Contributions of metalloporphyrin linkers and Zr6 nodes in gas adsorption on a series of bioinspired zirconium-based metal-organic frameworks: A computational study

In this study, gases adsorption on a series of mesoporous zirconium-based metal-organic framework analogues [PCN-222(M) where M = Mg, Fe, Co, Ni, Cu, and Zn)] has been evaluated by quantum mechanical calculations. These bioinspired frameworks are one of the most stable MOF materials, comprising the metalloporphyrin linkers/building blocks and the Zr6 nodes. The metalloporphyrins, open-zirconium coordination sites, and terminal hydroxyl groups on the nodes have been considered for the interactions. The structural and electronic properties of the complexes were investigated via the atoms in molecules (AIM), natural bond orbital (NBO), and harmonic oscillator model of aromaticity (HOMA) index. The results showed that the iron-porphyrin is an appropriate candidate for the ammonia capture. It is observed that the hydrogen bond interactions of H2O with the hydroxyl groups of node are stronger than the others, while the interactions of NH3 with the open-zirconium coordination sites are stronger than the others. The all results indicated that the PCN-222(Fe) is selective for adsorption of NH3 over the other gases.