Synthesis of mono- and bis-spirooxindole derivatives "on water" using double salt of aluminum sulfate-sulfuric acid as a reusable catalyst.

The preparation of double salt of aluminum sulfate-sulfuric acid (Al4(SO4)6·(H2SO4)·24H2O) by the reaction of aluminum sulfate and sulfuric acid in water is described. Aluminum sulfate-sulfuric acid is characterized via some spectroscopic and microscopic techniques such as infrared spectroscopy (IR), X-ray diffraction spectroscopy (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) which corroborated the structure of the double salt. This double salt is soluble in water and insoluble in organic solvents. It was employed as a new catalyst for the synthesis of spirooxindole compounds on water with good to excellent yields. The double salt could be recycled and reused without appreciable loss of activity.

1,2,3-Triazole framework: a strategic structure for C-H⋯X hydrogen bonding and practical design of an effective Pd-catalyst for carbonylation and carbon-carbon bond formation.

1,2,3-Triazole is an interesting N-heterocyclic framework which can act as both a hydrogen bond donor and metal chelator. In the present study, C-H hydrogen bonding of the 1,2,3-triazole ring was surveyed theoretically and the results showed a good agreement with the experimental observations. The click-modified magnetic nanocatalyst Pd@click-Fe3O4/chitosan was successfully prepared, in which the triazole moiety plays a dual role as both a strong linker and an excellent ligand and immobilizes the palladium species in the catalyst matrix. This nanostructure was well characterized and found to be an efficient catalyst for the CO gas-free formylation of aryl halides using formic acid (HCOOH) as the most convenient, inexpensive and environmentally friendly CO source. Here, the aryl halides are selectively converted to the corresponding aromatic aldehydes under mild reaction conditions and low Pd loading. The activity of this catalyst was also excellent in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acids in EtOH/H2O (1 : 1) at room temperature. In addition, this catalyst was stable in the reaction media and could be magnetically separated and recovered several times.

Synthesis, Structural Studies, and α-Glucosidase Inhibitory, Antidiabetic, and Antioxidant Activities of 2,3-Dihydroquinazolin-4(1H)-ones Derived from Pyrazol-4-carbaldehyde and Anilines.

A series of new quinazoline derivatives were designed and synthesized via a one-pot condensation reaction between isatoic anhydride and aromatic aldehydes with anilines using aluminum sulfate as a catalyst in refluxing ethanol. Their structures were confirmed by their physical, IR, 1H NMR, 13C NMR, and mass spectroscopy data and evaluated for some biological effects, including the antioxidant and α-glucosidase inhibitory activities as well as some in vivo hematological parameters. The ability of synthesized compounds in the inhibition of α-glucosidase was also investigated through the in silico study. The significant and important changes in some hematological tests were perceived. Notably, compound 4h showed more reducing effects on cholesterol and triglyceride levels. This molecule certainly has the potential to be developed as the antihyperlipemic compound. The tested compounds, in particular, compounds 4j and 4l, were found to be uniquely reducing blood sugar levels. The entire synthesized compounds showed the potent α-glucosidase inhibitory activity compared with acarbose as a standard material. Amongst, the compounds 4h and 4i showed the strongest enzyme inhibitory potentials than the standard drug acarbose. There was a good correlation between in vitro and in silico studies for ligands 4i and 4l. The majority of compounds presented a good radical scavenging activity, though the compound 4j exhibited the strongest activity, even to the standard of ascorbic acid. Further studies are required to determine whether these main compounds could be a potential treatment for diabetes and hyperlipidemia diseases.

Antibacterial studies of hydroxyspiro[indoline-3,9-xanthene]trione against spiro[indoline3,9-xanthene]trione and their use as acetyl and butyrylcholinesterase inhibitors.

Xanthene derivatives are well known for their effective biological activities. In search of effective antibacterial agents, the spiro[indoline3,9-xanthene]-trione (A) and hydroxy-spiro[indoline-3,9-xanthene]-trione (B), were synthesized and tested for in vitro antibacterial activity against Staphylococcus aureus and Escherichia coli. Furthermore, the synthesized compounds were tested in vitro and in silico for their anticholinesterase activities. The anticholinesterase activities for six substitutes of the hydroxy derivative (B1-B6) were also studied through the molecular docking. All concentrations of compounds presented a dose-dependent antibacterial activity. The docking results showed that all compounds are more constant than the galantamine. Amongst, compound B1 exhibited the minimum binding energy in both AChE and BChE enzymes. Results indicate the importance of xanthene derivatives as potential antibacterial and anticholinesterases agents.

