Spectroscopic, quantum chemical DFT/HF study and synthesis of [2.2.1] hept-2'-en-2'-amino-N-azatricyclo [3.2.1.0(2,4)] octane

The compound 4-N-bicyclo [2.2.1] hept-2'-en-2'-amino-N-azatricyclo [3.2.1.0(2,4)] octane (2) has been synthesized and characterized by elemental analysis, IR, UV-vis, mass and NMR. Density functional theory (DFT) and Hartree-Fock (HF) calculations have been carried out for the title compound by using the standard 6-31G* basis set. The calculated results show that the predicted geometry can well reproduce the structural parameters. Predicted vibrational frequencies have been assigned and compared with experimental IR spectra and they complement each other. The theoretical electronic absorption spectra have been calculated by using CIS, TD-DFT and ZINDO methods. The (13)C NMR and (1)H NMR of compound (2) have been calculated by means of Becke 3-Lee-Yang-Parr (B3LYP) density functional method with 6-31G* basis set. Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for predicting NMR properties. On the basis of vibrational analyses, the thermodynamic properties of the title compound at different temperatures have been calculated.     

Controlled Ethylene Polymerization Catalyzed by Cp$\rm{{_{2}^{\ast}}}$ZrBu2/[Ph3C] [B(C6F5)4]/iBu4Al2O above Room Temperature

The ternary system composed of Cp ZrBu₂ (Cp*=Me₅Cp), [CPh₃][B(C₆F₅)₄], and tetraisobutyldialuminoxane (TIBAO) catalyzed the polymerization of ethylene in a controlled fashion at temperatures up to 60 °C. The consumption of ethylene remained constant during the polymerization process, the molecular weight of the polyethylene increased linearly with time, and polydispersity indexes down to 1.3 were obtained. Characterization of the polyethylene by ¹³C‐NMR and FT‐IR spectroscopy did not indicate any branching or CC linkages, even for polymer produced at 40 °C or above. The linear and saturated polymer structure is due to the absence of β‐hydride transfer, β‐hydride elimination and chain walking during the polymerization. The absence of termination reactions is consistent with the system's demonstrated controlled polymerization.     

Composition of essential oil and biological activity of extracts of Viola odorata L. from central Iran

Essential oil composition of the leaves of Viola odorata L. growing wild in Kashan, central Iran, was extracted by hydro distillation-solvent extraction method and analysed using GC-MS technique. The analysis revealed the presence of 25 identified compounds, representing 92.77% of the oil with butyl-2-ethylhexylphthalate (30.10%) and 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone (12.03%) being the two main components. Several components were identified for the first time in this chemotype of V. odorata. Antioxidant and antibacterial activities of the oil, methanol and chloroform extracts were also evaluated for the first time in this research work.     

Synthesis and characterization of ordered mesoporous carbon as electrocatalyst for simultaneous determination of epinephrine and acetaminophen

In this research, we report an easy method for synthesis of ordered mesoporous carbon (OMC) with hexagonal arrays of tubes (CMK-5). The synthesized OMC was characterized using X-ray diffraction (XRD), scanning electronic microscopy (SEM) and nitrogen sorption isotherms techniques. Due to the large surface area and high conductivity of OMC, OMC-modified glassy carbon (OMCs/GC) electrode was prepared. The unique electrochemical activity of OMCs/GC electrode was illustrated using cyclic voltammetry (CV) and electron impedance spectroscopy (EIS) in which OMC showed a faster electron transfer rate, as compared with glassy carbon electrode. The electrochemical behavior of epinephrine (EN) and acetaminophen (AP) at OMC/GC electrode was also investigated using cyclic voltammetry. The OMC/GC electrode exhibited high electrocatalytic activities toward oxidation of EN and AP and displayed good voltammetric peak separation between them. In differential pulse voltammetry technique, both EN and AP give sensitive oxidation peaks at 120?mV and 320?mV, respectively. Therefore, investigated method was applied for simultaneous determination of EN and AP. AP and EN give linear response over the range of 0.2–15?μM and 4–100?μM, respectively. The lower detection limits were found to be 0.07?μM for AP and 0.94?μM for EN.     

