Fluorinated Biphenyldicarboxylate-Based Metal–Organic Framework Exhibiting Efficient Propyne/Propylene Separation
Zhao-Ting Lin, Qing‐Yan Liu, Ling Yang, Chun‐Ting He, Libo Li, Yu‐Ling Wang
Abstract
A novel fluorinated biphenyldicarboxylate ligand of 3,3′,5,5′-tetrafluorobiphenyl-4,4′-dicarboxylic acid (H2-TFBPDC) and its terbium metal–organic framework, {[Tb2(TFBPDC)3(H2O)]·4.5DMF·0.5H2O}n (denoted as JXNU-6), were synthesized. JXNU-6 exhibits a three-dimensional (3D) framework built from one-dimensional (1D) terbium carboxylate helical chains bridged by TFBPDC2– linkers. The 3D framework of JXNU-6 features 1D fluorine-lined channels. The gas adsorption experiments show that the activated JXNU-6 (JXNU-6a) displays distinct adsorption behavior for propyne (C3H4) and propylene (C3H6) gases. The effective removal of a trace amount of C3H4 from C3H6 was achieved by JXNU-6a under ambient conditions, which is demonstrated by the column-breakthrough experiments. The modeling studies show that the preferential binding sites for C3H4 are the exposed F atoms on the pore surface in 1D channels. The strong C–H···F hydrogen bonds between C3H4 molecules and F atoms of TFBPDC2– ligands dominate the host–guest interactions, which mainly account for the excellent C3H4/C3H6 separation performance of JXNU-6a. This work provides a strategy for specific recognition toward C3H4 over C3H6 through the C–H···F hydrogen bond associated with the fluorinated organic ligand.