Communication
Three-Dimensional Triptycene-Based Covalent Organic Frameworks
with ceq or acs Topology
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ABSTRACT: The growth of three-dimensional covalent organic frameworks (3D COFs) with new topologies is still considered as a
great challenge due to limited availability of high-connectivity building units. Here we report the design and synthesis of 3D
triptycene-based COFs, termed JUC-568 and JUC-569, following the deliberate symmetry-guided design principle. By combining a
triangular prism (6-connected) node with a planar triangle (3-connected) or another triangular prism node, the targeted COFs adopt
non-interpenetrated ceq or acs topology, respectively. Both materials show permanent porosity and impressive performance in the
adsorption of CO2 (∼98 cm3/g at 273 K and 1 bar), CH4 (∼48 cm3/g at 273 K and 1 bar), and especially H2 (up to 274 cm3/g or
2.45 wt % at 77 K and 1 bar), which is highest among porous organic materials reported to date. This research thus provides a
promising strategy for diversifying 3D COFs based on complex building blocks and promotes their potential applications in energy
storage and environment-related fields.
ovalent organic frameworks (COFs), an emerging family
of crystalline porous polymers, are assembled from
by an organic cage molecule as a triangular prism node and
adopts a 2-fold interpenetrated acs topology.36 It must be
noted, however, that, except for a few successful examples, 3D
COFs using high-connectivity monomers still remain largely
unexplored.
C
organic reactants by reversible covalent bonds.1−5 Due to
their high surface areas, modular nature, and good thermal/
chemical stability, COF materials have attracted considerable
attention in gas storage/separation,6−9 organic elec-
tronics,10−14 heterogeneous catalysis,15−20 and some other
fields.21−25 Over the past decade, most reports were focused
on conjugated two-dimensional (2D) sheets, in which the
abundant building blocks allowed well developed synthetic
strategies to be established.5 By contrast, three-dimensional
(3D) COFs are still less studied due to the scant availability of
appropriate molecular building units and relatively complex
structure determination.4 Up until now, only very limited
topologies in 3D COFs have been reported,26−34 such as dia,
ctn, and bor. Moreover, almost all known 3D COFs were
constructed by using tetrahedral (4-connected) building
blocks, including the derivatives of tetraphenylmethane,
tetraphenylsilane, and adamantane, which has greatly confined
the structural diversity and functionalization of 3D COFs.
Despite the above issues, 3D COFs are considered as an
exciting platform for practical applications due to their unique
features,4 e.g., interconnective porous structures, high specific
surface areas, and easily accessible active sites. In principle, the
employment of high-connectivity building units, such as
triangular prism (6-connected) monomers, can set up new
architectures in 3D COFs, proved by several cases that
appeared recently. For example, we synthesized the first 3D
large-pore COF, JUC-564, with stp topology constructed from
a triptycene-based triangular prism monomer, which has the
largest pore (43 Å) among 3D COFs and record-breaking low
density (0.108 g cm−3) in porous crystalline materials to
date.35 Subsequently, Cooper and co-workers also reported the
first cage-based 3D COF, 3D-CageCOF-1, which is fabricated
Herein we report the design and synthesis of 3D COFs,
termed JUC-568 and JUC-569 (JUC = Jilin University China),
based on triptycene derivatives with a triangular prism node.
By combining the triptycene-based monomer with a planar
triangle (3-connected) node, JUC-568 shows a ceq topology.
Besides, from the assembly of two similar triangular prism
building units, JUC-569 adopts a non-interpenetrated acs
topology. To the best of our knowledge, this study represents
the first example of COFs with non-interpenetrated ceq or acs
topology, which effectively expands the structural varieties of
3D COFs. More importantly, owing to the high crystallinity
and permanent porosity, these triptycene-based COFs
demonstrate an impressive performance in the capture of
CO2 (∼98 cm3/g at 273 K and 1 bar) and CH4 (∼48 cm3/g at
273 K and 1 bar), and particularly H2 (up to 274 cm3/g at 77
K and 1 bar), which is higher than those from porous organic
materials reported so far. During this manuscript review,37
a
3D COF with 2-fold interpenetrated ceq topology, 3D-ceq-
COF, constructed from the same strategy has been
published,38 and thus, the structure of JUC-568 and associated
Received: December 1, 2020
Published: February 10, 2021
J. Am. Chem. Soc. 2021, 143, 2654−2659
© 2021 American Chemical Society
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