NISCAIR Online Periodicals Repository Collection: IJC-A Vol.48A(12) [December 2009]

Effect of temperature on the partial molar volumes of some bivalent transition metal nitrates and magnesium nitrate in the water-rich region of binary aqueous mixtures of dimethyl acetamide

Sat, 28 Nov 2009 22:58:59 GMT

Title: Effect of temperature on the partial molar volumes of some bivalent transition metal nitrates and magnesium nitrate in the water-rich region of binary aqueous mixtures of dimethyl acetamide

Authors: Parmar, M L; Banyal, D S

Abstract: Partial molar volumes of some bivalent transition metal nitrates, viz., manganese nitrate, cobalt nitrate, nickel nitrate, copper nitrate, zinc nitrate and magnesium nitrate have been determined in binary aqueous mixtures of N,N-dimethylacetamide (DMA) in the water-rich region (5, 10, 15, 20 and 25% by weight) of DMA from solution density measurements at 303.15 K, and in 5% w/w DMA + H₂O at five equidistant temperatures (298.15, 303.15, 308.15, 313.15 and 318.15 K). The density data have been analysed by Masson’s equation. The partial molar volumes and experimental slopes have been interpreted in terms of ion-solvent and ion-ion interactions, respectively. The partial molar volumes vary with temperature as a power series of temperature. Structure making/breaking capacities of electrolytes have been inferred from the sign of the second derivative of partial molar volumes with respect to temperature at constant pressure. All the electrolytes have been found to act as structure breakers in binary aqueous mixtures of dimethyl acetamide.

Page(s): 1667-1672

First alkaline earth 2-carbamoyl-4-nitrobenzoate: Synthesis and supramolecular structure

Sat, 28 Nov 2009 22:58:59 GMT

Title: First alkaline earth 2-carbamoyl-4-nitrobenzoate: Synthesis and supramolecular structure

Authors: Srinivasan, Bikshandarkoil R; Shetgaonkar, Santosh Y; Raghavaiah, Pallepogu

Abstract: 2-Carbamoyl-4-nitrobenzoic acid (2-ca-4nbaH) has been prepared by alkaline hydrolysis of 4-nitrophthalimide. Aqueous reaction of MgCO₃ with 2-ca-4nbaH results in the formation of [Mg(H₂O)₆](2-ca-4nba)₂, which crystallizes in the centrosymmetric monoclinic space group P2₁/c with Mg(II) situated on an inversion center. The crystal structure consists of a distorted octahedral hexaaquamagnesium(II) cation and a free uncoordinated 2-ca-4nba anion. The cation and anion are involved in three varieties of H-bonding interactions, resulting in a supramolecular bilayer of 2-ca-4nba anions sandwiched between layers of [Mg(H₂O)₆]²⁺ cations.

Page(s): 1662-1666

Pairwise energy effects of rings in benzo-annelated perylenes

Sat, 28 Nov 2009 22:58:59 GMT

Title: Pairwise energy effects of rings in benzo-annelated perylenes

Authors: Radenković, Slavko; Linert, Wolfgang; Gutman, Ivan; Jeremić, Svetlana

Abstract: DFT calculations have been used to corroborate two regularities resulting from the analysis of cyclic conjugation in benzo-annelated perylenes reported earlier, viz., (a) the annelation of a benzene ring in angular position increases the extent of cyclic conjugation in the central ring, and, (b) the annelation of a benzene ring in linear position decreases the extent of cyclic conjugation in the central ring of benzo-annelated perylenes [Gutman et al., Mon Chem, 135 (2004) 1389]. In addition, a new method for assessing the pairwise energy effect is used to rationalize the obtained results. In the case of benzo-annelated perylenes, the pairwise energy effect is found to be related to the total -electron energy of the two-ring-deleted conjugated fragment.

Page(s): 1657-1661

Designing of type-I polymeric superlattices using genetic and ant algorithms: A comparative study

Sat, 28 Nov 2009 22:58:59 GMT

Title: Designing of type-I polymeric superlattices using genetic and ant algorithms: A comparative study

Authors: Kaur, Avneet; Wazir, Mohsineen; Garg, Aparna; Bakhshi, A K

Abstract: Genetic and ant algorithms, a class of metaheuristic algorithms, have been applied in combination with the negative factor counting method to the designing of copolymers to find the optimum concentrations of the constituent homopolymers which would give the most conducting copolymer (with minimum band-gap and maximum delocalization). Quasi-one dimensional model ternary polymeric superlattices belonging to type-I have been investigated using both genetic and ant algorithms and a comparative study of the results has been made. Further the dependence of the optimized results on factors like the random sequence generated (depending on the seed used) has been investigated. It has been found that the band gap, of the copolymers studied, lies close to that of the constituent lowest band gap homopolymer. The optimized solutions are nearly seed independent. Also, the results obtained from both the algorithms are found to be more or less the same.

Page(s): 1652-1656