FT-IR study and solvent-implicit and explicit effect on stepwise tautomerism of Guanylurea: M06-2X as a case of study.

All 66 conformers of guanylurea were optimized and frequency calculations were performed at M06-2X/6-311++G(d,p) level of theory. Theses conformers were categorized into five tautomers, and the most stable conformer of each tautomer were found. Geometrical parameters indicated that these tautomers have almost planar structure. Complete stepwise tautomerism were studied through both intramolecular proton transfer routs and internal rotations. Results indicated that the proton transfer routs involving four-membered heterocyclic structures were rate-determining steps. Also, intramolecular proton movement having six-membered transition state structures had very low energy barrier comparable to the transition states of internal rotation routs. Differentiation of studied tautomers could easily be done through their FT-IR spectra in the range of 3200 to 3900cm-1 by comparing absorption bands and intensity of peaks. Solvent-implicit effects on the stability of tautomers were also studied through re-optimization and frequency calculation in four solvents. Water, DMSO, acetone and toluene had stabilization effect on all considered tautomers, but the order of stabilization effect was as follows: water>DMSO>acetone>toluene. Finally, solvent-explicit, base-explicit and acid-explicit effect were also studied by taking place of studied tautomer nearside of acid, base or solvent and optimization of them. Frequency calculation for proton movement by contribution of explicit effect showed that formic acid had a very strong effect on proton transfer from tautomer A1 to tautomer D8 by lowering the energy barrier from 42.57 to 0.8kcal/mol. In addition, ammonia-explicit effect was found to lower the barrier from 42.57 to 22.46kcal/mol, but this effect is lower than that of water and methanol-explicit effect.

Synthesis of functionalized dihydro-2-oxopyrroles using graphene oxide as heterogeneous catalyst.

A mild, efficient synthetic approach for the synthesis of highly functionalized dihydro-2-oxopyrroles is developed by using graphene oxide, a readily available and inexpensive material, as an eco-benign solid acid catalyst in ethanol at room temperature. The present methodology displays several advantages such as practical simplicity, high atom economy, easy workup procedure, and high yields of the products.

A green route for the cross-coupling of azide anions with aryl halides under both base and ligand-free conditions: exceptional performance of a Cu2O-CuO-Cu-C nanocomposite.

A convenient, inexpensive and effective route for the preparation of a Cu2O-CuO-Cu-C nanocomposite is described here by applying Cu(ii) as a source of copper. Characterization of the nanocomposite was performed with X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), high-resolution TEM (HR-TEM), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX). Analysis of the data showed that the particles of the nanocomposite are uniformly distributed and show high catalytic activity in the cross-coupling of sodium azide with various aryl iodides and bromides. This nanocomposite has a high level of performance, and even led to the synthesis of the products at room temperature. In addition, this is the first report of the synthesis of aryl azides under both base- and ligand-free conditions. For the first time, both ligand- and base-free conditions were applied for the synthesis of aryl azides, which implies exceptional performance of the Cu2O-CuO-Cu-C nanocomposite. Simultaneous removal of the base and ligand in a green solvent is the main advantage of this reaction. Unfortunately, aryl bromides and aryl iodides with electron-withdrawing functional groups in their scaffold did not give the desired aryl azides.

Synthesis of new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones under catalyst-free and solvent-free conditions.

Several new 1,5-diaryl-3-(arylamino)-1H-pyrrol-2(5H)-ones were synthesized via the three-component condensation reaction of aldehydes, aromatic amines, and ethyl pyruvate under catalyst-free and solvent-free conditions. Also, 5-(4-hydroxyl-3-nitrophenyl)-1-(4-methoxy-phenyl)-3-(4-methoxyphenylamino)-1,5-dihydro-pyrrol-2-one was synthesized using oxime instead of aldehyde. The eco-friendly, simple procedure, green procedure, catalyst-free and solvent-free conditions, short reaction times, and high yields of the products are the advantages of this method.

Silica chemically bonded N-propyl kriptofix 21 and 22 with immobilized palladium nanoparticles for solid phase extraction and preconcentration of some metal ions.

