Toluene-assisted synthesis of RHO-type zeolitic imidazolate frameworks: synthesis and formation mechanism of ZIF-11 and ZIF-12.
Toluene was discovered as the structure template for the synthesis of large-cage RHO-type zeolitic imidazolate frameworks (ZIF-11 and ZIF-12) in an alcohol-based solution where benzimidazole-toluene interactions play a decisive structure-directing role; otherwise it leads to small-cage SOD-type ZIF-7 and ZIF-9 without toluene. The specific π-π interactions make toluene molecules adopt a specific and oriented arrangement in the unit cell. XRD intensity of the (100) plane is strongly dependent on the amount of toluene: apparent intensity degradation is observed after removing toluene by solvent exchange or thermal treatment, and the peak intensity is recoverable by filling of the pores with toluene vapor. More-polar methanol as compared to ethanol is favorable for the formation of RHO-type ZIFs due to the enhanced interactions between toluene and imidazolate linkers.
College of Science, Nanjing Forestry University, Jiangsu 210037, China.
Ming
M
He
Jianfeng
J
Yao
Qi
Q
Liu
Zhaoxiang
Z
Zhong
Huanting
H
Wang
D000431:Ethanol / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D033362:Powder Diffraction; D012997:Solvents / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014050:Toluene / Q000737:chemistry*; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry*
D007093:Imidazoles; D012997:Solvents; D017641:Zeolites; D014050:Toluene; D000431:Ethanol; D000432:Methanol