Synthesis and Properties of Some Derivatives of 1,2,3, 4-Tetrafluoroacridine for Solid State Emitting Systems

The resonant energy transfer (RET) between fluorescent organic molecules is a very important phenomenon widely investigated for its potential in developing devices such as light-emitting diodes and lasers. Energy transfer processes take place between two different molecules and they are usually observed when the emission spectrum of the first molecule (called donor) overlaps with the absorption spectrum of the other one (called acceptor). The individuation of this kind of molecule inside a common structural motif represents an interesting approach aimed at simplifying the modeling of their synthetic procedure; indeed the desired couple can be obtained simply acting on the electronic properties of substituents present on the molecule and helps the understanding of the energy transfer processes. The tetrafluoroacridines, readily accessible from aniline and pentafluorobenzaldehyde, have been selected as a structural motif because their absorption and emission properties can be easily tuned by acting on the nature of substituents present on the starting aniline. The synthesis of new terms of these molecules along with a preliminary study on their optical, electrochemical, and structural properties, in solution and in the solid state, is described. We present here a study on the optical properties of a molecular crystal of donor doped with molecules of acceptor, both chosen among the prepared tetrafluoroacridines; the temperature dependence of luminescence spectrum allowed us to take a glance upon the energy transfer and excitation migration phenomena occurring in this system.