Magnetic Field Effect on the Intramolecular Exciplex Fluorescence of Chain-Linked Pyrene/<i>N</i>,<i>N</i>-Dimethylaniline Systems

Abstract

Abstract The magnetic field effect (MFE) (≤ 13 T) on the intramolecular exciplex fluorescence of chain-linked pyrene/N,N-dimethylaniline systems is studied. In the case of pyrenyl-(CH2)2-O-(CH2)10-N(CH3)-phenyl, the exciplex fluorescence lifetimes are 34.2 (0 T), 50.6 (1 T), and 36.1 ns (13 T) in tetrahydrofuran/N,N-dimethylformamide (1 : 1) mixed solvent at room temperature. The lifetime decrease above 1 T is explained in terms of a Δg mechanism. Solvent dependence of the MFE maximum is discussed in terms of stabilization energy of the intramolecular radical ion pair, which is in fast dynamic equilibrium with the singlet exciplex. Influences of chain length and temperature are also discussed.