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Guest-Controlled Incommensurate Modulation in a Meta-Rigid Metal–Organic Framework Material

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posted on 30.10.2020, 14:29 by Jiangnan Li, Zhengyang Zhou, Xue Han, Xinran Zhang, Yong Yan, Weiyao Li, Gemma L. Smith, Yongqiang Cheng, Laura J. McCormick McPherson, Simon J. Teat, Mark D. Frogley, Svemir Rudić, Anibal J. Ramirez-Cuesta, Alexander J. Blake, Junliang Sun, Martin Schröder, Sihai Yang
Structural transitions of host systems in response to guest binding dominate many chemical processes. We report an unprecedented type of structural flexibility within a meta-rigid material, MFM-520, which exhibits a reversible periodic-to-aperiodic structural transition resulting from a drastic distortion of a [ZnO4N] node controlled by the specific host–guest interactions. The aperiodic crystal structure of MFM-520 has no three-dimensional (3D) lattice periodicity but shows translational symmetry in higher-dimensional (3 + 2)­D space. We have directly visualized the aperiodic state which is induced by incommensurate modulation of the periodic framework of MFM-520·H2O upon dehydration to give MFM-520. Filling MFM-520 with CO2 and SO2 reveals that, while CO2 has a minimal structural influence, SO2 can further modulate the structure incommensurately. MFM-520 shows exceptional selectivity for SO2 under flue-gas desulfurization conditions, and the facile release of captured SO2 from MFM-520 enabled the conversion to valuable sulfonamide products. MFM-520 can thus be used as a highly efficient capture and delivery system for SO2.