Equimolar Binary Solutions Research Articles

FTIR spectroscopic studies and DFT calculations on the binary solution of methyl acetate with m-xylene

FTIR spectra have been recorded for pure methyl acetate, pure m-xylene and their equimolar binary solution. Shifts have been observed in all the vibrational modes of methyl acetate, m-xylene in the solution indicating the possibilities for molecular interactions. To get more precise information on the molecular interactions, DFT calculations have been performed. From these calculations it is found that methyl acetate dimers of four different geometries are possible. The most stable among these dimers is the one with C − H⋯O = C interactions stronger than the C − H⋯O − C. If the scenario is opposite in a dimer, the stability becomes the least. These four dimers dissociate in the investigated binary solution and 1:2 (m-xylene:methyl acetate) complexes of five different geometries are formed. In one of the complexes, the homointeractions C − H⋯O = C among the methyl acetate molecules are more stronger than any other interactions and the stability of the complex is the least. In all the other complexes the interactions (methyl acetate)C − H⋯π (m − xylene) are the strongest. In complexes where the hydrogens attached to ring carbons of m-xylene do not involve in hydrogen bonds with methyl acetate, the stability of the complexes is more. If these hydrogen bonds are formed, the stabilities of those complexes are reduced.

Homo/hetero interactions in the binary solutions of toluene with acetonitrile: FTIR spectroscopic, theoretical and dielectric studies

FTIR spectroscopic studies has been carried out on the equimolar binary solution of toluene with acetonitrile which predicts the existence of molecular interactions. DFT calculations reveal that B3LYP functional with Grimme's dispersion correction D3 level is more suitable than the ωB97XD functional for investigating the molecular interactions in the toluene-acetonitrile system. These theoretical calculations suggest that the hydrogen bond interactions among the acetonitrile dimers through the n→σ∗ transitions are more stronger than any of the interactions in the 1:2 (toluene: acetonitrile) complex. However the stability of this complex is found to be more than that of the acetonitrile dimer as implied by their interaction energies. To investigate the effect of the homo/heterointeractions on the dielectric parameters of the toluene-acetonitrile solutions, dielectric relaxation studies has been carried out on these solutions over the entire composition range in the frequency range: 10 MHz–28 GHz at 298 K. Despite the presence of molecular interactions, linearity is observed in the εm vs X2 curve for some of the solutions.

FTIR spectroscopic studies and DFT calculations on the toluene- propionitrile binary system

FTIR spectroscopic studies has been carried out on pure toluene (TOL), propionitrile (PN) and their equimolar binary solution at room temperature. DFT calculations (using B3LYP functional with the Grimme's dispersion correction D3 and ωB97XD with the D2 version of Grimme's dispersion) have also been carried out on PN dimers and various TOL-BN heteroassociated networks that are supposed to exist in neat PN and binary solution, respectively, on the basis of the shifts suffered by the fundamental absorptions of TOL and PN upon mixing with each other. Formation of (methyl)C−H⋯N≡C and (methylene)C−H⋯N≡C hydrogen bonded dimers in neat PN has been identified. The dominant interaction forces that stabilize the 1:2 (TOL: PN) complex formed in the binary solution are (TOLmethyl)C−H⋯N≡C and (TOLring)C−H⋯N≡C intermolecular H-bonds.

Hydrogen bond interactions in the binary solutions of ethyl acetate with nitrobenzene: Spectroscopic, theoretical and dielectric studies

FTIR spectroscopic studies has been carried out on pure ethyl acetate (EA), nitrobenzene (NBZ) and their equimolar binary solution. Theoretical calculations have been performed to validate the results of the FTIR spectral studies. Through the calculations, it is found that dimers of cyclic geometry with the hydrogen bonds between the methyl/methylene hydrogen and ester linkage oxygen (oxygen that is bonded with carbon through the single bond) can prevail in neat EA. These dimers, being highly unstable, dissociate into monomers in the binary solution and participate in the formation of 1:1 and 1:2 (EA:NBZ) systems. The 1:2 system is found to be more stable than the NBZ and EA dimers and the 1:1 system. The EA-NBZ solutions of entire composition range have been subjected to dielectric relaxation studies at 298K using Time Domain Reflectometry (TDR) in the frequency range 10MHz to 30GHz. The results obtained have been interpreted with the aid of the findings of FTIR studies and DFT calculations.

