Isomers of Pyrene–Imidazole Compounds: Synthesis and Configuration Effect on Optical Properties

Two pyrene-imidazole-based structural isomers, axisymmetric syn-PyDTI and centrosymmetric anti-PyDTI, have been easily produced and successfully separated in a one-pot reaction. Crystalline syn-PyDTI exhibited a 2-fold higher quantum efficiency than anti-PyDTI and displayed a much better performance in OLEDs with a η_c.max of 11.4 cd A^–1 (8.8 cd A^–1 for anti-PyDTI), although they possess the same apparent electronic structure. Observations revealed that the molecular excited-state properties are derived from distinct structural symmetries.