Synthesis of Metal-Organic Framework Cr-MIL-101 by a 4-Nitroimidazole-Assistant Route

In this work, the function of 4-nitroimidazole (4-NIm) in the formation of Cr-MIL-101 was confirmed. It was found that 4-NIm is an effective additive in the formation of Cr-MIL-101 synthesized at lower temperature. The investigation of crystallization time showed that 4-NIm can prevent Cr-MIL-101 phase converting into Cr-MIL-53 phase. The effect of concentration of 4-NIm on the morphology and the yield of Cr-MIL-101 may therefore be explained by increasing the nucleation rate. The investigation of crystallization temperature revealed that 4-NIm changes the synthesis temperature range of Cr-MIL-101 into 423–463 K. The assistant function of 4-NIm was played through interaction with H + and NO 3 − in the synthesis system, which may lead to enhancement of the deprotonation of H 2 BDC.