Crystal Transformation in Zeolitic-Imidazolate Framework

• Published in: Crystal growth & design Vol. 14; no. 12; pp. 6589 - 6598
• Main Authors: Low, Ze-Xian, Yao, Jianfeng, Liu, Qi, He, Ming, Wang, Zhouyou, Suresh, Akkihebbal K, Bellare, Jayesh, Wang, Huanting
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 03-12-2014
• Subjects: Condensed matter: structure, mechanical and thermal properties; Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Organic compounds; Other materials; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Porous materials; granular materials; Specific materials; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Metal organic framework; Imidazole derivatives; Scanning electron microscopy; Infrared spectroscopy; Crystal lattices; Phase transformations; Porous materials; Organometallic compounds; Crystallization; XRD; SAED; Zinc; Kinetic model; Lamellar structure; Nuclear magnetic resonance
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg501502r

The phase transformation of a zinc-2-methylimidazole-based zeolitic-imidazolate framework (ZIF), from a recently discovered ZIF-L to ZIF-8, was reported. ZIF-L is made up of the same building blocks as ZIF-8, having two-dimensional crystal lattices stacked layer-by-layer. Results indicated that the phase transformation occurs in the solid phase via the geometric contraction model (R2), a kinetic model new to ZIF. The phase transformation was monitored by means of ex situ powder X-ray diffraction, nitrogen sorption, Fourier transform infrared spectroscopy, selected-area electron diffraction, scanning electron microscopy, and in situ nuclear magnetic resonance spectroscopy. This work also demonstrates the first topotactic phase transformation in porous ZIFs, from a 2D layered structure to a 3D structure, and provides a new insight into metal–organic framework crystallization mechanisms.