A Stable Yttrium-Based Metal-Organic Framework Built on Ladder Building Units for Size-Exclusion Separation of Hexane Isomers

Abstract

The separation of hexane isomers represents a critical industrial process, which remains challenging due to their similar physicochemical properties. In this study, we report a three-dimensional (3D) Y-based metal-organic framework (MOF), [Y2(μ3-F)2(TBTC)(2-FBA)·1.5DMF]{denoted as HIAM-320, H3TBTC=1,3,5-tris[4-(carboxyphenyl)oxymethyl]-2,4,6-trimethylbenzene}, which features one-dimensional (1D) channels with appropriate pore size for size-sieving of hexane isomers. The compound is constructed from unique double-chain ladder-like {Y(μ3-F)} 2-n inorganic building units, rendering it exceptionally high structural stability. HIAM-320 adsorbs linear n-hexane (nHEX) and mono-branched 3-methylpentane (3MP), while effectively excluding di-branched 2,2-dimethylbutane (22DMB). The separation capability has been confirmed by multicomponent breakthrough experiments. Density functional theory (DFT) calculations validate the size-sieving separation mechanism and reveal the domains of guest-host interactions.