posted on 2024-02-26, 14:09authored byFeng Tao, Wenwen Zhou, Zuyi Li, Xuekai Jiang, Lianke Wang, Zhipeng Yu, Jie Zhang, Hongping Zhou
Vinylene-linked covalent–oganic
frameworks (COFs),
as novel
photocatalysts, have garnered considerable attention due to their
exceptional stability, remarkable π-electron delocalization,
and precisely customizable structures. However, the design of novel
monomers for constructing vinylene-linked COFs with tunable electronic
structures is still in its early stages and poses a number of challenges.
Addressing this, a tritopic monomer was developed by attaching a 3-fold
2-methylpyridine unit to the triphenyl-1,3,5-triazine core. The tritopic
monomer was further condensed with tritopic aromatic dialdehydes via
a solid-state Knoevenagel polycondensation reaction to form two vinylene-linked
2D COFs (TP-PB and TP-PT COF), which exhibited excellent crystallinity,
preeminent stability, and outstanding π-electron delocalization.
More importantly, by modulation of the donor–acceptor (D–A)
interaction within the COFs, the semiconducting properties of the
two COFs could be optimized. Due to the stronger D–A interactions
in the TP-PB COF containing 1,3,5-triphenylbenzene unit than the TP-PT
COF containing triphenyl-1,3,5-triazine unit, the TP-PB COF exhibited
broader visible light absorption, narrower band gap, stronger photocurrent
response, and lower charge transfer resistance, which makes the TP-PB
COF a more efficient photocatalyst for the photocatalytic selective
conversions of organic sulfides to sulfoxides and C-3 thiocyanation
of indole derivatives with high catalytic activity and recyclability.
This work not only demonstrates the construction of vinylene-linked
via 2-methylpyridine Knoevenagel polycondensation but also presents
a facile strategy for regulating the semiconducting properties of
such COFs by fine-tuning the donor–acceptor (D–A) interactions
within the COF matrices.