Mixture Of Cl Research Articles

The η2 Complex of Nickel Bis(diphenylphosphanyl)propane with Fullerene: {Ni(dppp)(η2‐C60)}·(Solvent) Obtained by Reduction

AbstractThe η2 complex of nickel bis(diphenylphosphanyl)propane with fullerene, {Ni(dppp)(η2‐C60)}·(C6H14)0.84·(C6H4Cl2)0.16 (1) (C6H14: hexane, C6H4Cl2: o‐dichlorobenzene), has been obtained by reduction of the Ni(dppp)Cl2 and C60 mixture with sodium fluorenone in o‐dichlorobenzene and slow precipitation of the single crystals by diffusion of hexane. Nickel coordinates to the 6–6 bond of C60 by η2‐coordination to form Ni–C(C60) bonds with a length of 1.948–1.951(2) Å, which are the shortest M–C bonds among known η2 complexes of fullerenes. The 6–6 bond length [1.488(3) Å] where the Ni atom is coordinated is noticeably longer than the average length of other 6–6 bonds in C60 [1.388(2) Å]. Coordination of nickel to C60 results in the splitting of two bands for two IR‐active modes of C60 into three bands, because of the lower symmetry of C60, and a noticeable shift in the F1u(4) mode of C60 to lower frequencies, as a result of π back‐donation. The dark green complex manifests two absorption bands at 664 and 890 nm in the visible range. The complex is EPR silent since only a weak narrow signal with g = 2.0000 and ΔH = 0.17 mT was found in the EPR spectrum of 1 at room temperature, which originates from about 0.1 % of spins of the total amount of C60.

Trimethylglycine complexes with carboxylic acids and HF: solvation by a polar aprotic solvent

A series of strong H-bonded complexes of trimethylglycine, also known as betaine, with acetic, chloroacetic, dichloroacetic, trifluoroacetic and hydrofluoric acids as well as the homo-conjugated cation of betaine with trifluoroacetate as the counteranion were investigated by low-temperature (120-160 K) liquid-state NMR spectroscopy using CDF(3)/CDF(2)Cl mixture as the solvent. The temperature dependencies of (1)H NMR chemical shifts are analyzed in terms of the solvent-solute interactions. The experimental data are explained assuming the combined action of two main effects. Firstly, the solvent ordering around the negatively charged OHX region of the complex (X = O, F) at low temperatures, which leads to a contraction and symmetrisation of the H-bond; this effect dominates for the homo-conjugated cation of betaine. Secondly, at low temperatures structures with a larger dipole moment are preferentially stabilized, an effect which dominates for the neutral betaine-acid complexes. The way this second contribution affects the H-bond geometry seems to depend on the proton position. For the Be(+)COO(-)···HOOCCH(3) complex (Be = (CH(3))(3)NCH(2)-) the proton displaces towards the hydrogen bond center (H-bond symmetrisation, O···O contraction). In contrast, for the Be(+)COOH···(-)OOCCF(3) complex the proton shifts further away from the center, closer to the betaine moiety (H-bond asymmetrisation, O···O elongation). Hydrogen bond geometries and their changes upon lowering the temperature were estimated using previously published H-bond correlations.

A thermogravimetric study of refractory clays chlorination

The chlorine effect on different samples of refractory clays has been studied within a wide temperature interval. The isothermal and non isothermal calcination assays were carried out in currents of N 2 and a mixture of Cl 2/N 2 (1:1), using a thermogravimetric system designed in our laboratory and masses of approximately 300 mg. Isothermal assays were also performed with masses of 2 g, using a fixed bed reactor with horizontal dynamic flow. The initial samples of refractory clays and the residues resulting from thermal treatments were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), electron probe microanalysis (EPMA), specific surface area analysis (BET) and CIELAB colorimetry. The thermograms in N 2 and Cl 2/N 2 showed two mass losses, between room temperature and 650 °C, due to the elimination of the mineral hydration water and the transformation of kaolinite into metakaolinite. A third mass loss was observed over 750 °C in Cl 2/N 2 due to the chlorination and elimination of the iron contained in the samples. The X-ray diffractograms of the residues from the different thermal treatments showed that the calcination produced the total transformation of kaolinite and other phases contained in the mineral. The XRF analysis of the residues resulting from the isothermal assays in Cl 2/N 2 permitted to determine that the iron contained in the samples might be completely removed by chlorination at 900 °C for 2 h. The colorimetric analysis of the chlorination residues indicated that the discoloration and bleaching of samples were caused by the deferrification of the mineral. The results of the characterizations using SEM and EPMA supported the previous observations.

