Donor Geometry Engineering for Regulating Spatial Charge Distribution in Heptazine‐Based D‐A Porous Organic Polymers Toward Efficient Photocatalysis

ABSTRACT

Regulating the spatial charge distribution in donor‐acceptor (D‐A) porous organic polymers (POPs) to suppress charge recombination remains a formidable challenge in the field of photocatalysis. Herein, donor geometry engineering as a design method is proposed to address this issue. Three novel heptazine‐based donor‐acceptor porous organic polymers (D‐A POPs) with varied fusion patterns and connection sites of the polycyclic aromatic hydrocarbons (PAH) donors have been constructed. DFT calculations reveal that the linear 2,7‐bis(4‐aminophenyl)pyrene donor in Py‐2,7‐Cy confines holes exclusively to the pyrene core and electrons dominantly to the heptazine acceptor, minimizing the wavefunction overlap, whereas hole delocalization to peripheral phenyl rings in Phe‐2,7‐Cy and Py‐1,6‐Cy leads to more significant overlap. Such geometry‐dependent spatial separation of the photogenerated carriers in Py‐2,7‐Cy directly translates into a reduced exciton binding energy, suppressed charge recombination, and extended exciton lifetimes. Consequently, Py‐2,7‐Cy achieves 95% conversion of methyl phenyl sulfide dramatically outperforming Phe‐2,7‐Cy (12%) and Py‐1,6‐Cy (25%) under the same conditions, and exhibits excellent recyclability and broad substrate scope. This work establishes that donor geometry engineering is a powerful method to tune the charge dynamics in D‐A POPs.