JOURNAL OF THE IRANIAN CHEMICAL SOCIETY(JICS)
Year:2015 | Volume:12 | Issue:1|Papers Count:20

Adsorption characteristics and doxycycline (DC) removal efficiency of Fe3O4 magnetic nanoparticles as adsorbents have been determined by investigating the effects of pH, concentration of the DC, amount of adsorbents, contact time, ionic strength and temperature. The mechanism of adsorption was also studied. The adsorption of DC to the Fe3O4 magnetic nanoparticles could be described by Langmuir-type adsorption isotherms. Short contact time between the reagents, reusability of Fe3O4 for three times after recycling of the nanoparticles, good precision and accuracy, wide working pH range and high breakthrough volume are among the highlights of this procedure. The proposed extraction and determination procedure based on magnetic nanoparticles as adsorbent was successfully applied to the determination of DC spiked in honey and various water samples. The method presented here is fast, simple, cheap and robust, and it does not require the use of organic solvents. Also, the method needs only a magnet and can be performed in any laboratory without sophisticated equipment.

In recent decades, a large number of reports related to synthesis of N-, O- and S-containing heterocycles have appeared owing to a wide variety of their biological activity. The metal-catalyzed synthesis of heterocycles is becoming an important and highly rewarding protocol in organic synthesis. This review focuses on the use of metal as a catalyst for the synthesis of nitrogen-containing heterocycles. It describes the formation of higher-membered heterocyclic rings.

Saccharose was applied as an efficient and homogeneous catalyst for one-pot, four-component synthesis of 1, 4-dihydropyrano [2, 3-c] pyrazole derivatives from aromatic aldehydes, malononitrile, ethyl acetoacetate and hydrazine monohydrate under thermal solvent-free conditions. This protocol has a considerable number of advantages including mild condition, high yields, operational simplicity, environmentally benign and simple work-up procedures.

A dispersive liquid–liquid microextraction (DLLME) method for separation/preconcentration of ultra trace amounts of Co (II) and its determination with FAAS was developed. The DLLME behavior of Co (II) using Aliquat 336-chloride as ion pairing agent was systematically investigated. The factors influencing the ion pair formation and extraction by DLLME method were optimized. Under the optimized conditions for 150 mL of extraction solvent (carbon tetrachloride), 1.5 mL disperser solvent (acetonitrile) and 5 mL of sample, the enrichment factor was 30. The detection limit was 5.6 mg L-1 and the RSD for replicate measurements of 1 mg L-1 was 1.32%. The calibration graph using the preconcentration system for cobalt was linear from 40 to 400 mg L-1 with a correlation coefficient of 0.999. The proposed method was successfully applied for determination of cobalt in black tea, paprika and marjoram real samples.

SBA-Pr-NH2 was found to be a sui table and efficient catalyst for the condensation of acenaphthenequinone, malononitrile/ethylcyanoacetate, and a-methylencarbonyl compounds via a simple, facile, efficient and three-component procedure. The corresponding product was found to have a surprising antimicrobial activity.

Cu nanoparticles@graphene oxide composites (CGC) were synthesized by a simplistic and effective chemical reduction method. The resulting CGC composites were characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The performance of the CGC composites for dechlorination of carbon tetrachloride was evaluated. The batch investigations indicated that carbon tetrachloride could be almost completely removed by CGC after 75 min. The adsorption isotherm was also discussed. The high removal capacities of CGC with respect to the bare nanoscale zerovalent copper owe to the increased adsorption sites in the composites that are resulted from aggregation inhibition, which leads to the reduced Cu nanoparticles size.

CeO2/TiO2 nanocomposite was synthesized by particulate sol–gel method. The X-ray diffractogram shows the presence of cubic CeO2 and anatase TiO2 in the composite. The high resolution scanning electron micrographs reveal the nanoparticulate nature of the prepared composite. The composite absorbs UV light and exhibits near-band gap emission corresponding to TiO2 and deep level emission due to crystal defects. The Nyquist plot displays two semicircular arcs indicating the material heterogeneity. The physicochemical characteristics of the synthesized nanocomposite are in favour of its application as an ingredient of sunscreen formulations; under UV light the photocatalytic activity of CeO2/TiO2 composite, tested through the degradation of rhodamine B, is very much less than that by pristine anatase TiO2. Reduced adsorption of moisture by the nanocomposite is a possible reason for the observed very low photocatalytic activity.

