Evolution of Local Structure and Pore Architecture during Zeolitic Imidazolate Framework-L to Zeolitic Imidazolate Framework-8 Phase Transformation Investigated Using Raman, Extended X-ray Absorption, and Positron Annihilation Lifetime Spectroscopy

• DOI: 10.1021/acs.chemmater.3c00292
• Publication Date: 2023-08-16T17:22:20Z
• Authors: Jaideep Mor; Pranav Utpalla; Ravi Kumar; Jitendra Bahadur; Sandeep Kumar Sharma
• Keywords: Zeolitic imidazolate framework; Sodalite; Imidazolate; Linker; Positron annihilation spectroscopy

Zeolitic imidazolate framework-leaf (ZIF-L) is transformed to ZIF-8 through a topotactic phase transformation. This transformation driven by the removal of hydrogen-bonded linker molecules from 2D galleries ZIF-L, leading distortion in structure. Investigation crystallization kinetics ZIF-L shows that crystalline particles are formed within first minute, and growth leaf-type structures finished nearly 10 minutes. During transformation, leaf-like cleaved 3D nanocrystals. The chemical bonding structure investigated Fourier transform infrared Raman spectroscopy shifting narrowing characteristic peaks stretching modes corresponding Zn–N during It confirms distortions occur phase. X-ray absorption modifications local around Zn atom due reorientation fully bridged without affecting bond distances basic ZnN4 tetrahedral unit or ZIF-8. Pore architecture evolution positron annihilation lifetime spectroscopy. pores initially expanded with decrease their number density breakdown walls intercalated molecules. With increase phase, channel network sodalite topology along inter-crystalline voids gradually produced. A significant pore tuning achieved depending on time, which can be utilized for enhancement gas separation efficiency ZIF-8- ZIF-L-based membranes.