An Olefin-Linked Pyridinium Covalent Organic Frameworks Bearing Donor–acceptor Structure for Highly Efficient Photocatalytic Organic Transformations

As we know, the photoelectric properties of the covalent organic frameworks (COFs) can be properly adjusted by introducing an electron donor–acceptor (D–A) structure. In here, a two-dimensional D–A type Py-BPDAIP-COF with an excellent photoelectric characteristic was prepared in a post-modified method. Significantly, the introducing of very strong electron-withdrawing pyridinium structure dramatically improve inductive and conjugative effects of the electron acceptor unit of Py-BPDAIP-COF. And the electron-rich pyrene skeleton on the knot of the COF was as an electron donor. Then a strong electron push–pull effect between the donor and acceptor units can be transmitted to the COFs backbone, significantly improving the transfer and separation of light-generated electrons. The Py-BPDAIP-COF showed very excellent photocatalytic activity in visible light-induce aerobic hydroxylation, thiocyanation transformation and oxidative C-H functionalization. Therefore, we design and construct a highly efficient olefin-linked D–A type COF photocatalysts via tuning inductive and conjugative effects of pore wall surface.