Molecular interactions in ethyl acetate-chlorobenzene binary solution: Dielectric, spectroscopic studies and quantum chemical calculations

Dielectric studies using Time Domain Reflectometry method has been carried out on the binary solution of Ethyl acetate (EA) with Chlorobenzene (CBZ) over the entire composition range. Spectroscopic (FTIR and 13C NMR) signatures of neat EA, CBZ and their equimolar binary solution have also been recorded. The results of the spectroscopic studies favour the presence of (CBZ) CH⋯OC (EA), (EA) methylene CH⋯π electrons (CBZ) and (EA) methyl CH⋯Cl (CBZ) contacts which have been validated using quantum chemical calculations. Dimerization of CBZ has been identified. Presence of β-clusters has been identified in all the solutions. Although EA and CBZ molecules have nearly equal molar volumes, CBZ molecules experience larger hindrance for the rotation than EA molecules. Very small excess dielectric constant (εE) values may be correlated with weak heteromolecular forces and/or closed heteromolecular association.

The mechanism of adsorption of zinc and cadmium ions onto bentonite clay

Adsorption of zinc and cadmium ions onto bentonite clays from the Zyryanskoe deposit (Kurgan region, Russia) was studied as a function of contact duration, pH, and temperature. Silanol and aluminol groups of the clay were found to participate in ion exchange and in complex formation with zinc and cadmium ions; a certain process prevails depending on pH. Adsorption of zinc and cadmium ions from equimolar binary solutions was studied. Adsorption of ions onto clay increases with temperature increasing from 293 to 333 K. Adsorption mechanisms of Zn(II) and Cd(II) ions were proposed.

Sequential adsorption of egg-white proteins at the air–water interface suggests a stratified organization of the interfacial film

The aim of this work was to get further insight into the formation of the interfacial film by ovalbumin and lysozyme in equimolar binary solutions, as well as the organization of these proteins inside the interfacial film. Our approach consisted in the sequential adsorption of the two proteins, with or without previous replacement of the sub-phase with protein-free buffer before injection of the second protein. The results suggest that ovalbumin controls surface pressure of the interfacial film and whatever the order of adsorption, there would be a specific and stratified organization of the two proteins inside the interfacial film: an ovalbumin monolayer in direct contact with the air–water interface and multilayers of lysozyme below this top layer. The experiments of replacement of the sub-phase suggest that, for both proteins, the adsorption film is almost resistant to this replacement with protein-free buffer, showing an apparently irreversible adsorption for the time-scale considered and at high concentrations. Moreover, the synergy between ovalbumin and lysozyme put into evidence during the concomitant adsorption of the two proteins in a previous work ( Le Floch-Fouéré et al., 2009, Food Hydrocolloids 23, 352–365) is a phenomenon which occurs as the result of adsorption of the proteins at the air–water interface.

Electrolytic behavior and application to lithium batteries of monofluorinated dimethyl carbonate

Dimethyl carbonate (DMC) was fluorinated by F 2 gas (direct fluorination) to form four fluorinated DMC derivatives, such as monofluorinated DMC (MFDMC), two difluorinated DMCs (DFDMC(a) and DFDMC(b)) and trifluorinated DMC (TFDMC). The electrolytic behavior and charge–discharge characteristics of the lithium electrode were examined in MFDMC and MFDMC-ethylene carbonate (EC) equimolar binary solutions. The dielectric constant and viscosity of MFDMC are higher than those of DMC. This means that the molecular interaction in MFDMC becomes larger due to the introduction of a high electron withdrawing fluorine atom. In addition, oxidation durability of MFDMC is higher than that of DMC. The specific conductivity in EC-MFDMC equimolar binary solution containing 1 M LiPF 6 is 8.5 mS cm − 1 at 25 °C which means a good electrolyte for lithium batteries. The lithium electrode cycling efficiency in EC-MFDMC equimolar binary solution containing 1 M LiPF 6 is higher than 70%. The surface of the film formed on the electrode in the solution is homogeneous, and consists of the uniform and small grain size.

