A bisindolylmaleimide-naphthalimide building block for the construction of the energy transfer cassette.

Double build-in chromophores with naphthalimide and bisindolylmaleimide incorporating to one molecule were synthesized efficiently and characterized fully. Its spectral properties were investigated. Effective intramolecular energy transfer together with the strong emission in solution and solid state were discussed in terms of its electronic structures. Optimized structure and frontier molecular orbital were calculated based on D3(mol) platform. Obviously electron delocalization before and after excitation was observed according to the molecular orbital calculation, which corresponds to the mechanism of excitation energy transfer through space occurred in the donor-linker-acceptor molecular system. The opto-physical properties of the dye indicated potential application of electro-optical materials.