Novel disubstituted phenylene-linked bis-imidazole derivatives: Facile synthesis and optical properties

Six novel disubstituted phenylene-linked bis-imidazole derivatives, 3a-3f, were prepared by a one-pot, microwave-assisted method under solvent-free conditions, in yields ranging from 61.6 to 85.6%. The new compounds were characterized by ¹H- and ¹³C-NMR, UV/VIS, and fluorescence spectroscopy, and mass spectrometry, as well as by elemental analyses. The influence of substituents and solvents on the optical properties of 3a-3f was investigated. It was found that there is little influence on absorption and excitation spectra in contrast to emission spectra. Compounds 3a-3f exhibit strong fluorescence in solution, their fluorescence quantum yields ranging from 0.27 to 0.96.