Physical and electrolytic properties of difluorinated dimethyl carbonate

The physical and electrolytic properties of difluorinated dimethyl carbonate (DFDMC) synthesized using F 2 gas (direct fluorination) were examined. The dielectric constant and viscosity of DFDMC are higher than those of monofluorinated dimethyl carbonate (MFDMC) and dimethyl carbonate (DMC). The oxidative decomposition voltage of DFDMC is higher than those of DMC and MFDMC. The specific conductivity in DFDMC solution is considerably lower than those in MFDMC and DMC solutions. The ethylene carbonate (EC)-DFDMC equimolar binary solution containing 1 mol dm −3 LiPF 6 shows a moderate conductivity of 6.91 mS cm −1 at 25 °C. The lithium electrode cycling efficiency (charge–discharge coulombic cycling efficiency of lithium electrode) in EC-DFDMC equimolar binary solution containing 1 mol dm −3 LiPF 6 is higher than 80%. The EC-DFDMC solution is a good electrolyte for rechargeable lithium batteries.

A Novel Lithium Salt with a Chelate Compound of Phosphorus for Lithium Battery Electrolytes

Abstract We have synthesized a novel Li salt with a chelate compound of phosphorus, lithium tris[4-methyl-1,2-benzenediolato(2–)-O,O′]phosphate (4-MLTBP). The thermal stability and electrolytic properties of 4-MLTBP, and the charge–discharge characteristics of a lithium electrode are investigated. The thermal decomposition temperature of 4-MLTBB is higher than those of a common lithium salt with phosphorus, LiPF6, and lithium tris[1,2-benzenediolato(2–)-O,O′]phosphate, which we previously synthesized. The specific conductivities and the cycling efficiencies become higher in an ethylene carbonate– and a propylene carbonate–dimethyl carbonate equimolar binary solutions containing a mixture of 4-MLTPB with LiPF6.

Application of Lithium Organoborate with Salicylic Ligand to Lithium Battery Electrolyte

The thermal characteristics of lithium bis[salicylato(2-)]borate (LBSB) and its novel derivatives synthesized by us, such as lithium bis[3-methylsalicylato(2-)]borate (3-MLBSB), lithium bis[3,5-dichlorosalicylato(2-)]borate (DCLBSB), and lithium bis[3,5,6-trichlorosalicylato(2-)]borate (TCLBSB) were examined by thermogravimetric analysis (TG). The thermal decomposition in air begins at 260, 290, 310, and 320°C for TCLBSB, LBSB, DCLBSB, and 3-MLBSB, respectively. The thermal stabilities of 3-MLBSB and DCLBSB are nearly equal to those of and The order of the stability toward oxidation of these organoborates is which differs from the thermal stability. Ionic dissociation properties of LBSB and its derivatives were examined by conductivity measurements in ethylene carbonate-1,2-dimethoxyethane (EC-DME) equimolar binary dilute solutions. The conductivities of the 0.1 mol dm−3 DCLBSB and TCLBSB electrolytes become higher than those in the LBSB and 3-MLBSB electrolytes. It means that DCLBSB and TCLBSB have high dissociating abilities in EC-DME mixture. The 0.5 mol dm−3 LBSB/EC-DME equimolar binary solution exhibits the highest lithium electrode cycling efficiency of more than 85% in the higher range of cycle numbers. This is a good electrolyte for rechargeable batteries. © 2001 The Electrochemical Society. All rights reserved.

Application to lithium battery electrolyte of lithium chelate compound with boron