[Mn (salen) Cl-cellulose] was synthesized by immobilization of homogeneous Mn (salen) Cl complex on cellulose and characterized by FT-IR, TGA and atomic absorption spectroscopy. The resulted catalyst exhibited moderate to high reactivity in the oxidation of benzylic alcohols into carbonyl compounds using oxone as oxidant in ambient conditions. The catalytic activity of Mn (salen) Cl and [Mn (salen) Cl-cellulose] in this reaction was investigated. The heterogeneous catalyst showed higher catalytic activity with respect to neat Mn (salen) Cl complex.

Nanoparticles (NPs) are considered as an important environmental risk factor for cognitive impairments and neurodegenerative disorders. Recent evidences have reported a glutamatergic system response against air-borne NPs. Zinc and copper oxides (ZnO and CuO) NPs are the most common metal oxide NPs in industries. The effects of these NPs on hippocampal voltage-dependent ion channels and spatial cognition have been previously studied. However, there is a lack of evidence regarding the effects of ZnO and CuO NPs on glutamatergic synapse neurotransmission in central nervous system. In the present study, the effects of ZnO and CuO NPs on glutamate (Glu) release and uptake have been investigated in isolated nerve terminals (synaptosomes). Our findings have shown that, even in high doses of ZnO and CuO NPs, no significant effect on Glu release is observed. However, a decrease has been observed in uptake of Glu. Hence, ZnO and CuO NPs can be considered as hazardous agents inducing neurodegenerative disorders through Glu excitotoxicity.

Ordered mesoporous silica material MCM-41 with covalently anchored boric acid groups located inside the mesochannels has been utilized as an acid catalyst for the ‘green’ synthesis of 2-aryl-2, 3-dihydroquinazolin-4 (1H) -one derivatives under solvent-free condition. This novel synthetic method offers advantages, such as excellent yields, simple reaction procedure, short reaction times and mild reaction conditions.

An efficient one-pot synthesis of novel 2, 5-dihydro-1, 2-oxaphosphole derivatives via a three-component reaction of triphenyl phosphine, dialkyl acetylenedicarboxylates, and methyl (arylmethylidene) pyruvates has been reported. Carrying out the reaction in mild reaction conditions and synthesis of functionalized oxaphospholes are advantages of this approach.

A simple and efficient oxidative conversion of benzyl derivatives of halides, amines, alcohols, and aldehydes into corresponding nitriles is described using trans -3, 5-dihydroperoxy-3, 5-dimethyl-1, 2-dioxolane in the presence of NH4Br. The reactions proceeded smoothly at room temperature to afford the products in high-to-excellent yields.

The ligand 1, 2-dimorpholinoethane (DME) was used to prepare Zn (II) and Ni (II) complexes of the general formulation MLX2 (L=DME, X=Cl or NO3). Zinc (II) complex exhibits spectral properties indicative of a distorted tetrahedral geometry, with DME coordinating through two nitrogen atoms and two chlorides completing the tetrahedron. This is in contrast to the six-coordinated, distorted octahedral geometry exhibited by nickel (II) complex of DME when NO3 was used as counter ions. The X-ray diffraction confirms the structures of two complexes and shows that the ligand coordinates through two nitrogen atoms while the two ether linkages are not involved in complexation, which would have been the case if the morpholine rings were in the boat form. The ligand and related complexes have antibacterial activity against the five Gram-positive bacteria: Bacillus subtilis ATCC 6633, Staphylococcus aureus ATCC 6538, Bacillus cereus NRRL-B-3711, Enterococcus faecalis ATCC 29212 and Streptococcus pyogenes and also against the three Gram-negative bacteria: Escherichia coli ATCC 11230, Pseudomonas aeruginosa ATCC 15442 and Klebsiella pneumonia ATCC 70063. The results showed that in some cases the antibacterial activity of the complexes exceeded the one of sulfisoxazole used as a standard.

The reaction of phosphorus ylide, acetylmethylenetriparatolylphosphorane (L) with HgX2 (X=Cl, Br, I and NO3) in equimolar ratios using acetone and dimethylformamide as solvents leads to binuclear products. 31P NMR spectroscopy was used to investigate the stoichiometry and stability of a HgX2 complex with CH3COCHP (p -tolyl) 3 (L) in binary acetone–dimethylformamide mixtures of varying composition. In all cases studied, the variation of 31P NMR chemical shift with the [HgX2] / [L] mole ratio indicated the formation of 1: 1 complexes. The formation constants of the resulting complexes were evaluated from computer fitting of the mole ratio data to an equation that relates the observed chemical shifts to the formation constant. In all mercuric salts used, the stabilities of the resulting 1: 1 complexes varied in the order Hg (NO3) 2>HgCl2>HgBr2>HgI2. It was found that, in the case of all complexes, an increase in the percentage of dimethylformamide in the solvent mixtures significantly decreases the stability of the complexes.

