Conductive Knitting of Covalent Organic Framework Manipulates Spin Density, Orbital Reorganization, and Charge Mobility for Outstanding Photoreactivity

Covalent organic frameworks (COFs) are promising photocatalysts but are hindered by inherent limitations such as low interlayer charge mobility, restricted active site accessibility, and inefficient charge separation. Herein, we constructed a thiophene-porphyrin-based COF photocatalytic system, comprising a COF with thiophene-modified pore walls and a quasi-three-dimensional (3D) COF formed via in situ oxidative polymerization-generated polythiophene chains covalently linked to the COF skeleton. The knitting of 2D COF layers with conjugated polythiophene units endows the 3D COF with enhanced light absorption capability and improved conductivity by four orders of magnitude. The synergistic structural and functional merits of this 3D COF achieve exceptional performance in quinazolinone photosynthesis (99% conversion, > 96% selectivity), doubling the selectivity of its 2D COF. Spectroscopic and computational studies reveal that thiophene polymerization induces pronounced HOMO-LUMO spatial separation and a substantial increase in spin density. These results demonstrate that interlayer covalent linkages of thiophene can manipulate active site density and charge mobility to improve photocatalytic efficiency. The polythiophene chains serve as conjugated bridges, narrowing the bandgap, and creating additional electron transport pathways. This discovery pioneers a paradigm for enhancing photocatalytic activity via interlayer conductive weaving strategy in COF architectures.