Multiple–color AIE coumarin–based Schiff bases and potential application in yellow OLEDs

Three new coumarin–based derivatives with similar molecular structure were synthesized through a simple Schiff base reaction and their fluorescent properties were investigated in detail. Among of the compounds showed aggregation–induced emission (AIE) characteristics and high quantum efficiency (ΦF), of which compound 1 powder showed the strongest emission peak 570 nm (ΦF = 25.3%), compound 2 solid exhibited 610 nm fluorescence emission peak (ΦF = 3.3%), while the maximum emission wavelength of compound 3 powder red–shift to 640 nm (ΦF = 16.8%). Meanwhile, compounds 1–3 showed long fluorescence lifetimes with respective 8.86 μs, 8.97 μs and 8.51 μs. The appearance of fluorescence properties can be attributed to efficient the excited state intramolecular proton transfer (ESIPT) and the twisted intramolecular charge transfer (TICT). Furthermore, due to the good luminescent properties, high stabilities and the large Stokes–shifts, the three compounds were ideal candidates for promising applications in organic lightemitting diodes (OLEDs).