Modeling and Simulation of Crystallization of Metal–Organic Frameworks

Abstract

Metal–organic frameworks (MOFs) are the porous, crystalline structures made of metal–ligands and organic linkers that have applications in gas storage, gas separation, and catalysis. Several experimental and computational tools have been developed over the past decade to investigate the performance of MOFs for such applications. However, the experimental synthesis of MOFs is still empirical and requires trial and error to produce desired structures, which is due to a limited understanding of the mechanism and factors affecting the crystallization of MOFs. Here, we show for the first time a comprehensive kinetic model coupled with population balance model to elucidate the mechanism of MOF synthesis and to estimate size distribution of MOFs growing in a solution of metal–ligand and organic linker. The oligomerization reactions involving metal–ligand and organic linker produce secondary building units (SBUs), which then aggregate slowly to yield MOFs. The formation of secondary building units (SBUs) and their evolution into MOFs are modeled using detailed kinetic rate equations and population balance equations, respectively. The effect of rate constants, aggregation frequency, the concentration of organic linkers, and concurrent crystallization of organic linkers are studied on the dynamics of SBU and MOF formation. The results qualitatively explain the longer timescales involved in the synthesis of MOF. The fundamental insights gained from modeling and simulation analysis can be used to optimize the operating conditions for a higher yield of MOF crystals.

Ultrasound-Assisted Synthesis of Luminescent Micro- and Nanocrystalline Eu-Based MOFs as Luminescent Probes for Heavy Metal Ions

“…This state is called the “pre-equilibrium”. Further nucleation is associative and fast because the central atom has several weakly coordinated solvent molecules and can easily react with other 1:1 complexes resulting in the formation of oligomeric secondary building units (SBUs) [ 31 ]. Increasing the concentration of the metal ions and the organic linker leads to the domination of 1:2 and 1:3 M:L complexes.…”

Current Research Trends and Perspectives on Solid-State Nanomaterials in Hydrogen Storage

“… (a) Schematic illustration of the mechanism and formation of metal-organic frameworks (MOFs) [ 102 ]. (b) Chemical structure of BDC and MOF-5 and (c) BDC and MOF-177.…”

“…The structures of MOFs are reproduced with permission [ 109 ]. Reproduced with permission [ 102 ]. Copyright 2019, Multidisciplinary Digital Publishing Institute.…”

Modeling the Layer-by-Layer Growth of HKUST-1 Metal-Organic Framework Thin Films

“…Available theoretical strategies that can be considered to investigate the growth of MOFs include ab initio approaches, in particular, Density Functional Theory (DFT), force-field-based Molecular Dynamics (MD), Monte Carlo (MC) methods, as well as other numerical schemes such as the kinetic model [ 20 ], and the coupling of a kinetic model with a population balance model [ 21 ]. The crystallization of MOFs is a complex process that requires complex models.…”