Charge transfer fluorescence of some N-benzoylindoles

1987 ◽  
Vol 65 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Bimsara W. Disanayaka ◽  
Alan C. Weedon
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Poor Correlation ◽  
Indole Derivatives ◽  
Solvent Interaction ◽  
Polarity Parameter ◽  
Transfer State

The fluorescence properties of various N-carbonyl-substituted indoles (compounds 1–7) are examined. The N-benzoyl-indole derivatives 1 and 3–5 are shown to fluoresce weakly and the effect of solvent polarity upon the energy of the emitting state and upon the quantum yield of fluorescence is described. It is concluded that the initially formed singlet excited state is non-emissive and can relax to an intramolecular charge transfer state which is weakly fluorescent. The solvent effects are consistent with a general type of solvent interaction, and the solvent-induced shifts in the wavelength of the fluorescence emission correlate well with the Lippert equation relating the stabilisation of the excited state to a function of solvent dielectric and refractive index. A poor correlation with the empirical ET(30) solvent polarity parameter is observed.

scholarly journals Donor-acceptor substituted phenylethynyltriphenylenes – excited state intramolecular charge transfer, solvatochromic absorption and fluorescence emission

2010 ◽  
Vol 6 ◽  
pp. 992-1001 ◽  
Author(s):  
Ritesh Nandy ◽  
Sethuraman Sankararaman
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Linear Correlation ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Donor And Acceptor ◽  
Electron Donor And Acceptor ◽  
Stokes Shifts

Several 2-(phenylethynyl)triphenylene derivatives bearing electron donor and acceptor substituents on the phenyl rings have been synthesized. The absorption and fluorescence emission properties of these molecules have been studied in solvents of different polarity. For a given derivative, solvent polarity had minimal effect on the absorption maxima. However, for a given solvent the absorption maxima red shifted with increasing conjugation of the substituent. The fluorescence emission of these derivatives was very sensitive to solvent polarity. In the presence of strongly electron withdrawing (–CN) and strongly electron donating (–NMe2) substituents large Stokes shifts (up to 130 nm, 7828 cm−1) were observed in DMSO. In the presence of carbonyl substituents (–COMe and –COPh), the largest Stokes shift (140 nm, 8163 cm−1) was observed in ethanol. Linear correlation was observed for the Stokes shifts in a Lippert–Mataga plot. Linear correlation of Stokes shift was also observed with E T(30) scale for protic and aprotic solvents but with different slopes. These results indicate that the fluorescence emission arises from excited state intramolecular charge transfer in these molecules where the triphenylene chromophore acts either as a donor or as an acceptor depending upon the nature of the substituent on the phenyl ring. HOMO–LUMO energy gaps have been estimated from the electrochemical and spectral data for these derivatives. The HOMO and LUMO surfaces were obtained from DFT calculations.

Spectroscopic Studies of Dimethylamino Derivatives of Fluorene

2000 ◽  
Vol 55 (11-12) ◽  
pp. 902-908 ◽  
Author(s):  
J. Heldt ◽  
J. R. Heldt ◽  
T. Redzimski ◽  
H. Diehl ◽  
P. Schultz
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Fluorescence Spectra ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Spectroscopic Studies ◽  
Polar Solvents ◽  
Derivatives Of ◽  
Transfer State

Abstract 2-dimethylamino-9-fluorenol and 2-dimethylamino-9(4'dimethylamino)phenyl-9-fiuorenol in polar solvents in the excited state undergo conformation changes in which two fluorescent isomers are created. The isomers (in the local excited (LE) and charge transfer (CT) configuration) possess separate fluorescence bands, one appearing from the S1 (LE) state and the second from the intramolecular charge transfer state S1 (CT) of the neutral, aromatic molecule. Both bands show a solvatochromic effect. Using the method of the solvent induced Stokes shift of the absorption and fluorescence spectra the permanent dipole moment of the excited state of fluorene and its two derivatives have been determined. The dipole moment of the ground state and the Onsager cavity radius of the studied molecules were calculated with the Auestion Model 1 (AM1) program.

Direct observation of an intramolecular charge transfer state in epigenetic nucleobase N6-methyladenine

2019 ◽  
Vol 21 (13) ◽  
pp. 6878-6885 ◽  
Author(s):  
Zhongneng Zhou ◽  
Xueli Wang ◽  
Jinquan Chen ◽  
Jianhua Xu
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Direct Observation ◽  
Intramolecular Charge Transfer ◽  
Charge Transfer State ◽  
Transfer State

Solute–solvent H-bonding accelerates excited state relaxation of an intramolecular charge transfer state in N6-methyladenine.

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