(2,4,6-triisopropylphenyl)pyridin-2-yl]amine (Ap*H) and (2,6-diisopropylphenyl)[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (Ap,H) (Ap = aminopyridinate). Deprotonation of Ap*H in diethyl ether using BuLi results (after workup in hexane) in a colourless crystalline material. X-ray structural analysis reveals it to be a monomeric three-coordinate lithium aminopyridinate. In toluene solution, an equilibrium between [(Ap*Li)2] (in excess at room temperature) and [Ap*Li(OEt2)] (prominent at low temperature) is observed. Reaction of Ap,H with BuLi in diethyl ether gives rise to [Ap*LiAp*Li(OEt2)]. Deprotonation of Ap*H and Ap,H using KH leads to [Ap*K]n and [Ap,K],, respectively. [Ap,K], is a rare example of a crystalline organometallic polymer, as determined by X-ray analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Extended X-ray Absorption Fine Structure Study of Copper(I) and Copper(II) Complexes in Atom Transfer Radical PolymerizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2003Tomislav Pintauer Abstract Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy has been used to investigate structural features of CuIBr and CuIIBr2 complexes with dNbpy, PMDETA, Me6TREN, tNtpy, and Me4CYCLAM in various solvents {dNbpy = 4,4,-bis(5-nonyl)-2,2,-bipyridine, PMDETA = N,N,N,,N,,,N,, -pentamethyldiethylenetriamine, Me6TREN = tris[2-(dimethylamino)ethyl]amine, tNtpy = 4,4,,4,,-tris(5-nonyl)-2,2,:6,,2,,-terpyridine, Me4CYCLAM = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane}. The structures of the CuI and CuII complexes were found to depend on the solvent polarity and the number of nitrogen atoms in the ligand. Generally, in non-polar media and with monomers typically used in ATRP, CuI complexes preferred a tetracoordinate geometry, and were either ionic as observed in [CuI(dNbpy)2]+[CuIBr2], (CuI,NAV = 2.00 Å, CuI,BrAV = 2.25 Å) and [CuI(Me4CYCLAM)]+[CuIBr2], (CuI,NAV = 2.06 Å, CuI,BrAV = 2.23 Å), or neutral as in [CuI(PMDETA)Br] (CuI,NAV = 2.12 Å, CuI,BrAV = 2.33 Å), and [CuI(tNtpy)Br] (CuI,NAV = 2.03 Å, CuI,BrAV = 2.29 Å). The EXAFS analysis of CuIIBr2 complexes indicated a preference for a coordination number of five, such as in [CuII(dNbpy)2Br]+[Br], (CuII,NAV = 2.03 Å, CuII,BrAV = 2.43 Å), [CuII(PMDETA)Br2] (CuII,NAV = 2.03 Å, CuII,Br1,AV = 2.44 Å, CuII,Br2,AV = 2.64 Å) and [CuII(Me6TREN)Br]+[Br], (CuII,NAV = 2.09 Å, CuII -BrAV = 2.39 Å), with the exception of the neutral tetracoordinate [CuII(dNbpy)Br2] (CuII,NAV = 2.02 Å, CuII,BrAV = 2.36 Å), which has been observed in non-polar media. Additionally, polar media were found to favor bromide dissociation in [CuII(Me6TREN)Br]+[Br], and [CuII(PMDETA)Br2], as indicated by a decrease in the Br and Cu coordination numbers at the Cu- and Br- K -edges, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Direct Synthesis of (PhSe)4Ge and (PhTe)4Ge from Activated Hydrogenated Germanium , Crystal Structure and Twinning of (PhTe)4GeEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2003Sabine Schlecht Abstract The germanium chalcogenolates (PhSe)4Ge and (PhTe)4Ge were synthesized from activated hydrogenated germanium (Ge*) and diphenyldiselenide or diphenylditelluride, respectively. (PhTe)4Ge is the first homoleptic organotellurolate of germanium. It was characterized spectroscopically and by X-ray crystal structure analysis. (PhTe)4Ge crystallizes in the monoclinic space group P21/c with a = 12.8018(14), b = 9.1842(9), c = 23.690(3) Å and , = 105.458(8)°. The molecules show a tetrahedral GeTe4 core. Weak Te-Te interactions connect neighbouring tetrahedra to infinite helices along [010]. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Ilicic Acid as a Natural Quiron for the Efficient Preparation of Bioactive ,- and ,-EudesmolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2009Alejandro F. Barrero Abstract An efficient procedure for the isolation of the sesquiterpene ilicic acid (3) on a multigram scale of extracts obtained from aerial parts of Inula viscosa (Asteraceae) was developed. Acid 3 is an appropriate starting material for short, enantiospecific syntheses of ,-eudesmol (1) and ,-eudesmol (2), natural products featuring significant antiangiogenic and anti-Alzheimer properties. Synthesis of 1 was achieved in six steps and the synthesis of 2 in seven, producing overall yields of 52 and 41,%, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis of Enantiomerically Pure Highly Functionalized Furanoid Glycal and 2,5-Dihydrofuran Building Blocks,,§EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2009Pinki Pal Abstract Differently protected enantiomerically pure furanoid glycals (5a,d) and highly functionalized 2,5-dihydrofurans (6a,b) were synthesized from their respective 2,3,4-trisubstituted tetrahydrofurans. These furanoid glycals were identified as1,4-anhydro-2-deoxy-5,6- O -isopropylidene-3- O -benzyl- L -arabino-hex-1-enitol, 1,4-anhydro-2-deoxy-5,6- O -isopropylidene-3- O -benzyl- L -ribo-hex-1-enitol, 1,4-anhydro-2-deoxy-5,6- O -isopropylidene-3- O -benzyl- D -ribo-hex-1-enitol and 1,4-anhydro-2-deoxy-5,6- O -isopropylidene-3- O -benzyl- D -arabino-hex-1-enitol, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Enantiocomplementary Chemoenzymatic Asymmetric Synthesis of (R)- and (S)-ChromanemethanolEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2009Michael Fuchs Abstract A non-lipase-based, enantiocomplementary chemoenzymatic route towards enantiopure (R)- and (S)-chromanemethanol (12), which are the key building blocks for the synthesis of stereoisomerically pure ,-tocopherols, has been achieved by the biocatalytic resolution of a racemic 2,2-disubstituted oxirane using an epoxide hydrolase and a halohydrin dehalogenase, which exhibit opposite enantiopreferences. The introduction of chirality at an early stage of the synthesis ensured a high efficiency, leading to total overall yields of 16 and 26,% for (R)- and (S)-chromanemethanol (12), respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Syntheses of O6 -Alkyl- and Arylguanine Derivatives: Nucleobase Adducts Derived from Styrene 7,8- and 3,4-OxidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2006Jan Novák Abstract A series of O6 -alkyl and -arylguanine derivatives that may be formed in vivo after exposure to styrene has been prepared by reaction of 6-(4-aza-1-azoniabicyclo[2.2.2]octyl)-purine with alkoxides and aryloxides, respectively. Themonoprotected diols 2-allyloxy- or 2-benzyloxy-1-phenylethanol and 2-allyloxy- or 2-benzyloxy-2-phenylethanol were used as synthetic equivalents of styrene 7,8-oxide. 4-Vinylphenol, 2-(4-hydroxyphenyl)ethanol and 4-hydroxyphenylacetic acid were used as synthetic equivalents of arene oxide metabolites of styrene, i.,e., styrene 3,4-oxide, 4-(2-hydroxyethyl)benzene 1,2-oxide and 4-carboxymethylbenzene 1,2-oxide, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] On the Mechanism of the Reductive Metallation of Asymmetrically Substituted Silyl ChloridesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2005Martin Oestreich Abstract An investigation of the stereochemical course of the reductive metallation of silyl chlorides with silicon-centred chirality has revealed two major events which are detrimental to stereoselection during silyl anion formation: (1) chloride-induced racemisation of silyl chlorides and (2) nonstereoselective formal dimerisation during metallation providing the corresponding disilane. In control experiments, the stereochemical course of these processes has been independently verified for the reductive metallation of the enantioenriched cyclic silyl chloride (SiS)- 7a (R = H, er , 88:12). A screening of several related derivatives of (SiS)- 7a led to the sterically encumbered silyl chloride (SiR)- 7c (R = iPr, er , 94:6) which displays some unique features. This structural modification prevents racemisation by lithium chloride (T < ,40 °C) as well as dimerisation (T < ,100 °C) thus allowing for the first generation of an asymmetrically substituted silyl anion (SiS)- 8c (er = 74:26) by reductive metallation of a silyl chloride with silicon-centred chirality. Moreover, the enantiospecificity of the preparation of (SiR)- 7c by chlorination [(SiS)- 9c , (SiR)- 7c] and its reduction with aluminium hydrides [(SiR)- 7c , (SiR)- 9c] have been unambiguously determined by X-ray crystallography as retention (,99%) and inversion (,99%), respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Numerical taxonomic evaluation of calcium oxalate and calcium carbonate crystals in the leaves of certain Ficus species (Moraceae)FEDDES REPERTORIUM, Issue 5-6 2004S. M. Sharawy Dr. The type and the distribution of calcium oxalate and calcium carbonate crystals were investigated in the leaves of 33 taxa of Ficus belonging to the three subgenera Urostigma, Ficus and Sycomorus for a speculation to the inter-subgeneric affinity. Numerical analysis of 55 characters grouped the taxa under 13 groups. The sizes of the latter with respect to the number of taxa they contain were calculated. Some resultant groups comprised taxa from different subgenera. So far as the present data are concerned and in agreement with previous workers, the var. decora of Ficus elastica and var. comosa of Ficus benjamina are better raised to the specific levels F. decoraHort and F. comosaRoxb. respectively. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Numerisch-taxonomische Auswertung von Calciumoxalat- und Calciumcarbonat-Kristallen in einigen Arten der Gattung Ficus (Moraceae) An den Blättern von 33 Taxa der Gattung Ficus aus den drei Subgenera Urostigma, Ficus und Sycomorus wurden die Art und die Verteilung von Calciumoxalat- und Calciumcarbonat-Kristallen untersucht, um ihre inter-subgenerische Verwandtschaft zu ermitteln. Num-merische Analysen von 55 Eigenschaften gestatten eine Unterteilung in 13 Gruppen. Der Umfang letzterer in Bezug auf die Anzahl der sie umfassenden Taxa wurde betrachtet. Einige dieser Gruppen umfassen Taxa aus unterschiedlichen Subgenera. Auf Grund der hier gewonnenen Daten und in Übereinstimmung mit früheren Bearbeitern werden Ficus elastica var. decora und F. benjamina var. comosa in den Artrang F. decoraHort bzw. F. comosaRoxb. erhoben. [source] | ||||||||||||||||||||||||||||