The role of thermodynamically stable configuration in enhancing crystallographic diffraction quality of flexible MOFs
He Zhao,
Jiaxiang Huang,
Pei-Pei Zhang,
Jian-Jun Zhang,
Wang-Jian Fang,
Xue-Dan Song,
Shuqin Liu,
Chunying Duan
Affiliations
He Zhao
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China; School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Jiaxiang Huang
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Pei-Pei Zhang
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Jian-Jun Zhang
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China; School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China; Corresponding author
Wang-Jian Fang
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Xue-Dan Song
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Shuqin Liu
School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China
Chunying Duan
State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, China; Zhang Dayu College of Chemistry, Dalian University of Technology, Dalian 116024, China; Corresponding author
Summary: Single-crystal X-ray diffraction (SCXRD) is a widely used method for structural characterization. Generally, low temperature is of great significance for improving the crystallographic diffraction quality. Herein we observe that this practice is not always effective for flexible metal-organic frameworks (f-MOFs). An abnormal crystallography, that is, more diffraction spots at a high angle and better resolution of diffraction data as the temperature increases in the f-MOF (1-g), is observed. XRD results reveal that 1-g has a reversible anisotropic thermal expansion behavior with a record-high c-axial positive expansion coefficient of 1,401.8 × 10−6 K−1. Calculation results indicate that the framework of 1-g has a more stable thermodynamic configuration as the temperature increases. Such configuration has lower-frequency vibration and may play a key role in promoting higher Bragg diffraction quality at room temperature. This work is of great significance for how to obtain high-quality SCXRD diffraction data.
