Gel-based morphological design of zirconium metal–organic frameworks

Abstract

The ability of zirconium metal–organic frameworks (MOFs) to gelate under specific synthetic conditions opens up new opportunities in the preparation and shaping of hierarchically porous MOF monoliths, which could be directly implemented for catalytic and adsorptive applications.

Assessing Crystallisation Kinetics of Zr Metal–Organic Frameworks through Turbidity Measurements to Inform Rapid Microwave‐Assisted Synthesis

“…Scherrer analysis of the main Bragg reflection at 2 θ =7.32° gives a particle size of 10.4 nm, correlating well with the SEM images. Nanocrystal formation is consistent with the use of zirconyl chloride in solvothermal syntheses which also produces particularly small particles . These conditions led to the synthesis of a gel, which upon washing and drying gave a solid pellet which was ground down for analysis.…”

“…For example, the possibility of ZrCl 4 hydrolysing in humid air, reacting with one mole of H 2 O to form ZrOCl 2 and two moles of HCl, is a process which may lead to reproducibility issues as potential molecular influences on kinetics are consumed (H 2 O) and released (HCl) . Additionally, ZrOCl 2 is thought to be a precursor to the hexanuclear SBU of UiO‐66; its direct use as source of Zr leads to very small nanoparticles and gels, suggesting rapid nucleation.…”

Self‐Assembly of Metal–Organic Frameworks into Monolithic Materials with Highly Controlled Trimodal Pore Structures

“…These results demonstrate an ew strategy for designing trimodal porous structures in network-forming monolithic materials.T he self-assembly-induced phase separation process has been successfully applied to the sol-gel process of Zr-BDC-NH 2 type metal-organic frameworks.M acroporous structures of the samples were controlled by freezing the transient structures of phase separation at different timing. By choosing appropriate reorganization conditions,t he low crystalline Zr-BDC-NH 2 frameworks were converted to crystalline UiO-66-NH 2 with controllable mesopore size distributions.Extending this approach to other type of MOFs should permit the design of microporous structures with suitable meso-/macroporous structures for applications.W e believe that this two-step structural ordering process of MOFs can be extended to other type of MOFs,s uch as other zirconium-based MOFs, [23] aluminum-based MOFs, [10] ironbased MOFs, [9,10] and chromium-based MOFs, [45] because sol-gel transition behaviors of these MOFs have been reported. In addition, the acceleration and suppression of the crystallization tendencyo ft he MOFs have been investigated over the past decade.…”

“…In this study,a saproof of concept, we focused on Zrbased UiO-66 type MOF,which undergoes sol-gel transition by self-assembly of Zr clusters and terephthalic acid. [11,22,23] TheM OF UiO-66, with the formula [Zr 6 O 4 (OH) 4 (bdc) 6 ] (bdc = 1,4-benzenedicarboxylate), is one of the most important MOFs owing to its high thermal, chemical, and mechanical stabilities, [24,25] and has been increasingly studied for av ariety of applications for example,c atalyst, [26,27] catalyst support, [28,29] adsorbent, [30] gas storage medium, [11] and liquid or gas separation medium. [31,32] We used 2-aminoterephthalic acid (BDC-NH 2 )a so rganic linker to obtain UiO-66-NH 2 because of its good solubility in solvents such as N,Ndimethylformamide (DMF).…”

Synthesis, characterization and luminescence properties of ZrBDC:Eu3+,Tb3+ nanoscaled metal organic frameworks

“…[7,8] Currently, there are many ways of preparing the ZrO2:RE 3+ nanomaterials, such as colloidal, coprecipitation, combustion, sol-gel, sonochemistry, hydrothermal and microwave-assisted methods. [7][8][9] Nowadays, there is an emerging trend in preparing the ZrO2 nanoparticles based metal organic frameworks. [10] In this study, we used the nanoscaled metal organic frameworks of ZrBDC:RE 3+ as precursors for the manufacture of ZrO2:RE 3+ nanoparticles (RE = Eu, Tb) via heat treatment process at 800 o C for 1 hour.…”