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/H2/O2/Ar/N2 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 1D channels of [Cu(tba)2]n to allow a single-crystal X-ray analysis, which reveals the presence of not only C(δ+)-H···O(δ-) bonds between the host framework and CO2 but also quadrupole-quadrupole (CO2(δ-)···(δ+)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.

No abstract

Zinc and cobalt 5-aminonicotinate (5-AN -) complexes, Co(5-AN) 2 (H 2 O) 4 (1) and {[Zn(5-AN) 2 ] (H 2 O)} n (2), have been hydrothermally synthesized and structurally characterized. Single-crystal X-ray diffraction results indicate that coordination geometries are different (octahedral for Co II and tetrahedral for Zn II ) and 5-AN − adopts distinct binding modes (terminal in 1 and bridging in 2), forming a simple mononuclear coordination motif for 1 and a 2-D (4,4) coordination layer for 2. The higher-dimensional supramolecular architectures for both complexes are constructed via hydrogen bonding. Both complexes have been characterized by IR, microanalysis, and powder X-ray diffraction techniques and, their thermal stability and fluorescence have also been investigated.

No abstract