Single-Crystal Synthesis and Structures of Highly Stable Ni₈-Pyrazolate-Based Metal–Organic Frameworks

Pyrazolate-based (Pz-based) metal–organic frameworks (MOFs) acting as a class of highly stable porous materials have exhibited great application potential in various fields and have been receiving a dense attention in developing new MOF members, as well as expanding their practical applications. However, compared with carboxylate-based MOFs, the advancement in exploring the Pz-based MOFs is relatively slow, especially for the Ni8-pyrazolate (Ni8-Pz)-based MOFs. One important reason is that it is quite difficult to obtain single crystals of this type of MOFs. Herein, single crystals suitable for single-crystal X-ray diffraction (SCXRD) of six Ni8-Pz-based MOFs were synthesized through the fine control over the solvothermal reaction conditions, and structurally characterized. For all we know, this is the first time the structures of Ni8-Pz MOFs are definitely determined by SCXRD. Simultaneously, the first Ni8-Pz MOF with a 3-connected tri(pyrazoles) ligand was identified.