NOPR Collection:

Algebraic structure count of linear phenylenes

1993-04-01T00:00:00Z

Title: Algebraic structure count of linear phenylenes Authors: Gutman, Ivan Abstract: A general combinatorial expression is deduced for the algebraic structure count (ASC) of linear phenylenes. The conditions under which ASC is equal to zero are determined. Because ASC = 0 implies that the respective conjugated system has an open-shell π-electron configuration, the results obtained enable one to distinguish between stable and unstable phenylene derivatives. Page(s): 281-284

Photosensitization of thin film n-ZnO electrode by an oxouranium(VI) complex in non-aqueous (acetonitrile) photoelectrochemical cell

1993-04-01T00:00:00Z

Title: Photosensitization of thin film n-ZnO electrode by an oxouranium(VI) complex in non-aqueous (acetonitrile) photoelectrochemical cell Authors: Bahadur, Lal; Pandey, J P Abstract: Spectral sensitization of semiconducting n-ZnO thin film electrode by tetramethylammonium tris(diethyldithiocarbamato)dioxouranate (VI), Me₄N[UO₂(dtc)₃], has been studied in acetonitrile medium with hydroquinone as the redox reagent. Wavelength (of light) dependence of the photocurrent has provided evidence for the sensitization effect of this complex on photocurrent. Quantum efficiency of sensitized photocurrent is found to be ~ 6% at wavelength 440 nm of monochromatic light. In the presence of the sensitizer in solution, the transient response of n-ZnO electrode to light has also been recorded in terms of open-circuit photovoltage as well as current at a fixed applied potential. Although appreciable photocurrent is observed at high anodic potential, the current-voltage (J-V) curve does not show any tendency of saturation in photocurrent. Long-term stability of ZnO electrode in acetonitrile medium has been tested in presence of this complex and photocurrent has been found to be almost constant up to 7h of continuous illumination, particularly at lower intensity of light (66 mW/cm²) without showing any deterioration in photoelectrode. Page(s): 285-289

Fluorescence quenching of benzimidazoles by chlorinated methanes

1993-04-01T00:00:00Z

Title: Fluorescence quenching of benzimidazoles by chlorinated methanes Authors: Nigam, Shalini; Dogra, Sneh K Abstract: Fluorescence quenching of benzimidazole (BI), 2-methylbenzimidazole (MBI), 5, 6- dimethyl-benzimidazole (DMBI), 1-ethyl-2-methyl-benzimidazole (EMBI), 2, 5, 6-trimethylbenzimidazole (TMBI),2-phenylbenzimidazole (PBI) and 1-ethyl-2-phenylbenzimidazole (EPBI) by CH₂CI₂, CHCI₃ and CCI₄ have been studied in cyclohexane, methanol and acetonitrile and the values of k_q have been determined. Correlation of log k_q versus electron affinity(EA) of the quencher clearly indicates that deactivation of the excited state of BI's by above quenchers proceeds through the formation of charge transfer type complex. The high value of k_q in more polar acetonitrile as compared to that in non-polar cyclohexane. The static quenching can be described by the sphere of action model with a radius of 1nm for BI and TMBI. The quenching efficiency of CCl₄ is nearly unity, 0.36 to 10^-2 for CHCl₃ and 10^-3 to 10^-2 for CH₂Cl₂ respectively. Page(s): IJC-A Vol.32A(04) [April 1993]

Electron localization in substituted derivatives of poly(aniline)

1993-04-01T00:00:00Z

Title: Electron localization in substituted derivatives of poly(aniline) Authors: Gupta, Mool C; Warhadpande, Seema V; Umare, Suresh S Abstract: Aromatic ring substituted and N-substituted derivatives of poly(aniline) have been synthesized. Their electronic spectra, magnetic properties, ESR and electrical conductivity data have been presented and (discussed in terms of electron localization due to substituent in the ring of poly(aniline). Page(s): 298-302