Synthesis and complexation study of calix[4]arene diamine derivative incorporated in a polymeric backbone with chiral monomers

The novel chiral polymeric compounds containing more than one calix[4]arene have been synthesized by reacting a new calix[4]arene diamine derivative with two chiral monomers. These newly prepared compounds were studied by extraction of toxic heavy metal (Cu²⁺, Co²⁺, Cd²⁺, Hg²⁺), silver and alkali metal (Na⁺, K⁺) cations from aqueous phase. It was observed that the resulting calixarene-based polymers have a good complexing ability towards silver, alkali metal and toxic heavy metal cations.     

Influence of acidic ionic liquids as an electrolyte additive on the electrochemical and corrosion behaviors of lead-acid battery

The aim of this study is to introduce the application of some acidic ionic liquids (ILs) as an electrolyte additive in lead-acid batteries. A family of alkylammonium hydrogen sulfate ILs, which are different in the number of alkyl chain, is investigated with the aim to compare their effects on the electrochemical behavior of Pb–Sb–Sn alloy in sulfuric acid solution. The hydrogen and oxygen gas evolution potential and anodic layer characteristics were investigated employing cyclic and linear sweep voltammetric methods. The morphological changes of the PbSO₄ layer that formed on the electrode surface were confirmed using scanning electron microscopy. Also, potentiodynamic polarization curves, electrochemical impedance spectroscopy, and an equivalent circuit analysis were used to evaluate the corrosion behaviors of the Pb–Sb–Sn alloy in the presence of ILs. The obtained results indicate that hydrogen and oxygen evolution overpotential of lead–antimony–tin alloy increases in the solution containing IL and mainly depends on the number of alkyl chain in alkylammonium cation. It is clearly observed that the morphology of PbSO₄ layer changes under the influence of ILs. The corrosion studies show an increase in corrosion resistance of lead alloy in the presence of some ILs. Also, the electrochemical effects of ILs in conversion of PbSO₄ to PbO₂ and vice versa were investigated by carbon-PbO paste electrode. Cyclic voltammogram of carbon-PbO electrode shows that in the presence of ILs, oxidation and reduction peak currents increase, while reversibility decreases.     

Ionic liquid promoted selective oxidation of organic compounds with NaBrO3

1-Butyl-3-methylimidazolium bromide ([bmim]Br) as an ionic liquid promoted selectively the oxidation of alkyl arenes and alcohols to the corresponding carbonyl compounds with NaBrO₃ in excellent yields under neutral conditions at the 70°C. Among the various ionic liquids examined, the [bmim]Br exhibited the best performances with NaBrO₃. The ionic liquid can be recycled and reused for several runs without any significant loss of activity. Correspondence: Ahmad Shaabani, Department of Chemistry, Shahid Beheshti University, P.O. Box 19839-4716, Tehran, Iran.     

Multiple hydrogen bondings in a platinum complex

An unprecedented example of a platinum(II) complex with simultaneous formation of intermolecular NH···I-Pt and CH···I-Pt H-bondings (with neighboring platinum center) and an intramolecular CH···Pt hydrogen bonding in solid state is described. There are indications showing that the complex in solution probably forms a different kind of H-bonding type interaction.     

Podophyllotoxin from suspension culture of Linum album

Callus and suspension cultures of Linum album as an Iranian species for synthesis of aryltetralin lactone were used. After cultivation period; we can isolate and characterize podophyllotoxin as glycosides compounds. Maximal product yield is 0.5% of the dry weight in dark grown cultures.     

Solution equilibria of pyridinecarboxylic acids: Complexation reaction of 2-mercaptonicotinic acid-copper (II) complex with thiosalicylic acid

The reaction of 2-mercaptonicotinic-copper (II) complex (Cu²⁺-MENA, 1 3n 1) with thiosalicylic acid (TSA) has been investigated spectrophotometrically in ethanol-water solution (50%, v/v) at I=O.IM (NaClO₄) and 25°C. Under the acidic conditions encountered in this study, there are competing equilibria between protonation of the Cu²⁺-MENA binary chelate, the formation of the Cu(MENA)(TSA) ternary complex and protonation of the second ligand (TSA). The equilibrium constants for the complexation reactions and the stability of the mixed-ligand complex are determined. The optimum conditions for the predominance of the ternary complex are established and the enhancement of this complex over binary complex formation is evaluated. Complex-forming equilibria have also been examined by potentiometric-pH titrations and the experimental data are discussed in relation to various equilibria existing in solution. Structural and bonding features of the mixed-ligand complex are illustrated from considerations of the IR spectral data.     

