Rational Fine‐Tuning of MOF Pore Metrics: Enhanced SO <sub>2</sub> Capture and Sensing with Optimal Multi‐Site Interactions
Shanghua Xing, Abdulrahman Mohabbat, István Boldog, Jens Möllmer, Marcus Lange, Yu. S. Haiduk, Tobias Heinen, Vladimir Pankov, Oliver Weingart, Christoph Janiak
Abstract
Abstract Selective capture of sulfur dioxide (SO 2 ), important in the context of environmental protection, is reachable by specially tailored porous materials endowed with physisorptive complementarity. Metal–organic frameworks (MOFs) can potentially be leading materials for physisorptive SO 2 capture due to their excellent tailorability. Here, a series of highly stable DMOFs, [Ni 2 L 2 (DABCO)], where L = 1,4‐benzenedicarboxylate (BDC), 1,4‐naphthalenedicarboxylate (NDC), 2,6‐naphthalenedicarboxylate (2,6‐NDC), 9,10‐anthracendicarboxylate (ADC), and 1,4‐diazabicyclo[2,2,2]octane (DABCO) aiming at optimal SO 2 physisorption characteristics, is reported. The extension of the aromatic core by conjugated benzene rings allows to reach an optimal pore diameter at 4–5 Å in the case of the DMOF‐ADC, maximizing the multi‐site MOF···SO 2 interactions, which improve the SO 2 binding at low concentrations, as revealed by density‐functional theory (DFT) calculations. The improved SO 2 separation performance of DMOF‐ADC is demonstrated by single SO 2 and SO 2 /CO 2 ‐mixed‐component adsorption (a SO 2 /CO 2 selectivity >100 is reached at 0.01 bar, which is significantly better than the value for the benchmark DUT‐8 material) and dynamic breakthrough experiment. The use as a chemiresistive sensor for SO 2 sensing is demonstrated for the best performing DMOF‐ADC at low concentrations (doubled resistive response at 100 ppm and T < 120 °C).