Divergent Kinetic and Thermodynamic Hydration of a Porous Cu(II) Coordination Polymer with Exclusive CO2 Sorption Selectivity

Selective adsorption and separation of CO2 are of great importance for different target applications. Metal organic frameworks (MOFs) represent a promising class of porous materials for this purpose. Here we present a unique MOF material, [Cu(tba)(2)](n) (tba = 4-(1H-1,2,4-triazol-1-yl)benzoate), which shows high CO2 adsorption selectivity over CH4/H-2/O-2/Ar/N-2 gases (with IAST selectivity of 41-68 at 273 K and 33-51 at 293 K). By using a critical point dryer, the CO2 molecules can be well sealed in the ID channels of [Cu(tba)(2)](n) to allow a single-crystal X-ray analysis, which reveals the presence of not only C delta+-H center dot center dot center dot O delta- bonds between the host framework and CO2 but also quadrupole quadrupole (CO2 delta-center dot center dot center dot delta+CO2) interactions between the CO2 molecules. Furthermore, [Cu(tba)(2)](n) will suffer divergent kinetic and thermodynamic hydration processes to form its isostructural hydrate {[Cu(tba)(2)](H2O)}(n) and a mononuclear complex [Cu(tba)(2)(H2O)(4)] via single-crystal to single-crystal transformations.