Fluorescent Pyrene-Based Bis-azole Compounds: Synthesis and Photophysical Analysis

A rational synthetic procedure for the preparation of a series of pyrene-based neutral and dicationic bis-azole compounds is reported. The method allows the tailored design of pyrene-based azoles with different substituents at the nitrogen atoms of the heterocycles, for which the relative conformation of the resulting bis-azoles can be easily controlled. The bis-azoliums were used for the preparation of the related diplatinum complexes by reaction with [{Pt(ppy)(μ-Cl)2 }2 ] (ppy=2-phenylpyridinate). The X-ray molecular structure of one of the resulting compounds, a diplatinum(II) bis(N-heterocyclic carbene) complex, is described. Studies on the photophysical properties of all new species are described. The emission of the bis-azole-based compounds seems to be independent of their substitution patterns, which basically indicates that physical properties such as solubility, melting point, and viscosity can be fine-tuned while maintaining the luminescence properties. Finally, the energies associated with the HOMO and LUMO levels suggest that this family provides versatility to match the energy levels of a wide range of host materials, which is important for the preparation of organic light-emitting devices.