Design, synthesis, and gas separation of metal-organic frameworks
Metal-organic frameworks (MOFs), also known as porous coordination polymers (CPs), are a new class of crystalline and porous materials in which metal ions or clusters (usually transition metals) work as nodes and link by a variety of organic compounds as bridging ligands which work as linkers. Due to the wide variety of organic and inorganic components which are the basic unit to build MOFs, there is the opportunity to synthesize a number of MOF crystals that have a variety of structures with exceptional properties and can be applied in important applications.
Gas sorption is one of the applications of MOFs, and is potentially useful in gas storage and separation. We have discovered two new microporous MOFs, which is UTSA-72 and UTSA-73. UTSA-72 was synthesized by mixing Zn(II) ions with (H4PTTB), which is tetracarboxylates multi-donate organic linker to form two-dimensional MOF. The X-ray crystal structure of UTSA-72 showed that UTSA-72 has the formula [Zn2 (PTTB)(DMF) 2]n.(DMF) n; in addition, X-ray illustrate that UTSA-72 has a small pore size. The measurements of the surface area for the UTSA-72 confirmed that this MOF has permanent porosity. As a result of this porosity, this MOF has the ability to be highly selective toward small gas molecules. The activated UTSA-72a exhibits moderately high selective gas separation for C2 H2 /CH4, CO2 /CH4, and CO2 /N2 at room temperature.
In addition, we have presented another new microporous MOF which is UTSA-73. This MOF was synthesized by mixing Zn(II) ions with (H4 BPTT), which is tetracarboxylates multi-donate organic linker, to form two-dimensional MOF. The crystallographic data show that this MOF is in the space group (P21/n); moreover, the two zinc atoms are five coordinated, in which four of them are from the organic ligand, and the fifth is from the DMF. Furthermore, we studied the gas sorption for this MOF as an application, and it showed that The activated UTSA-73a exhibits permanent porosity and moderately high selectivities for CO2 /N2 and CO2 /CH4 gas separations at room temperature because of the small pores within the framework.