Tuning Water Sorption in Highly Stable Zr(IV)-Metal–Organic Frameworks through Local Functionalization of Metal Clusters

Water
adsorption of metal–organic frameworks (MOFs) is attracting
intense interest because of their potential applications in atmospheric
water harvesting, dehumidification, and adsorption-based heating and
cooling. In this work, through using a hexacarboxylate ligand, four
new isostructural Zr­(IV)-MOFs (BUT-46F, -46A, -46W, and -46B) with
rare low-symmetric 9-connected Zr6 clusters were synthesized
and structurally characterized. These MOFs are highly stable in water,
HCl aqueous solution (pH = 1), and NaOH aqueous solution (pH = 10)
at room temperature, as well as in boiling water. Interestingly, the
rational modification of the metal clusters in these MOFs with different
functional groups (HCOO–, CH3COO–, H2O/OH, and PhCOO–)
enables the precise tuning of their water adsorption properties, which
is quite important for given application. Furthermore, all four MOFs
show excellent regenerability under mild conditions and good cyclic
performance in water adsorption.