Large Titanium-Oxo Clusters as Precursors to Synthesize the Single Crystals of Ti-MOFs

Titanium­(IV)-based
metal-organic frameworks (Ti-MOFs) have received
significant attention in recent years because of their numerous photocatalytic
applications; however, the synthesis of new Ti-MOFs with precise crystal
structures is still challenging. Herein, three new Ti-MOFs with single-crystal
structures (denoted as FIR-125–FIR-127) are rationally synthesized
by employing a large Ti44-oxo cluster as the precursor
to assembly with the organic ligand. Big single-crystals can be successfully
obtained and structurally determined by single-crystal X-ray diffraction.
During the synthesis, the large Ti44-oxo cluster is transferred
to small Ti8O8(CO2)16 building
units in the Ti-MOF. In addition, FIR-125 exhibit high stability,
permanent porosity, and photocatalytic activity. This work provides
a new strategy toward the big crystal growth of Ti-MOFs through the
slow transformation of large titanium-oxo clusters.