A. M. Swinnen

On the electronic structure of exciplexes with aliphatic amines II

In this contribution a theoretical model for the electronic structure of an exciplex with n‐type donors is developed. The model is applied to the intramolecular exciplexes in which a parasubstituted phenyl acts as acceptor. This allows one to determine values for the emission maximum and the fluorescence rate constant which approach the experimental observed values of these quantities within the experimental error.

Intramolecular formation and properties of exciplexes in α-Aryl-ω-N,N-dialkylaminoalkanes

Abstract Fluorescence properties of intramolecular exciplexes in α-aryl-ω-N,N-dialkylaminoalkanes, with aryl equal to phenyl. 1-naphthyl, 2-naphthyl and pyrenyl, are compared with calculated ones on the basis of a semi-empirical model. The importance of the difference in the coulombic term in this series is stressed. Optimum geometries for the exciplex structure are proposed.

Intramolecular exciplex formation in 1-(1-pyrenyl)-3-(N-skatolyl)propane☆

Abstract The photophysical properties of 1-(1-pyrenyl)-3-( N -skatolyl)propane were investigated. Excitation of the pyrene chromophore leads to the formation of an intramolecular exciplex. This complex has a larger dipole moment than that of the corresponding intermolecular complex. The kinetics of exciplex formation are analysed in solvents of various polarities. The binding energy of the complex increases with solvent polarity. The decay pattern of the pyrene fluorescence indicates fast equilibration between the various conformers in comparison with the rate of exciplex formation.

On the electronic structure of exciplexes in α-(1- OR 2-naphthyl)-ω-N,N-dialkylaminoalkanes

Abstract In this paper the theoretical model for the electronic structure of an exciplex with aromatic donors and acceptors, developed by Weller and modified for intramolecular exciplexes in which a parasubstituted phenyl acts as acceptor and an aliphatic amine as donor, is applied to compounds of type I: This model allows the exciplex geometry to be estimated and values for the emission maximum and the fluorescence rate constant which approach the experimental observed values of these quantities within the experimental error to be determined. The influence of the solvent polarity can also be mimicked. These data show a substantial difference between 1-dimethyl-amino)-2-(1-naphthyl)ethane (1N2NM) and 1-(dimethylamine)-2-(2-naphthyl)-ethane (2N2NM) as to the nature of the excited state exciplex in solvents of low polarity.

Quenching of the 1(1-pyrenyl), 3n(3-methylindole)propane exciplex by m-dicyanobenzene. Formation of an emitting terplex consisting of three different components

Abstract The intramolecular exciplex 1(1-pyrenyl), 3N(3-methylindole)propane is quenched by m -dicyanobenzene. The pyrene and the exciplex fluorescence is quenched and their respective rate constants equal 1.5 × 10 10 l mol −1 s −1 and 1.1 × 10 10 l mol −1 s −1 . The quenching of the exciplex results in the emission of a new species, which does not arise from exciplex substitution, but can be ascribed to a triple exciplex (mDCB −1 Py-C 3 H 6 -In + ).

Influence of the substitution pattern and chain length on the electronic structure of α-pyrenyl-ω-alkylamine exciplexes

Abstract Fluorescence properties of intramolecular exciplexes in α-(1-, 2- or 4-)pyrenyl-ω-N,N-dimethylaminoalkanes are calculated on the basis of a semi-empirical model. This model allows one to estimate the exciplex geometry and to determine values for the emission maximum and the fluorescence rate constant which approach the available experimentally observed values within the experimental error. The importance of the different contributing states toward the exciplex structure is seen to be dependent on which carbon the aromatic acceptor substitutes and on the length of the linking chain.