Storage and Diffusion of Carbon Dioxide in the Metal Organic Framework MOF-5─A Semi-empirical Molecular Dynamics Study

Polarity profiling of porous architectures: solvatochromic dye encapsulation in metal-organic frameworks

Metal-organic frameworks (MOFs) have gathered significant interest due to their tunable porosity leading to diverse potential applications. In this study, we investigate the incorporation of the fluorosolvatochromic dye 2-butyl-5,6-dimethoxyisoindoline-1,3-dione ([double bond, length as m-dash]Phth) into various MOF structures as a means to assess the polarity of these porous materials. As a purely inorganic compound, zeolite Y was tested for comparison. The fluorosolvatochromic behavior of Phth, which manifests as changes in its emission spectra in response to solvent polarity, provides a sensitive probe for characterizing the local environment within the MOF pores. Through systematic variation of the MOF frameworks, we demonstrate the feasibility of using (fluoro-)solvatochromic dyes as probes for assessing the polarity gradients within MOF structures. Additionally, the fluorosolvatochromic response was studied as a function of loading amount. Our findings not only offer insights into the interplay between MOF architecture and guest molecule interactions but also present a promising approach for the rational design and classification of porous materials based on their polarity properties.

Towards hybrid quantum mechanical/molecular mechanical simulations of Li and Na intercalation in graphite - force field development and DFTB parametrisation

In this work a previously established QM/MM simulation protocol for the treatment of solid-state interfaces was extended towards the treatment of layered bulk materials enabling for instance investigation of metal intercalation in graphitic carbon materials. In order to study the intercalation of Li in graphite, new density functional tight binding (DFTB) parameters for Li have been created. Molecular dynamics (MD) simulations at constant temperatures (273.15, 298.15 and 323.15 K) have been carried out to assess the performance of the presented DFTB MD simulation approach. The intercalation of variable lithium and sodium content was investigated via z-distribution functions and analysis of the diffusivity in the direction parallel to the graphene plane. Both the calculated diffusion coefficients and the activation energy in case of lithium are in good agreement with experimental data. The comparison of the QM/MM MD simulation results provide detailed insights into the structural and dynamical properties of intercalated metal ions.