Control the Structure of Zr-Tetracarboxylate Frameworks through Steric Tuning

Ligands with flexible conformations
add to the structural diversity
of metal–organic frameworks but, at the same time, pose a challenge
to structural design and prediction. Representative examples include
Zr-tetracarboxylate-based MOFs, which afford assorted structures for
a wide range of applications, but also complicate the structural control.
Herein, we systematically studied the formation mechanism of a series
of (4,8)-connected Zr-tetracarboxylate-based MOFs by altering the
substituents on different positions of the organic linkers. Different
ligand rotamers give rise to three types of structures with flu, scu, and csq topologies. A
combination of experiment and molecular simulation indicate that the
steric hindrance of the substituents at different positions dictates
the resulting MOF structures. Additionally, the controllable formation
of different structures was successfully implemented by a combination
of linkers with different steric effects at specific positions.