Temperature-Dependent Behavior of the Dual Fluorescence of 2-(3-Fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione

Abstract

Dedicated to Prof. Andre M. Braun on the occasion of his 60th birthdayThe fluorescence behavior of 2-(3-fluorophenyl)-2,3-dihydro-1H-benzo[f]isoindole-1,3-dione (1) was studied in solvents of different polarity and viscosity. Dual luminescence is observed and the short-wavelength emission is found to increase considerably with the solvent polarity. The ratio of the fluorescence quantum yield of the two states emitting, the one (SW*) at short wavelength and the other (LW*) at long wavelength, shows a bell-shaped dependence on the reciprocal of the temperature in diethyl ether, butyronitrile, and propane-1,2,3-triol triacetate (glycerol triacetate; GTA). This has been interpreted as the result of a reversible interconversion between the two states. The enthalpy difference between the SW* and LW* excited states, as deduced from the slope of the ln (F LW f /F SW f ) vs. 1/T curves in the high temperature range, is found to be solvent polarity and solvent viscosity independent as the same value (À 7.3 kJ/mol) is obtained in the three above-mentioned solvents. The independence from polarity is the consequence of a similar difference in dipole moment between the ground-state and the SW* and LW* excited states (4.5 and 4.9 D, respectively, derived from solvatochromy). The activation energy of the SW* 3 LW* step deduced from the low temperature measurements in the nonviscous solvents, increases with solvent polarity (11.6 and 17.5 kJ/mol for diethyl ether and butyronitrile, respectively); they are greater than the viscous-flow activation energy of the solvents indicating that the resolvation of the excited dipole controls the kinetics. In the nonviscous solvents, the LW* state originates from the SW* state, while in the viscous GTA solution, both states are formed simultaneously within the 1-ps laser pulse.

Pressure dependence of the dual luminescence of twisting molecules. The case of substituted 2,3-naphthalimides

“…Furthermore, the decrease of the temperature increases significantly the polarity of the medium. 11 We have found recently 12 that the ratio of the SW* and LW* state fluorescence quantum yields of N-(3-fluoro-phenyl)-2,3-NI 2 varies with the temperature as a result of an energy barrier between the two excited states. Therefore, the experiments have been carried out at constant temperature, in order to limit our study to the sole influence of the viscosity of the medium.…”

The influence of hydrogen bond formation on the dual luminescence of n-phenyl-2,3-naphthalimide derivatives

“…As a model of dual luminescent compounds, N-(3-fluorophenyl)-2,3-naphtalimide (MFPN) (where the LE → ICT reaction is reversible [6,7]) and N-(4-methoxyphenyl)-2,3naphtalimide [4] (PMPN) (where the ICT state has clear intramolecular charge transfer character [4]) were selected.…”

Synthesis and Emission Behavior of 1,3-diarylisobenzofuran-5,6-dicarboximides and Their Transformation into Naphthalene-2,3:6,7-bis(dicarboximide)s

“…Arene-dicarboximides show interesting photochemical and photophysical properties, such as photoreduction [1,2] photocycloaddition [3,4], and photo-excited emission [5][6][7][8]. Heagy et al reported that dual fluorescent naphthalene-2,3dicaboximides could be used in white organic light-emitting devices (OLEDs) [9].…”

“…We have applied our improved method to synthesize the title heterocyclic com pounds. In this paper, we describe the synthesis of the 1,3-diarylisobenzofuran-5,6-dicarboximides (6)(7)(8) and their A solution of 2,5-diaryl-3,4-bis(methoxycarbonyl)furan (19.0 mmol) in 70 mL of THF was added slowly to a suspension of 1.14 g of LiAlH 4 (30.0 mmol) in 50 mL of THF at 0ºC. After being stirred at room temperature for 30 h, the reaction mixture was carefully quenched by ethanol/water.…”