Tetragonal versus Hexagonal: Structure-Dependent Catalytic Activity of Co/Zn Bimetallic Metal–Organic Frameworks

Tetragonal and hexagonal phases of
monometallic Zn and bimetallic Co/Zn metal–organic frameworks
(MOFs), with secondary building units (SBUs) containing a M3O (M = metal) cluster, were synthesized from identical constituents
using a benzenetricarboxylate (BTC3–) linker that
forms decorated 3,6- and 3,5-connected networks, respectively. There
exist subtle differences between the SBUs; one of the metal atoms
in the M3O cluster in the tetragonal phase has one dissociable
DMF solvent molecule while that in the hexagonal phase has three.
Connectivities between the SBUs form one-dimensional channels in both
MOFs. These MOFs catalyze the chemoselective addition of amines to
epoxides, giving exclusively β-hydroxyamine under heterogeneous
conditions. A ring-opening reaction of a symmetrical epoxide showed
that the hexagonal phase diastereoselectively yields trans-alcohol, exhibiting an exquisite model for structure-dependent activity.