Chemical Energy Release in Several Recently Discovered Detonation and Deflagration Flows

Several recent experiments on complex detonation and deflagration flows are analyzed in terms of the chemical energy release required to sustain these flows. The observed double cellular structures in detonating gaseous nitromethane–oxygen and NO2–fuel (H2, CH4, and C2H6) mixtures are explained by the amplification of two distinct pressure wave frequencies by two exothermic reactions, the faster reaction forming vibrationally excited NO* and the slower reaction forming highly vibrationally excited N2**. The establishment of a Chapman-Jouguet (C-J) deflagration behind a weak shock wave, the C-J detonation established after a head-on collision with a shock front, and the C-J detonation conditions established in reactive supersonic flows are quantitatively calculated using the chemical energy release of a H2 + Cl2 mixture. For these three reactive flows, these calculations illustrate that different fractions of the exothermic chemical energy are used to sustain steady-state propagation. C-J detonation calculations on the various initial states using the CHEETAH chemical equilibrium code are shown to be in good agreement with experimental detonation velocity measurements for the head-on collision and supersonic flow detonations.

Geometries and Tautomerism of OHN Hydrogen Bonds in Aprotic Solution Probed by H/D Isotope Effects on 13C NMR Chemical Shifts

The (1)H and (13)C NMR spectra of 17 OHN hydrogen-bonded complexes formed by CH(3)(13)COOH(D) with 14 substituted pyridines, 2 amines, and N-methylimidazole have been measured in the temperature region between 110 and 150 K using CDF(3)/CDF(2)Cl mixture as solvent. The slow proton and hydrogen bond exchange regime was reached, and the H/D isotope effects on the (13)C chemical shifts of the carboxyl group were measured. In combination with the analysis of the corresponding (1)H chemical shifts, it was possible to distinguish between OHN hydrogen bonds exhibiting a single proton position and those exhibiting a fast proton tautomerism between molecular and zwitterionic forms. Using H-bond correlations, we relate the H/D isotope effects on the (13)C chemical shifts of the carboxyl group with the OHN hydrogen bond geometries.

Permeant anions contribute to voltage dependence of ClC‐2 chloride channel by interacting with the protopore gate

It has been shown that the voltage (V(m)) dependence of ClC Cl(-) channels is conferred by interaction of the protopore gate with H(+) ions. However, in this paper we present evidence which indicates that permeant Cl(-) ions contribute to V(m)-dependent gating of the broadly distributed ClC-2 Cl() channel. The apparent open probability (P(A)) of ClC-2 was enhanced either by changing the [Cl(-)](i) from 10 to 200 mM or by keeping the [Cl(-)](i) low (10 mM) and then raising [Cl(-)](o) from 10 to 140 mM. Additionally, these changes in [Cl(-)] slowed down channel closing at positive V(m) suggesting that high [Cl(-)] increased pore occupancy thus hindering closing of the protopore gate. The identity of the permeant anion was also important since the P(A)(V(m)) curves were nearly identical with Cl(-) or Br(-) but shifted to negative voltages in the presence of SCN() ions. In addition, gating, closing rate and reversal potential displayed anomalous mole fraction behaviour in a SCN(-)/Cl() mixture in agreement with the idea that pore occupancy by different permeant anions modifies the V(m) dependence ClC-2 gating. Based on the ec1-ClC anion pathway, we hypothesized that opening of the protopore gate is facilitated when Cl(-) ions dwell in the central binding site. In contrast, when Cl(-) ions dwell in the external binding site they prevent the gate from closing. Finally, this Cl(-)-dependent gating in ClC-2 channels is of physiological relevance since an increase in [Cl(-)](o) enhances channel opening when the [Cl(-)](i) is in the physiological range.

