Covalent organic frameworks (COFs)
with improved stability and
extended π-conjugation structure are highly desirable. Here,
two imine-linked COFs were converted into ultrastable and π-conjugated
fused-aromatic thieno[3,2-c]pyridine-linked COFs
(B-COF-2 and T-COF-2). The successful conversion
was confirmed by infrared and solid-state 13C NMR spectroscopies.
Furthermore, the structures of thieno[3,2-c]pyridine-linked
COFs were evaluated by TEM and PXRD. It is noted that a slight difference
in the structure leads to totally different photoactivity. The fully
π-conjugated T-COF-2 containing triazine as the
core exhibited an excellent photocatalytic NADH regeneration yield
of 74% in 10 min.
Developing a facile strategy for the construction of vinylene-linked fully π-conjugated covalent organic frameworks (COFs) remains a huge challenge. Here, a versatile condition of Knoevenagel polycondensation for constructing vinylene-linked 2D COFs was explored. Three new examples of vinylene-linked 2D COFs (BTH-1, 2, 3) containing benzobisthiazoles units as functional groups were successfully prepared under this versatile and mild condition. The electron-deficient benzobisthiazole units and cyano-vinylene linkages were both integrated into the π conjugated COFs skeleton and acted as acceptor moieties. Interestingly, we found the construction of a highly ordered and conjugated D-A system is favorable for photocatalytic activity. BTH-3 with benzotrithiophene as the donor with a strong D-A effect exhibited an attractive photocatalytic HER of 15.1 mmol h−1g−1 under visible light irradiation.
Two 2D COFs containing both naphthalene diimides (NDIs) as an electron acceptor (A) and triphenylamine (PT-N-COF) or triphenylbenzene (PT-B-COF) as electron donors (D) were prepared successfully. The in-plane donor and...
Developing visible-light-active
porous organic polymers with high
photocatalytic efficiency is highly desirable. Here, two triazine-based
conjugated microporous polymers were synthesized. The structures were
controllably adjusted to explore the structure–photocatalytic
activity relationship. T-CMP-1 containing more triazine
units exhibited a hydrogen evolution rate of 3214.3 μmol h–1 g–1, much higher than that of T-CMP-2 (242.1 μmol h–1 g–1). The increasing contents of triazine units bring better hydrogen
evolution efficiency.
A fully π-conjugated nitrogen-rich three-dimensional
covalent
organic framework (PYTRI-COF-2) containing both pyrazine
and triazine units was prepared through a post-synthetic strategy.
The imine linkages in the pre-prepared PYTRI-COF-1 were
converted into heterocyclic quinoline by the Povarov reaction. The
obtained PYTRI-COF-2 displayed high Li-ion storage capacity
and excellent cycling stability when it was used as the lithium (Li)-ion
battery electrode.
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