The Solvent Induced Inter‐Dimensional Phase Transformations of Cobalt Zeolitic‐Imidazolate Frameworks

Abstract

Studying inter-dimensional phase transitions of zeolitic-imidazolate frameworks (ZIFs) is essential for developing strategies in controlling morphology and properties. Herein, the inter-dimensional topotactic phase transformations of 3D ZIF-67 to 2D ZIF-L are investigated in detail by employing a simple and efficient solvent-induced growth method. In addition to ZIF-67 and ZIF-L, a series of novel core-shell composites of ZIF-67@ZIF-L, with unprecedented morphologies, are also obtained and well-defined. The different behaviors of the amine hydrogen of 2-MIM in the solvents play a pivotal role for inter-dimensional phase transformations, and in combination with the concentration of 2-MIM, the 2D to 3D phase transformations are also revealed. The findings are very beneficial for morphological design of the ZIFs, along with exploration of the corresponding properties. Impressively, Co-ZIFs exhibit interesting tunable CO adsorption behaviors with the phase evolution, which might bring broader understanding for designing CO detection and adsorption devices.

Cobalt metal–organic framework-based ZIF-67 for the trace determination of herbicide molinate by ion mobility spectrometry: investigation of different morphologies

“…It is known that the EDX analysis has an error in detecting elements with a low atomic number. 41 However, overall, this method conrmed the presence of Co and O, N, C with the desired Hmim/Co 2+ molar ratios in the as-prepared sample ( Fig. 9a-d).…”

“…3b). 34,41 Fig . 4 displays the FE-SEM images of Co-MOF-based ZIF-67 prepared using different solvents: SO 1 (methanol), SO 2 (ethanol), SO 3 (water), SO 4 (methanol-water), and SO 5 (ethanolwater).…”

Solvent‐Dependent Adsorption‐Driven Mechanism for MOFs‐Based Yolk–Shell Nanostructures

“…To our knowledge,the gate-opening behavior of ZIF-8 can be triggered by the adsorption of gas or even solvent molecules, which is at opological transition due to the partial reorientation of imidazolyl-linked ligands. [31][32][33][34] Thus,t he mechanism for the formation of yolk-shell structures may be attributed to selective or competitive adsorption of CH 3 OH and H 2 Oo n the hydrophobic backbone of ZIF-8 and microporous compounds,aswell as nanoscale Ostwald ripening.…”

Sugar-alcohol@ZIF nanocomposites display suppressed phase-change temperatures

“…It is well known that synthesis conditions have a signicant effect on ZIF crystal morphology, size, and topology. 26 Solvent selection, 33 precursor ratios, 34 reaction temperature, 35 and reaction time 36 have all been shown to play a central role in the ZIF crystallization process. ZIF-L crystals made in DI water have for example been shown to convert into ZIF-8 crystals, simply by suspending them in ethanol for 8 hours at 60 C. 30 Any or all of these factors could be responsible for our reaction having yielded a ZIF-L rather than a ZIF-8 crystal structure.…”