Magnetic field effect on the intramolecular exciplex fluorescence of chain-linked pyrene/N,N-dimethylaniline systems

The magnetic field effect (MFE) (less than or equal to 13 T) on the intramo lecular exciplex fluorescence of chain-linked pyrene/N,N-dimethylaniline sy stems 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 r oom temperature. The lifetime decrease above 1 T is explained in terms of a Delta g mechanism. Solvent dependence of the MFE maximum is discussed in t erms of stabilization energy of the intramolecular radical ion pair, which is in fast dynamic equilibrium with the singlet exciplex. Influences of cha in length and temperature are also discussed.