Twisted node modulation of 2D-COFs for programmable long-afterglow luminescence

Controlled interlayer stacking, solvent processing, and long -after-glow luminescence have been challenges in the development of two-dimensional covalent organic frameworks (2D-COFs). We pro-pose a twisted node modulation strategy to address these issues simultaneously. Consistency of node distortion types causes stack-ing style to become non-adjustable: eclipsed stacking (non-twisted node) and inclined stacking (twisted node). By alternating the intro-duction of twisted and non-twisted nodes into a 2D-COFs system, a reversible crystal transformation between eclipsed and inclined stacking is achieved. The inclined COFs can be easily exfoliated into nanosheets for solution processing. Confining isolated exfoli-ated nanosheets within the polymethyl methacrylate achieves pro-grammable long-afterglow luminescence, which is for writing and printing, as well as imaging, anti-counterfeiting, and emergency lighting. This work provides a strategy for the design of 2D-COFs with different stackings to address the challenges of difficult pro-cessing for novel functional applications.