Full Text Available The asymmetric unit of the title compound, [Ni(C19H16I4N2O2], comprises half of a Schiff base complex. The NiII atom is located on a twofold rotation axis which also bisects the central C atom of the 2,2-dimethylpropane group of the ligand. The geometry around the NiII atom is distorted square-planar, with a dihedral angle of 21.7 (3° between the symmetry-related N/Ni/O coordination planes. The dihedral angle between the symmetry-related benzene rings is 27.9 (3°. In the crystal, short intermolecular I...I [3.8178 (9 and 3.9013 (10 Å] interactions are present.
We describe a novel adsorbent for effective extraction of lead(II), chromium(III) and copper(II). It consists of ruthenium nanoparticles loaded on activated carbon that were modified with N,N-bis-(α-methylsalicylidene)-2,2-dimethylpropane-1,3-diamine. The sorbent was applied to solid-phase extraction combined with ionic-liquid based dispersive liquid-liquid microextraction method. The effects of parameters such as amounts of adsorbent, type and volume of elution solvent, type and volume of extraction and dispersing solvents, etc. were evaluated. The ions were then quantified by flame atomic absorption spectrometry. Under the best conditions, limits of detection, linear dynamic ranges and enrichment factors for these ions ranged from 0.02 to 0.09 μg L−1, 0.08 to 45 μg L−1 and 328 to 356, respectively. The results showed that the method, in addition to its sensitivity, selectivity and good enrichment factor, is simple and efficient. It was applied to the determination of the three ions in blood plasma, food (broccoli, coriander and spinach), and in (spiked) samples of tap, spring and river water. (author)
Full Text Available In the title complex, [Ni(C23H28N2O4]·H2O, the NiII ion is coordinated by the N2O2 unit of the tetradentate Schiff base ligand in a slightly distorted planar geometry. The asymmetric unit of the title compound comprises one complex molecule and a water molecule of crystallization. The H atoms of the water molecule make bifurcated intermolecular hydrogen bonds with the O atoms of the phenolate and ethoxy groups with R12(5 and R12(6 ring motifs, which may, in part, influence the molecular configuration. The dihedral angle between the two benzene rings is 31.43 (5°. The crystal structure is further stabilized by intermolecular C—H...O and C—H...π interactions, which link neighbouring molecules into one-dimensional extended chains along the a axis. An interesting feature of the crystal structure is the short intermolecular C...C [3.3044 (14 Å] contact which is shorter than the sum of the van der Waals radii.
2D N.m.r. spectra (55.28 MHz) have been obtained for samples of ethane, propane, 2-methylpropane, and 2,2-dimethylpropane produced during the exchange of the hydrocarbons with deuterium over silica-supported platinum and rhodium catalysts. The results provide new evidence about the mechanism of the exchange reactions of these metals and about the isotopic shifts associated with deuterium atoms in different positions in the molecules. (author)
Full Text Available TMS is the commonest standard reference for both protons and 13C NMR spectroscopy. The Magnetic Shielding and its Polarizabilities, plus the static polarizability have been calculated for TMS, tetramethyl ammonium cation and 2,2-dimethylpropane. An investigation of continuum solvation effects on these highly symmetrical molecules, whose first surviving electric moment is the octopole, showed interaction with solvent makes little change to these magnetic properties. This small change is however consistent with both the high symmetry of the molecules and the available extensive experimental data for TMS. A rationalization of the signs and magnitudes of A in a sequence of related molecules has been suggested.
The drift velocity, w, of excess electrons as a function of the applied uniform electric field, E, in liquid 2,2-dimethylpropane (TMC), tetramethylsilane (TMS), tetramethylgermanium (TMG), tetramethyltin (TMT), 2,2,4,4-tetramethylpentane (TMP) and in mixtures of TMS with TMP (mole ratio M = 1.31/1) and n-pentane (M = 102/1, 17/1, and 5.6/1) has been measured for E-values up to ∼105 V cm-1. The thermal electron mobility in the above liquids is 71.5, 119.3, 114.7, 85.7, 31.8, 39.1, 118, 85, and 47.6 cm2 s-1 V-1, respectively. 8 refs., 2 figs., 1 tab
Azam, Mohammad; Velmurugan, Gunasekaran; Wabaidur, Saikh Mohammad; Trzesowska-Kruszynska, Agata; Kruszynski, Rafal; Al-Resayes, Saud I; Al-Othman, Zeid A; Venuvanalingam, Ponnambalam
Two derivatives of organouranyl mononuclear complexes [UO2(L)THF] (1) and [UO2(L)Alc] (2), where L = (2,2'-(1E,1'E)-(2,2-dimethylpropane-1,3-dyl)bis(azanylylidene, THF = Tetrahydrofuran, Alc = Alcohol), have been prepared. These complexes have been determined by elemental analyses, single crystal X-ray crystallography and various spectroscopic studies. Moreover, the structure of these complexes have also been studied by DFT and time dependent DFT measurements showing that both the complexes have distorted pentagonal bipyramidal environment around uranyl ion. TD-DFT results indicate that the complex 1 displays an intense band at 458.7 nm which is mainly associated to the uranyl centered LMCT, where complex 2 shows a band at 461.8 nm that have significant LMCT character. The bonding has been further analyzed by EDA and NBO. The photocatalytic activity of complexes 1 and 2 for the degradation of rhodamine-B (RhB) and methylene blue (MB) under the irradiation of 500W Xe lamp has been explored, and found more efficient in presence of complex 1 than complex 2 for both dyes. In addition, dye adsorption and photoluminescence properties have also been discussed for both complexes. PMID:27595801
Ma, Xiaoguang; Zhu, Yinghao; Liu, Yang
The gamma-ray spectra of pentane (C5H12) and its two isomers, i.e., 2-Methylbutane (CH3C(CH3)HC2H5) and 2,2-Dimethylpropane (C(CH3)4) have been studied theoretically in the present work. The recent experimental gamma-ray spectra of these three molecules show that they have the same Doppler shifts, although their molecular structures are dramatically different. In order to reveal why the gamma-ray spectra of these molecules are less sensitive to the molecular structures, the one-dimensional gamma-ray spectra and spherically averaged momentum (SAM) distributions, the two-dimensional angular correlation of annihilation radiation (ACAR), and the three-dimensional momentum distributions of the positron-electron pair are studied. The one-centered momentum distributions of the electrons are found to play more important role than the multi-centered coordinate distributions. The present theoretical predictions have confirmed the experimental findings for the first time. The dominance of the inner valence electrons in the positron-electron annihilation process has also been suggested in the present work.
