NOPR Collection:

A novel use of Hückel parameters (h, k) for the pairing of eigenvalues in graph spectrum

2017-04-27T06:51:16Z

Title: A novel use of Hückel parameters (h, k) for the pairing of eigenvalues in graph spectrum Authors: Patra, Swarna M; Mishra, Rama K; Mishra, Bijaya K Abstract: An unusual use of the Hückel parameters (h and k) has been noticed for the derivation of the characteristic polynomial (CP) of the vertex-edge weighted graphs. A new pairing scheme for the eigenvalues (x_j) of the weighed graphs has been proposed in the light of Coulson-Rushbrooke pairing theorem for the non-bipartite graphs,
x_j + x_{n+ 1-j} = 1/2 h_p ± a for j = 1, 2, 3 ..., n where n, p and ‘a’ are the number of vertices, number of heteroatoms and a numerical quantity respectively. Page(s): 813-817

Dual fluorescence of 2-phenoxyaniline

2017-04-27T06:43:15Z

Title: Dual fluorescence of 2-phenoxyaniline Authors: Rajendiran, Narayanasamy; Swaminathan, Meenakshisundaram Abstract: 2-Phenoxyaniline (2POA) shows a dual fluorescence in hydrogen bonding solvents. The increase in Stokes shift with increase in polarity is much more for longer wavelength abnormal fluorescence band (FA) than for shorter wavelength fluorescence band (FN). It is found that FA band arises only due to bulk properties of solvent and not due to complex formation. A mechanism involving twisted intramolecular charge transfer (TICT) state is proposed for the dual fluorescence of 2POA. pHstudies indicate that the stretched sigmoid curve obtained for the neutral-monocation equilibrium is due to overlap of proton induced fluorescence quenching and monocation formation curves. Page(s): 818-824

Solvation behaviour of HCIO₄, NaCIO₄ and KCIO₄ species under varying conditions

2017-04-27T06:41:07Z

Title: Solvation behaviour of HCIO₄, NaCIO₄ and KCIO₄ species under varying conditions Authors: Bhat, J Ishwara; Mohan, T P; Susha, C B Abstract: This paper presents the measurement and analysis of the solvation behaviour of perchloric acid, sodium and potassium perchlorates in water, dimethylformamide and varying compositions of water-dimethylformamide (v/v) as a function of temperature. Data have been analysed by four conductivity models. Limiting molar conductance and dissociation as well as association constants have been calculated from the respective methods and these values have been used to interpret the preferential/ selective solvation of cations by DMF. Energy of activation of the rate process and thermodynamic parameters have also been evaluated. Walden product, and Stoke's molecular radius under prevailing conditions have been computed and the effect of variation in temperature and dielectric constant on the conductance identified. These data have been used for the qualitative study of ion-solvent and solvent-solvent interaction involved in the system. Page(s): 825-831

Surface tension and surface excess heats of mixing of n-butyric acid with various solvents

2017-04-27T06:38:33Z

Title: Surface tension and surface excess heats of mixing of n-butyric acid with various solvents Authors: Kaur, Satindar; Lark, Bhajan S; Aggarwal, Suresh K; Singh, Surjit Abstract: Surface tension (σ) of binary mixtures of n-butyric acid (BA) + cyclohexane, + n-octane, + benzene, + toluene, + carbon tetrachloride, + chloroform, + methanol, + acetone, has been measured at 298.15 and 308.15 K over the entire composition range using a differential capillary rise method. The surface tension data have been used to evaluate the excess surface tension (σ^E). It is found that σ^E values, in accordance with the prediction of Gibbs adsorption equation, for the first five of the eight systems negative at both the temperatures while for the remaining three systems are positive. This may be ascribed to the heteromolecular hydrogen bonding. Page(s): 832-835

NOPR Collection:

A novel use of Hückel parameters (h, k) for the pairing of eigenvalues in graph spectrum

Dual fluorescence of 2-phenoxyaniline

Solvation behaviour of HCIO4, NaCIO4 and KCIO4 species under varying conditions

Surface tension and surface excess heats of mixing of n-butyric acid with various solvents

Solvation behaviour of HCIO₄, NaCIO₄ and KCIO₄ species under varying conditions