Robust molecular crystals of titanium(IV)-oxo-carboxylate clusters showing water stability and CO2 sorption capability.

A series of new Ti(IV)-oxo clusters supported by carboxylate ligands are synthesized by solvothermal reactions, and their crystal structures and gas sorption properties are studied in detail. Depending on the reaction medium, two types of Ti6O6 clusters are formed with benzoate-derived ligands whose 2- or 4-position is substituted by a hydrophobic moiety. The molecular packing structures of these Ti clusters are found stable against water- and heat-treatments. Gas sorption studies reveal that a dense-packed Ti-carboxylate cluster can adsorb almost the same number of CO2 molecules as the one with considerable intermolecular voids in the packing structure. The effect of benzoate substituents on the gas sorption behavior is discussed.

Unprecedented and highly symmetric (6,8)-connected topology in a porous metal-organic framework through a Zn-Ti heterometallic approach.

The Zn(II)-Ti(IV) heterometallic approach is successfully adopted to produce a highly symmetric, binodal metal-organic framework with unprecedented topology in network solids. This material, ZTOF-2, possesses permanent porosity as shown by reversible sorption of various gases.

Nonporous titanium-oxo molecular clusters that reversibly and selectively adsorb carbon dioxide.

Nonporous titanium(IV) clusters supported by carboxylate ligands show selective sorption of carbon dioxide even in the amorphous phase. A ring-type Ti8 cluster with a permanent inner pore also adsorbs gases, but not selectively.

Unique coordination-based heterometallic approach for the stoichiometric inclusion of high-valent metal ions in a porous metal-organic framework.

A heterometallic metal-organic framework incorporating Zn(2+) and Ti(4+) is successfully synthesized. The unique coordination mode of each metal ion to 2-oxido-1,4-benzenedicarboxylate leads to Zn6Ti2 building blocks, which extend to form a double-walled primitive cubic net. This material possesses a permanent porosity and long-term stability.