Amphipathic Helical Cationic Antimicrobial Peptides Promote Rapid Formation of Crystalline States in the Presence of Phosphatidylglycerol: Lipid Clustering in Anionic Membranes

Five AHCAPs exhibiting a broad-spectrum of antimicrobial activity, were examined with regard to their action in lipid mixtures with two anionic lipids, PG and CL. We find that all of the peptides studied were capable of promoting the formation of crystalline phases of DMPG in mixtures of DMPG and CL, without prior incubation at low temperatures. This property is indicative of the ability of these peptides to cluster CL away from DMPG. In contrast, the well studied antimicrobial cationic peptide magainin 2 does not cluster anionic lipids. We ascribe the lower anionic lipid clustering ability of magainin to its low density of positive charges compared with the five other AHCAPs used in this work. The peptide MSI-1254 was particularly potent in segregating these two anionic lipids. Consequently, clusters enriched in DMPG appear in a lipid mixture with CL. These can rapidly form higher temperature crystalline phases because of the increased permeability of the bilayer caused by the AHCAPs. The polyaminoacids, poly-L-Lysine and poly-l-arginine are also very effective in causing this segregation. Thus, the clustering of anionic lipids by AHCAPs is not confined only to mixtures of anionic with zwitterionic lipids, but it extends to mixtures containing different anionic headgroups. The resulting effects, however, have different consequences to the biological activity. This finding broadens the scope for which an AHCAP agent will cluster lipids in a membrane.

Study on the kinetic model of Cr/H/Air/Cl mixture

Constructing a reasonable reaction kinetic model for Cr-containing waste incineration is of high significance to study the effect of various factors, such as temperature, Cl, on its hexavalent chromium compounds. In this paper, a primary Cr/H/Air/Cl reaction kinetic model is built and studied by Gaussian 03 code with quantum chemistry theory. Numerical results show that there are two overall reactions in the model, each of the two overall reactions consists of their respective two elementary reactions. So the two overall reactions should be omitted from the model. Instead, the four elementary reactions should be added in the Cr/H/Air/Cl reaction kinetic model. The activation energies of the four elementary reactions are also calculated.

Surface texturing of GaAs using a nanosphere lithography technique for solar cell applications

In this study, we present novel methods to texture the surface of GaAs substrates using the nanosphere lithography (NSL) technique that is based on arrays of SiO 2 nanospheres. Closed-packed arrays of SiO 2 nanospheres were formed on a benzocyclobutene (BCB) layer, followed by embedding SiO 2 nanospheres into the BCB layer. To texture the GaAs surface, three patterns were fabricated by nanosphere lithography. First, a convex pattern from the shape of the nanospheres was produced on the surface of GaAs. Second, a concave shape was produced on the surface of GaAs by additional wet etching to remove SiO 2 nanospheres. These two methods were found to be effective in reducing the reflectance to a range of 400–800 nm. Finally, the arrays of SiO 2 nanospheres were transferred onto the GaAs by dry-etching using a mixture of Cl 2 and BCl 3 gases, resulting in arrays of GaAs nanorods. The dry-etched surface structure showed the lowest reflectance.

