Quantum chemical calculations and X-ray crystallographic studies of cis-dioxomolybdenum(VI) Schiff base complex

Treatment of the Schiff base 2-((E)-(2-hydroxy propylimino)methyl)phenol with MoO₂(acac)₂ in dry methanol gave the mononuclear complex (methanol{6-[(2-oxidopropyl)iminometh-yl]phenolato}dioxidomolybdenum(VI), which was characterized by X-ray crystal analysis, and it has monoclinic space group p2₁/c, and a = 10.330(17) Å, b = 9.397(15) Å, c = 13.695(2) Å, V = 1252.1(3) Å³, and Z = 4. B3LYP theoretical method with DZP basis sets calculations nicely reproduces the X-ray experimental geometry, molecular orbital levels and the other structural properties for this complex.     

Magnetic Nanoparticles Supported Ionic Liquids Improve Firefly Luciferase Properties

Ionic liquids as neoteric solvents, microwave irradiation, and alternative energy source are becoming as a solvent for many enzymatic reactions. We recently showed that the incubation of firefly luciferase from Photinus pyralis with various ionic liquids increased the activity and stability of luciferase. Magnetic nanoparticles supported ionic liquids have been obtained by covalent bonding of ionic liquids-silane on magnetic silica nanoparticles. In the present study, the effects of [γ-Fe₂O₃@SiO₂][BMImCl] and [γ-Fe₂O₃@SiO₂][BMImI] were investigated on the structural properties and function of luciferase using circular dichroism, fluorescence spectroscopy, and bioluminescence assay. Enzyme activity and structural stability increased in the presence of magnetic nanoparticles supported ionic liquids. Furthermore, the effect of ingredients which were used was not considerable on K _m value of luciferase for adenosine-5′-triphosphate and also K _m value for luciferin.     

Enhanced control release of thyme essential oils from electrospun nanofiber/polyamidoamine dendritic polymer for antibacterial platforms

The motive of the present investigation is to probe the role of polyamidoamine dendritic polymer (PAMAM) as a nano‐carrier function on the stepwise‐release rate of thyme oil (TEO) as natural extract with a superior antibacterial property. To represent quantitative and kinetic trends of release from nylon 6 electrospun fiber mats of TEO from mats, single‐sensor gas diagnosis device as an applicable diagnostic tool was tested in a distinct time sheet. All mats were characterized using scanning electron microscopy (SEM), Fourier‐transform infrared spectroscopy (FTIR), surface tension, contact angle, and antibacterial activity. As an outcome, PAMAM is major responsible for the pretending burst release due to the remarkable branches and cavities of PAMAM which encapsulate TEO. Noticeably, long‐term exposure of TEO was reached compared to the counterpart sample and a higher amount of PAMAM renders further functionality to protect guest molecules and not let them move easily in the atmosphere. It is realized that the essence release of mats with 2 and 10 wt% of PAMAM moieties last up to 9 and 12 days, respectively. Interestingly, all functionalized samples prevent the growth of Escherichia coli and Staphylococcus aureus bacteria and antibacterial value for samples with PAMAM surpassed 100% while decreased around 15 to 50% for mats without PAMAM over a 2‐week period. The results revealed that the functionalized samples were a promising fragrance delivery system with more effective antibacterial activity.     

Numerical investigation of nanofluid laminar forced convection heat transfer between two horizontal concentric cylinders in the presence of porous medium

Journal of Thermal Analysis and Calorimetry - In this paper, the finite volume method is used to investigate the laminar forced convection of water–copper nanofluid between two porous...     

Effect of milling speed on mechanical activation of Al/ZrO2/H3BO3 system to prepare Al2O3–ZrB2 composite powder

A powder mixture of Al/ZrO₂/H₃BO₃ system was mechanically milled under argon in a high-energy planetary mill at different speeds. The XRD and DSC analyses of the as-synthesized samples show that milling operation affects the mechanism, efficiency, and ignition temperature of combustion behavior of the system. XRD analysis of the as-milled samples shows that low-speed milling does not change the phases presented in the sample, while high-speed milling (350, 450 rpm) has led to the formation of new intermetallic phases. This confirms that some reactions between reactants have occurred during high-speed milling.     

A nanosized cadmium(II)-imprinted polymer for use in selective trace determination of cadmium in complex matrices

We describe a nanosized Cd(II)-imprinted polymer that was prepared from 4-vinyl pyridine (the functional monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator), neocuproine (the ligand), and Cd(II) (the template ion) by precipitation polymerization in acetonitrile as the solvent. The imprinted polymer was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The maximum adsorption capacity of the nanosized sorbent was calculated to be 64 mg g^?1. Cadmium(II) was then quantified by FAAS. The relative standard deviation and limit of detection are 4.2 % and 0.2 μg L^?1, respectively. The imprinted polymer displays improve selectivity for Cd(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This nanosized sorbent is an efficient solid phase for selective extraction and preconcentration of Cd(II) in complex matrices. The method was successfully applied to the trace determination of Cd(II) in food and water samples.

Aromatization of Hantzsch Ester 1,4‐Dihydropyridines with Iodine under Normal Conditions and Ultrasound Irradiation

A variety of Hantzsch ester 1,4‐dihydropyridines are efficiently oxidized to their corresponding pyridine compounds with iodine under normal conditions and ultrasound irradiation. The reactions were carried out in refluxing CH₃CN.     

Modelling phase equilibria of pure ionic liquids from a new equation of state

A perturbed hard-trimer (PHT) equation of state (EOS) has been employed to model densities and some derived thermodynamic properties of 39 ionic liquids (ILs) considering a trimer expression obtained from the statistical associating fluid theory as the reference physical model. The van der Waals dispersion forces were applied as perturbation term. The proposed model was tested using ILs containing imidazolium, pyrrolidinium, pyridinium, phosphonium and piperidinium cations. Two parameters appeared in the PHT EOS which are temperature-dependent, reflecting the dispersive energy parameters among trimers, ε and the hard-core diameter, σ, were determined based on the molecular scaling parameters. The performance of the proposed PHT EOS has been evaluated by predicting the volumetric and first and second derivatives thermodynamic properties in the pressure and temperature ranges within 0.1–200 MPa and 273–472.6 K, respectively. From 6331 data points examined, the average absolute deviation (AAD) of the correlated (at 0.1 MPa) and predicted (at high pressures) densities from the experimental ones was found to be 0.18 %. Furthermore, the isothermal compressibilities and thermal expansion coefficients as well as the heat capacities were estimated through the PHT EOS with uncertainties of the order of ±11.09, ±11.76 and ±3.34 %, respectively. Further, the vapour pressures of ILs are also predicted by the proposed model. The trend of the predicted vapour pressure is in accord with those reported in literature.

     

Oxoperoxo tungsten(VI) complex immobilized on Schiff base-modified Fe3O4 magnetic nanoparticles as a heterogeneous catalyst for oxidation of alcohols with hydrogen peroxide

Oxoperoxo tungsten(VI) complex immobilized on Schiff base-modified Fe₃O₄ super paramagnetic nanoparticles were synthesized and appropriately characterized using FT-IR, XRD, SEM, TEM, EDX, BET, and VSM analysis. The synthesized nanoparticles efficiently catalyzed oxidation of benzylic alcohols with H₂O₂ as oxidant in high yields, with high to excellent selectivity. The catalyst can be recovered using an external magnetic field and recycled for subsequent oxidation reactions without any appreciable loss of efficiency. The simple preparation, high activity, excellent selectivity, and simple recoverability of the catalyst are advantageous.