Optimization of the synthesis and characterizations of chemical bath deposited Cu2S thin films

Semiconducting copper sulphide (Cu₂S) thin films have been deposited on various substrates (SnO₂:F/glass, glass) by the simple and economical chemical bath deposition technique. The depositions were carried out during a deposition time of about 32.5 min in the pH range of 9.4 to 11. The synthesized Cu₂S thin films were characterized using various techniques without any annealing treatment. X-ray diffraction study shows that Cu₂S films exhibit the best crystallinity for pH = 10.2. For this pH value, Auger electron spectroscopy investigations show that Cu₂S thin films grown on an SnO₂/glass substrate exhibit stochiometric composition with [Cu]/[S] concentrations ratio equal to 2.02. Using the Kelvin method, the work function difference (Ф_material– Ф_probe) for the Cu₂S films deposited on SnO₂/glass substrates at the optimum pH value was found to be equal to 145 meV. Hall measurements confirm the p-type electrical conductivity of the obtained films. The electrical resistivity was of the order of 3.85 × 10⁻⁴ Ω-cm. The transmission and reflection coefficients vary in the range of [35–60] % and [5–15] % respectively, in the visible range, and the band gap energy is about 2.37 eV.     

Ferrocene based chiral binuclear η6‐benzene‐Ru(II)‐phosphinite complexes: Synthesis,characterization and catalytic activity in asymmetric reduction of ketones

In the present study, a series of chiral C₂‐symmetric ferrocenyl based binuclear η⁶‐benzene‐Ru(II) complexes bearing diphenylphosphinite and diisopropylphosphinite moieties have been synthesised. The new binuclear η⁶‐benzene‐Ru(II)‐phosphinite complexes were characterised based on nuclear magnetic resonance (¹H, ¹³C, ³¹P–NMR), FT‐IR spectroscopy and elemental analysis. Then, these complexes have been screened as catalytic precursors in the transfer hydrogenation of acetophenone with 2‐propanol as both the hydrogen source and solvent in the presence of KOH. The corresponding optically active secondary alcohols were obtained in excellent conversion rates between 96 and 99% and moderate to good enantioselectivities (up to 78% ee). The complex 5 was the most efficient catalyst among the four new complexes investigated herein.     

p-sulfonic acid calix[4]arene: An efficient reusable organocatalyst for the synthesis of bis(indolyl)methanes derivatives in water and under solvent-free conditions

In this work, a green, simple and highly efficient procedure for the synthesis of bis(indolyl)methanes is described. The condensation of indoles catalyzed by p-sulfonic acid calix[4]arene in water and under solvent-free conditions afford the title compounds in high yields and relatively short reaction times.     

Syntheses, characterization, X-ray crystal structures and emission properties of five oxovanadium(V) complexes with pyridyl/pyrimidyl-pyrazole derived ditopic ligands

Four oxovanadium(V) complexes of heterocycle based ditopic ligands PyPzOAP (N-[amino(pyridin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PyPzOAPz (N-[amino(pyrazin-2-yl)methylidene]-5-methyl-1-(pyridin-2-yl)-1H-pyrazole-3-carbohydrazonic acid), PymPzOAP (N-[amino(pyridin-2-yl)methylidene]-1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-1H-pyrazole-3-carbohydrazonic acid) and PyPzCAP (5-methyl-1-(pyridin-2-yl)-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) and a binuclear (di-μ-oxo) oxovanadium(V) complex of the ligand PymPzCAP (1-(4,6-dimethylpyrimidin-2-yl)-5-methyl-N′-[1-(pyridin-2-yl)ethylidene]-1H-pyrazole-3-carbohydrazide) have been investigated. The ligands act as uninegative NNO tridentates donors for the VO₂⁺ ion exhibiting their monotopicity. The ligands show varying emission properties due to the presence of fluophoric groups like 1-(2-pyridyl)pyrazole or 1-(2-pyrimidyl)pyrazole. The vanadium(V) complexes show fluorescence quenching with respect to the used ligands to a varying extent. The complexes were characterized by UV-Vis, IR, cyclic voltammetry and X-ray crystallography.     

Determination of abamectin in citrus fruits using SPE combined with dispersive liquid–liquid microextraction and HPLC–UV detection

A new pretreatment method, SPE combined with dispersive liquid–liquid microextraction, was proposed for the determination of abamectin in citrus fruit samples for the first time. In this method, fruit samples were extracted by ultrasound‐assisted extraction followed by SPE. Then, the SPE was used as a disperser solvent in the next dispersive liquid–liquid microextraction step for further purification and enrichment of abamectin. The effects of various parameters on the extraction efficiency of the proposed method were investigated and optimized. Good linearity of abamectin was obtained from 0.005 to 10.0 mg/kg for B_1a and from 0.05 to 10.0 mg/kg for B_1b with correlation coefficient (r²) of 0.998 for B_1a and 0.991 for B_1b, respectively. The LODs were 0.001 and 0.008 mg/kg (S/N = 3) for B_1a and B_1b, respectively. The relative recoveries at three spiked levels were ranged from 87 to 96% with the RSD less than 11% (n = 3). The method has been successfully applied to the determination of abamectin in citrus fruit samples.     

Cellulose-Supported Ni(NO3)2 · 6H2O/2,4,6-Trichloro-1,3,5-triazine (TCT) as a Mild,Selective, and Biodegradable System for Nitration of Phenols

Nitration of certain phenols and naphthols in the presence of biodegradable cellulose-supported Ni(NO₃)₂ · 6H₂O/2,4,6-trichloro-1,3,5-triazine was carried out in acetonitrile at room temperature. Ortho nitrated phenols were obtained regioselectively within a short reaction time with good yields. The reaction condition was mild, and the employed cellulose could be recovered several times for further use.      

Solid state radiolysis of non-proteinaceous amino acids in vacuum: astrochemical implications

The analysis of the amino acids present in Murchison meteorite and in other carbonaceous chondrites has revealed the presence of 66 different amino acids. Only eight of these 66 amino acids are proteinaceous amino acids used by the present terrestrial biochemistry in protein synthesis, the other 58 amino acids are somewhat “rare” or unusual or even “unknown” for the current terrestrial biochemistry. For this reason in the present work a series of “uncommon” non-proteinaceous amino acids, namely, l-2-aminobutyric acid, R(?)-2-aminobutyric acid, 2-aminoisobutyric acid (or α-aminoisobutyric acid), l-norleucine, l-norvaline, l-β-leucine, l-β-homoalanine, l-β-homoglutamic acid, S(?)-α-methylvaline and dl-3-aminoisobutyric acid were radiolyzed in vacuum at 3.2 MGy a dose equivalent to that emitted in 1.05 × 10⁹ years from the radionuclide decay in the bulk of asteroids or comets. The residual amount of each amino acid under study remained after radiolysis was determined by differential scanning calorimetry in comparison to pristine samples. For optically active amino acids, the residual amount of each amino acid remained after radiolysis was also determined by optical rotatory dispersion spectroscopy and by polarimetry. With these analytical techniques it was possible to measure also the degree of radioracemization undergone by each amino acid after radiolysis. It was found that the non-proteinaceous amino acids in general do not show a higher radiation and radioracemization resistance in comparison to the common 20 proteinaceous amino acids studied previously. The unique exception is represented by α-aminoisobutyric acid which shows an extraordinary resistance to radiolysis since 96.6 % is recovered unchanged after 3.2 MGy. Curiously α-aminoisobutyric acid is the most abundant amino acid found in carbonaceous chondrites. In Murchison meteorite α-aminoisobutyric acid represents more than 20 % of the total 66 amino acids found in this meteorite.