Home About us Contact
|
Home About us Contact | ||
|
|
||
Similar Compounds (similar + compound)
Selected AbstractsCrystal growth and structural refinement of NaMn7O12CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005E. Gilioli Abstract We report the crystal growth and the structural refinement of NaMn7O12, a manganite having a double perovskite structure. As in many similar compounds, there is coexistence of Mn3+ and Mn4+ but in this material they orderly occupy different sites for crystallographic reasons. Therefore, this peculiar structure can be considered as a model system for studying complex mechanisms such as charge, orbital and spin ordering. High purity bulk samples and "large" single crystals are needed to study tiny modifications in the crystallographic and magnetic structures associated to the ordering phenomena. Almost single phase (more than 96% pure) and single crystals (up to about 150 µm) of NaMn7O12 were synthesized by solid state reaction under pressure in a multi-anvil apparatus. Single crystal x-ray diffraction and SEM analysis have been used to characterize the crystals. The structure refinement indicates that NaMn7O12 crystallizes in the cubic Im3 space group, with a = 7.312 Å and Z = 2. Further studies are in progress to optimize the synthesis conditions, in order to grow larger crystals. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Microbial Biosensor for p -Nitrophenol Using Arthrobacter Sp.ELECTROANALYSIS, Issue 14 2003Yu Lei Abstract This article reports the construction, optimization of performance variables and analytical characterization of a sensitive and selective microbial amperometric biosensor for measurement of p -nitrophenol (PNP), a U.S. Environmental Agency priority pollutant. The biosensor consisted of PNP-degrading/oxidizing bacteria Arthrobacter sp. JS443 as biological sensing element and a dissolved oxygen electrode as the transducer. The best sensitivity and response time were obtained using a sensor constructed with 1.2,mg dry wt. of cells and operating in pH,7.5, 50,mM citrate-phosphate buffer. Using these conditions, the biosensor was able to measure as low as 28,ppb (0.2,,M) of PNP selectively without interference from structurally similar compounds, such as phenol, nitrophenols and chlorophenols. The service life of the microbial biosensor is around 5,days when stored in the operating buffer at 4,°C. The applicability to lake water is demonstrated. [source] Estimations of vapor pressure and activity coefficients in water and octanol for selected aromatic chemicals at 25°CENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2000Sum Chi Lee Abstract A roupcontribution method is developed to estimate the supercooled liquid vapor pressure and the activity coefficients in water and octanol at 25°C of 98 selected monoaromatic compounds, many of which are or have been produced as chlorinated by-products in the manufacture of pulp and paper. The set includes alkylphenols, chlorinated phenols, anisoles, catechols, cymenes, guaiacols, syringols, and veratroles. The method can be used to estimate vapor pressures, solubilities in water, octanol-water partition coefficients, octanol-air partition coefficients, and Henry's law constants. It can also be used for predicting these partition coefficients as well as solubilities and vapor pressures for these and structurally similar compounds. [source] Structure Variation and Luminescence Properties of Lanthanide Complexes Incorporating a Naphthalene-Derived Chromophore Featuring Salicylamide Pendant ArmsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2008Xue-Qin Song Abstract A new potentially bridging ligand containing two salicylamide pendant arms separated by a 2,3-dimethoxynaphthalene spacer has been prepared and its coordination chemistry with LnIII ions has been investigated. An analysis of the presented crystal structures indicates that the diversity of these supramolecular structures is mainly dictated by the nature of the metal ions. These compounds represent good examples of tuning crystal structures arising from the flexibility of the ligands and the Ln contraction effect. Luminescence studies showed that the introduction of the methoxyl substituents on the naphthalene backbone lowers the triplet energy and considerably changes the luminescent behaviors of the EuIII and TbIII complexes, which is very different from the literature data on similar compounds. In the emission spectra of the Tb complex the ligand fluorescence remains relatively important because of the back-energy transfer from the TbIII ion to the ligand, which to the best of