Understanding the Crystal Structure of Heterometallic Metal-Organic Frameworks in Cadmium Imidazolate Framework-1 with Periodic Density Functional Theory

摘要

Determining the effect of mixed-metal in metal-organic frameworks (MOFs) is vital to understand the crystal structure and its related properties. The tunability of MOFs provides an opportunity to develop functionalized materials with a specific task. Herein, cadmium imidazolate framework-1 (CdIF-1) as part of MOFs was investigated through a computational approach regarding its possibility for the formation of mixed-metal CdIF-1. The studies were performed by replacing Cd~(2+) ions in the crystal structure of CdIF-1 with Zn~(2+) ions to obtain several possible configurations of heterometallic CdIF-1. The calculations were conducted using periodic density functional theory (DFT) with the addition of dispersion correction scheme. Several aspects in the crystal structure were investigated such as the changing in the lattice parameters and unit cell volume, and the bond properties. Replacing several Cd~(2+) ions with Zn~(2+) would affect the crystal structure particularly lattice parameters and pore diameters. When all the Cd~(2+) ions were replaced with Zn~(2+) ions, a new crystal phase was obtained to give zeolitic imidazolate framework-8 (ZIF-8) material. This study provides an insight into the mechanism in which CdIF-1 is transformed into new crystal phase of ZIF-8.