ABSTRACT
Quantum mechanics/molecular mechanics (QM/MM) simulations offer an efficient way to model reactions occurring in complex environments. This study introduces a specialized set of charge and Lennard-Jones parameters tailored for electrostatically embedded QM/MM calculations, aiming to accurately model both adsorption processes and catalytic reactions in zirconium-based metal-organic frameworks (Zr-MOFs). To validate our approach, we compare adsorption energies derived from QM/MM simulations against experimental results and Monte Carlo simulation outcomes. The developed parameters showcase the ability of QM/MM simulations to represent long-range electrostatic and van der Waals interactions faithfully. This capability is evidenced by the prediction of adsorption energies with a low root mean square error of 1.1 kcal mol-1 across a wide range of adsorbates. The practical applicability of our QM/MM model is further illustrated through the study of glucose isomerization and epimerization reactions catalyzed by two structurally distinct Zr-MOF catalysts, UiO-66 and MOF-808. Our QM/MM calculations closely align with experimental activation energies. Importantly, the parameter set introduced here is compatible with the widely used universal force field (UFF). Moreover, we thoroughly explore how the size of the cluster model and the choice of density functional theory (DFT) methodologies influence the simulation outcomes. This work provides an accurate and computationally efficient framework for modeling complex catalytic reactions within Zr-MOFs, contributing valuable insights into their mechanistic behaviors and facilitating further advancements in this dynamic area of research.
ABSTRACT
Metal-organic framework (MOF) in biomass valorization is a promising technology developed in recent decades. By tailoring both the metal nodes and organic ligands, MOFs exhibit multiple functionalities, which not only extend their applicability in biomass conversion but also increase the complexity of material designs. To address this issue, quantum mechanical simulations have been used to provide mechanistic insights into the catalysis of biomass-derived molecules, which could potentially facilitate the development of novel MOF-based materials for biomass valorization. The aim of this review is to survey recent quantum mechanical simulations on biomass reactions occurring in MOF catalysts, with the emphasis on the studies of the catalytic activity of active sites and the effects of organic ligand and porous structures on the kinetics. Moreover, different model systems and computational methods used for MOF simulations are also surveyed and discussed in this review.
ABSTRACT
The heterogeneous metal-organic framework Bi-BTC successfully catalyzed the synthesis of para-xylene from bio-based 2,5-dimethylfuran and acrylic acid in a promising yield (92 %), under relatively mild conditions (160 °C, 10â bar), and with a low reaction-energy barrier (47.3â kJ mol-1 ). The proposed reaction strategy also demonstrates a remarkable versatility for furan derivatives such as furan and 2-methylfuran.
ABSTRACT
We present a dielectric spectroscopy study of dipolar dynamics in the hydrated UiO-66(Zr) type metal-organic frameworks (MOFs) functionalized with -NH2 and -F groups. Experiments are performed in a broad temperature and frequency ranges allowing us to probe several dipolar relaxations. For both samples at temperature below 220 K, we observe confined supercooled water dynamics, which can be described by the Arrhenius law. At slightly higher temperature, a second less pronounced dipolar relaxation is identified, and its origin is discussed. At even higher temperature, the dielectric permittivity exhibits anomalous increase with increasing temperature due to the proton conductivity. Upon further heating, the permittivity shows a sudden decrease indicating a reversible removal of water molecules. Measurements of the dehydrated samples reveal absence of all three dipolar processes.
Subject(s)
Dielectric Spectroscopy , Metal-Organic Frameworks/chemistry , Organometallic Compounds/chemistry , Phthalic Acids/chemistry , Water/chemistry , Algorithms , Models, Chemical , Molecular Structure , TemperatureABSTRACT
Metal-organic frameworks (MOFs) nanoparticles are a class of porous crystalline materials constructed from the bonding metal ions or clusters linked with organic ligands to form frameworks. MIL-101(Cr), one of the most representative MOFs, is a three-dimensional chromium terephthalate-base porous material consisted of chromium (III)-trimers cross-linked by 1,4-benzene dicarboxylate. The present study focused on determining the safety of MIL-101(Cr) nanoparticle. The acute oral toxicity and 28-day oral toxicity in mice were investigated. An acute oral toxicity test of MIL-101(Cr) nanoparticle for female mice showed that no mortality or any significant change observed at 2000â¯mg/kg body weight. A dose-dependent 28-day oral toxicity evaluation of MIL-101(Cr) nanoparticle for male and female mice revealed no significant effects on mortality, feed consumption, body weight, organ weight, and behavior. Assessments of hematology, clinical biochemistry, and histopathology revealed no adverse effects in mice treated with MIL-101(Cr) nanoparticle (10-1000â¯mg/kg). These results suggest that MIL-101(Cr) nanoparticle has no significant acute and subacute toxicity. The no observed adverse effect level of MIL-101(Cr) nanoparticle was defined as at least 1000â¯mg/kg/day orally for 28 days for male and female mice.
