Comparative efficacy of Eucalyptus globulus (Labill) hydrodistilled essential oil and temephos as mosquito larvicide

Abstract

In this study Eucalyptus globulus essential oil was tested on major mosquito species and toxicity was compared with temephos. Mortality was calculated after 24?h and 48?h post treatment. In 24?h treatment essential oil show strong larvicidal activity with LC₅₀ and LC₉₀ values were 30.198ppm, 103.389ppm for Anopheles stephensi, 13.578ppm, 106.755ppm for Aedes aegypti; and, 7.469ppm, 32.454ppm for Culex quinquefasciatus and 48?h post treatment LC₅₀ and LC₉₀ values were, 12.576, 49.380ppm for Anopheles stephensi, 7.926, 34.470ppm for Aedes aegypti and 4.408, 21.048ppm for Culex quinquefasciatus. Chemical composition of essential oil using GC-MS and FT-IR analysis shows the presence of 1,8-cineol, (71.7%); α-pinene, (9.14%) as a major compounds. Our findings suggest that essential oil from Eucalyptus globulus leaves can be used for control of mosquito larvae.     

Iridium-catalyzed carbonyl group-directed oxidative coupling of arenes with alkenes

The iridium complex [Cp¹IrCl₂]₂ is a good catalyst for the directed oxidative coupling of arenes with alkenes; a wide range of carbonyl functionalities (NHCOR, CONH₂ and COR) can be employed as the directing group.     

Visible-Light-Driven One-Pot Synthesis of Benzimidazoles,Benzothiazoles, and Quinazolinones Catalyzed by Scalable and Reusable Ba-Doped CoMoO4 Nanoparticles Under Air Atmosphere

Herein we report a simple and efficient oxidative coupling of various aryl methyl amines with diverse coupling partners, such as o-phenylenediamine (benzene-1,2-diamine), 2-aminobenzenethiol and 2-aminobenzamide, to synthesize the corresponding heterocycles using scalable and reusable heterogeneous catalysts under visible light irradiation. A systematic investigation led to the synthesis of benzimidazoles, benzothiazoles and quinazolinones under air atmosphere in very good to excellent yields. The strategy is atom economical and found to be tolerance towards different functional groups, and wide range of substrate scope. Furthermore, the methodology was demonstrated for its suitability on scale up and reusability. The density functional theory (DFT) calculations and the analysis of band structures of pristine and Ba doped CoMoO₄ systems showed that the doping of Ba in place of Co improved the catalytic performance of the system.     

A note on overpotential dependence of AC impedance data

Charge-transfer resistance [R _ct = (dη/di)_{η = 0}] and Tafel plots of current density (i) versus overpotential (η) data are generally known to yield values of the energy-transfer coefficient (α) and exchange current density (i _o) of an electrochemical reaction. In the present investigation, the resistance (dη/di)_η≠0 that could be calculated by differentiating a wide range of i−η curves was also shown to provide the values of α and i _o, by plotting ln(dη/di)_η≠0 against η. Since α and i _o could also be evaluated directly from the experimental DC polarization data, the procedure was not of significant importance. Nevertheless, it was considered important in evaluating α and i _o from AC impedance data, because the procedure was based on data analysis, which was much simpler than that reported in the literature. A cobalt electrode prepared from fine metal powder was used in 1 M KOH electrolyte and the hydrogen evolution reaction was studied by AC impedance at several potentials. The resistance values measured from the complex plane impedance diagram were plotted against the potential, and the values of α and i _o were evaluated. Received: 8 October 1998 / Accepted: 11 January 1999     

Experimental and Theoretical Insights into the Optical Properties and Intermolecular Interactions in Push-Pull Bromide Salts

