Solvent and pressure dependence of the absorption and fluorescence spectra of anthronitrile

Abstract

Solvent and pressure dependences of the absorption (430–300 nm) and fluorescence spectra of anthronitrile are reported and compared with earlier studies of anthracene. The origins of the solvent dependences are analyzed in terms of dielectric theories developed by McRae and by Baur and Nicol. Satisfactory fits of the experimental data are obtained, which suggest that the dipole moment of the 1La excited singlet state of anthronitrile is 2.5±1.0 times as large as the dipole moment of the ground state. Two absorption bands at 27.4±103 and 28.8× 103 cm−1 (in hexane solutions) are assigned as the 1Lb transition, and the solvent dependences of these bands are interpreted as suggesting that the dipole moment of the molecule is not changed by this transition. Although pressure dependences of the spectra of polymethylmethacrylate and polyacrylonitrile solutions of anthronitrile can be qualitatively interpreted in terms of the solvent dependences, quantitative discrepancies between the anthronitrile and anthracene results indicate that solvent shift theories based upon the dielectric continuum approximation are inadequate to explain the pressure dependences quantitatively.

Spectroscopic Characteristics and Intermolecular Interactions of Thiophene/Phenylene Co-Oligomers in Solutions

“…N 2 laser pulses of a 337 nm wavelength were used as an excitation light source. Quantum efficiencies of fluorescence (Φ F ) were measured by the comparative method against standard samples of quaterthiophene (Φ F = 0.18) 13 and anthracene (Φ F = 0.22) , dissolved in ethanol. Spectroscopic grade chloroform, dichloromethane, acetonitrile, and ethanol provided by Tokyo Kasei Co., were used as solvents without further purification.…”

Medium Effects on Charge Transfer in Metal Complexes

“…“Pure” π → π* bands usually have small solvent dependences because the transitions involve a redistribution of electron density within the same π-framework. ,,, In the polypyridyl complexes they gain a solvent dependence by mixing with lower or higher energy MLCT transitions. The orbital basis for mixing in these nominally π → π* transitions is by dπ(Ru III , Ru II ) mixing with π,π*(bpy) with dπ−π mixing dominating, at least in this case …”