Polymorph Selection of Zeolitic Imidazolate Frameworks via Kinetic and Thermodynamic Control

Exploring the kinetics of metal–organic framework crystallization is crucial in order to design novel synthesis methods benefiting from far-from-equilibrium conditions, such as flow, microfluidic, or gel-phase reactors. Herein we focus on zeolitic imidazolate frameworks (ZIFs) obtained reaction 2-methylimidazolate and zinc ions a model system. The room-temperature carried out pure water solvent without addition any alkaline chemical yields highly crystalline product with good conversion within minutes. short-term kinetic characteristics were determined by high-speed camera, result which was complemented UV–vis photometer based long-term investigation. At low concentrations moderate linker excess, facilitate sluggish coordination precipitation, fast colloid formation followed delayed remarkable recrystallization, leads dense dia(Zn) polymorph ZIF. Although this thermodynamically favored route, it should be avoided due nonporous structure product. same stoichiometric excess together higher gives rise production less stable ZIF: i.e., ZIF-8 sodalite-like via control. Similar conclusions are drawn case cobalt(II)-containing frameworks, highlights that control selection might achieved for other MOFs well. Our results supported scanning electron microscopy, powder X-ray diffraction, nitrogen gas adsorption, Fourier-transformed infrared Raman spectroscopy.