The electrolytic conductivities and charge–discharge characteristics of lithium electrode are examined in propylene carbonate (PC)- and ethylene carbonate (EC) tetrahydrofurans, such as 2-methyltetrahydrofuran (2-MeTHF) and 2,5-dimethyltetrahydrofuran (2,5-DMeTHF), binary solvent electrolytes containing lithium bis[1,2-benzenediolato(2-)- O, O′]borate (LBBB), lithium bis[2,3-naphthalenediolato(2-)- O, O′]borate (LBNB), lithium bis[2,2′-biphenyldiolato(2-)- O, O′]borate (LBBPB) and lithium bis[salicylato(2-)]borate (LBSB). The order of specific conductivities in PC- and EC-based equimolar binary solutions containing these organoborates is LBBB≥LBNB>LBSB>LBBPB. The conductivity in LBNB electrolyte with higher viscosity than that in LBSB electrolyte becomes high. The PC–2-MeTHF and PC–2,5-DMeTHF equimolar binary solutions containing LBSB and a mixed electrolyte (LBBPB+LiPF 6) show very high cycling efficiencies more than 90% at a higher range of cycle number. The EC–THF and EC–2-MeTHF equimolar binary solutions are moderate electrolytes with about 80% cycling efficiencies. It is found by using scanning electron microscope (SEM) that the films formed on the electrode in PC–2-MeTHF and PC–2,5-DMeTHF electrolytes with higher cycling efficiencies have a homogeneous surface with uniform grain size.

Spectroelectrochemical Sensing Based on Multimode Selectivity Simultaneously Achievable in a Single Device. 8. Selectivity at Poly(vinyl alcohol)-Polyelectrolyte Blend Modified Optically Transparent Electrodes

Poly(vinyl alcohol) (PVA)-based polymer blends show potential utility as polymer films for a newly designed spectroelectrochemical sensor to achieve three modes of selectivity: charge-selective partitioning, electrolysis potential, and spectral absorption wavelength. The polymer blends were formulated by entrapping two polyelectrolytes, poly(vinylbenzyltrimethylammonium chloride) (PVTAC) and poly(acrylic acid) (PAA) into a cross-linked PVA matrix, which was covalently coated onto the surface of ITO glass. Sensing of the analyte is based on the change in attenuation of the light guiding through an optical substrate resulting from an electrochemical reaction of the analyte induced by electromodulation. The signal of the analyte in a competitive binary system is isolated by careful choice of polymer modifying film, potential window and monitoring wavelength. A 10−4 M equimolar binary solution of Ru(BiPy)32+ and Fe(CN)63– was used to study the selectivity of charge-selective partitioning. Cyclic voltammograms clearly demonstrated the exclusion of same charged ions from the selective layer with polymer blend modified sensors. 10−4 M equimolar Ru(CN)64– and Fe(CN)64– was chosen to demonstrate the selectivities of electrolysis potential and spectral absorbance wavelength. The detailed kinetics and associated electrochemical and optical waveforms from the spectroelectrochemical sensors in competitive binary mixtures of analytes are presented.

Inhibition of Listeria locomotion by mosquito oostatic factor, a natural oligoproline peptide uncoupler of profilin action

Mosquito oostatic factor, a naturally occurring decapeptide (YDPAPPPPPP), strikingly resembles the primary structure of oligoproline-rich regions within the protein ActA, a bacterial surface protein required for Listeria motility in host cells. When microinjected into Listeria-infected PtK2 cells, the insect oostatic factor rapidly blocks Listeria-induced actin rocket tail assembly as well as intracellular locomotion of this pathogen. At intracellular concentrations of about 90 nM, transient inhibition of rocket tail formation and bacterial locomotion occurs, followed by full recovery of tail length and motility. However, at 0.9 microM oostatic factor, both processes are permanently arrested. Introduction of oostatic factor by microinjection also causes PtK2 peripheral membrane retraction in both Listeria-infected and uninfected cells. Epifluorescence microscopy with bodipy-phallacidin reveals that cells microinjected with the insect factor lose all actin stress fibers and accumulate F-actin in regions of membrane retraction. When the insect peptide is combined with profilin as an equimolar binary solution (1 microM [final concentration] each), intracellular addition fails to inhibit Listeria rocket-tail formation, fails to block intracellular bacterial movement, and no longer causes marked membrane retraction. The ability of profilin to neutralize the inhibitory action of oostatic factor is consistent with complex formation, and this finding suggests that profilin may interact directly with ActA peptide as well as a host cell peripheral membrane component to promote actin filament assembly by locally generating ATP-actin. Dispersal of profilin from such sites by oligoproline-rich peptide inhibitors suggests that profilin is directly involved in intracellular pathogen locomotion and reorganization of actin cytoskeleton of the host cell peripheral membrane.