Coupling Catalyst Planarization and Built‐in Electric Fields Enhancement by Ringexpansion of Conjugated Microporous Polymers for Boosting Charge Migration in C(sp 3 )‐H Phosphorylation

Comprehensive Summary Minimizing energy dissipation during charge transfer is essential for constructing efficient photocatalysts. However, the inherent steric constraints within building blocks inevitably induce torsional distortions in the photocatalyst framework, thereby impeding efficient charge migration. To address this, catalyst ring expansion was proposed to enhance catalytic performance. Conjugated microporous polymers (CMPs) were synthesized using [2,2']‐bithiophene‐5,5'‐dicarbaldehyde (donor) and formyl positional isomers (1,3‐ or 1,4‐diacetylbenzene linkers). Structural characterization revealed that compared to m ‐SSCMP (1,3‐linker), p ‐SSCMP constructed with the 1,4‐linker exhibits an expanded cyclic architecture, increased intramolecular D‐A configurations and a reduced phenyl‐pyridine dihedral angle. These structural modifications significantly accelerated charge migration efficiency. As a result, the optimized catalysts facilitated efficient C(sp 3 )‐H phosphorylation reactions, offering a sustainable strategy for introducing phosphoryl groups into optoelectronic materials and bioactive molecules. Importantly, correlation between monomer structure and catalyst charge migration efficiency was established, providing molecular‐level insights for the design of polymeric photocatalysts.