One‐Pot stereoselective synthesis of trans‐4,5‐dialkoxy‐1,3‐bis (2‐pyrimidinyl)imidazolidines through a three‐component reaction

Stoichiometric reaction of 2‐aminopyrimidine with formaldehyde in the presence of formic acid catalyst in water gave N,N′‐bis(2‐pyrimidinyl)methanediamine ( 5 ). Subsequent cyclocondensation of 5 with glyoxal in alcohol (MeOH, EtOH, PrOH and i‐PrOH) under reflux conditions led to the formation of the corresponding 4,5‐dialkoxy‐1,3‐bis(2‐pyrimidinyl)imidazolidines ( 6a‐d ). 4,5‐Dihydroxy‐1,3‐bis(2‐pyrimidinyl) imidazolidine ( 6e ) was obtained when the reaction was carried out in acetonitrile. Based on ¹H NMR analysis, it was found that the trans‐dialkoxyimidazolidines ( 6 ) were selectively obtained in these cyclocondensation reactions.     

Dispersive liquid–liquid microextraction based on the solidification of floating organic drop followed by inductively coupled plasma-optical emission spectrometry as a fast technique for the simultaneous determination of heavy metals

A simple, rapid and efficient dispersive liquid–liquid microextraction based on the solidification of floating organic drop (DLLME–SFO) method, followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) was developed for the simultaneous preconcentration and determination of heavy metals in water samples. One variable at a time method was applied to select the type of extraction and disperser solvents. Then, an orthogonal array design (OAD) with OA₁₆ (4⁵) matrix was employed to study the effects of different parameters on the extraction efficiency. Under the best experimental conditions (extraction solvent: 140 μL of 1-undecanol; disperser solvent: 2.0 mL of acetone; ligand to metal mole ratio: 20; pH: 6 and without salt addition), the enhancement factor ranged from 57 to 96. The calibration graphs were linear in the range of 0.5–250 μg L⁻¹ for Mn, 1.25–250 μg L⁻¹ for Cr, Co and Cu with correlation coefficient (r) better than 0.990. The detection limits were between 0.1 and 0.3 μg L⁻¹. Finally, the developed method was successfully applied to extraction and determination of the mentioned metal ions in the tap, sea and mineral water samples and satisfactory results were obtained.     

Characterization of a Redox-responsive Molecular Switch Based on Dibenzo[1,2]dithiine Using DFT

Structural and electronic properties of a bistable redox-responsive molecular switch based on dibenzo[1,2]dithiine (PSBH) were studied using the DFT-B3LYP/6-31G* method. The results confirmed that the electrical conductivity of the closed form of considered molecular switch is higher than that of the open form. NBO electric charges on heavy atoms of biphenyl unit revealed that the positive charge on sulfur atoms reinforced, which caused the collapse of disulfide bond.     

Chemical speciation and contamination assessment of Zn and Cd by sequential extraction in surface sediment of Klang River, Malaysia

The concentration and chemical speciation of Cd and Zn as well as total organic carbon (TOC) were studied in surface sediments from 21 stations along Klang River. Sequential extraction technique (SET) was applied to assess the four (exchangeable, acid-reducible, oxidisable-organic and residual) fractions in surface sediment. And also, to obtain an overall classification of cadmium and zinc pollution in this area. This investigation was the first study on the basis of the chemical speciation of Cd and Zn in surface sediments of the Klang River. The total concentrations of metals were ranged (0.60–2.26 µg g^{− 1}) for Cd and (33.26–268.24 µg g^{− 1}) for Zn. The chemical speciation of Cd and Zn in most sampling stations were in the order of residual > acid-reducible > oxidisable-organic > exchangeable, and it showed that the Zn in Klang River surface sediments existed in the nonresistant fractions, whilst Cd existed in the resistant fraction. The degree of surface sediments contamination was determined for individual contamination factors (ICF) and global contamination factor (GCF). The result of ICF and GCF values showed that those stations located vicinity of municipal area had high potential risk to fauna and flora of the Klang River. The relationship between the concentration of cadmium and zinc at the oxidation-organic fraction with TOC in surface sediment was identified. The results showed that TOC had a positive function to complex with Cd and Zn in the surface sediment of Klang River.     

Convenient and Efficient Method for the Synthesis of N-Heteroaryl Aminonaphthols under Solvent-Free Conditions

A convenient, efficient and green synthesis of N‐heteroaryl aminonaphthols has been developed by one‐pot, three‐component condensation of β‐naphthol, heteroaryl amines and substituted benzaldehydes under solvent‐free conditions at elevated temperature. The advantages of these reactions are simplicity of the reaction procedure, short reaction times, simple work‐up, catalyst‐free conditions and pure products in good to excellent yields.     

Composition of essential oil and biological activity of extracts of Viola odorata L. from central Iran

Essential oil composition of the leaves of Viola odorata L. growing wild in Kashan, central Iran, was extracted by hydro distillation-solvent extraction method and analysed using GC-MS technique. The analysis revealed the presence of 25 identified compounds, representing 92.77% of the oil with butyl-2-ethylhexylphthalate (30.10%) and 5,6,7,7a-tetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone (12.03%) being the two main components. Several components were identified for the first time in this chemotype of V. odorata. Antioxidant and antibacterial activities of the oil, methanol and chloroform extracts were also evaluated for the first time in this research work.     

Solvent- and Catalyst-Free Synthesis of New Unsymmetrical Multidentate Thio-bis-aminophenol Ligands by Mannich Condensation

A one-pot, three-component, Mannich condensation of electron-rich aromatic compounds such as 5-methyl-2-hydroxyphenyl sulfide, 2-aminopyrimidine, and various aromatic aldehydes were used to prepare a series of new unsymmetrical multidentate aminophenol ligands. These compounds were synthesized in solvent-free conditions as a fast, simple, convenient, and uncatalyzed method. Details of the reaction conditions are discussed.     

High electrochemical stability of polyvinylidene fluoride (PVDF) porous membranes using phase inversion methods for lithium-ion batteries

Journal of Solid State Electrochemistry - Polyvinylidene fluoride (PVDF) porous membranes were prepared by non-solvent-induced phase separation (NIPS) method. The membranes were made by different...