Linker Installation: Engineering Pore Environment with Precisely Placed Functionalities in Zirconium MOFs

Precise
placement of multiple functional groups in a highly ordered
metal–organic framework (MOF) platform allows the tailoring
of the pore environment, which is required for advanced applications.
To realize this, we present a comprehensive study on the linker installation
method, in which a stable MOF with coordinatively unsaturated Zr6 clusters was employed and linkers bearing different functional
groups were postsynthetically installed. A Zr-MOF with inherent missing
linker sites, namely, PCN-700, was initially constructed under kinetic
control. Twelve linkers with different substituents were then designed
to study their effect on MOF formation kinetics and therefore resulting
MOF structures. Guided by the geometrical analysis, linkers with different
lengths were installed into a parent PCN-700, giving rise to 11 new
MOFs and each bearing up to three different functional groups in predefined
positions. Systematic variation of the pore volume and decoration
of pore environment were realized by linker installation, which resulted
in synergistic effects including an enhancement of H2 adsorption
capacities of up to 57%. In addition, a size-selective catalytic system
for aerobic alcohol oxidation reaction is built in PCN-700 through
linker installation, which shows high activity and tunable size selectivity.
Altogether, these results exemplify the capability of the linker installation
method in the pore environment engineering of stable MOFs with multiple
functional groups, giving an unparalleled level of control.