posted on 2022-04-14, 03:43authored byXuan Wang, Xing Han, Cheng Cheng, Xing Kang, Yan Liu, Yong Cui
A large number of covalent organic
frameworks (COFs) with two-dimensional
(2D) layered structures have been reported, but their network structures
are restricted to only seven topologies (namely, hcb, hxl, kgm, sql, tth, bex, and kgd) because of the limited choice of
building blocks. In this work, we illustrate how linking pseudo-fivefold
symmetric 1,2,3,4,5-penta(4-formylphenyl)pyrrole with linear aromatic
diamines through dynamic imine bonds produces three 2D porous COFs
with an unprecedented cem topology, which represent the
first examples of five-vertex semiregular Archimedean tessellations
in COFs. The three 2D COFs are isostructural, and each adopts an eclipsed
stacking structure with unidirectional hierarchical pores, in which
the pyrrole unit is utilized as the five-vertex of network to form
both square and triangular pores in a 33.42 sequence.
With high thermal and chemical resistances, the COF-packed HPLC columns
show excellent performance to provide separation of 10 different polycyclic
aromatic hydrocarbons, a group of the most widespread organic environmental
pollutants. The implementation of five-vertex Archimedean tessellations
thus couriers a strategy to design COFs with new topologies and paves
a new way to expand the inimitable properties of COF materials.