Structure and dynamics of the excited states of 1,3-diarylisobenzofurans: an experimental and theoretical study

The emission properties of a series of substituted 1,3-diarylisobenzofurans have been studied. Most compounds exhibit very intense emission in the nanosecond timescale at room temperature as well as at 77 K. The room temperature emission is attributed to the deactivation of a twisted intramolecular charge transfer excited state, based on its energy, shape and solvent dependence. The experimental results are strongly supported by a theoretical study on one representative compound. The DFT/TD-DFT calculations demonstrate that the initial excited state relaxes toward a twisted structure.