Solid-State Synthesis of Defect-Rich Zr-UiO-66 Metal–Organic Framework Nanoparticles for the Catalytic Ring Opening of Epoxides with Alcohols

Abstract

Perfect crystals do not exist; however, the introduction of defects can tailor the physical and chemical properties of materials. Defects in metal−organic frameworks (MOFs) have been demonstrated to be important in many applications, including but not limited to catalysis, gas separation, and energy storage. While a few liquid-phase synthesis methods have been reported to prepare defect-rich UiO-66, the heavy use of organic solvents may cause irreversible environmental problems. Here, we present a green, rapid, and facile solid-state synthesis approach to prepare UiO-66. All UiO-66 crystals remain in the nanometer size due to the limited diffusivity of growth species in solid-state synthesis without a large quantity of the solvent. The defect concentrations can be fine-tuned by the content of ethanol addition. Defect-rich UiO-66 shows excellent catalytic activity to the ring opening of epoxides with alcohols. This work provides insights into the large-scale production of defect-rich MOFs.

Insights into the Solid-State Synthesis of Defect-Rich Zr–UiO-66

“…We anticipated that chlorine could not be completely replaced by H 2 BDC during the solid-state synthesis, as demonstrated by the previous report. 31 As shown in Figure 3d, two main peaks corresponding to the Zr 3d 3/2 (185.24 eV) and Zr 3d 5/2 (182.86 eV) could be found in UiO-66−S. The Zr 3d fine spectra of UiO-66−MeOH and UiO-66−EtOH were close to UiO-66−S.…”

“…The typical synthesis procedure for UiO-66 was modified based on our previous work. 31 The entire MOF−X− Y (X: organic modulator; Y equiv. X to Zr) series could be synthesized by using a variety of organic ligands (H 2 BDC, H 2 BDC− NH 2 , H 2 BDC−Br, and DMT) and different amounts of added organic modulators [DMF, DEF, MeOH, EtOH, PrOH, BuOH, HeOH, 2-PrOH, 2-BuOH, HOAc, EtOAc, and OC(CH 3 ) 2 ] at their boiling points, respectively.…”

“…The UiO-66−S could be produced based on previous reports. 31,32 Ring-Opening of Epoxides with Alcohols. In a typical experiment, a 15 mL glass vial with solid catalyst (10 mg), styrene oxide (0.5 mmol), and MeOH (0.05 mol) was kept at 55 °C for different times under stirring.…”

“…29,30 In addition, our group successfully synthesized UiO-66 using ZrCl 4 as the metal source through ethanol (EtOH)-vapor-induced solid-state synthesis. 31 Herein, we have successfully synthesized Zr-MOFs with SBUs via a solid-state conversion approach using simple salts (ZrCl 4 ) (Figure 1). The reaction proceeds simply by heating premixed organic ligands (H 2 BDC, H 2 BDC−Br, and H 2 BDC− NH 2 ) and metal salts with a minimized amount of organic modulator.…”

“…Generally, UiO-66 is synthesized using N , N -dimethylformamide (DMF) as the solvent and carboxylic acid as the modulator . Using the solid-state synthetic approach to produce UiO-66 has been reported recently. ,,− For example, UiO-66 could be synthesized using preconstructed Zr 6 or Zr 12 clusters with additives through solid-state synthesis. , Costantino and co-workers had reported that UiO-66 could be synthesized by grinding precursors and a small amount of modulator or solvents. An accelerated aging step at a certain temperature was also required. , In addition, our group successfully synthesized UiO-66 using ZrCl 4 as the metal source through ethanol (EtOH)-vapor-induced solid-state synthesis .…”