Impact of Linker Defects on the Dielectric Properties of the Metal-Organic Framework HKUST-1: Insights from Molecular Dynamics Simulations

Ultra-low dielectric materials are essential for the modern microelectronics industry, and metal-organic frameworks (MOFs) are promising candidates for the next generation of such materials. In this work, we use molecular dynamics simulations and the generic UFF4MOF force field to predict how missing linker defects influence the dielectric properties of a very well-known MOF like HKUST-1. The thermalized Drude oscillators are introduced to develop the DO-UFF4MOF force field for the polarization response of the MOF framework. This polarizable force field is first benchmarked against the dielectric constant of pristine HKUST-1 and then applied to simulate derivatives containing missing linker defects. Our simulations suggest that a defect engineering approach could effectively reduce the dielectric susceptibility by up to ca. 30%, potentially achieving the lowest dielectric constant for this framework type (kappa = 1.5). We observe a linear correlation between the dielectric constant and the concentration of linker defects, driven by a strong reduction in material polarizability that significantly outweighs the decrease in mass density. Furthermore, even low concentrations of missing linker defects substantially accelerate the dielectric relaxation.