Synthesis and photophysics of extended π-conjugated systems of substituted 10-aryl-pyrenoimidazoles.

摘要: The synthesis of π-extended 10-aryl-pyrenoimidazoles having different substituents was realised via Ru(II)-catalyzed oxidative annulation 10-aryl-pyrenoimidazole with diphenylacetylene. single crystal X-ray structure trifluoromethyl and carboxylate substituted annulated-10-aryl-pyrenoimidazoles confirms the near coplanarity pyrene imidazole moieties presence twisted conformation resulting in intermolecular C–H⋯π interactions. lowest energy absorption maximum becomes red-shifted characteristic to nature substituent owing extended π-conjugation, specifically nitro shows intense visible region at 440 nm. All molecules were found show fluorescence both solution solid states. Strikingly, 170 nm a large Stokes shift ca. 7000 cm−1 for derivative, value nearly two-fold higher than parent compound despite its rigid polyaromatic skeleton observed. combination electron rich π-conjugated aromatic systems deficient induces intramolecular charge transfer interactions, which has been corroborated theoretical calculations.