Phase-Selective Microwave Assisted Synthesis of Iron(III) Aminoterephthalate MOFs

Abstract

Iron(III) aminoterephthalate Metal-Organic Frameworks (Fe-BDC-NH2 MOFs) have been demonstrated to show potential for relevant industrial and societal applications (i.e., catalysis, drug delivery, gas sorption). Nevertheless, further analysis is required in order to achieve their commercial production. In this work, a systematic synthetic strategy has been followed, carrying out microwave (MW) assisted hydro/solvothermal reactions to rapidly evaluate the influence of different reaction parameters (e.g., time, temperature, concentration, reaction media) on the formation of the benchmarked MIL-101-NH2, MIL-88B-NH2, MIL-53-NH2 and MIL-68-NH2 solids. Characterization of the obtained solids by powder X-ray diffraction, dynamic light scattering and transmission electron microscopy allowed us to identify trends to the contribution of the evaluated parameters, such as the relevance of the concentration of precursors and the impact of the reaction medium on phase crystallization. Furthermore, we presented here for the first time the MW assisted synthesis of MIL-53-NH2 in water. In addition, pure MIL-101-NH2 was also produced in water while MIL-88-NH2 was the predominant phase obtained in ethanol. Pure phases were produced with high space-time yields, unveiling the potential of MW synthesis for MOF industrialization.

Historical Developments in Synthesis Approaches and Photocatalytic Perspectives of Metal-Organic Frameworks

“…Microwave-assisted synthesis methods make use of the interaction of electromagnetic waves with polar solvent ionic species (Figure 10). MIL-101(Fe) was synthesized at 150°C using dimethyl formamide, with a yield of 20% and particle sizes similar to 200 nm [51]. Increasing the concentration of water or the pH reduced crystal size.…”

Iron-Based Metal–Organic Frameworks in Drug Delivery and Biomedicine

“…In a study laying the foundations of green industrial synthesis of MOFs, a microwave-assisted procedure was used to synthesize MIL-53(Fe)-NH 2 and MIL-101(Fe)-NH 2 in water and MIL-88B(Fe)-NH 2 in ethanol. 29 2.4. Dry Gel Conversion Synthesis.…”

“…Other metals or rare-earth elements have been introduced as dopants into the structure of MIL-100 (Fe), leading to bimetallic MIL-100 (Fe, M) materials. In a study laying the foundations of green industrial synthesis of MOFs, a microwave-assisted procedure was used to synthesize MIL-53­(Fe)-NH 2 and MIL-101­(Fe)-NH 2 in water and MIL-88B­(Fe)-NH 2 in ethanol …”

Multivariate metal–organic framework MTV-MIL-101 via post-synthetic cation exchange: is it truly achievable?

“…On the other side, reconsidering the type of solvent involved has been one of the key parameters for the synthesis of other single-metal MIL-101s from many trivalent metals other than chromium. 12,13,17,65,66 Other studies dealing with the synthesis of mixed-metal MOFs through PSE have carefully considered the used solvent and the conditions applied during the process to match those applied during direct synthesis. 67,68 For our case, MIL-101(Fe) has often been reported to be prepared from a FeCl 3 solution in N,N-dimethylformamide (DMF) at a temperature ranging from 110 °C to 150 °C.…”