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

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