Some kinetics aspects of chlorine-solids reactions

The present paper describes detailed kinetics investigations on some selected chlorine-solid reactions through thermogravimetric measurements. The solids studied in this article include chemical pure oxides and sulfides as well as their natural bearing materials. The chlorinating agents employed are gaseous mixtures of Cl 2 +N 2 (chlorination), Cl 2 +O 2 (oxychlorination), and Cl 2 +CO (carbochlorination). Results are presented as effects of various parameters on the reaction rate of these solids with these chlorinating agents. It was observed that the reactivity of these solids towards different chlorinating agents varied widely. Sulfides could be chlorinated at room temperature, while carbochlorination of chromium (III) oxide was possible only above 500 °C. The variation of the chlorination rate of these complex materials with respect to gas velocity, composition and temperature enabled us to focus some light on the plausible reaction mechanisms and stoichiometries. The obtained results were used for selective removal of iron from chromite concentrates, extraction of valuable metals from sulfide materials, purification of MgO samples, etc.

Experimental and theoretical characterization of molecular complexes formed between OCS and XY molecules (X, Y = F, Cl and Br) and their role in photochemical matrix reactions

Molecular complexes between OCS and ClF, Cl(2), Br(2), or BrCl have for the first time been isolated in solid matrixes at low temperature, and characterized by their IR spectra. 1 : 1 adducts between OCS and ClF, Cl(2), or BrCl were formed by broad-band UV-visible photolysis of matrix-isolated FC(O)SCl, ClC(O)SCl or BrC(O)SCl, respectively. Co-deposition of gaseous mixtures of OCS and ClF or Br(2) diluted with Ar on a CsI window cooled to approximately 15 K led to the identification of 1 : 1 complexes, while similar mixtures of OCS and Cl(2) gave rise mainly to 1 : 2 species. The differences in the structures and stoichiometries of the molecular complexes may well be responsible for the different reaction channels observed for the photochemical matrix reactions between OCS and Cl(2) or Br(2). The structures, energy differences, vibrational spectra, and bonding properties of all the possible complexes formed between OCS and XY (XY = ClF, Cl(2), Br(2), or BrCl) have been studied with different theoretical approximations.

Rate constant of the reaction of chlorine atoms with methanol over the temperature range 291–475 K

AbstractThe rate constant of the reaction Cl + CH3OH (k1) has been measured in 500–950 Torr of N2 over the temperature range 291–475 K. The rate constant determination was carried out using the relative rate technique with C2H6 as the reference compound. Experiments were performed by irradiating mixtures of CH3OH, C2H6, Cl2, and N2 with UV light from a fluorescent lamp whose intensity peaked near 360 nm. The resultant temperature‐dependent rate expression is k1 = 8.6 (±1.3) × 10−11 exp[−167 (±60)/T] cm3 molecule−1 s−1. Error limits represent data scatter (2σ) in the current experiments and do not include error in the reference rate constant. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 42: 113–116, 2010

Heavy atom nitroxyl radicals. III. Identification of the Cl2P=S free radical in the gas phase by laser spectroscopy and ab initio calculations

The dichlorothiophosphoryl (Cl(2)PS) free radical has been identified in the gas phase for the first time by a combination of laser-induced fluorescence and single vibronic level emission spectroscopy. High level ab initio calculations of the properties of the ground and first two excited states have been undertaken to aid in the interpretation of the data. The radicals were produced by an electric discharge through a dilute mixture of Cl(3)PS in high pressure argon at the exit of a pulsed supersonic expansion. An extensive band system was observed in the 760-560 nm region and has been assigned as the B (2)A(')-X (2)A(') electronic transition in which an electron in the ground state pi orbital is promoted to the pi( *) orbital. Three excited state and four ground state vibrational frequencies and their chlorine isotope effects have been measured and found to be in good accord with the theoretical predictions. Theory indicates that the radical is nonplanar in the ground state with increased pyramidalization and a longer PS bond in the first (A (2)A(") n-pi( *)) and second excited electronic states.

Photoacoustic beam profiling of pulsed lasers

We introduce a beam profiler of pulsed lasers based on the photoacoustic technique. The method assumes that the initial pressure distribution inside the acoustic cell follows the laser intensity pattern if absorbed energy relaxes rapidly. This initial pressure condition can be described as a superposition of acoustic modes of different amplitudes and phases. We analyze how to reconstruct the intensity profile of the laser beam from the recorded acoustic signals. Finally, we present preliminary results obtained with a frequency doubled Nd:YAG laser that excites NO(2)-CF(2)Cl(2) mixtures.

