NOPR Collection:

Estimation of inductive effect PMO-parameter of t-butyl group from charge transfer bands of some π-molecular complexes of furan and thiophene derivatives

1989-12-01T00:00:00Z

Title: Estimation of inductive effect PMO-parameter of t-butyl group from charge transfer bands of some π-molecular complexes of furan and thiophene derivatives Authors: Datta, K K; Mukherjee, A K Abstract: The systematic red shift of the charge transfer (CT) absorption maxima of π-molecular complexes of tetracyanoethylene with furan and thiophene by t-butyl substitution at 2- and 3-positions of the donors has been utilised to get the inductive effect PMO parameter of t-butyl group. The HOMOs of furan and thiophene have been calculated by HMO method and those of the 2- and 3-t-butyl substituted derivatives have been obtained as a function of the PMO parameter (h_t) of the t-butyl group by applying Coulson-Longuet-Higgins perturbation method. The value of h_t is found to be -0.516, a value which is somewhat higher, as expected, than the PMO parameter for methyl group reported earlier for π -molecular complexes of methylated electron donors. Thiophene MOs have been calculated by two models and one of them, proposed by Longuet-Higgins, has been shown to be more reliable. Page(s): 1025-1028

Electronic structure of poly (thiophene-thieno[3,4-c]thiophene) copolymers: Design of quasi-one-dimensional superlattices

1989-12-01T00:00:00Z

Title: Electronic structure of poly (thiophene-thieno[3,4-c]thiophene) copolymers: Design of quasi-one-dimensional superlattices Authors: Bakhshi, A K Abstract: The electronic spectrum of quasi-one-dimensional superlattices of thiophene and thieno[3,4- c]thiophene has been calculated numerically using the simple negative factor counting method. The results show that, in contrast to the periodic chains, the a periodic chains have smaller band gaps and broader regions of allowed energy states. The trends in the electronic properties of the block copolymer chains (A_mB_n)_x as a function of the size of the blocks and of their arrangement in the chain are also discussed. Page(s): 1029-1033

Role of surfactant-surfactant interactions in mixed micelle solutions

1989-12-01T00:00:00Z

Title: Role of surfactant-surfactant interactions in mixed micelle solutions Authors: Singh, Prem P; Anand, K; Yadav, O P Abstract: Mixed critical micelle concentration (cmc) data have been determined at 303.15 K and 313.15 K by surface tension method for aqueous solutions of sodium dodecylsulphate (SDS) (A) + Triton X-100 (B), and dodecyltrimethylammoum bromide (DTAB) (A) + Triton X-100 (B).The data have been analysed in terms of Rubingh's approach. The analysis has revealed that surfactant-surfactant interaction energies in .the mixed micelles of SDS (A) + Triton X-100 (B) and DTAB (A) + Triton X-100 (B) depend on the bulk mole fraction (X_A) of A. The interaction energy data have been rationalized in terms of molecular interactions between the surfactants A and B and the same have been further supported by viscosity data of these binary surfactant systems. Page(s): 1034-1037

Metachromatic interactions of toluidine blue with heteropolyanions

1989-12-01T00:00:00Z

Title: Metachromatic interactions of toluidine blue with heteropolyanions Authors: Ram, Shyam Narain; Yadav, K D S; Sharma, B; Singh, Chanan Abstract: Tungsto 12-zincic acid, potassium 13-vanadomanganate, potassium 13-vanado nickelate, potassium 11-tungsto phospho-nickelate, potassium 11-tungsto cobaltosilicate, ammonium 11-tungstodicobaltoate and sodium 12-tungsto borate have been shown to induce metachromatic effects in toluidine blue; the effects being hypochromacity coupled with hypsochromic shifts.The titration profiles of dye-heteropolyan- ion meta-chromatic complexes versus MgCl₂, KCl and HCI show three distinct portions indicating two other distinct types of interactions in addition to the electrostatic interaction between positively charged toluidine blue dye and negatively charged heteropolyanion surfaces. Page(s): 1038-1041