Synthesis of 2-julolidin-imidazo[1,2-a]pyridines via Groebke–Blackburn–Bienaymé reaction and studies of optical properties

A series of sixteen new 2-julolidin-imidazo[1,2-a]pyridine bound-type bis-heterocycles were synthesized in good to excellent yields (61–98%) via an MW-assisted Groebke–Blackburn–Bienayme (GBB) reaction. Then, experimental studies were conducted to determine the luminescence properties of these compounds. Various high quantum yields were found. In fact, one product exhibited a quantum yield (86.6%) comparable to that of the reference compound rhodamine (94.8%). Finally, further computational studies were performed by means of TD-DFT to calculate their HOMO–LUMO distributions and theoretical absorption spectra. A good agreement between the experimental and computational results was obtained, which provides a rationalized explanation for the observed structure/property relationships.