NMR and X-ray Study Revealing the Rigidity of Zeolitic Imidazolate Frameworks

Abstract

NMR relaxation studies and spectroscopic measurements of zeolitic imidazolate framework-8 (ZIF-8) are reported. The dominant nuclear spin–lattice relaxation (T 1) mechanism for ZIF-8 in air arises from atmospheric paramagnetic molecular oxygen. The 13C T 1 measurements indicate that the oxygen interacts primarily with the imidazolate ring rather than the methyl substituent. Similar relaxation behavior was also observed in a ZIF with an unsubstituted ring, ZIF-4. Single-crystal X-ray diffraction was used to provide data for the study of the thermal ellipsoids of ZIF-8 at variable temperatures from 100 to 298 K, which further confirmed the rigid nature of this ZIF framework. These results highlight a rigid ZIF framework and are in contrast with dynamic metal–organic frameworks based on benzenedicarboxylate linking groups, for which the relaxation reflects the dynamics of the benzenedicarboxylate moiety.

Zeolitic Imidazolate Frameworks (ZIF): A Potential Membrane for CO2/CH4Separation

“…Different from MOFs, ZIFs consist of transition metal cations connected by imidazolate anions into tetrahedral frameworks, which resemble the zeolite topologies (59,61,(63)(64)(65)(66). ZIFs are presented in formula M(Im) 2 where M is the transition metal and Im is the imidazolate linker.…”

H2S interaction with HKUST-1 and ZIF-8 MOFs: A multitechnique study

“…The second MOF of this study, ZIF-8 (Zeolitic Imidazolate Framework) [22,23] is porous and crystalline framework in which the tetrahedral metal ions are linked by imidazolate (Im) units. ZIF structures may be compared with those of zeolites, as the bridging angle formed by this linkage is analogous to that between silicon oxygen and aluminium oxygen units in zeolites.…”

Crystalline arrays of molecular rotors with TIPS-trityl and phenolic-trityl stators using phenylene, 1,2-difluorophenylene and pyridine rotators

“…8 Furthermore, the available theoretical and experimental evidence has shown the enormous inuence of crystal packing in the dynamic behavior, 9 an interesting example being the BIBCO rotor (1,4-bis-(iodoethynyl)bicyclo[2.2.2]octane), in which the same molecule experiences two distinct rotational dynamics in the solid state. 11 These molecules tend to pack less densely (oen with solvent molecules), 12 in a way that facilitates the dynamic behavior in the solid state. 11 These molecules tend to pack less densely (oen with solvent molecules), 12 in a way that facilitates the dynamic behavior in the solid state.…”