The First Sulfate‐Pillared Hybrid Ultramicroporous Material, SOFOUR‐1‐Zn, and Its Acetylene Capture Properties

Abstract

Hybrid ultramicroporous materials, HUMs, are comprised of metal cations linked by combinations of inorganic and organic ligands. Their modular nature makes them amenable to crystal engineering studies, which have thus far afforded four HUM platforms (as classified by the inorganic linkers). HUMs are of practical interest because of their benchmark gas separation performance for several industrial gas mixtures. We report herein design and gram‐scale synthesis of the prototypal sulfate‐linked HUM, the fsc topology coordination network ([Zn(tepb)(SO4)]n), SOFOUR‐1‐Zn, tepb=(tetra(4‐pyridyl)benzene). Alignment of the sulfate anions enables strong binding to C2H2 via O⋅⋅⋅HC interactions but weak CO2 binding, affording a new benchmark for the difference between C2H2 and CO2 heats of sorption at low loading (ΔQst=24 kJ mol−1). Dynamic column breakthrough studies afforded fuel‐grade C2H2 from trace (1 : 99) or 1 : 1 C2H2/CO2 mixtures, outperforming its SiF62− analogue, SIFSIX‐22‐Zn.

Recent advances in microporous metal–organic frameworks as promising adsorbents for gas separation

“…55,157–161 Herein, we will summarize some of the critical advances achieved for efficient C 2 H 2 /CO 2 separation over the past five years. 162–195…”

“…Similar work was then conducted by Sensharma et al on a sulfate-pillared SIFSIX material, exhibiting its excellent performance for trace separation of C 2 H 2 from CO 2 . 175…”

Pillar Modularity in fsc Topology Hybrid Ultramicroporous Materials Based upon Tetra(4-pyridyl)benzene

“… 30 Our group recently reported the fsc frameworks SIFSIX-22-Zn and SOFOUR-1-Zn , both of which are based on the tepb linker. 31 …”

“… 24 We recently reported SIFSIX-22-Zn and SOFOUR-1-Zn using the same tetrapyridyl linker and SiF 6 2– or SO 4 2– pillars, respectively. 31 In the present work, we report a crystal engineering study of fsc HUMs involving substitution of the inorganic pillars in [Zn(tepb)SiF 6 ] ( SIFSIX-22-Zn ) to afford an additional five members of this platform: [Zn(tepb)TiF 6 ] ( TIFSIX-6-Zn) , [Zn(tepb)SnF 6 ] ( SNFSIX-2-Zn ), [Zn(tepb)GeF 6 ] ( GEFSIX-4-Zn ), [Zn(tepb)ZrF 6 ] ( ZRFSIX-3-Zn ), and [Zn(tepb)TaF 7 ] ( TAFSEVEN-1-Zn ).…”

A new boron cluster anion pillared metal organic framework with ligand inclusion and its selective acetylene capture properties

“…NbOF 5 2− and TaOF 5 2− ), 21–23 (3) networks cross-linked by tetrahedral MO 4 2− oxyanions ( e.g. CrO 4 2− , MoO 4 2− , SO 4 2− ), 24 (4) DICRO coordination networks that are sustained with Cr 2 O 7 2− dianions, 25 and (5) boron cluster anion pillared supramolecular metal organic frameworks (BSFs) featuring closo -[B 12 H 12 ] 2− or closo -[B 12 H 11 I] 2− as the inorganic pillars. 26–32…”