NOPR Collection:

Dissociation dynamics of host-guest interaction between substituted calix[4]- arene and 4-chloronitrobenzene

2016-03-20T14:28:26Z

Title: Dissociation dynamics of host-guest interaction between substituted calix[4]- arene and 4-chloronitrobenzene Authors: Kumar, Ashok; Sharma, Pratibha; Sharma, Pawan Kumar; Ahuja, Monika; Matisz, Gergely; Kollar, Laszlo; Kunsagi-Mate, Sandor Abstract: The inclusion complexation of upper rim substituted calix[4]arene with neutral 4-chloronitrobenzene has been studied by quantum-chemical and spectrophotometric measurements. The effect of varying temperature on the formation versus dissociation of the host-guest complex has been investigated. The formation of stable host-guest complexes is determined using DFT/B3LYP/ 6-311G(d) level of theory. The π-π interaction based dissociation dynamics of the host-guest complex has been studied. In the host-guest interaction, a 1:1 complex stoichiometry is observed. The low activation energy of dissociation, obtained from the MD simulations, indicates that the complex formation equilibrium is thermodynamically controlled. Page(s): 304-308

Determination of sunset yellow and tartrazine using silver and poly (L-cysteine) composite film modified glassy carbon electrode

2016-03-01T00:00:00Z

Title: Determination of sunset yellow and tartrazine using silver and poly (L-cysteine) composite film modified glassy carbon electrode Authors: Tang, Youxia; Wang, Yanming; Liu, Gen; Sun, Dengming Abstract: Silver and poly(L-cysteine) composite film modified glassy carbon electrode (PLC/Ag/GCE) has been fabricated via cyclic voltammetry and used for investigation of the electrochemical behavior of sunset yellow (SY) and tartrazine (TT). A pair of anodic peak at 0.760 V (vs. Ag/AgCl) and cathodic peak at 0.701 V (vs. Ag/AgCl) for SY and an anodic peak at 1.013 V (vs. Ag/AgCl) of TT are observed in pH 4.5 phosphate buffer solution. Based on the two well-resolved anodic peaks of SY and TT, a novel electrochemical method has been successfully developed for simultaneous determination of SY and TT using differential pulse voltammetry. Under the optimized experimental conditions, the linear range for the determination of SY and TT are 5.00×10^-7 –3.00×10^-4 mol L^-1 and 7.50×10^-7–7.50×10^-4 mol L^-1, respectively with detection limits of 7.50×10^-8 mol L^-1 and 2.50×10^-7 mol L^-1, respectively. The proposed method has been applied for simultaneous determination SY and TT in beverage with satisfactory results. Page(s): 298-303

In situ chemical oxidative polymerisation for ordered conducting polythiophene nanostructures in presence of dioctyl sodium sulfosuccinate

2016-03-20T14:19:57Z

Title: In situ chemical oxidative polymerisation for ordered conducting polythiophene nanostructures in presence of dioctyl sodium sulfosuccinate Authors: Jose, M Anne; Varghese, Smitha; Antony, M Jinish Abstract: Polythiophenes (PTs) have been synthesized by chemical oxidative polymerization of thiophene in the presence of an anionic surfactant dioctyl sodium sulfosuccinate (AOT) using ferric chloride as an oxidant in chloroform solvent. Different monomer/surfactant ratios have been employed to study the effect of surfactant on synthesis and properties of polythiophenes. The PTs have been characterized by FT-IR spectroscopy, wide-angle powder X-ray diffraction and elemental analysis. The properties of PTs prepared using AOT surfactant have been compared with those of PT synthesized without surfactant. Four probe electrical conductivity measurements of the samples reveal that the conductivity is in the range of (7.4–1.0)×10^-3S cm^-1 for AOT doped polythiophene samples. The band gap of the polymers determined from diffuse reflectance spectroscopy is in the range of 2.25–2.50 eV. Scanning electron microscopic images of the samples exhibited spherical nanoparticle morphology with size in the range of 800 ± 50 nm. Page(s): 292-297

TX-100 reverse micelles as microreactors for alkaline hydrolysis of tris(2,2ʹ-bipyridine) iron(II) complex

2016-03-01T00:00:00Z

Title: TX-100 reverse micelles as microreactors for alkaline hydrolysis of tris(2,2ʹ-bipyridine) iron(II) complex Authors: Kundu, Arjama; Mahapatra, Ambikesh Abstract: Alkaline hydrolysis reaction of tris(2,2ʹ-bipyridine)iron(II) complex with sodium hydroxide has been investigated in TX-100 reverse micelles using cyclohexane/water with hexanol as cosurfactant by spectrophotometric method. In reverse micellar medium, the reaction is first order with respect to each reactant. The effects of water pool size and surfactant concentration are investigated. The rate decreases as the [water]/[surfactant] molar ratio (W) increases, but increases as surfactant concentration increases. Effect of both W and surfactant concentration are prominent at lower regions of W. The results are explained by considering the occurrence of two reactions at a measurable speed in reverse micellar medium, i.e., aqueous dissociation and alkaline hydrolysis reactions. Both these reactions in the reverse micellar medium are catalyzed. In the water pool, properties of water are such that at lower W, dissociation reaction is favorable, whereas at higher W, hydrolysis is favorable. Experimental results also conclude that dissociation occurs mainly at the interface and hydrolysis in the cavity of the water pool. Page(s): 286-291