Synthesis and study of the fluorescent behavior of 3-pyridinecarbonitriles

Abstract  

A series of (2E)-3-(1-chloro-6-methoxy-3,4-dihydronaphthalen-2-yl)-1-(4-aryl)prop-2-en-1-ones (chalcones) have been synthesized by a new synthetic route. The 3-pyridinecarbonitrile derivatives were synthesized by the Michael reaction of malononitrile (in base) and aroylacetonitriles (in acid) with chalcones in one pot. The fluorescent properties and quantum yields of these compounds were studied.     

Fast chromatographic method for the determination of dyes in beverages by using high performance liquid chromatography—Diode array detection data and second order algorithms

A fast chromatographic methodology is presented for the analysis of three synthetic dyes in non-alcoholic beverages: amaranth (E123), sunset yellow FCF (E110) and tartrazine (E102). Seven soft drinks (purchased from a local supermarket) were homogenized, filtered and injected into the chromatographic system. Second order data were obtained by a rapid LC separation and DAD detection. A comparative study of the performance of two second order algorithms (MCR-ALS and U-PLS/RBL) applied to model the data, is presented. Interestingly, the data present time shift between different chromatograms and cannot be conveniently corrected to determine the above-mentioned dyes in beverage samples. This fact originates the lack of trilinearity that cannot be conveniently pre-processed and can hardly be modelled by using U-PLS/RBL algorithm. On the contrary, MCR-ALS has shown to be an excellent tool for modelling this kind of data allowing to reach acceptable figures of merit. Recovery values ranged between 97% and 105% when analyzing artificial and real samples were indicative of the good performance of the method. In contrast with the complete separation, which consumes 10 mL of methanol and 3 mL of 0.08 mol L⁻¹ ammonium acetate, the proposed fast chromatography method requires only 0.46 mL of methanol and 1.54 mL of 0.08 mol L⁻¹ ammonium acetate. Consequently, analysis time could be reduced up to 14.2% of the necessary time to perform the complete separation allowing saving both solvents and time, which are related to a reduction of both the costs per analysis and environmental impact.     

Triangular CdS nanostructure: effect of Mn doping on photoluminescence,electron spin resonance,and magneto-optical properties

In this paper, we report synthesis and study of magneto-optic Faraday effect for dilute magnetic semiconductor nanostructure. The colloidal CdS nanocrystals were prepared via hot injection method and successfully doped with Mn²⁺ cations. The synthesized nanoparticles were characterized by using UV–Vis spectroscopy, X-ray diffraction, photoluminescence spectroscopy, transmission electron microscopy, and electron spin resonance spectroscopy. Systematic studies on effect of Mn²⁺ doping on photoluminescence, electron spin resonance, and magneto-optical properties are carried out. UV–Vis spectral analysis confirms blue shift in bandgap of CdS nanoparticles due to quantum confinement effect. The X-ray diffraction study confirms hexagonal wurtzite phase formation of CdS nanoparticles without any impurity phases. TEM analysis confirms uniform particle size, having particle size distribution around 5 nm. As-synthesized undoped CdS shows triangular-shaped nanocrystals with hexagonal structure; however, triangular shape of CdS nanoparticles is not conserved after Mn²⁺ doping. The photoluminescence characteristic spectra of Mn²⁺-doped CdS nanocrystals showed emission band at 660 nm and its intensity was found to increase with increasing Mn²⁺ concentration. Electron spin resonance signal, with six-line hyperfine structure splitting, confirmed doping of Mn²⁺ ions in CdS lattice. Magneto-optic measurements showed linear variation of Faraday rotation with respect to applied magnetic field, indicating paramagnetic behavior of Mn-doped CdS. The highest Verdet constant 24.81 deg/T cm was observed for 2% Mn-doped CdS nanocrystals, which further decreases with increasing Mn²⁺ concentration.

