Dielectric Dependence of Magnetic Field Effect: A Tool for Identification of Exciplex and Triplex

The molecule, 4,4‘-bis(dimethylamino)diphenylmethane (DMDPM), having two potential donor sites is able to form both luminescent exciplex (1:1) and triplex (1:2) with photoexcited pyrene (PY), which is inferred from the maximization of magnetic field effects at two different dielectric constants of the solvent media. The DMDPM molecule can be considered as two N, N -dimethylaniline (DMA) molecules linked through a methylene chain. Therefore, electron hopping is likely to occur from one DMA unit to the other through the intermediate >CH 2 group, which is reflected in the B 1/2 measurements and is in agreement with Schulten's theory of intramolecular electron exchange. The nature of charge transfer and electron hopping is substantiated with theoretical calculations highlighting relative orientations of PY and DMDPM.