Study on the synthesis and structure-effect relationship of multi-aryl imidazoles with their fluorescence properties

In this paper, 23 multi-aryl imidazole derivatives were synthesized and identified by nuclear magnetic resonance, ultraviolet-visible and elemental analysis. At the same time, their ultraviolet-visible maximum absorption (λ(ab)(max)), fluorescence emission maximum (λ(em)(max)) and quantum yields (Ф(f)) were measured. The relationships between the optical behaviors and structures for these compounds were assessed. The results show that the λ(max)(ab) and λ(max)(em) are red-shifted and the fluorescence Ф(f) are increased by the introduction of electron-withdrawing substituents and the increase in the planarity of multi-aryl imidazole molecules. The results also showed that the fluorescence quantum yields of the compounds containing two imidazole nuclei are double the corresponding mono-imidazole nucleus compounds.