This paper reports on a newly developed electrokinetic chromatographic method for the simultaneous separation and determination of steviol glycosides in real stevia samples by capillary electrophoresis and supported by molecular docking studies. Our results obtained using 30-mM heptakis- (2, 3, 6-tri-o -methyl betacyclodextrin) as a separating agent, suggest that at optimum experimental conditions the detection limits of 2.017×10-5 and 7.386×10-5 M and relative standard deviations (n=5) of 1.10 and 1.17 were obtained for rebaudioside-A and stevioside, respectively. In addition, the molecular docking studies explained to a certain extent why the separation was successful. The calculated binding free energy results for the rebaudioside-A and stevioside complexes formed with the separating agent showed that although both ligands penetrated deeply into the hydrophobic cavity of the separating agent, the presence of additional hydrogen bonding in the case of stevioside is probably responsible for its stronger binding affinity than that of rebaudioside-A.

Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA’s extraordinary interesting properties and possible application fields.12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1–12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH>6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacunary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH>11.0. The results of the performed study contribute to understand the behavior of WSiA in the water–methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water–methanol solutions, as well.

A supported carbon material is shown to be a highly efficient, eco-friendly and recyclable solid acid catalyst for the Biginelli reaction of aldehyde, b-ketoester and urea or thiourea under microwave irradiation in the absence of solvent. This method offers significant advantages such as efficiency, the excellent yield, avoidance of the organic solvents, mild reaction conditions, easy separation and simple operation. In addition, because of employing microwave as heating source and reducing use of organic solvents, this novel method emerges as a green-approach leading to less harmful residues. Furthermore, a mechanism was proposed to rationalize the reaction and the role of NiO–MWCNTs was also investigated in these transformations.

In this study, synthesis and application of diphenylphosphorylated PEG200 (DPPPEG200) are described. Herein, we report a very simple procedure for the preparation of DPPPEG200 as a stable solid through the reaction of PEG200 with ClPPh2. This compound was used as a very suitable ligand for the in situ generation of nano-Pd (0) particles through its reaction with PdCl2 as a pre-catalyst. Isolation of this catalyst is very simple through addition of diethyl ether to the reaction mixture and centrifugations. Full characterization of the nano-Pd (0) /DPPPEG200 was performed by XRD spectra, UV–Vis spectra, and also by TEM image. This nano-complex was used as an efficient catalyst for copper-free Sonogashira and homocoupling reactions of aryl halides. The sonogashira reaction of aryl halides was conducted at 80 °C in PEG. However, the homocoupling reaction was performed at 100 °C for aryl iodides and activated aryl bromides and at 130 oC for deactivated aryl bromides and aryl chlorides in PEG. The catalyst was recovered and recycled for four consecutive runs.

One of the serious problems in the present century is chemical and biological pollution of the environment. Nanocomposites are multiphase solid materials that have been used as adsorbent of pollutants such as dyes, pesticides, anions and etc. in the last decades. In this study, a novel nanocomposite including silver nanoparticles and ordered mesoporous alumina (OMA) has been synthesized and used for the removal of dyes pollutants (methyl orange, bromothymol blue and reactive yellow) from aqueous solution. The characterization of synthesized nanocomposite has been performed by TEM, N2 adsorption/desorption, XRD and energy dispersive X-ray spectroscopy analysis. The adsorption kinetic and equilibrium data have been obtained by UV–vis spectroscopy. The results show that the silver/OMA nanocomposite (Ag/OMA nanocomposite) is good adsorbent for the removal of anionic dyes from aqueous solution, and also this nanocomposite has a biocidal action against both Gram-negative and Gram-positive bacteria.

In this research, the electrophoretic deposition method was used to prepare a titanium electrode coated with multiwall carbon nanotubes–titanium dioxide composite (MWCNTs–TiO2/Ti). The electrode was characterized by transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction and cyclic voltammetry. The photoelectrocatalysis (PEC) activity of MWCNTs–TiO2 composite electrode was investigated through the degradation of Acid Red 33 (AR33) as a model pollutant. A comparison was performed among electrochemical oxidation (EO), direct photolysis (DP), photocatalysis (PC) and PEC processes for decolorization of AR33 solution. Results indicated that color removal (CR) efficiency follows the decreasing order: PEC>PC>DP>EO. In addition, the effect of initial pH of dye solution and current density on decolorization of AR33 was studied. A total 98% CR and 41.66% mineralization of AR33 dye were achieved after 60 min of photoelectrocatalytic treatment using the MWCNTs–TiO2/Ti composite electrode operated at a current density of 7.5 mA cm-2 and pH=5.2.