The TeO2-Na2O System: Thermal Behavior,Structural Properties,and Phase Equilibria

Thermal behavior, structural properties, and phase equilibria of the (100−x)TeO₂-xNa₂O system were studied in the 5 ≤ x ≤ 50 mol% composition range. Investigation of glass formation behavior in the binary system was realized, and the glass formation range was determined as 7.5 ≤ x ≤ 40 mol%. Differential thermal analysis (DTA) and Fourier transform infrared (FTIR) spectroscopy techniques were used for thermal and structural characterization of the glasses. Influence of Na₂O content on glass transition temperature (T_g), glass stability (∆T), density (ρ), molar volume (V_M), oxygen molar volume (V_O), and oxygen packing density (OPD) values of sodium tellurite glasses was evaluated considering the structural transformations in the glass network. For the phase equilibria studies, DTA, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive X-ray (SEM/EDS) techniques were utilized to characterize the heat-treated samples. According to the phase equilibria studies, three eutectic regions were detected in the 0 < x < 50 mol% composition range of the (100−x)TeO₂-xNa₂O system. A new invariant endothermic reaction was detected for the compositions between 40 ≤ x ≤ 45 mol%. Na₂O.8TeO₂ (11.11 mol% Na₂O) compound that was claimed to exist in the binary system in the literature was found to be the metastable δ-TeO₂ phase.     

Synthesis, Characterization and Crystal Structure of a Novel Three-Dimensional Supramolecular Framework Containing Ni···π Interaction Heteronuclear Complex: {[Cu(4(5)-Meim)4][Ni(CN)4] · H2O}n

The heteronuclear complex, {[Cu(4(5)-Meim)₄][Ni(CN)₄] · H₂O}_n (1), (4(5)-Meim = 4(5)-methylimidazole) was synthesized and characterized by FT-IR spectroscopy, single crystal X-ray diffraction, thermal analysis and elemental analysis. The Cu(II) ion has a distorted square planar geometry, extended to (4 + 2) weak coordination by two nitrogen atoms of the cyano group. The coordination sphere around the Ni(II) ion should be described as a 4 + 2 geometry with the four cyano groups and the axial coordination site is located at the imidazole ring though a weak Ni···π interaction. The coordination bond is much stronger than the Ni···π interactions and it is expected that the formation of the coordination bond will affect more significantly the position of the absorption bands associated with the vibrations of the ligand. In addition, the out-of-plane modes of 4(5)-Meim are shifted to higher frequencies relative to free ligand. We propose that these shifts are indicative of the weak CH∙∙∙π and Ni∙∙∙π interactions, according to the crystallographic and spectroscopic data.     

Experimental and modeling study for the removal of formic acid through bulk ionic liquid membrane using response surface methodology

Abstract

In this study, formic acid removal from its aqueous solutions through bulk ionic liquid membrane (BILM) was investigated. Tributyl phosphate (TBP) as a carrier in imidazolium-based ionic liquids was used. D-optimal design based on response surface methodology has been applied to investigate the effect of various operating factors. Initial formic acid concentration, TBP concentration, and NaOH concentration were selected as numerical factors, and ionic liquid type was chosen as a categorical factor. The model equations were obtained to determine BILM process behavior. The removal efficiencies, represented by the extraction and stripping efficiencies, were calculated from the experimental data. The highest removal efficiencies were determined at higher concentration values of TBP and NaOH. All ionic liquids studied in this study had good transport selectivity for the removal of formic acid. The design study showed that BILM is an effective method for the removal of formic acid from the water.     

Optimum insulation thickness of the piping system with combined economic and environmental method

In the present study, an alternative method combining economic and environmental costs is suggested for the pipe insulation. This method is called as combined economic and environment method (CEEM). Bilecik, which is located in the Marmara region, Turkey, is chosen. Rockwool and glass wool are chosen as insulation materials. The optimum insulation thicknesses of three different methods including CEEM, economic, and environmental approaches are calculated and compared. Optimum points are 0.46 m (CEEM), 0.39 m (economic approach), and 0.54 m (environmental approach) for rockwool; and 0.46 m (CEEM), 0.40 m (economic approach), and 0.59 m (environmental approach) for glass wool. In addition, annual cost savings and energy savings are determined.     

