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Keywords:

  • metal acetate salt;
  • metal–organic frameworks;
  • N,N′-dimethylformamide;
  • rapid synthesis;
  • solvent effects;
  • zeolitic imidazolate framework

Abstract

In this study, a new method was developed for the rapid and cost-effective synthesis of nanosized zeolitic imidazolate framework-7 (ZIF-7) nanocrystals with a high yield and a low molar ratio of benzimidazole ligand to metal salt (2:1) by using N,N′-dimethylformamide (DMF) as the solvent and zinc acetate dihydrate (Zn(OAc)2⋅2 H2O) as the metal source. The synthesized ZIF-7 nanocrystals have a size of approximately 50–80 nm, and tend to aggregate or become intergrown to form irregular nanoparticles of about 200–300 nm in size. The morphology and yield of the ZIF-7 nanocrystals can be tuned easily by changing the synthetic parameters such as the composition of the solvent and concentrations of reagents. The synthesized ZIF-7 nanocrystals exhibit good thermal and chemical stability, CO2 capture capability, and fluorescent properties. Remarkably, we find that the synthetic strategy developed here can be extended to the syntheses of other kinds of ZIFs including ZIF-69 and ZIF-90. This study offers a new, simple synthetic strategy for the high-yield preparation of ZIF materials.