A Dynamic, Breathing, Water-Stable, Partially Fluorinated, Two-Periodic, Mixed-Ligand Zn(II) Metal–Organic Framework Modulated by Solvent Exchange Showing a Large Change in Cavity Size: Gas and Vapor Sorption Studies

Abstract

A mixed-ligand, partially fluorinated, 2-periodic metal–organic framework [Zn(hfipbb)(bpt)]n·n(DMF)2·n(H2O) (1) has been synthesized from the unique combination of a V-shaped dicarboxylic acid ligand, H2hfipbb = 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) and a bent pyridyl based colinker, bpt = 4-amino-3,5-bis(4-pyridyl)-1,2,4-triazole. This framework undergoes single-crystal-to-single-crystal solvent exchange that leads to the formation of four additional structures [Zn(hfipbb)(bpt)]n·n(EtOH)2 (2), [Zn(hfipbb)(bpt)]n·n(DCM)2·n(H2O) (3), [Zn(hfipbb)(bpt)]n·n(DMA)2·n(H2O)2 (4), and [Zn(hfipbb)(bpt)]n·n(H2O)3 (5). The solvent-induced “breathing” of the 2-periodic frameworks results in potential void spaces varying from 15.2 to 35.4%, resulting mainly from the conformational twisting and ligation angle of the bpt ligand accompanied by rotation of the carboxylate group of the hfipbb ligand causing a change from mono- to bidentate ligation. Variable-temperature powder X-ray diffraction shows that removal...