our knowledge, may be the first example of salicylamide lanthanide complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Rearrangement of Azobenzene upon Interaction with an Aluminum(I) Monomer LAl {L = HC[(CMe)(NAr)]2, Ar = 2,6- iPr2C6H3}EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2005Hongping Zhu Abstract Reaction of LAl (1) or [LAl{,2 -C2(SiMe3)2}] (2) {L = HC[(CMe)(NAr)]2, Ar = 2,6- iPr2C6H3} with azobenzene affords a five-membered ring compound [LAl{N(H)- o -C6H4N(Ph)}] (3). In the formation of 3 a three-membered intermediate [LAl(,2 -N2Ph2)] (A) is suggested by a [1 + 2] cycloaddition reaction; A is not stable and further rearranges to 3. DFT calculations on similar compounds with modified L' {L' = HC[(CMe)(NPh)]2} show that the complexation energy of the reaction of L'Al with azobenzene to form [L'Al(,2 -N2Ph2)] is about,39 kcal,mol,1, and the best estimate of the energy difference between [L'Al(,2 -N2Ph2)] and [L'Al{N(H)- o -C6H4N(Ph)}] is,76 kcal,mol,1. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Raman and IR spectral studies of D -phenylglycinium perchlorateJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2002S. Ramaswamy The Raman and infrared spectra of D -phenylglycinium perchlorate were recorded at room temperature. Tentative vibrational assignments of the observed wavenumbers were made by comparison with the vibrational wavenumbers of glycine, phenylalanine and other similar compounds. Anions were found to coordinate through hydrogen bonding interactions to other ligands in the crystal, affecting the Td symmetry and thereby causing the degeneracies of several modes to be removed. The extensive intermolecular hydrogen bonding in the crystal leads to a shift of bands due to the stretching and bending modes of various functional groups. The broadening and appearance of multiple bands for the carbonyl stretching mode due to the resonance interaction is also discussed. Copyright © 2002 John Wiley & Sons, Ltd. [source] Incommensurate structure of InAl1,,,xTixO3,+,x/2 [x = 0.701,(1)]: comparison between modulated and composite modelsACTA CRYSTALLOGRAPHICA SECTION B, Issue 4 2008P. J. Bereciartua The structure of the monoclinic phase of the compound InAl1,,,xTixO3,+,x/2 with x = 0.701,(1) has been analyzed within the (3,+,1)-dimensional superspace formalism. Two different models were refined describing the structure as an incommensurate modulated layer and modulated composite, respectively. Both models include the same composition,structure relation. In the composite approach it is derived from the mismatching between the two subsystems. In the incommensurate modulated system, it is derived from a closeness condition between O atomic domains. The distribution and coordination of the cations is discussed and compared with previously proposed models for similar compounds. [source] Substitutional and positional disorder in Sr2.88Cu3.12(PO4)4ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2010Ljiljana Karanovi The title compound, a hydrothermally synthesized strontium copper(II) phosphate(V) (2.88/3.12/4), is isotypic with Sr3Cu3(PO4)4, obtained previously by solid-state reaction, but not with Sr3Cu3(PO4)4, obtained previously by the hydrothermal method. A surplus of copper was observed by both structural and chemical analysis, and the formula obtained by the structural analysis is in full agreement with results of the EDX (energy-dispersive X-ray diffraction) analysis. The structure consists of layers of Cu3O12 groups which are linked via the PO4 tetrahedra. The Cu3O12 groups are formed by one Cu1O4 and two Cu2O5 coordination polyhedra sharing corners. The central Cu1 atom of the Cu3O12 group is located at an inversion centre (special position 2a). The unique structural feature of the title compound is the presence of 12% Cu in the Sr1 site (special position 2b, site symmetry ). Moreover, disordered Sr2 atoms were observed: a main site (Sr2a, 90%) and a less occupied site (Sr2b, 10%) are displaced by 0.48,(3),Å along the b axis. Such substitutional and positional disorder was not observed previously in similar compounds. [source] Dithioether ligands containing a 2,6-disubstituted pyridine linker with two thioether-heterocycle armsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2010Archimede Rotondo The structure of 2,6-bis(2-pyridyltsulfanylmethyl)pyridine (pytmp), (I), C17H15N3S2, presents a twisted conformation, with the three planar moieties almost perpendicular to each other. The structures of two related derivatives, namely 2,6-bis(6-methyl-2-pyridylsulfanylmethyl)pyridine (mpytmp), (II), C19H19N3S2, and 