A new method for measuring the diffusion coefficient in a gas phase

A new and fast method for measuring the diffusion coefficients of binary gas mixtures using ion mobility spectrometry (IMS) has been developed. In this method, the sample is injected as a short pulse into the flowing drift gas, forming a Gaussian concentration profile inside the drift region. This Gaussian cloud is irradiated with a fast moving swarm of electrons to create negative ions. The flash of electrons is so short that the negative ions do not move much during the exposure time. The ions then drift toward the detector, where they are collected. The collected ion signal pattern reflects the spatial distribution of the sample inside the cloud at the time of exposure. This is repeated in intervals of 300-400 ms to monitor the spatial spreading of the molecules in the drift region. Consecutive IMS spectra show the evolution of the cloud over time. The collected spectra are fit to Gaussian functions to extract diffusion coefficients. Using this method, the diffusion coefficient of O(2), CHCl(3), and C(2)H(2)Cl(2) were measured, and the results are in good agreement with the previously reported experimental data.     

Intermolecular energy transfer across nanocrystalline semiconductor surfaces

The yields and dynamics for energy transfer from the metal-to-ligand charge-transfer excited states of Ru(deeb)(bpy)(2)(PF(6))(2), Ru(2+), and Os(deeb)(bpy)(2)(PF(6))(2), Os(2+), where deeb is 4,4'-(CH(3)CH(2)CO(2))(2)-2,2'-bipyridine, anchored to mesoporous nanocrystalline (anatase) TiO(2) thin films were quantified. Lateral energy transfer from Ru(2+)* to Os(2+) was observed, and the yields were measured as a function of the relative surface coverage and the external solvent environment (CH(3)CN, THF, CCl(4), and hexanes). Excited-state decay of Ru(2+)*/TiO(2) was well described by a parallel first- and second-order kinetic model, whereas Os(2+)*/TiO(2) decayed with first-order kinetics within experimental error. The first-order component was assigned to the radiative and nonradiative decay pathways (tau = 1 micros for Ru(2+)*/TiO(2) and tau = 50 ns for Os(2+)*/TiO(2)). The second-order component was attributed to intermolecular energy transfer followed by triplet-triplet annihilation. An analytical model was derived that allowed determination of the fraction of excited-states that follow the two pathways. The fraction of Ru(2+)*/TiO(2) that decayed through the second-order pathway increased with surface coverage and excitation intensity. Monte Carlo simulations were performed to estimate the Ru(2+)* --> Ru(2+) intermolecular energy transfer rate constant of (30 ns)(-1).     

Tyrosine sensing on phthalic anhydride functionalized chitosan and carbon nanotube film coated glassy carbon electrode

Phthaloylchitosan (PHCS) has been synthesized by a simple and low-cost method using chitosan and phthalic anhydride as organic precursors by microwave irradiation. Techniques of nuclear magnetic resonance (NMR), FT-IR spectroscopy and transmission electron microscope (TEM) were used to characterize the structure and properties of the Phthaloylchitosan. Moreover, glassy carbon electrode modified with Phthaloylchitosan and carbon nanotube (PHCS–CNT/GCE) was prepared by casting of the PHCS–CNT solution on GCE. The electrochemical behavior of PHCS–CNT/GCE was investigated and compared with the electrochemical behavior of Phthaloylchitosan modified GC (PHCS/GC), carbon nanotube modified GC (CNT/GC) and unmodified GC using cyclic voltammetry (CV). The Phthaloylchitosan film is electrochemically inactive; similar background charging currents are observed at bare GC. Electrochemical parameters, including apparent diffusion coefficient for the Fe(CN)₆^3-/4- redox probe at PHCS–CNT/GCE is comparable to values reported for GCE, CNT/GCE and PHCS/GCE. The PHCS–CNT/GCE sensor responded linearly to tyrosine (Tyr) in the concentration of 1.0 × 10^–6 to 8.0 × 10^–4 M with detection limit of 3.0 × 10^–7 M at 3σ using amperometry. In addition, the PHCS–CNT/GCE displayed good reproducibility, high sensitivity and good selectivity towards the determination of Tyr, making it suitable for the determination of Tyr in clinical and medicine.     