A comparative homocoupling reaction of aryl halides using monomeric orthopalladated complex of 4‐methoxybenzoylmethylenetri‐ phenylphosphorane under conventional and microwave irradiation conditions

The activity of [Pd(C₆H₄CH₂NH₂‐κ²‐C‐N)PPh₃MOBPPY]OTf complex, A (MOBPPY = 4‐methoxybenzoylmethylenetriphenylphosphoraneylide) was investigated in the homocoupling reaction of a vast range of aryl halides under both conventional and microwave irradiation conditions and their results were compared. The complex was active and showed high efficiency in the formation of new C‐C bonds. The yields were excellent using a catalytic amount of [Pd(C₆H₄CH₂NH₂‐κ²‐C‐N)PPh₃MOBPPY]OTf complex in N, N‐dimethylformamide at 120 °C. In comparison to conventional heating conditions, the reactions under microwave irradiation gave higher yields in shorter reaction times. Copyright © 2011 John Wiley & Sons, Ltd.     

The estimation of the hydrophobic and electrostatic contributions to the free energy change upon cationic surfactants binding to Jack bean urease

The binding of a homologous series of n-alkyltrimethyl ammonium bromides with Jack bean urease (JBU) have been studied previously. It has been suggested that both electrostatic and hydrophobic interactions are involved in the formation of surfactant-protein complexes, but there is not any quantities analyzing method for resolution of their contributions in the process. In the present study, at first, the intrinsic Gibbs free energy of binding, ΔG_b,ν, has been calculated for these systems and the trend of variation for both binding sets have been interpreted on basis of cooperativity and hydrophobicity of surfactants. Subsequently, a novel approach has been introduced for estimation of electrostatic and hydrophobic interactions in ΔG_b,ν, by considering of this fact that ΔG_b,ν is the summation of electrostatic, ΔG_b,ν(ele), and hydrophobic, ΔG_b,ν(hyd), parts and considering this fact that just ΔG_b,ν(hyd) is a function of hydrocarbon tail length of surfactant (C_n). The results represents the higher positive rule of electrostatic interactions in binding affinity of first set and inhibiting rule of this interaction in the second binding set. The predominate driving force in the second binding set is entropy statistical effect, which arises from numerous number of binding sites in this set. A binding mechanism on basis of structural changes in JBU due to its interaction with cationic surfactants has also been proposed.     

Cobalt nanoparticles supported on ionic liquid‐functionalized multiwall carbon nanotubes as an efficient and recyclable catalyst for Heck reaction

A novel and environmentally friendly cobalt nanoparticle catalyst supported on ionic liquid‐functionalized multiwall carbon nanotubes was successfully prepared and evaluated as a heterogeneous catalyst for the Mizoroki–Heck reaction. Several reaction parameters, including type and amount of solvent and base, were evaluated. This nanocatalyst could also be recovered and reused at least six times without any discernible decrease in its catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.     

Compositions of the seed oil of the Borago officinalis from Iran

In order to investigate the composition of borage (Borago officinalis L.) seed oil, this research was performed under the field conditions at Shahriyar and Garmsar zones, Iran during the 2012 planting year. The oil yield of borage was 31.46% and 33.7% at Shahriyar and Garmsar zone, respectively, and nine and eight fatty acids were identified in the seed oil of borage at Shahriyar and Garmsar, respectively – palmitic, linoleic, stearic and γ-linolenic acids were dominant in the seed oil of borage from both zones. Unsaturated fatty acid content was more than the saturated fatty acids in both zones. The ratio of linoleic acid and α-linolenic acid in the borage cultivated at Shahriyar and Garmsar zones was 2.13 and 2.29. The fatty acid profile of Garmsar borage, oleic and oleic/linoleic acid ratio, increased. Locations with different ecological conditions resulted in changes in both seed oil content and fatty acid profile of borage.