Silica gel chemically bonded N-propyl kriptofix 21 (SBNPK 21) and N-propyl kriptofix 22 (SBNPK 22) and subsequently immobilized with palladium nanoparticles (PNP-SBNPK 21 and PNP-SBNPK 22) to produce two new complexing lipophilic materials. Then these novel sorbents were applied for the enrichment of some metal ions and their subsequent determination by flame atomic absorption spectroscopy (FAAS). The influences of the variables including pH, amount of solid phase, sample flow rate, eluent conditions and sample volume on the metal ion recoveries were investigated. The detection limit of proposed method was in the interval 2.1-2.3 and 1.7-2.8 ng mL(-1) for PNP-SBNPK 21 and PNP-SBNPK 22 respectively, while the preconcentration factor was 80 for two sorbents. The relative standard deviations of recoveries were between 1.23-1.31 and 1.28-1.49 for PNP-SBNPK 21 and PNP-SBNPK 22 respectively. The method has high sorption-preconcentration efficiency even in the presence of various interfering ions. Due to the reasonable selectivity of proposed method, the relative standard deviation of recoveries of all understudied metal ions in some complicated matrices was less than 3.0%.

Simultaneous determination of Mn2+ and Fe3+ as 4,4'[(4-cholorophenyl)methylene] bis(3-methyl-1-phenyl-1H-pyrazol-5-ol) complexes in some foods, vegetable and water samples by artificial neural networks.

A simple and sensitive spectrophotometric method to the simultaneous determination of Mn(2+) and Fe(3+) in foods, vegetable and water sample with the aid of artificial neural networks (ANNs) is described. It relies on the complexation of analytes with recently synthesised bis pyrazol base ligand as 4,4'[(4-cholorophenyl)methylene] bis(3-methyl-1-phenyl-1H-pyrazol-5-ol)(CMBPP). The analytical data show that the ratio of ligand to metal in metal complexes is 1:1 and 1:2 for Fe(3+) and Mn(2+), respectively. It was found that the complexation reactions are completed at pH 6.7 and 5 min after mixing. The results showed that Mn(2+) and Fe(3+) could be determined simultaneously in the range of 0.20-7.5 and 0.30-9.0 mgl(-1), respectively. The analytical characteristics of the method such as the detection limit and the relative standard error predictions were calculated. The data obtained from synthetic mixtures of the metal ions were processed by radial basis function networks (RBFNs) and feed forward neural networks (FFNNs). The optimal conditions of the neural networks were obtained by adjusting various parameters by trial-and-error. Under the working conditions, the proposed methods were successfully applied to the simultaneous determination of elements in different water, tablet, rice, tea leaves, tomato, cabbage and lettuce samples.

Combination of flotation and flame atomic absorption spectrometry for determination, preconcentration and separation of trace amounts of metal ions in biological samples.

An efficient enrichment procedure based on the combination of flame atomic absorption spectrometry (FAAS) and flotation for determination of Cd(2+), Ag(+) and Zn(2+) ions in various biological samples using new collector is studied. The influence of pH, amount of 2-(((1H-benzo[d]imidazol-2-yl)methoxy)methyl)-1H-benzo[d]imidazole (HBIMMHBI) as collector, sample matrix, type and amount of eluting agent, type and amount of surfactant as floating agent, ionic strength and air flow rates on the extraction efficiency were evaluated and optimized. It is ascertained that under study metal ions is preconcentrated simultaneously from matrix in the presence of 0.005 M HBIMMHBI, 0.085% (w/v) of SDS form 750 mL at pH 6.5. The floated complexes metal ions eluted quantitatively with 6 mL of 1.0 M HNO3 in methanol lead to achieve preconcentration factor of 125. The detection limits for analyte ions were in the range of 1.3-2.4 ng mL(-1), with recoveries more than 95% and relative SD lower than 4%.

A cloud point extraction procedure for preconcentration/flame atomic absorption spectrometric determination of silver, zinc, and lead at subtrace levels in environmental samples.

A cloud point extraction (CPE) procedure was presented for the preconcentration of silver, zinc, and lead ions in various samples. The complexes of these metal ions with 2-(((1H-benzo[d]imidazol-2-yl)methoxy)methyl)-1H-benzo[d]imidazole (BIMMBI) are quantitatively extracted into the Triton X-114-rich phase after centrifugation. A solution of 1.0 M HNO3 in methanol was added to the surfactant-rich phase as the effective eluant before analysis by flame atomic absorption spectrometry. The influence of effective parameters such as the concentrations of BIMMBI, Triton X-114, and HNO3, pH, bath temperature, centrifuge rate, and time on method sensitivity and efficiency was optimized. Detection limits of 2.8, 1.7, and 1.1 ng/mL for Pb2+, Ag+, and Zn2+, respectively, along with a preconcentration factor of 30 and enrichment factors of 33, 48, and 53 for Pb2+, Ag+, and Zn2+, respectively, were obtained. The present CPE method is suitable for accurate and precise determination of trace amounts of analyte ions in complex matrixes. The proposed CPE procedure was applied to the determination of these ions in biological, natural water, wastewater, soil, and blood samples.