In vitro bioactivity of essential oils and methanol extracts of Salvia reuterana from Iran

The chemical composition of the essential oils, antioxidant activity (DPPH and beta-carotene/linoleic acid assays) and total phenolic content (Foline-Ciocalteu) of the flowers and leaves of Salvia reuterana were determined. Essential oils extracted from the flowers and leaves by hydrodistillation were analyzed by GC and GC/MS. Forty-four constituents, representing 99.7-99.9% of the oils, were identified. The major components were germacrene D, benzoic acid hexyl ester, bicyclogermacrene, beta-gurjunene and ishwarene, constituting 33.7-31.9% of the oils. The highest radical-scavenging activity (DPPH test) was shown by the methanol extract of the flowers (IC50 = 77.6 microg/mL). In the beta-carotene/linoleic acid assay, the methanol extract of the leaves showed the highest inhibition (40.3%) which was only slightly lower than that shown by BHT (82.9%). The total phenolic contents of the methanol extracts of the flowers and leaves as gallic acid equivalents were 81.4 and 88.3 microg/mg, respectively. The plant also showed good antimicrobial activity against three strains of tested microorganisms.     

Computational study of a supersonic free jet rotating perpendicular to the streamwise direction

We study the flow structure of supersonic jets rotating perpendicular to the streamwise direction using RANS simulations, and we assess the performance of different turbulence model rotation corrections. The Coriolis and centrifugal terms were added to the equations of motion to perform calculations in this non-inertial (rotating) frame of reference. An explicit, cell-centred, finite-volume numerical method, coupled to a k?ε turbulence model, was used for the computations. The turbulence model rotation corrections of Howard et al. (1980), Park and Chung (1999), and Cazalbou et al. (2005) were attempted. In the absence of experimental data for jets rotating perpendicular to the streamwise direction, the rotation corrections were examined against the available measurements of a swirling jet; the comparison of the numerical and experimental data indicates that the Cazalbou et al. (2005 Cazalbou, J.B. 2005. Two-equation modeling of turbulent rotating flows. Physics of Fluids, 17(5): 1–14. [Crossref], [Web of Science ®] , [Google Scholar]) and Park and Chung (1999 Park, J.Y. and Chung, M.K. 1999. A model for the decay of rotating homogeneous turbulence. Physics of Fluids, 11(6): 1544–1549. [Crossref], [Web of Science ®] , [Google Scholar]) corrections improve the performace of the turbulence model. Simulations were then run of a supersonic jet rotating perpendicular to the stream direction at 0, 50, 100 and 150 rad/s, using no turbulence model rotation correction, and using the three rotation corrections. The results indicate that the Cazalbou et al. (2005 Cazalbou, J.B. 2005. Two-equation modeling of turbulent rotating flows. Physics of Fluids, 17(5): 1–14. [Crossref], [Web of Science ®] , [Google Scholar]) correction is more physical than the other two, as it yields results that are qualitatively consistent with the known effects of rotation: that turbulence is enhanced and suppressed on the concave and convex sides of a rotating jet centreline, respectively, and that the effect of rotation saturates as the rotation rate increases. The findings are in qualitative agreement with the available literature.     

Synthesis and antibacterial activity of new N-[2-(thiophen-3-yl)ethyl] piperazinyl quinolones

As a part of continuing search for potential antibacterial agents in the quinolones field, we have synthesized novel quinolone agents bearing N-[2-(thiophen-3-yl)ethyl] piperazinyl moiety in the 7-position of the quinolone ring. In vitro antibacterial evaluation of the target compounds showed that N-[2-(thiophen-3-yl)ethyl] group attached to piperazine ring served as promising C-7 substituent for piperazinyl quinolone antibacterials. Among these derivatives, ciprofloxacin analogues, containing N-[2-(thiophen-3-yl)-2-hydroxyiminoethyl] or N-[2-(thiophen-3-yl)-2-methoxyiminoethyl] residue provided a high inhibition against all the tested Gram-positive organisms including methicillin-resistant Staphylococcus aureus comparable or superior with respect to the reference drugs norfloxacin and ciprofloxacin.