NOPR Collection:

Tailoring electrically conducting polymers: An overview

2019-03-19T06:05:15Z

Title: Tailoring electrically conducting polymers: An overview Authors: Bakhshi, A K Abstract: Current efforts to design novel conducting polymers with desired conduction properties are reviewed. The strategy and the methodology used to achieve this tailoring are discussed. Some recent results on the electronic structure and conduction properties of tailored conducting polymers and their superlattices are briefly discussed. It is found that quasi-one-dimensional polymeric superlattices of conducting polymers are promising candidates for tailoring copolymers with conduction properties intermediate between those of its components. Finally, the future possibilities in this direction are briefly outlined. Page(s): 291-302

Crystal and molecular structure of aquoethylenediaminetetra-acetatoruthenium (III) and its extraordinary lability towards substitution

2019-03-19T06:02:47Z

Title: Crystal and molecular structure of aquoethylenediaminetetra-acetatoruthenium (III) and its extraordinary lability towards substitution Authors: Khan, M M Taqui; Venkatasubramanian, K; Bajaj, H C; Shririn, Zahida Abstract: The crystal and molecular structure of [Ru(HEDTA) (H₂O)] (2), was determined using single crystal X-ray diffraction techniques. The complex crystallizes with 4 molecules in the space group P2₁/c with the unit cell dimensions a = 8.414(1)Ǻ, b = 8.835(1)Ǻ, c= 17.610(4)Ǻ, β = 99.64*. The structure has been solved taking advantage of the fact that the complex is isomorphous with the analogous Rh(III) complex. The

structure is refined to an R value 0.033 (Rw = 0.043) for 5983 observed reflections. Ru occurs as a distorted octahedron. Ethylenediaminetetraacetic acid is a pentadentate ligand, with one free carboxylate group.

Water approaches the coordination sphere trans to one of the nitrogens of the ethylenediamine moiety. Ring R2 is planar, while rings R₁ and G are envelopes. Ring E occurs as a half-chair. The structure is held in three-dimensional space by an elaborate network of hydrogen bonds. Water exchange rate constants show that the complex is labile. An attempt is made to rationalize the unusual lability of the complex. Page(s): 303-308

Sodium ruthenate catalysis in the oxidation of substituted benzyl alcohols by hexacyanoferrate(III)

2019-03-19T05:56:43Z

Title: Sodium ruthenate catalysis in the oxidation of substituted benzyl alcohols by hexacyanoferrate(III) Authors: Lalitha, T Venkata; Rao, M Prasad; Sethuram, B Abstract: Ru(VI) catalysis in the oxidation of benzyl alcohol and its monosubstituted analogues by hexacyanoferrate(III) [Fe(III)]in t-butanol (25%, v/v) in alkaline medium has been studied. The reaction is first order in [Ru(VI)], fractional order in [alcohol] and zero order each in [Fe(III)], [base] and [t - butanol]. The primary kinetic isotopic effect (k_H/k_D) is 4.12 at 298 K. The solvent isotopic effect (k/k) is 0.948 at 298 K. The reaction exhibits a reaction constant ρ of - 0.540 at 298 K. A mechanism involving the transfer of a hydride ion to the oxidant is suggested. The activation enthalpies and entropies are linearly related. Page(s): 309-312

Electrochemical characterization of membranes

2019-03-19T05:43:55Z

Title: Electrochemical characterization of membranes Authors: Singh, Kehar; Tiwari, A K Abstract: The determination of electrochemical characteristics of membranes on the basis of membrane potential measurements and electrochemical impedance studies has been described. Cellulose acetate membrane has been used alongwith sodium chloride and magnesium chloride solutions to investigate variation of transport number, pennselectivity and fixed charge density with concentration and pH. Alteration in these membrane characteristics in the presence of lecithin has also been investigated. Dependence of impedance of Dowex-50 membrane with frequency has been studied over a .wide range using solution of sodium chloride with and without cholesterol with the object of estimation of membrane conductance and capacitance; and to examine their variation with surfactant concentration. The results indicate progressive accumulation of surfactant molecules in the membrane solution interfacial region which is significantly altered with the electrical potential to which the membrane is subjected. Page(s): 313-316