Effect of hydrogen on the physical and mechanical properties of silicon carbide-derived carbon films

In this study, the effect of hydrogen on the structure and mechanical properties of carbon films produced by selective etching of monolithic SiC was examined. The process to produce carbon films from SiC (i.e., SiC-derived carbon, CDC) was carried out in a gas mixture of Cl 2 and H 2 at 1000 °C for 20 h. The Raman intensity ratio, I D/ I G, where subscripts D and G refer to diamond and graphite, decreased as the hydrogen concentration in the gas mixture increased, indicating a decrease in the sp 2 carbon cluster. XRD analysis also showed that the fraction of graphitization decreased as the hydrogen concentration increased. The addition of hydrogen that prevented the formation of graphite (sp 2 bonding) also resulted in a reduction in the film thickness. The hardness and elastic modulus of the carbon films tended to decrease as the H 2 content increased owing to the contribution from the C–H bond and the nano-size pore.

Diamond-on-SOI Field Emission Device Patterning

Nanocrystalline diamond films deposited on SOI and electron beam patterning techniques are used to fabricate a field emission device with sub-micron cathode-anode separation. The subsequent aluminum evaporation and dry etch creates a mask for the electrode features, demonstrating that the nanodiamond (ND) roughness does not compromise the device delineation when proper EBL write parameters are used. A mixture of BCl3 and Cl2 were used to dry etch the aluminum, oxygen O2 plasma was used to etch the nanodiamond, and SF6 gas was used to etch the active layer of silicon followed by KOH:DIH2O wet etching.

Mechanism of olfactory masking in the sensory cilia

Olfactory masking has been used to erase the unpleasant sensation in human cultures for a long period of history. Here, we show a positive correlation between the human masking and the odorant suppression of the transduction current through the cyclic nucleotide–gated (CNG) and Ca2+-activated Cl− (Cl(Ca)) channels. Channels in the olfactory cilia were activated with the cytoplasmic photolysis of caged compounds, and their sensitiveness to odorant suppression was measured with the whole cell patch clamp. When 16 different types of chemicals were applied to cells, cyclic AMP (cAMP)-induced responses (a mixture of CNG and Cl(Ca) currents) were suppressed widely with these substances, but with different sensitivities. Using the same chemicals, in parallel, we measured human olfactory masking with 6-rate scoring tests and saw a correlation coefficient of 0.81 with the channel block. Ringer's solution that was just preexposed to the odorant-containing air affected the cAMP-induced current of the single cell, suggesting that odorant suppression occurs after the evaporation and air/water partition of the odorant chemicals at the olfactory mucus. To investigate the contribution of Cl(Ca), the current was exclusively activated by using the ultraviolet photolysis of caged Ca, DM-nitrophen. With chemical stimuli, it was confirmed that Cl(Ca) channels were less sensitive to the odorant suppression. It is interpreted, however, that in the natural odorant response the Cl(Ca) is affected by the reduction of Ca2+ influx through the CNG channels as a secondary effect. Because the signal transmission between CNG and Cl(Ca) channels includes nonlinear signal-boosting process, CNG channel blockage leads to an amplified reduction in the net current. In addition, we mapped the distribution of the Cl(Ca) channel in living olfactory single cilium using a submicron local [Ca2+]i elevation with the laser photolysis. Cl(Ca) channels are expressed broadly along the cilia. We conclude that odorants regulate CNG level to express masking, and Cl(Ca) in the cilia carries out the signal amplification and reduction evenly spanning the entire cilia. The present findings may serve possible molecular architectures to design effective masking agents, targeting olfactory manipulation at the nano-scale ciliary membrane.

