Charge-mediated Cuδ+ sites in dimension-controlled covalent organic frameworks enable base-free continuous photothermal CO2 cyclization
Xingwang Lan, Yize Zhang, Lu Chen, Riyuan Zhang, Haobo Xu, Guoyi Bai, Zhiming Zhang
Abstract
ABSTRACT The structural topology of covalent organic frameworks (COFs) critically governs their catalytic performance. However, the structure–property correlation regarding dimension-dependent charge polarization at catalytic sites remains poorly understood. Herein, we describe a dimensional engineering strategy to tailor the local microenvironment of Cu sites through constructing phenanthroline-based COFs with distinct architectures (2D vs 1D). Systematic characterization and theoretical analyses reveal that the molecular flexibility and mesoporous channels in 2D COFs promote non-radiative transitions and mass transport, while their layered architecture enables light-controlled thermal modulation of Cuδ+ (1 ≤ δ ≤ 2) electronic states, synergistically enhancing substrate adsorption and activation. Remarkably, a Cu-2D-COF achieves near-quantitative yield (99.9%) in visible-light-driven carboxylative cyclization of propargylic amines with CO2 under base-free conditions. We further engineered a continuous-flow photocatalytic system that demonstrates exceptional operational stability, delivering 2.143 g of pharmaceutical-grade 2-oxazolidinones with >95% purity. This work provides strategies for manipulating the local microenvironment through dimension-controlled frameworks in CO2 conversion.