Electronic absorption and fluorescence spectra and excited singlet-state dipole moments of biologically important pyrimidines

1992 ◽  
Vol 3 (4) ◽  
pp. 277-289 ◽  
Author(s):  
Cyril Párkányi ◽  
Christian Boniface ◽  
Jean-Jacques Aaron ◽  
Mame Diabou Gaye ◽  
Ratna Ghosh ◽  
...  
Keyword(s):  
Electronic Absorption ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Dipole Moments ◽  
Excited Singlet State ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet

Solvent Effects upon the Electronic Absorption and Fluorescence Spectra of Pteridines and Riboflavin and Their Ground and First Excited Singlet State Dipole Moments

Pteridines ◽  
1991 ◽  
Vol 3 (3) ◽  
pp. 153-163 ◽  
Author(s):  
J.-J. Aaron ◽  
M. D. Gaye ◽  
C. Párkányi ◽  
C. Boniface ◽  
T. W. N Bieze ◽  
...  
Keyword(s):  
Electronic Absorption ◽  
Singlet State ◽  
Dipole Moments ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Excited Singlet State ◽  
Theoretical Ground ◽  
Excited Singlet ◽  
Solvatochromic Shift ◽  
Wide Range

The electronic absorption. fluorescence excitation, and fluorescence emission spectra of a series of pteridines (lumazine, xanthopterin, isoxanthopterin, biopterin) and riboflavin (vitamin B2) were measured at room temperature (298 K) in a number of solvents covering a wide range of polarities (dioxane, ethyl ether, chloroform, ethyl acetate, 1-butanol. 2-propanol, ethanol, methanol, dimethylformamide, acetonitrile, and dimethyl sulfoxide). The effects of the solvent upon the spectral properties are discussed. Experimental groundstate dipole moments were measured for selected compounds and were used in combination with the spectral data to evaluate their first excited singlet-state dipole moments by means of the solvatochromic shift method (Bakhshiev's and Kawski-Chamma-Viallet's equations based on the variation of the Stokes shift with the solvent dielectric constant-refractive index term). The theoretical ground and excited singlet-state dipole moments for all pteridines and riboflavin were calculated as a vector sum of the π-component (obtained by the PPP method) and the a-component (obtained from a-bond moments). A second set of theoretical values was obtained by using the CNDO/2method. A good agreement was observed between the experimental and the theoretical values. Excited singlet-state dipole moments are higher than the ground state values by 1 to 6 Debye units for all the pteridines under study with the exception of xanthopterin.

Absorption and Fluorescence Spectra of some 1,3,4-Oxadiazole Derivatives in n-Paraffins at 77 K

1978 ◽  
Vol 33 (6) ◽  
pp. 731-735 ◽  
Author(s):  
P. Bałuk ◽  
A. Kawski
Keyword(s):  
Infrared Spectra ◽  
Ground State ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Vibrational Structure ◽  
Excited Singlet State ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet ◽  
Oxadiazole Derivatives

Abstract The quasilinear absorption and fluorescence spectra of 2- (1-naphthyl) -5-phenyl 1,3,4 oxadiazole, 2-(2-naphthyl)-5- phenyl 1,3,4 oxadiazole, 2-(1-naphthyl) -5-(4-biphenylyl) - 1,3,4 oxadiazole and 2-(2-naphthyl)-5-(4-biphenylyl)-1,3,4 oxadiazole have been studied in n-hexane, decane and nonane at 77 K. An analysis of the vibrational structure in the first electronic excited singlet state (S1) and in the ground state (S0) is given. Internal oscillations in the investigated molecules found from the quasilinear spectra are in agreement with those found in the infrared spectra.

Fluorescence of some simple umbelliferone derivatives

1979 ◽  
Vol 44 (2) ◽  
pp. 508-518 ◽  
Author(s):  
Vladimír Mikeš
Keyword(s):  
Excited State ◽  
Hydrogen Bonds ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Excited Singlet State ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet ◽  
Nonpolar Medium ◽  
Phenolic Group

The absorption and fluorescence spectra of umbelliferone were studied; it was found that in the excited state the basicity of the α-pyrone part of the molecule increases to such an extent that it exceeds that of the phenolate oxygen of the molecule. This is responsible for the neutral nondissociated form of umbelliferone being only in nonpolar medium which prevents the dissociation of the phenolic group in the excited state. In nonpolar medium, umbelliferone behaves as a substance with closely lying π → π* and n → π* transitions. Hydrogen bonds affect the fluorescence of 7-methoxycoumarin so that the π → π* transition is preserved as the lowest excited singlet state.

A solvatochromic study of new benzo[a]phenothiazines for the determination of dipole moments and specific solute—solvent interactions in the first excited singlet state

1996 ◽  
Vol 101 (2-3) ◽  
pp. 127-136 ◽  
Author(s):  
Jean-Jacques Aaron ◽  
Mounir Maafi ◽  
Christophe Kersebet ◽  
Cyril Párkányi ◽  
Maged Shafik Antonious ◽  
...  
Keyword(s):  
Singlet State ◽  
Dipole Moments ◽  
Excited Singlet State ◽  
Excited Singlet ◽  
Solvent Interactions
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