Filters
Results 1 - 10 of 7557
Results 1 - 10 of 7557.
Search took: 0.033 seconds
| Sort by: date | relevance |
[en] This paper is dedicated to the spectral and quantum-chemical studies of higher excited states of merocyanine derivatives of azaazulene and indandione. A particular attention is paid to the analysis of fluorescence excitation anisotropy spectra of the mentioned compounds. The long-wave shift by ≈ 50 nm of a deep clear minimum in the fluorescence excitation anisotropy spectrum due to an elongation of the polymethine dye chromophore is established. Such shift is close in a value to the bathochromic shift of the first minimum in the anisotropy spectrum of symmetric ionic polymethine dyes, in which this minimum corresponds to the second electronic transition. The parallel spectral study and quantum-chemical calculations allowed us to correctly interpret the fluorescence excitation anisotropy spectra of merocyanines and relate the first clear minimum with the seventh electronic transition. The last resembles the second electronic transition between delocalized molecular orbitals (MO) in polymethine dyes. (author)
Journal
Ukrayins'kij Fyizichnij Zhurnal (Kyiv); ISSN 0372-400X; 
; v. 65(no.4); p. 319-324
; v. 65(no.4); p. 319-324
[en] highly sensitive spectrophotometric method for the analysis of catecholamine drugs; L-dopa and methyldopa, is described. The analysis is based on the reaction of drug molecules with vanadium (V) which is reduced to vanadium (IV) and form complex with eriochrome cyanine R to give products having maximum absorbance (λmax) at 565 nm. Beer's law is obeyed in the range 0.028-0.84 and 0.099-0.996 μg mL-1 for L-dopa and methyldopa, respectively. The statistical analysis as well as comparison with reported methods demonstrated high precision and accuracy of the proposed method. The method was successfully applied in the analysis of pharmaceutical preparations. (author)
Journal
Quimica Nova On-Line; ISSN 1678-7064; ; v. 34(3); p. 373-376
; v. 34(3); p. 373-376
[en] We report here the synthesis of a distyrylbenzene derivative with end substituent as Weinreb amide. This Weinreb amide-based distyrylbenzene (WADSB) gives indications of highly efficient laser dye as well as a nonlinear optical medium. The photophysical parameters of the dye are given here. The lasing spectra of the dye have been measured in a cuvette configuration. The third-order nonlinear susceptibility has been measured by laser-induced transient grating technique (LITG). A comparison with the existing standard molecules shows that it is a comparably an efficient lasing material as well as an efficient nonlinear optical material at the pump wavelength of 355 nm.
Journal
[en] A review on the development of ternary complexes in spectrophotometric determination of thorium in the past ten years and the application of color-developing agent is presented
Journal
| 1 | 2 | 3 | Next |