Experimental and theoretical insights into the nature of intermolecular interactions and their effect on optical properties of 1-allyl-4-(1-cyano-2-(4-dialkylaminophenyl)vinyl)pyridin-1-ium bromide salts ( I and II ) are reported. A comparison of optical properties in solution and in the solid-state of the salts ( I and II ) with their precursors ( Ia and IIa ) is made. The experimental absorption maxima (λ_max) in CHCl₃ is at 528 nm for I and at 542 nm for II , and a strong bathochromic shift of ∼110 nm is observed for salts I and II compared with their precursors. The absorption bands in solid-state at ∼627 nm for I and at ∼615 nm for II that are assigned to charge transfer (CT) effect. The optical properties and single crystal structural features of I and II are explored by experimental and computational tools. The calculated λ_max and the CT are in good agreement with the experimental results. The intermolecular interactions existing in the crystal structures and their energies are quantified for various dimers by PIXEL, QTAIM and DFT approaches. Three types of interactions, (i) the cation⋅⋅⋅cation interactions, (ii) cation⋅⋅⋅anion interactions and (iii) anion⋅⋅⋅anion interactions are observed. The cationic moiety is mainly destabilized by C−H⋅⋅⋅N/π and π⋅⋅⋅π interactions whereas the cation and anion moiety is predominantly stabilized by strong C−H⋅⋅⋅Br⁻ interactions in both structures. The existence of charge transfer between cation and anion moieties in these structures is established through NBO analysis.     

NO2 sensing properties of YSZ-based sensor using NiO and Cr-doped NiO sensing electrodes at high temperature

Nickel oxide and chromium-doped nickel oxide (Ni_0.95Cr_0.03O_1−δ ) were prepared by thermal decomposition of nitrates. The obtained NiO and Ni_0.95Cr_0.03O_1−δ samples were utilized as sensing electrodes (SEs) in yttria-stabilized zirconia (YSZ)-based sensors for detection of NO₂ at 800 °C under wet condition (5 vol.% H₂O). While the mixed-potential-type planar sensor attached with NiO-SE gave rather large NO₂ sensitivity, the sensor attached with Ni_0.95Cr_0.03O_1−δ -SE exhibited fast recovery rate with an acceptable sensitivity. The Δemf (electromotive force) of the sensors varied linearly with NO₂ concentration in the examined range of 50–400 ppm on a logarithmic scale. Based on the results of measurements for polarization, complex impedance and gas phase catalysis, the fast recovery was attributable to the high rate for the anodic reaction of O₂ at the Ni_0.95Cr_0.03O_1−δ /YSZ interface, and the lower NO₂ sensitivity was caused by both the high rate for the anodic reaction of O₂ and the high degree for the gas phase conversion of NO₂ to NO.     

Synthesis and evaluation of ketophosph(on)ates as beta-lactamase inhibitors

A series of amidoketophosph(on)ates of general structure PhCH2OCONHCH(R)COCHR'(CH2)n(O)P(O2-)(O)R' (R = H, CH3; R' = H, CH3; n = 0, 1; R' = H, CH3, Et, Ph) have been prepared as a potential source of beta-lactamase inhibitors. The phosphonates (n = 0) were obtained by means of the Arbuzov reaction while most of the phosphates were achieved from reaction of phosph(or/on)ic acids with the appropriate diazoketone PhCH2OCONHCH(R)COCR'N2. The electrophilicity of the carbonyl group in the resulting phosph(on)ates was assessed by the degree of hydration in aqueous solution, determined from NMR spectra. These compounds inhibited typical class C and class D beta-lactamases, particularly the latter group, but showed no activity against class A enzymes. To enhance the carbonyl electrophilicity, an alpha-difluorinated analogue (R = H, CHR' = CF2, n = 0, R' = Et) was also prepared, but no enhanced inhibitory activity was observed. All evidence suggested that these compounds inhibited in the carbonyl form rather than by formation of tetrahedral adducts at the beta-lactamase active site. They show promise as leads to specific class D beta-lactamase inhibitors.     

Synthesis of novel indole based cyclophanes and cylindrical cyclophanes by tandem alkylation methodology using NaH

Treatment of 1 equiv of 1,3-bis(bromomethyl)benzene and 2,6-bis(bromomethyl)pyridine with 1 equiv of indole in the presence of NaH in THF afforded the symmetrical cyclophanes 1 and 2. Using similar methodology, cylindrical cyclophanes 3 and 4 were obtained from 2 equiv of 1,3,5-trimethyl-2,4,6-tris(bromomethyl)benzene and 1,3,5-tris(bromomethyl)benzene with 3 equiv of indole.