Efficient separation of C6 alkane isomers by branching degree is important for upgrading light naphtha, yet remains challenging because of their subtle size differences. Herein, we report a ligand-conformation-directed strategy to construct a robust zinc-pyrazolate framework, BUT-312, for C6 alkane separation. Methyl substitution on a tritopic pyrazolate ligand induces a twisted conformation, redirecting the assembly from conventional linear zinc-pyrazolate chains to helical inorganic chains. The resulting framework features one-dimensional helical channels with alternating cavities and narrow apertures, enabling selective adsorption of n-hexane and 3-methylpentane while largely excluding 2,2-dimethylbutane. BUT-312 exhibits high uptakes of n-hexane and 3-methylpentane at 303 K, reaching 2.54 and 2.83 mmol g −1 , respectively. Dynamic breakthrough experiments confirm efficient ternary separation of n-hexane/3-methylpentane/2,2-dimethylbutane with good cycling performance. Moreover, BUT-312 maintains crystallinity and porosity after exposure to water, acidic solution, and boiling saturated NaOH solution, demonstrating exceptional chemical stability. This work highlights ligand conformational engineering as an effective route to robust MOFs with precisely defined apertures for challenging hydrocarbon separations.
Li et al. (Tue,) studied this question.