Xiaokai Song

Transmetalations in two metal–organic frameworks with different framework flexibilities: Kinetics and core–shell heterostructure

While only a partially transmetalated network was observed in a rigid metal–organic framework (MOF), not only a completely transmetalated isostructural network but also a partially transmetalated core–shell heterostructural network could be obtained in a flexible MOF by controlling the reaction conditions.

A two-fold interpenetrated (3,6)-connected metal–organic framework with rutile topology showing a large solvent cavity

A two-fold interpenetrated metal–organic framework (MOF), [(Zn4O)2L4(DMF)2(H2O)3], was prepared using the tritopic ligand 4,4′,4′′-[1,3,5-benzenetriyltris(carbonylimino)]trisbenzoic acid (H3L) and zinc nitrate. The MOF, based on the hexatopic tetranuclear Zn4O(COO)6 secondary building unit, has a (3,6)-connected network with an rtl topology and a large solvent cavity.

Hybrid bimetallic metal-organic frameworks: modulation of the framework stability and ultralarge CO2 uptake capacity.

A series of isostructural hybrid bimetallic metal-organic frameworks (MOFs), Ni(x)M(1-x)-ITHDs [M = Zn(II), Co(II)], have been prepared via a conventional solvothermal reaction in the presence of varying mole ratios of Ni(II)/Zn(II) or Ni(II)/Co(II) mixed metal ions. While a critical amount of the doped Ni(II) ion (more than ≈0.2 mol fraction) is needed to have any enhancement of the framework stability of the hybrid bimetallic NixZn1-x-ITHDs, even a very small amount of the doped Ni(II) ion (≈0.1 mol fraction) produced a full enhancement of the framework stability of the hybrid bimetallic Ni(x)Co(1-x)-ITHDs. The highly porous and rigid Ni(x)Co(1-x)-ITHDs activated via a conventional vacuum drying process shows a Brunauer-Emmett-Teller specific surface area of 5370 m(2) g(-1), which is comparable to that of pure Ni-ITHD. The CO2 uptake capacities of Ni-ITHD and Ni(0.11)Co(0.89)-ITHD (2.79 and 2.71 g g(-1), respectively) at 1 bar and 195 K are larger than those of any other reported MOFs under similar conditions and the excess CO2 uptake capacity at 40 bar and 295 K (≈1.50 g g(-1)) is comparable to those of other MOFs, which are activated via the supercritical carbon dioxide drying process, with similar pore volumes.

Isoreticular MOFs based on a rhombic dodecahedral MOP as a tertiary building unit

The solvothermal reactions of a Zn(II) ion with ligands containing two 1,3-benzene dicarboxylate residues linked via bent organic linkers with different flexibilities resulted in the isoreticular metal–organic frameworks (MOFs) PMOF-4 and PMOF-5 based on a rhombic dodecahedral metal–organic polyhedron (MOP) as a tertiary building unit (TBU). The rhombic dodecahedral MOP was built using six [Zn2(COO)4] clusters as a 4-c secondary building unit (SBU) and eight [Zn2(COO)3] clusters as a 3-c SBU. The network of the isoreticular MOFs based on the rhombic dodecahedral Zn–MOP is a 3,3,4-c net with a zjz topology, which is different from those of similar MOFs, PMOF-3 and PCN-12, based on a cuboctahedral Cu–MOP as a 24-c TBU. However, both 24-c TBUs in all MOFs were quadruply interlinked to six neighboring TBUs to form the same underlying pcu topology.

Microporous metal-organic framework containing cages with adjustable portal dimensions for adsorptive CO2 separation

The excellent breakthrough separation performance of a new microporous MOF for CO2/N2 and CO2/CH4 gas mixtures results from the combination of different equilibrium uptake amounts depending on the adsorption enthalpies of the adsorbates and different uptake kinetics depending on their kinetic diameters.