Green production and antioxidant activity study of new pyrrolo[2,1-a]isoquinolines

In current research, pyrrolo[2,1-a]isoquinoline derivative are synthesized via a new process of four component reaction of phthalaldehyde or its derivatives, primary amines, alkyl bromides, activated acetylenic compounds and potassium fluoride/Clinoptilolite nanoparticles (KF/CP NPs) under solvent-free conditions at room temperature. Also, Dielz-Alder reactions take place in the reaction of synthesized pyrrolo[2,1-a]isoquinoline derivatives, activated acetylenic compounds and triphenylphosphine in the presence of KF/CP NPs under solvent-free conditions at room temperature. As well, antioxidation property of some prepared pyrrolo[2,1-a]isoquinolines are investigated by employing of trapping diphenyl-picrylhydrazine (DPPH) radical and ability of ferric reduction experiment. Among investigated compounds, compounds 5c have good results relative to BHT and TBHQ as standard antioxidant. Our procedure has a few benefits relative to reported method such as good rate of reaction, product with high efficiency and simple removal of catalyst from mixture of reaction. In these reactions, KF/Clinoptilolite nanoparticles show a satisfactory recyclable activity.     

Pharmacophore elucidation and 3D-QSAR analysis of a new class of highly potent inhibitors of acid ceramidase based on maximum common substructure and field fit alignment methods

Comparative molecular field analysis (CoMFA) and comparative similarity indices analysis (CoMSIA) studies have been carried on a series of 2,4-dioxopyrimidine-1-carboxamides as acid ceramidase inhibitors. Two alignment rules for the compounds were defined using maximum common substructure and field fit. The best orientation was then searched by all-orientation search strategy, to minimize the effect of the initial orientation of the structures. The Kennard Stone algorithm was used to divide the entire set into training (25 compounds) and test (7 compounds) sets. Pharmacophore model identification was also performed using DISCOtech algorithm and refinement was carried out using GASP, to highlight important structural features that could be responsible for the inhibitory activity. All constructed models showed appropriate statistical parameters in terms of q ² and r _pred ² . Based upon the information obtained from CoMFA, CoMSIA, and developed pharmacophore pattern, some key features that may be used to design new inhibitors for acid ceramidase have been identified.     

‘Click Synthesis’ of Some Novel Benzimidazol Oxime Ethers Containing Heterocycle Residues as Potential ß‐Adrenergic Blocking Agents

The ‘click synthesis’ of some novel O‐substituted oximes, 5a – 5j , which contain heterocycle residues, as new analogs of ß‐adrenoceptor antagonists is described (Scheme 1). The synthesis of these compounds was achieved in four steps. The formation of (E)‐2‐(1H‐benzo[d]imidazol‐1‐yl)‐1‐phenylethanone oxime, followed by their reaction with 2‐(chloromethyl)oxirane, afforded mixture of oil compounds 3 and 4 , which by a subsequent tetra‐n‐butylammonium bromide (TBAB)‐catalyzed reaction with N H heterocycle compounds (Scheme 1), led to the target compounds 5a – 5j in good yields.     

Highly ordered mesoporous La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 as a very efficient nanocatalyst for green aerobic oxidative coupling of thiols to disulfides

Selective aerobic oxidative coupling of thiols that are catalyzed by La(III)-substituted 5-oxopyrrolidine-2-carboxylic acid (Glp) immobilized on SBA-15 (SBA-15@Glp–La; SBA = Santa Barbara amorphous) was studied. Using SBA-15@Glp–La, the complete conversion was achieved at room temperature in the presence of air without producing any over-oxidized yields. SBA-15@Glp–La was prepared by post-grafting technique. 5-Oxopyrrolidine-2-carboxylic acid (Glp) condensation followed by La(III) impregnation caused this La(III)-grafted 5-oxopyrrolidine-2-carboxylic acid (Glp) to immobilize on SBA-15. This SBA-15@Glp–La catalyst shows excellent catalytic activity in the selective aerobic oxidative coupling of thiols. Effects of amount of the catalyst, polarity of the solvent, effects of substrate, and catalyst reusability were investigated. It has been observed that seven repetitive reaction cycles did not cause any appreciable loss in the catalytic activity of this catalyst. The catalyst characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, transmission electron microscopy, inductively coupled plasma, elemental mapping, and N₂ adsorption–desorption is reported. The procedure developed is heterogeneous and environmentally benign.     

‘Click Synthesis’ of 1H‐1,2,3‐Triazolyl‐Based Oxiconazole (=(1Z)‐1‐(2,4‐Dichlorophenyl)‐2‐(1H‐imidazol‐1‐yl)ethanone O‐[(2,4‐Dichlorophenyl)methyl]oxime) Analogs

The ‘click synthesis’ of some oxiconazole analogs 5a – 5v having 1H‐1,2,3‐triazolyl residues by Huisgen cycloaddition was achieved in four steps (Scheme 1). Oximation of phenacyl chloride ( 1 ) followed by azidation of 2‐chloro‐1‐phenylethanone oxime ( 2 ) provided azido ketoxime 3 . The CuI‐catalyzed Huisgen cycloaddition of 3 with terminal alkynes gave the 4‐substituted (at the triazole) 2‐(1H‐1,2,3‐triazol‐1‐yl)‐1‐phenylethanone oximes 4a – 4i . The O‐alkylation of 4a – 4i with various alkyl halides resulted in the formation of the target molecules 5a – 5v in good yields.     

