Modulation of the Dynamics of a Two-Dimensional Interweaving Metal–Organic Framework through Induced Hydrogen Bonding

• Published in: Inorganic chemistry 2024-03, Vol.63 (12), p.5552-5558
• Main Authors: Fernández-Seriñán, Pilar, Roztocki, Kornel, Safarifard, Vahid, Guillerm, Vincent, Rodríguez-Hermida, Sabina, Juanhuix, Judith, Imaz, Inhar, Morsali, Ali, Maspoch, Daniel
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c04522

Inducing, understanding, and controlling the flexibility in metal–organic frameworks (MOFs) are of utmost interest due to the potential applications of dynamic materials in gas-related technologies. Herein, we report the synthesis of two isostructural two-dimensional (2D) interweaving zinc­(II) MOFs, TMU-27 [Zn­(bpipa)­(bdc)] and TMU-27-NH2 [Zn­(bpipa)­(NH2-bdc)], based on N,N′-bis-4-pyridyl-isophthalamide (bpipa) and 1,4-benzenedicarboxylate (bdc) or 2-amino-1,4-benzenedicarboxylate (NH2-bdc), respectively. These frameworks differ only by the substitution at the meta-position of their respective bdc groups: an H atom in TMU-27 vs an NH2 group in TMU-27-NH2. This difference strongly influences their respective responses to external stimuli, since we observed that the structure of TMU-27 changed due to desolvation and adsorption, whereas TMU-27-NH2 remained rigid. Using single-crystal X-ray diffraction and CO2-sorption measurements, we discovered that upon CO2 sorption, TMU-27 undergoes a transition from a closed-pore phase to an open-pore phase. In contrast, we attributed the rigidification in TMU-27-NH2 to intermolecular hydrogen bonding between interweaving layers, namely, between the H atoms from the bdc-amino groups and the O atoms from the bpipa-amide groups within these layers. Additionally, by using scanning electron microscopy to monitor the CO2 adsorption and desorption in TMU-27, we were able to establish a correlation between the crystal size of this MOF and its transformation pressure.