Eco-friendly synthesis of 1,4-benzodiazepine-2,5-diones in the ionic liquid [bmim]Br

The green reaction of isatoic anhydrides with α-amino acids in presence of the ionic liquid 1-butyl-3-methylimidazolium bromide afforded 1,4-benzodiazepine-2,5-diones in excellent yields in absence of a catalyst. The reaction workup is simple and the ionic liquid was easily recovered from the reaction and reused. The methodology was quite general and a range of cyclic and acyclic α-amino acids were examined to produce 1,4-benzodiazepine-2,5-diones.     

Eco-friendly synthesis of 1,4-benzodiazepine-2,5-diones in the ionic liquid [<Emphasis Type="Italic">bmim</Emphasis>]Br

The green reaction of isatoic anhydrides with α-amino acids in presence of the ionic liquid 1-butyl-3-methylimidazolium bromide afforded 1,4-benzodiazepine-2,5-diones in excellent yields in absence of a catalyst. The reaction workup is simple and the ionic liquid was easily recovered from the reaction and reused. The methodology was quite general and a range of cyclic and acyclic α-amino acids were examined to produce 1,4-benzodiazepine-2,5-diones. Correspondence: Khosrow Jadidi, Department of Chemistry, Shahid Beheshti University, PO Box 1983963113, Tehran, Iran.     

Modeling of a radial-flow moving-bed reactor for dehydrogenation of isobutane

A mathematical model for the performance of a radial-flow moving-bed reactor for dehydrogenation of light paraffins was developed. Assuming relevant kinetic expressions for the main reaction and catalyst deactivation, the kinetic parameters were obtained through lab-scale fixed-bed reactor testing using the integral method of analysis. The conversion was found to be a function of a dimensionless decay time, i.e., the ratio of a “catalyst deactivation time constant” to the residence time of the catalyst within the reactor. For a large dimensionless decay time (negligible catalyst decay), the performance equation approached that of a simple packed-bed reactor. The predictions of the model were compared with those of a commercial unit, and fair agreements were observed.     

Synthesis of 2-mercaptobenzothiazole/magnetic nanoparticles modified multi-walled carbon nanotubes for simultaneous solid-phase microextraction of cadmium and lead

This study describes the successful sequential modification of multi-walled carbon nanotube (MWCNT) by Fe₃O₄ magnetic nanoparticles and 2-mercaptobenzothiazole (MBT) followed by its application as a novel sorbent for simultaneous magnetic solid phase microextraction of lead and cadmium. Fourier transform infrared spectroscopy and scanning electron microscopy were employed to confirm the chemical surface modification of the MWCNT. The ions retained on the 2-MBT/magnetic nanoparticles modified MWCNTs were eluted with 1.0 mL of nitric acid (0.8 mol L^?1) in methanol solution and determined by the flame atomic absorption spectrometry. All parameters affecting the extraction condition were thoroughly investigated and optimised. Under the optimised condition preconcentration factor of 150.0, enhancement factors of 149.0 and 149.2 and limits of detection of 0.21 and 0.01 µg L^?1 were achieved for lead and cadmium, respectively. Using the prepared magnetic nanocomposite, the possible interference of other common ions associated with lead and cadmium determination was effectively avoided and the method was successfully applied to the simultaneous determination of the target ions in various environmental water samples.     

Application of SBA-Pr-SO<Subscript>3</Subscript>H in the synthesis of 2,3-dihydroquinazoline-4(1<Emphasis Type="Italic">H</Emphasis>)-ones: characterization,UV–Vis investigations and DFT studies

An efficient one-pot synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives 4a–l is described using SBA-Pr-SO₃H as a heterogeneous acid catalyst. The present methodology resulted in various derivatives of 2,3-dihydroquinazoline-4(1H)-one in good yield via a three-component reaction of isatoic anhydride, aldehydes and ammonium acetate. SBA-Pr-SO₃H played a significant role as an efficient mesoporous catalyst due to its pore size of 6 nm. Additionally, UV–Vis spectrum of the products was studied in order to investigate their application as UV absorbers.     

A theoretical study of the solvent effect on the interaction of C<Subscript>20</Subscript> and N<Subscript>2</Subscript>H<Subscript>2</Subscript>

In this work, the interaction of C₂₀ and the N₂H₂ fragment is investigated at the M062X/6-311G(d,p) level of theory in both gas and solution phases. The interaction energies obtained by the standard method are corrected by the basis set superposition error (BSSE) during the geometry optimization for all molecules at the same levels of theory. The results obtained from these calculations reveal that the interaction between C₂₀ and N₂H₂ increases in the presence of more polar solvents. Values of the electrophilic charge transfer show the charge flow from C₂₀ to N₂H₂. The influence of the solvent on the hyperpolarizability indicates that β_tot values decrease on passing from vacuum to the solution phase.     

In vivo fluorescent imaging of the mouse retina using adaptive optics

In vivo imaging of the mouse retina using visible and near infrared wavelengths does not achieve diffraction-limited resolution due to wavefront aberrations induced by the eye. Considering the pupil size and axial dimension of the eye, it is expected that unaberrated imaging of the retina would have a transverse resolution of 2 microm. Higher-order aberrations in retinal imaging of human can be compensated for by using adaptive optics. We demonstrate an adaptive optics system for in vivo imaging of fluorescent structures in the retina of a mouse, using a microelectromechanical system membrane mirror and a Shack-Hartmann wavefront sensor that detects fluorescent wavefront.     

Dysprosium pertraction through facilitated supported liquid membrane using D2EHPA as carrier

The pertraction of dysprosium (Dy) through a supported liquid membrane (SLM) system consisting of PTFE (polytetrafluoroethylene) support, D2EHPA (di-2-ethylhexyl phosphoric acid) dissolved in kerosene as membrane solution, and HNO₃ solution as stripping solution, was studied. The experiments were designed by the Taguchi method in order to investigate the effects of initial Dy concentration, feed phase pH, different stripping solution concentration, and D2EHPA concentration in the membrane phase on Dy pertraction. Optimal experimental conditions for Dy pertraction were obtained using an analysis of variance (ANOVA) (feed concentration: 130 mg L^?1, D2EHPA concentration: 0.90 M, feed phase pH: 5, stripping phase concentration: 2 M). In addition, the stability of the carrier in terms of its leaching from the membrane support was studied over a period of 6 days and was found to be satisfactory over that time.     

Quantum Mechanical Study of Substituent Dependence on the Structure,Spectroscopic (13C, 1H NMR and UV), NBO,Hyperpolarizability and HOMO?LUMO Analysis of Ru(NHC)2Cl2(CH‐p‐C6H4X) Complexes

In this work, we have explored the structural, electronic properties, ¹³C and ¹H NMR parameters and first hyperpolarizability of Ru(NHC)₂Cl₂(CH‐p‐C₆H₄X) complexes (XH, F, Cl, Me, NH₂, OH, CN, NO₂, CHO, COOH) by mpw1pw91 quantum method. The X‐substituent effect on structural parameters, frontier orbital energies, spectroscopic (¹H and ¹³C NMR, UV) of complex was carried out. The results indicate that the substituent has played a significant role on the structures and properties of complex. ¹H and ¹³C NMR chemical shifts were calculated by using the gauge‐invariant atomic orbital (GIAO) method. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were exhibited. In analyzing the bonding characteristics of this structure, Ru‐C_carbene and Ru‐C_NHC bonds were identified and characterized in details by Natural bond orbital (NBO) analysis.