Full Text Available Hydrate-bearing sediment cores were retrieved from the Joetsu Basin (off Joetsu city, Niigata Prefecture at the eastern margin of the Japan Sea during the MD179 gas hydrates cruise onboard R/V Marion Dufresne in June 2010. We measured molecular and stable isotope compositions of volatiles bound in the gas hydrates and headspace gases obtained from sediments to clarify how the minor components of hydrocarbons affects to gas hydrate crystals. The hydrate-bound hydrocarbons at Umitaka Spur (southwestern Joetsu Basin primarily consisted of thermogenic methane, whereas those at Joetsu Knoll (northwestern Joetsu Basin, about 15 km from Umitaka Spur contained both thermogenic methane and a mixture of thermogenic and microbial methane. The depth concentration profiles of methane, ethane, propane, CO2, and H2S in the sediments from the Joetsu Basin area showed shallow sulfate–methane interface (SMI and high microbial methane production beneath the SMI depth. Relatively high concentrations of propane and neopentane (2,2-dimethylpropane were detected in the headspace gases of the hydrate-bearing sediment cores obtained at Umitaka Spur and Joetsu Knoll. Propane and neopentane cannot be encaged in the structure I hydrate; therefore, they were probably excluded from the hydrate crystals during the structure I formation process and thus remained in the sediment and/or released from the small amounts of structure II hydrate that can host such large gas molecules. The lower concentrations of ethane and propane in the sediment, high δ13C of propane and isobutane, and below-detection normal butane and normal pentane at Umitaka Spur and Joetsu Knoll suggest biodegradation in the sediment layers.
Azam, Mohammad; Al-Resayes, Saud I; Velmurugan, Gunasekaran; Venuvanalingam, Ponnambalam; Wagler, Jörg; Kroke, Edwin
The synthesis of the tetradentate dianionic ligand, H2L (2,2'-(1E,1'E)-(2,2-dimethylpropane-1,3-dyl)bis(azanylylidene)bis(methanylylidene)diphenol), from 2,2-dimethyl-1,3-diaminopropane and its reaction with UO2(CH3COO)2·2H2O in a 1:1 molar ratio in methanol to produce the complex [UO2(L)(CH3OH)] are reported. The isolated compounds have been characterized by elemental analysis, ionization mass spectrometry (ESI-MS), UV/Vis, FT-IR, (1)H- and (13)C-NMR, DEPT-135 spectroscopy, TGA and single-crystal X-ray diffraction. As shown by X-ray crystallography, the coordination geometry around the uranium centre is distorted pentagonal bipyramidal with two imine nitrogen atoms, two phenolic oxygen atoms and one methanol O atom occupying equatorial sites, together with two axial oxo groups. To obtain insights into the structure and spectral properties of the studied complex, density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations have been carried out. The computed results show that LUMO of the complex is featured with uranium f orbital character. TD-DFT results indicate that the complex displays two intense bands and one weak charge transfer band. The charge transfer band is primarily due to HOMO → LUMO (53%). Two intense bands have main contributions from HOMO-2 → LUMO (81%) and HOMO-3 → LUMO (77%) transitions, respectively. TD-DFT results indicate that the complex displays the charge transfer band primarily due to HOMO → LUMO (53%) and other two charge transfer bands have main contributions from HOMO-2 → LUMO (81%), HOMO-3 → LUMO (77%) transitions, respectively. NBO analysis reveals that the ground state of the complex is mainly stabilized by n→n* interaction. EDA analysis reveals that the interaction existing between the ligand and other parts of the complex is mainly electrostatic in nature. PMID:25380389