Photoelectric covalent organic frameworks: Converting open lattices into ordered donor-acceptor heterojunctions

Ordered one-dimensional open channels represent the typical porous structure of two-dimensional covalent organic frameworks (COFs). Here we report a general synthetic strategy for converting these open lattice structures into ordered donor-acceptor heterojunctions. A three-component topological design scheme was explored to prepare electron-donating intermediate COFs, which upon click reaction were transformed to photoelectric COFs with segregated donor-acceptor alignments, whereas electron-accepting buckyballs were spatially confined within the nanochannels via covalent anchoring on the channel walls. The donor-acceptor heterojunctions trigger photoinduced electron transfer and allow charge separation with radical species delocalized in the π-arrays, whereas the charge separation efficiency was dependent on the buckyball content. This new donor-acceptor strategy explores both skeletons and pores of COFs for charge separation and photoenergy conversion.