Silica bonded S-sulfonic acid: a recyclable catalyst for the synthesis of quinoxalines at room temperature.

The reaction of 3-mercaptopropylsilica (MPS) and chlorosulfonic acid in chloroform afforded silica bonded S-sulfonic acid (SBSSA), which was used as a catalyst for the room temperature synthesis of quinoxaline derivatives from 1,2-diamino compounds and 1,2-dicarbonyl compounds. The catalyst could be recycled and reused several times without any loss of efficiency.

Cloud point extraction and flame atomic absorption spectrometric determination of cadmium(II), lead(II), palladium(II) and silver(I) in environmental samples.

The phase-separation phenomenon of non-ionic surfactants occurring in aqueous solution was used for the extraction of cadmium(II), lead(II), palladium(II) and silver(I). The analytical procedure involved the formation of understudy metals complex with bis((1H-benzo [d] imidazol-2yl)ethyl) sulfane (BIES), and quantitatively extracted to the phase rich in octylphenoxypolyethoxyethanol (Triton X-114) after centrifugation. Methanol acidified with 1molL(-1) HNO(3) was added to the surfactant-rich phase prior to its analysis by flame atomic absorption spectrometry (FAAS). The concentration of BIES, pH and amount of surfactant (Triton X-114) was optimized. At optimum conditions, the detection limits of (3 sdb/m) of 1.4, 2.8, 1.6 and 1.4 ng mL(-1) for Cd(2+), Pb(2+), Pd(2+) and Ag(+) along with preconcentration factors of 30 and enrichment factors of 48, 39, 32 and 42 for Cd(2+), Pb(2+), Pd(2+) and Ag(+), respectively, were obtained. The proposed cloud point extraction has been successfully applied for the determination of metal ions in real samples with complicated matrix such as radiology waste, vegetable, blood and urine samples.

A simple and efficient route for the synthesis of di and tri(bis(indolyl) methanes) as new triarylmethanes.

Preparation of di and tri(bis(indolyl) methanes) from di and trialdehydes and indoles in the presence of silica sulfuric acid was described. Reactions proceeded in good to excellent yields in acetonitrile as solvent at room temperature.

A solid phase extraction procedure for Fe3+, Cu2+ and Zn2+ ions on 2-phenyl-1H-benzo[d] imidazole loaded on Triton X-100-coated polyvinyl chloride.

A new and efficient solid phase extraction method is described for the preconcentration of trace heavy metal ions. The method is based on the adsorption of Fe(3+), Cu(2+) and Zn(2+) on 2-phenyl-1H-benzo[d] imidazole (PHBI) loaded on Triton X-100-coated polyvinyl chloride (PVC). The influences of the analytical parameters including pH and sample volume were investigated. Common coexisting ions did not interfere on the separation and determination of analytes under study. The adsorbed analytes were desorbed by using 5 mL of 4 mol L(-1) nitric acid. The preconcentration factor is 90. The detection limits (3 sigma) were in the range of 0.95-1 microg L(-1). The sorbent exhibited excellent stability and its sorption capacity under optimum conditions has been found to be more than 2.7 mg of ions per gram of sorbent. The recoveries of analytes were generally higher than 95%. The relative standard deviations (R.S.D.s) were generally lower than 4%. The method has been successfully applied to some real samples.

Flame atomic absorption spectrometric determination of trace amounts of heavy metal ions after solid phase extraction using modified sodium dodecyl sulfate coated on alumina.

A sensitive and selective solid phase extraction procedure for the determination of traces of Cu(II), Zn(II), Pb(II) and Fe(III) has been developed. An alumina-sodium dodecyl sulfate (SDS) coated on with meso-phenyl bis(indolyl) methane (MPBIM) was used for preconcentration and determination of Cu(II), Zn(II), Pb(II) and Fe(III) ions by flame atomic absorption spectrometry. The analyte ions were adsorbed quantitatively on adsorbent due to their complexation with MPBIM. Adsorbed metals were quantitatively eluted using 6 mL of 4 mol L(-1) nitric acid. The effects of parameters such as pH, amount of alumina, amount of MBITP, flow rate, type and concentration of eluting agent were examined. The effects of interfering ions on the separation-preconcentration of analytes were also investigated. The relative standard deviation of the method was found to be less than 3.0%. The presented procedure was successfully applied for determination of analytes in real samples.