Thermal performances and stabilities of nanofluids in an electrical oil heater

Journal of Thermal Analysis and Calorimetry - In this study, different nanofluids synthesized with aluminium oxide (alumina) and titanium dioxide in mass ratios of 1%, 3%, and 5% were tested in an...     

Synthesis,crystal structure and biological activity of the nickel(II) complex of 2,6-diacetylpyridinedihydrazone

A complex of Ni^II with 2,6-diacetylpyridinedihydrazone (L) towards nickel(II) has been prepared and characterized by means of elemental analyses, IR, electronic spectra and single crystal X-ray analyses. [NiL₂](NO₃) was crystallized in the tetragonal space group P-4 21 c. The complex exhibits the expected coordination sphere with six nitrogen atoms coordinated to the central Ni^II with a deformation from pseudo-octahedral geometry. Antimicrobial activities of the ligand and its complex were investigated.     

In situ IR monitoring of complexation reaction between 2,6-bis(3,5-dimethylpyrazoyl)pyridine and some metal ions

In situ complexation reactions between 2,6-bis(3,5-dimethylpyrazoyl)pyridine (bdmpp) and some transition metals (Cu²⁺, Co²⁺ and Ni²⁺) were studied with a new method in liquid cell using FT-IR. In this method, the FT-IR spectrum of the solution of ligand was defined as a background, and then the changes in the FT-IR spectra by the addition of the metal salts were investigated. This method allows one to obtain the spectra of the ligand-metal complex before yielding the solid-state product. Complexation ratios (M/L) of these metals with bdmpp were found 1/1, 1/2 and 1/2, for Cu, Co and Ni, respectively. Studying with Mg²⁺ and Ca²⁺ ions showed that there were no interaction between bdmpp and these metal ions in methanol.     

Synthesis,characterization, crystal structure and biological activity of the cobalt(IV) complex of 2,6-diacetylpyridine dioxime: [Co(dapdo)<Subscript>2</Subscript>]

The cobalt(IV) complex of 2,6-diacetylpyridine dioxime (dapdoH₂) was prepared and characterized by X-ray diffraction, elemental analysis and FT-IR. The titled complex was found to crystallize in the orthorhombic space group and was screened for antibacterial and antifungal activities by the disc diffusion and microtitter plate techniques using DMF as solvent. It has been found that the antimicrobial activity of the complex [Co(dapdo)₂] is slightly higher than the free ligand (dapdoH₂).     

Detection of relative dimer and rotamer concentrations of diacetamide in different solvents by FT-IR spectroscopy and DFT calculations

The relative rotamer, dimer and tautomer concentrations of diacetamide have been studied by means of infrared spectroscopy, with the recorded spectra being analyzed employing results from density functional theory calculations. It is observed that the cis–trans monomeric form of diacetamide (1) is found to be the most stable isomer in all studied solvents, with trans–trans diacetamide (2) being found to be 20% of total diacetamide in methanol. While the dimer form of diacetamide (3) is present only in carbontetrachloride (about 34% of the total), its tautomeric forms (4, 5) are not favorable in any of the studied solvents.     

Detection of tautomer proportions of dimedone in solution: a new approach based on theoretical and FT-IR viewpoint

Molecular structures of stable tautomers of dimedone [5,5-dimethyl-cyclohexane-1,3-dione (1) and 3-hydroxy-5,5-dimethylcyclohex-2-enone (2)] were optimized and vibrational frequencies were calculated in five different organic solvents (dimethylsulfoxide, methanol, acetonitrile, dichloromethane and chloroform). Geometry optimizations and harmonic vibrational frequency calculations were performed at DFT 6-31+G(d,p), DFT 6-311++G(2d,2p), MP2 6-311++G (2d,2p) and MP2 aug-cc-pVDZ levels for both stable forms of dimedone. Experimental FT-IR spectra of dimedone have also been recorded in the same solvents. A new approach was developed in order to determine tautomers’ ratio using both experimental and theoretical data in Lambert–Beer equation. Obtained results were compared with experimental results published in literature. It has been concluded that while DFT 6-31+G(d,p) method provides accurate enol ratio in DMSO, MeOH, and DCM, in order to obtain accurate results for the other solvents the MP2 aug-cc-pVDZ level calculations should be used for CH₃CN and CHCl₃ solutions.     

Background defining during the imine formation reaction in FT-IR liquid cell

Imine formation is a very important chemical reaction because of its relevance to biological process. Therefore, it is crucial to follow whole reaction process in detail. The current work performed to monitor the whole imination reaction in real time in liquid cell by FT-IR spectroscopy. The complex spectral futures due to solvent, unreacted reagents, acid catalysis and other additives are eliminated by defining a background at the beginning or at any time during the reaction. This procedure also makes it possible to monitor the changes in the concentration of each component in the liquid cell. The consumption of the functional groups of the reagents results in absorbance due to the direct difference spectra while the appearance of functional groups is monitored as percentage transmittance. The concentration changes in the cell arising from the reaction gives the product spectra without having to isolate it from the mixture. It is also possible to see the intermediates appearing and disappearing during the reaction. This report also illustrates a brief application of the technique by time dependence of the peak highs in absorption (ABS) mode.     

Callus induction and plant regeneration from different explants of Actinidia deliciosa

In this study, an efficient procedure was developed for callus induction and regeneration of kiwifruit (Actinidia deliciosa) using different organs of shoots developed under in vitro conditions. Effects of explants source and media (M₁, 1.0 mg l⁻¹ BA + 2.0 mg l⁻¹ 2,4-D–M₂, 1.0 mg l⁻¹ NAA + 2.0 mg l⁻¹ 2,4-D) on initiation of callus were examined in order to obtain callus for organogenesis. The best callus for plant regeneration was obtained from leaf explants on Murashige and Skoog’s medium (MS) supplemented with M₂. Formation of callus from leaf of kiwifruit (A. deliciosa) was cultured in MS medium containing different concentration of N⁶-benzylaminopurin (BA; 0.0, 1.0, 2.0, 4.0, 6.0, 8.0 mg l⁻¹) for callus proliferation and plant regeneration. Although the first shoot formation was appeared in medium containing 6.0 and 8.0 mg l⁻¹ BA, the best shoots formation was obtained in medium with 4.0 mg l⁻¹ BA.