Synthesis of substituted 1,4-diazepines and 1,5-benzodiazepines using an efficient heteropolyacid-catalyzed procedure

An efficient and improved procedure for the synthesis of 1,4-diazepine and 1,5-benzodiazepine derivatives via the reaction of ketimine intermediates with aldehydes in the presence of Keggin-type heteropolyacids (HPAs) was developed. High yields and short reaction times were obtained for both electron-releasing and electron-withdrawing substituted 1,4-diazepine and 1,5-benzodiazepines derivatives.     

Electrical conductivity and optical properties of ZnO nanostructured thin film

The electrical conductivity, structural and optical properties of ZnO nanostructured semiconductor thin film prepared by sol-gel spin coating method have been investigated. The X-ray diffraction result indicates that the ZnO film has the polycrystalline nature with average grain size of 28 nm. The optical transmittance spectrum indicates the average transmittance higher than 90% in visible region. The optical band gap, Urbach energy and optical constants (refractive index, extinction coefficient, real and imaginary parts of the dielectric constant) of the film were determined. The electrical conductivity of the film dependence of temperature was measured to identify the dominant conductivity mechanism. The conductivity mechanism of the film is the thermally activated band conduction. The electrical conductivity and optical results revealed that the ZnO film is an n-type nanostructured semiconductor with a direct band gap of about 3.30 eV at room temperature.     

Coumarin Based Highly Selective “off-on-off” Type Novel Fluorescent Sensor for Cu<Superscript>2+</Superscript> and S<Superscript>2−</Superscript> in Aqueous Solution

Solvent free synthesis of 6,7-dihydroxy-3-(3-chlorophenyl) coumarin (CFHC) was designed and obtained by the interaction of 2-(2,4,5-trimethoxyphenyl)-1-(3-chlorophenyl)acrylonitrile with pyridinium hydrochloride in the presence of silica gel by using microwave irradiation. The characterization of CFHC was confirmed by FT-IR, ¹H, ¹³C, ¹³C–APT and 2D HETCOR spectroscopy methods. The optical behavior of CFHC towards metal ions was investigated by UV-visible and fluorescence spectroscopy. CFHC showed “on–off” type fluorescence response towards Cu²⁺ with high selectivity in aqueous solution (CH₃CN/H₂O, 9/1, v/v). Once binding with Cu²⁺, CFHC-Cu²⁺ complex also displayed high selectivity for sulfide, resulting in “off–on” type sensing of sulfide anion.

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Graphical abstract Visual fluorescence changes upon addition of various metal ions (5.0 eq.) to CFHC in CH₃CN/H₂O (90:10, v/v) under UV excitation (365 nm)

     

Interaction of Thyroxine with 7 Hydroxycoumarin: A Fluorescence Quenching Study

The interaction between thyroxine hormone and 7 hydroxycoumarin (7HC) was investigated using fluorescence quenching method. The experimental results showed that thyroxine could quench the fluorescence of 7HC by forming the 7HC–thyroxine complex with static quenching. The apparent binding constants (K) between 7HC and thyroxine were determined to be 1.51 × 10⁴ (297 K) and 9.06 × 10³ (310 K). The binding sites (n) 0.98 ± 0.1. The thermodynamic parameters showed that the interaction between 7HC and thyroxine was driven mainly by hydrogen bonding interactions and van der Waals force. Calibration for thyroxine, based on quenching titration data, was linear in the concentration range 2.0 × 10⁻⁸ to 3.0 × 10⁻⁷ mol/l. The relative standard deviation was 2.58% for 2.0 × 10⁻⁷ mol/l thyroxine (n = 4) and the 3σ limit of detection was 3.42 × 10⁻⁸ mol/l in cationic surfactant CTAB medium.     

Structural, morphological and optical properties of CuAlS2 films deposited by spray pyrolysis method

The structural, morphological and optical properties of CuAlS₂ films deposited by spray pyrolysis method have been investigated. CuAlS₂ in the form of films is prepared at different deposition conditions by a simple and economical spray pyrolysis method. The structural, surface morphology and optical properties of the films were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscope (AFM) and absorbance spectra, respectively. The films were polycrystalline, crystallized in a tetragonal structure, and are preferentially orientated along the (1 1 2) direction. Grain size values, dislocation density, and d% error of CuAlS₂ films were calculated. The optical band gap of the CuAlS₂ film was found to be 3.45 eV. The optical constants such as refractive index, extinction coefficient and dielectric constants of the CuAlS₂ film were determined. The refractive index dispersion curve of the film obeys the single oscillator model. Optical dispersion parameters E_o and E_d developed by Wemple-DiDomenico were calculated and found to be 3.562 and 12.590 eV.     

Microstructure and electro-optical properties of sol–gel derived Cd-doped ZnO films

The microstructure, and the electrical and optical properties of undoped zinc oxide (ZnO) and cadmium-doped ZnO (CZO) films deposited by a sol–gel method have been investigated. The films have a polycrystalline structure with hexagonal wurtzite ZnO. Scanning electron microscopy (SEM) images indicated that the films have a wrinkle network with uniform size distributions. The elemental analyses of the CZO films were carried out by energy dispersive X-ray analysis. The fundamental absorption edge changed with doping. The optical band gap of the films decreased with Cd dopant. The optical constants of the films such as refractive index, extinction coefficient and dielectric constants changed with Cd dopant. A two-probe method was used to investigate the electrical properties, and the effect of Cd content on the electrical properties was investigated. The electrical conductivity of the films was improved by incorporation of Cd in the ZnO film.     

Synthesis and Characterization of Novel Alkyl-Substituted Aryl Diphenylphosphinate Esters

Abstract

In this work, the reactions of diphenylphosphinic chloride, (C₆H₅)₂P(O)Cl, 1, with the sodium salts of sterically hindered phenol derivatives (2a-2j) were investigated. Novel alkyl-substituted aryl diphenyl phosphinate esters (C₆H₅)₂P(O)OAr (3-12) were obtained from these reactions. Satisfactory analytical and spectroscopic results were obtained for all the new compounds.

GRAPHICAL ABSTRACT     

Nanostructured Modified Carbon Paste Electrode as Voltrammetric Sensor for Isoproturon Trace Analysis in Water

A new electrochemical sensor based on nanostructured carbon paste electrodes (CPEs) is developed for the sensitive detection of Isoproturon in water. The CPEs were nanostructured by incorporation of carbon nanotubes (NTCs) and synthetized copper oxide nanoparticles (CuO). They were characterized using the X‐ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM) and voltammetric methods. Electrochemical experiments showed that the adsorption of Isoproturon on to (GC‐NTC‐CuO)‐CPE, associated with nanomaterials (NTCs and CuO), provided remarkable analytical performances of the sensor such as a large quantification range from 1 to 200 μg L^?1 with a detection limit of 0.1 μg L^?1 of Isoproturon and no interferences of some another pesticides tested (specificity of ISO adsorption in acidified water). The tests carried out on real samples of water are conclusive. The analytical performances of the sensor showed that it is suitable for the specific determination of pesticide traces in water.