Metal-free redox-active diphenylpyrenediimides: A comparison between the photocatalytic performance of molecular and polymeric catalysts

Herein we described a donor–acceptor porous conjugated polydiphenylpyreneimide (DPPy-PI) with high thermal stability (530 °C) and surface area of 710 m.g prepared by condensation of 3,8-diphenylpyrene-1,2,6,7-tetracarboxylic dianhydride (DPPyDA) and tris(4-aminophenyl)benzene and a series of pyrenediimides (DPPy-DIs) as molecular references for comparative purposes. To evaluate the effect of the photoactive pyrene unit the polydiphenylperyleneimide (DPP-PI) having perylene units was also prepared. DPPy-PI has shown to see an efficient metal-free heterogeneous photocatalyst in the selective oxidation of aromatic sulfides and for Diels-Alder cycloadditions reaching almost full conversions with low reaction times and high selectivity that can be reused for at least fifteen cycles without significant loss of catalytic activity. Characterization data reveals that imide radicals are the important active intermediates during the redox processes of these PIs.