Dynamic covalent bonding for directed construction of molecular cages toward carbon dioxide reduction

Abstract

Zirconium-based metal–organic cages (Zr-MOCs) have garnered attention for their notable stability and enduring porosity. However, the rational design and precise synthesis of these structures remain challenging. In this context, we introduce a method that utilizes a dynamic covalent bond construction strategy for the meticulous stepwise synthesis of metal–organic cages. By applying this approach, a novel lantern-like metal–organic cage is synthesized (Schiff-base ZrOC-1). The Schiff-base ZrOC-1 was then investigated for photocatalytic carbon dioxide (CO₂) reduction. Notably, unlike the negligible catalytic activity of the precursor (Zr-CHO) and Zr-MOC without dynamic covalent bonds (ZrT-1), Schiff-base ZrOC-1 exhibits outstanding catalytic performance, converting CO₂ into CO with a yield of 2.55 mmol g⁻¹ h⁻¹. Experimental evidence suggests that the dynamic covalent bonds present within Schiff-base ZrOC-1 serve as the active sites for photocatalytic CO₂ reduction, and the cage's structure itself contributes positively to the photocatalytic activity.