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.