Infrared absorption of gaseous c-ClCOOH and t-ClCOOH recorded with a step-scan Fourier-transform spectrometer

Two conformers of ClCOOH were produced upon irradiation at 355 nm of a gaseous flowing mixture of Cl(2), HCOOH, and N(2). A step-scan Fourier-transform infrared spectrometer coupled with a multipass absorption cell was utilized to monitor the transient spectra of ClCOOH. Absorption bands with origins at 1808.0 and 1328.5 cm(-1) are attributed to the C=O stretching and COH bending modes of t-ClCOOH, respectively; those at 1883.0 and 1284.9 cm(-1) are assigned as the C=O stretching and COH bending modes of c-ClCOOH, respectively. These observed vibrational wavenumbers agree with corresponding values for t-ClCOOH and c-ClCOOH predicted with B3LYP/aug-cc-pVTZ density-functional theory and the observed rotational contours agree satisfactorily with simulated bands based on predicted rotational parameters. The observed relative intensities indicate that t-ClCOOH is more stable than c-ClCOOH by approximately 3 kJ mol(-1). A simple kinetic model is employed to account for the production and decay of ClCOOH.

H/D isotope effects on NMR chemical shifts of nuclei involved in a hydrogen bridge of hydrogen isocyanide complexes with fluoride anion

(1)H, (2)H, (19)F and (15)N NMR spectra of a strongly hydrogen-bonded anionic cluster, CNHF(-), as an ion pair with a tetrabutylammonium cation dissolved in CDF(3)-CDF(2)Cl mixture were recorded in the slow exchange regime at temperatures down to 110 K. The fine structure due to spin-spin coupling of all nuclei involved in the hydrogen bridge was resolved. H/D isotope effects on the chemical shifts were measured. The results were compared with those obtained earlier for a similar anion, FHF(-), and interpreted via ab initio calculations of magnetic shielding as functions of internal vibrational coordinates, namely an anti-symmetric proton stretching and a doubly-degenerate bending. The values of primary and secondary isotope effects on NMR chemical shifts were estimated using a power expansion of the shielding surface as a function of vibrational coordinates. A positive primary isotope effect was explained as a result of the decrease of the hydron stretching amplitude upon deuteration. We show that the proton shielding surface has a minimum close to the equilibrium geometry of the CNHF(-) anion, leading to the positive primary H/D isotope effect in a rather asymmetric hydrogen bond. We conclude that caution should be used when making geometric estimations on the basis of NMR data, since the shapes of the shielding functions of the internal vibrational coordinates can be rather exclusive for each complex.

Luminescence properties of heterodinuclear Pt–Eu complexes from unusual nonadentate ligands

The synthesis of ligand L(1), based on the tetramethyl ester of [4'-ethynyl-(6,6''-bis(aminomethyl))-2,2':6',2''-terpyridine]tetrakisacetate, and its acidic form L(2), are described. Using a Cu-assisted coupling reaction, L(1) was connected to the Pt atom of a [(tpy)Pt] precursor (tpy = 2,2':6',2''-terpyridine) to afford the [(tpy)PtL(1)](BF(4)) metallosynthon, from which a hydrolysis reaction gave Na(3)[(tpy)PtL(2)]. The photophysical properties of the metallosynthons were studied by means of absorption and steady state emission spectroscopic techniques in various solvents, which revealed a dramatic impact of the solvent polarity. DFT and TDDFT calculations (B3LYP) were used to investigate the absorption and emission properties of the [(tpy)PtL(1)](+) system both in vacuo and in different solvents. Spectrophotometric titrations of [(tpy)PtL(1)](+) with EuCl(3) x 6 H(2)O in acetonitrile revealed the formation of complicated mixtures of complexes with different [(tpyPt(1))(x)Eu(y)] stoichiometries, all of which display the typical Eu(III) centred luminescence upon excitation into the Pt centred (1)MLCT absorption band. The energy transfer from the Pt subunit of [(tpy)PtL(2)](3-) to Eu(III) is inefficient in polar solvents, but it is restored in a TFA-CH(2)Cl(2) mixture, together with the observation of a new emission band at 684 nm, likely arising from a charge transfer process involving reduction of Eu(III).