Engineering Donor–Acceptor Arrangement in Perylene Diimide‐Based Covalent Organic Frameworks for Enhanced Singlet Oxygen Photocatalysis

The photocatalytic efficiency of two‐dimensional covalent organic frameworks (2D COFs) is governed by the spatial arrangement of donor–acceptor (D–A) moieties, which strongly influences exciton transport. However, precise control over D–A alignment, especially across intra‐ and interlayer dimensions, remains a key challenge for optimizing singlet oxygen ( 1 O 2 ) generation. Here, we present a linker geometry‐directed approach to modulate D–A organization within perylene diimide (PDI)‐based COFs. Two imine‐linked 2D COFs, PDI‐TPE‐COF and PDI‐DBC‐COF, were synthesized by condensing a PDI acceptor with either a flexible tetraphenylethylene (TPE) or a rigid dibenzo[g,p]chrysene (DBC) donor. While PDI‐TPE‐COF adopts an eclipsed AA stacking, the rigid DBC linker induces an inclined AB stacking in PDI‐DBC‐COF, promoting both inter‐ and intralayer exciton migration. Both COFs exhibit quantitative 1 O 2 generation under visible light irradiation, but PDI‐DBC‐COF delivers a 42% higher quantum yield. This leads to markedly enhanced photocatalytic activity in quinoxaline and α ‐aminocarbonyl synthesis under low‐intensity LED light. Transient absorption (TA) studies and theoretical calculations confirm the key role of interlayer exciton transfer. PDI‐DBC‐COF also shows excellent recyclability and gram‐scale applicability under simulated sunlight. This work highlights the critical role of spatial D–A engineering in exciton control and offers design principles for high‐performance, metal‐free COF photocatalysts.