Antifungal Activity of Undecylenic Acid Emulsions by Microbiological Methods

Two nonionic surfactants (Simulsol 98 and Simulsol OL 50) alone and I:I mixtures, corn oil-undecylenic acid and water formed emulsions, oily isotropic liquid phases, lamellar and hexagonal liquid crystal phases. The optimum release of undecylenic acid from these phases were controlled microbiologically. The active ingredient undecylenic acid, is released more from emulsion systems containing liquid crystals than only liquid crystalline and oily isotropic liquid phases.     

Synthesis, Spectroscopic and Structural Properties of Heteropolynuclear Cyano-Bridged Complexes

Two novel cyano-bridged heteropolynuclear complexes, [Zn(mprd)₂Ni(μ-CN)₄]_n (1) and {[Cd(mprd)₂Ni(μ-CN)₄]·2H₂O}_n (2), (mprd = 4-methylpyrimidine), have been synthesized and characterized by FT-IR spectroscopy, Raman spectroscopy, thermal analyses (TG, DTG and DTA) and elemental analyses. The crystal structure of the 1 was determined by X-ray single crystal diffraction. The complex crystallizes in the monoclinic, space group C2/c. The crystal structure of 1 consists of a corrugated 2D network in which the Zn(II) and Ni(II) atoms are linked by cyanide groups. The Ni(II) atom is four coordinate with four carbon atoms in a square-planar geometry; and, the Zn(II) atom is six coordinate with four cyanide-nitrogen and two mprd-nitrogen atoms with a distorted octahedral geometry. The shifts of the cyano stretching vibration are evidence for the formation of cyano bridges. Vibration assignments are given for all the observed bands and the spectral features support the structure of the polymeric complexes.     

X-Ray crystal structure analysis and determination of azo-enamine and hydrazone-imine tautomers of two hetarylazo indole dyes

Two hetarylazo indole dyes were analyzed by single crystal X-ray diffraction. Dye 1 , C₁₈H₁₄N₄O, crystallises in the monoclinic system, space group P2₁/c, with two independent molecules in the asymmetric unit. Dye 2 , C₂₀H₁₆N₄, also crystallises in the monoclinic system, space group P2₁/n, Z  = 4. In both compounds, there are two intramolecular C–H...N hydrogen bonds which influenced the molecular conformation between the azo group and the indole ring system and its phenyl substituent. Each of the independent molecules of dye 1 interact through the N–H...N hydrogen bond, whereas no classical intermolecular hydrogen bond was observed in dye 2 . The molecules of dye 1 and dye 2 are packed differently in both structures.     

A theoretical and experimental investigation of vibrational spectra and electronic transitions on 3-methyldiphenylamine molecule as organic semiconductor

In this study, the structural and spectroscopic investigations of 3-methyldiphenylamine were reported. The molecular geometry was optimized from Density Functional Theory (B3LYP method) using 6-31+G(d,p) basis set on the ground state and the infrared wavenumbers and intensities were predicted by using this geometry. Calculated wavenumbers and intensities were compared with FT-IR spectrum of 3-methyldiphenylamine. Additionally, time depended density functional theory (TD-DFT) method using 6-31++G(d,p) basis set was used to determine the minimum energy structure of 3-methyldiphenylamine. According to the calculated results, the vibrational wavenumbers and excitation energies show an excellent agreement with the experimental data. Furthermore, these calculated results can be employed to predict the vibrational and electronic properties for improving organic semiconductor materials.     

One- and Two-Dimensional Cadmium(II) Tetracyanonickelate(II) Coordination Polymers With Imidazole and 2-Methylimidazole Ligands

Two novel cyano-bridged heteropolynuclear complexes, [Cd(im)₄Ni(μ-CN)₂(CN)₂] _n (1) and [Cd(mim)₂Ni(μ-CN)₄] _n (2) (im: imidazole and mim: 2-methylimidazole), have been synthesized and characterized. In 1, the trans-directed cyanide ligands of [Ni(CN)₄]²⁻ anions link two [Cd(im)₄]²⁺ units, whereas in 2, all the cyanide groups take part in bonding with two adjacent [Cd(mim)₂]²⁺ units, resulting 1D and 2D coordination polymers, respectively. The coordination environment of the Cd(II) ion described as distorted octahedral geometry, whereas around the Ni(II) centre had square planar geometry in both complexes. The crystals packing of 1 and 2 were a composite of hydrogen bonding, π···π and C–H···Ni interactions.