2,6-bis(4-methyl-2-pyrimidylsulfanylmethyl)pyridine (mprtmp) n- pentane hemisolvate, (III), C17H17N5S2·0.5C5H12, present extended planar fragments with just one quasi-perpendicular arylsulfanylmethyl side arm, such that the molecules are folded in an L-shaped conformation. All three conformations appear different from those adopted by similar compounds, demonstrating the great flexibility of such species, although such differences in conformational behaviour might drive specific coordination modes. [source] Hydrogen bonding in 2-(2-oxothiazolidin-3-yl)-4,5-dihydrothiazolium hydrogen sulfate monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2008Rodrigo S. Corrêa The asymmetric unit of the title compound, C6H9N2OS2+·HSO4,·H2O, contains a heterocyclic cation, a hydrogen sulfate anion and a water molecule. There are strong hydrogen bonds between the hydrogen sulfate anions and water molecules, forming an infinite chain along the [010] direction, from which the cations are pendent. The steric, electronic and geometric features are compared with those of similar compounds. In this way, structural relationships are stated in terms of the influence of the sulfate group on the protonation of the heterocycle and on the tautomeric equilibrium in the solid state. [source] Hydrogen bonding in the bromide salts of 4-aminobenzoic acid and 4-aminoacetophenoneACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2008Dominik Cin In the title compounds, 4-carboxyanilinium bromide, C7H8NO2+·Br,, (I), and 4-acetylanilinium bromide, C8H10NO+·Br,, (II), each asymmetric unit contains a discrete cation with a protonated amino group and a halide anion. Both crystal structures are characterized by two-dimensional hydrogen-bonded networks. The ions in (I) are connected via N,H...Br, N,H...O and O,H...Br hydrogen bonds, with three characteristic graph-set motifs, viz. C(8), C21(4) and R32(8). The centrosymmetric hydrogen-bonded R22(8) dimer motif characteristic of carboxylic acids is absent. The ions in (II) are connected via N,H...Br and N,H...O hydrogen bonds, with two characteristic graph-set motifs, viz. C(8) and R42(8). The significance of this study lies in its illustration of the differences between the supramolecular aggregations in two similar compounds. The presence of the methyl group in (II) at the site corresponding to the hydroxyl group in (I) results in a significantly different hydrogen-bonding arrangement. [source] [H3N(CH2)5NH3]·AlP2O8H, a one-dimensional aluminophosphateACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2000S. Phan Thanh The structure of the title compound, pentane-1,5-diammonium aluminium(III) hydrogen bis(phosphate), (C5H16N2)[AlP2O8H], obtained solvothermally at 473,K, has been determined by single-crystal X-ray diffraction. It consists of one-dimensional [AlP2O8H]2, macroanions, connected to each other by pentanediammonium cations. Contrary to similar compounds with P/Al = 2, the three-dimensional structure is mainly obtained via a network of hydrogen bonds. [source] Textile dye allergic contact dermatitis following paraphenylenediamine sensitization from a temporary tattooAUSTRALASIAN JOURNAL OF DERMATOLOGY, Issue 4 2004Helen Saunders SUMMARY Textile dye allergy is frequently caused by azo dyes, which can cross-react with structurally similar compounds, including paraphenylenediamine. A case of allergic contact dermatitis to azo textile dyes, presenting principally as a sock dermatitis, is presented. The patient also gave a history of an episode of scalp dermatitis consistent with contact allergy to paraphenylenediamine in hair dye. It is proposed that paraphenylenediamine sensitization from a temporary skin tattoo may have been the primary sensitizing event for these reactions. [source] High Diversity on Simple Substrates: 1,4-Dihalo-2-butenes and Other Difunctionalized Allylic Halides for Copper-Catalyzed SN2, ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 34 2008Caroline A. Falciola Dr. Abstract Enantioselective allylic alkylation with an organomagnesium reagent catalyzed by copper thiophene carboxylate (CuTC) was carried out on difunctionalized substrates, such as commercially available 1,4-dichloro-2-butene and 1,4-dibromo-2-butene, and on similar compounds of higher substitution pattern of the olefin for the formation of all-carbon chiral quaternary centers. The high regioselectivity obtained throughout the reactions favored good regiocontrol for the addition of phenyl Grignard reagents. Other difunctionalized substrates (allylic ethers and allylic alcohols) also underwent asymmetric SN2, substitution. [source] | ||||||||||