Molecular engineering of cyclic α-diketone aromatic ring bichromophoric molecules for studies of intramolecular electronic energy transfer

The design, structures and spectral properties of a number of bichromophoric molecules are presented. These bichromophoric molecules are composed of an aromatic ring connected by two methylene chains to an α-diketone moiety. Both absorption and emission spectra can be attributed to a superposition of the individual spectra of the separate chromophores. The critical transfer radius for electronic energy transfer from the aromatic (donor) chromophore to the α-diketone (acceptor) chromophore was calculated from the spectral overlap between the fluorescence spectrum of the aromatic moiety and the absorption spectrum of the α-diketone moiety. The results show that this series of molecules is well suited for a mechanistic study of short-range intramolecular electronic energy transfer.