New method for microextraction of ultra trace quantities of gold in real samples using ultrasound-assisted emulsification of solidified floating organic drops

A method was developed for the determination of gold ion in water samples using microextraction based on the ultrasound-assisted emulsification of solidified floating organic drops, followed by the flame atomic absorption spectrometry. N-(4-{4-[(anilinocarbothioyl)amino]benzyl}phenyl)-N-phenylthiourea was used as chelating agent. The parameters affecting the extraction and complex formation (including the type and volume of the extracting solvent, time of sonication and centrifugation, pH, amount of the chelating agent, and sample ionic strength) were optimized. Under the optimum conditions, the calibration graph is linear in the range from 1.5 to 400 ng mL^?1, with a limit of detection of 0.45 ng mL^?1. The relative standard deviation for ten replicate determinations of gold ion in a concentration of 175 ng mL^?1 was 1.7%. The procedure was successfully applied to the determination of gold in water samples, in pharmaceutical and synthetic samples, and in a standard reference material.

Chromium(III) Potentiometric Sensor Based on Para‐Tertiary‐Butyl Calix[4]arene

A new chromium(III) PVC membrane sensor incorporating p‐tertiary‐butyl calix[4]arene as ionophore, potassium tetrakis as additive and dibutyl phthalate (DBP) as plasticizer was constructed. The electrode exhibited an excellent potentiometric response over a wide concentration range of 1.0×10^?7–1.0×10^?1 M with a Nernstian slope of 20±0.5 mV per decade. The detection limit was 5.0×10^?8 M. The electrode showed a better performance over a pH range of 3.0–8.0, and had a short response time of about <15 s.The electrode was successfully applied to potentiometric titration of Cr (III) with EDTA and for direct determination of chromium(III) in waste water.     

Design and Preparation of Single‐Chain Nanocarriers Mimicking Disordered Proteins for Combined Delivery of Dermal Bioactive Cargos

Inspired by the multifunctionality of vitamin D‐binding protein and the multiple transient‐binding behavior of some intrinsically disordered proteins (IDPs), a polymeric platform is designed, prepared, and characterized for combined delivery of dermal protective and anticancer bioactive cargos on the basis of artificial single‐chain nano‐objects mimicking IDPs. For the first time ever, simultaneous delivery of folic acid or vitamin B₉, and hinokitiol, a relevant natural bioactive compound that exhibits anticancer activity against human malignant melanoma cells, from these multidirectionally self‐assembled unimolecular nanocarriers is illustrated.

     

Rice husk: A mild,efficient, green and recyclable catalyst for the synthesis of 12-Aryl-8, 9, 10, 12-tetrahydro [a] xanthene-11-ones and quinoxaline derivatives

Rice husk, as a green and cheap reagent, can be used for the promotion of the synthesis of 12-aryl -8, 9,10,12-tetrahydrobenzo[α] xanthen-11-one derivatives (ATXOs) via three-component reaction of aldehydes, 2-naphthol and 5,5-dimethyl-1,3-cyclohexadione (dimedone) under solvent-free conditions. This catalyst can also be used for the preparation of quinoxaline derivatives in a mixture of H₂O and CH₃CN at 50 °C. The present methodology offers several advantages such as high yields, simple procedure, low cost, short reaction times, mild reaction conditions and use of a green, cheap and reusable catalyst.     

A conductometric study of complexation reaction between dibenzo-24-crown-8 with yttrium cation in some binary mixed non-aqueous solvents

The complexation reaction of macrocyclic ligand, dibenzo-24-crown-8 (DB24C8) with Y⁺³ cation was studied in some binary mixtures of methanol (MeOH), ethanol (EtOH), acetonitrile (AN) and tetrahydrofuran (THF) with dimethylformamide (DMF) at different temperatures using the conductometric method. The conductance data show that in all solvent systems, the stoichiometry of the complex formed between DB24C8 and Y⁺³ cation is 1:1 (ML). The stability order of (DB24C8.Y)⁺³ complex in pure non-aqueous solvents was found to be: AN > EtOH > MeOH > DMF. A non-linear behaviour was observed for changes of log K_f of (DB24C8.Y)⁺³ complex versus the composition of the binary mixed solvents, which was explained in terms of solvent–solvent interactions and also the heteroselective solvation of the species involved in the complexation reaction. The obtained results show that the stability of (DB24C8.Y)⁺³ complex is sensitive to the mixed solvents composition. The values of thermodynamic parameters (?H°_c and ?S°_c) for formation of (DB24C8.Y)⁺³ complex were obtained from temperature dependence of the stability constant using the van’t Hoff plots. The results show that in most cases, the (DB24C8.Y)⁺³ complex is enthalpy destabilized but entropy stabilized and the values and also the sign of thermodynamic parameters are influenced by the nature and composition of the mixed solvents.