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Graphical abstract Illustration of Magneto-optic Faraday effect using dilute magnetic semiconductors (TEM image of triangular CdS nanoparticles)

     

Diacetoxyiodobenzene mediated one-pot synthesis of diverse carboxamides from aldehydes

A novel, one-pot, and highly facile protocol has been devised for an easy access of a series of novel glycosyl carboxamides from aldehydes using diacetoxyiodobenzene in the presence of ionic liquid at ambient temperature.     

Novel synthesis of 1,2,4‐triazolophanes and 1,3,4‐oxadiazolophanes: A dieckmann condensation approach

The Dieckmann condensation has been used for the first time for the syntheses of novel 1,2,4‐triazolophanes and 1,3,4‐oxadiazolophanes. The bis‐1,3,4‐oxadiazol‐2‐thiols 1a and 1b were reacted with ethyl bromoacetate to give the diesters 2a and 2b . Diesters 2a and 2b were treated under dry conditions with sodium methoxide in methanol to afford desired symmetrical 1,3,4‐oxadiazolophanes 3a and 3b . Similarly, diesters of macrocycle precursors containing 1,2,4‐triazole moiety, that is, 6a , 6b , 10 , 13a , 13b , and 13c were synthesized from 5a , 5b , 9 , 12a , 12b , and 12c , respectively. Dieckmann condensation of these diesters afforded symmetrical ketones 7a , 7b , 11 , 14a , 14b , and 14c . Extrusion of CO₂ was observed after in situ hydrolysis of the conventional Dieckmann product during neutralization by dilute mineral acids to afford highly symmetrical ketone in good yields. Further, the ketones 14a , 14b , and 14c were converted into their respective thiones by the reaction with Lawesson's reagent. All the products were synthesized with good yields, and structures were confirmed by various spectroscopic tools and elemental analyses. J. Heterocyclic Chem.,, (2012).     

Dynamics of Nodal Points and the Nodal Count on a Family of Quantum Graphs

We investigate the properties of the zeros of the eigenfunctions on quantum graphs (metric graphs with a Schr?dinger-type differential operator). Using tools such as scattering approach and eigenvalue interlacing inequalities we derive several formulas relating the number of the zeros of the n-th eigenfunction to the spectrum of the graph and of some of its subgraphs. In a special case of the so-called dihedral graph we prove an explicit formula that only uses the lengths of the edges, entirely bypassing the information about the graph??s eigenvalues. The results are explained from the point of view of the dynamics of zeros of the solutions to the scattering problem.     

Discrete conversion of gamma rays in 229Th and in highly ionized 125TeQ ions

The complex of problems associated with the discrete conversion of gamma rays is considered. The analogue of the internal conversion coefficient is determined for the case of discrete conversion, and specific computations are made. The calculated values of the half-life of the nuclear level E _γ = 35.492 keV in ¹²⁵Te^Q ions (Q = 45–48) are in good agreement with the measured quantities. Computations for the spectrum of optical photons accompanying the de-excitation of the nuclear level E _γ = 3.5 ± 1 eV in ²²⁹Th, carried out using the Dirac-Fock multiple configuration method, show that the highest-intensity spectral lines are situated in the region of 2.3–2.4 eV, which is in accord with the experimental data.     

Microwave-Assisted Copper Slag-Catalyzed Green S-Arylation of Arenethiols with Arylboronic Acids

Russian Journal of Organic Chemistry - Diaryl sulfides have been synthesized in moderate to excellent yield by S-arylation of arenethiols with arylboronic acids using copper slag as a catalyst....     

Σ-Hypernuclear (π−,K +) production

The (π ^?,K ⁺) reaction is proposed as an optimalσ-hypernuclear production process on nuclear tagets. Several ingredients of this process are discussed in connection with the choice of appropriate target nuclei. For demonstration, the excitation functions are calculated for the (π ^?,K ⁺) reaction on the⁵⁶Fe and²⁸Si targets by assuming a shallowσ well depth, varying the spin-orbit strength and smearing (conversion) widths.