A Partially Fluorinated Three-fold Interpenetrated Stable Metal- Organic Framework with Selective CO2 Uptake

Abstract

The hydrothermal reaction of Zn(NO3)2·H 2O and a linear 2, 2'-bis-trifluoromethyl-biphenyl-4, 4'-dicarboxylic acid (H2L) ligand with-CF3 groups at each phenyl moiety of the biphenyl rings leads to the formation of a three-fold interpenetrated metal-organic framework (MOF), {[Zn2.66O0.66(L) 2]·2H2O}n (1) at 180 °C. Single-crystal X-ray diffraction studies revealed that 1 is constructed from polynuclear clusters [Zn4O(COO)6] as secondary building units (SBU). These SBU are connected through the L2- to generate an overall three-dimensional structure with a 6-connected primitive cuboidal (α-Po) network. Thermogravimetric analyses and variable temperature powder X-ray diffraction measurements suggested that 1 is thermally stable. The porosity of 1 was estimated by N2, CO2, H2, and CH4 at different temperatures. The framework showed high selectivity of CO2 uptake over N2 and CH4. Furthermore, solid-state photoluminescence studies were carried out for complex 1 upon excitation at 275 nm at room temperature.