Effects of Acid Modulators on the Microwave-Assisted Synthesis of Cr/Sn Metal-Organic Frameworks

Abstract

Metal-organic frameworks (MOFs) have attracted remarkable attention for their distinguished structural designability. Precisely controlling the particle size and improving the structural stability of MOF nanoparticles influence their catalytic activity significantly. In this study, six acids (nitric, hydrochloric, formic, acetic, succinic, and citric acids) were used as modulators to prepare bimetallic MIL-101(Cr, Sn) (MIL stands for Materials of Institut Lavoisier) via a microwave-assisted hydrothermal method. Changes in volumetric, structural, stability, and catalytic properties, size, and shape of MIL-101 (Cr, Sn) were examined using scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, and N2 adsorption–desorption measurements. All modulators altered the MOF properties. Compared with other samples, acetic acid as a modulator mildly altered the MOF morphology by narrowing their particle size distribution, enhancing the specific surface area, and significantly improving their water and thermal stabilities. The addition of acetic acid was suitable for the catalytic conversion of glucose to 5-hydroxymethylfurfural (5-HMF), achieving a 43.1% 5-HMF yield with 91.4% glucose conversion in a mixed solution of γ-valerolactone and saturated salt water at 150 °C after 30 min.

Advancing stroke therapy: the potential of MOF-based nanozymes in biomedical applications

“…In instances where metal-ligand bonds exhibit exceptional strength, modulators are used to prevent the rapid precipitation of amorphous material. Modulators, such as benzoic acid, acetic acid, or hydrochloric acid, establish dynamic bonds with the metal precursor, competing with the linkers for metal coordination sites (Sugamata et al, 2020;Mao et al, 2022). They play a crucial role in the synthesis of Zr-MOFs, which contain robust Zr (IV)−O bonds.…”

Coordination modulation: a way to improve the properties of metal–organic frameworks

“…The presence of HF modulator has been demonstrated to be effective in controlling morphology, size and volume of pores, and acidity of the reaction medium during the synthesis of MOFs. 50,55,56 In addition to the direct competition with the linkers, the anion of the inorganic acid modulator also contributes to charge balancing. This signicantly inuences the process of self-assembly of the MOF.…”

“…The presence of HF modulator has been demonstrated to be effective in controlling morphology, size and volume of pores, and acidity of the reaction medium during the synthesis of MOFs. 50,55,56…”

Metal-organic frameworks for efficient drug adsorption and delivery

“…The use of TFA has been proven to create more active sites, while HF used during MOF synthesis increases the crystallinity and porosity of the material [161][162][163]. Formic acid, acetic acid, or hydrochloric acid affect the increase in the number of crystals and the number of defects and crystallinity, while benzoic acid, can control both the number and size of crystals and defects [83,[164][165][166]. There are two main types of defects called missing linker and missing cluster.…”