Modelling the Impact of Argon Atoms on a WO Surface by Molecular Dynamics Simulations.

Machine learning potential energy functions can drive the atomistic dynamics of molecules, clusters, and condensed phases. They are amongst the first examples that showed how quantum mechanics together with machine learning can predict chemical reactions as well as material properties and even lead to new materials. In this work, we study the behaviour of tungsten trioxide (WO) surfaces upon particle impact by employing potential energy surfaces represented by neural networks.

Computational Study of Carbon Dioxide Capture by Tertiary Amines.

The reaction mechanisms and corresponding structure-activity relationships of tertiary amines with respect to CO capture have been investigated using density functional theory (DFT) calculations. The reaction mechanism for CO capture via base-catalyzed hydration to form bicarbonate is proposed to proceed in a single step involving proton transfer and the formation of a carbon-oxygen bond. Based on the height of the reaction barriers, we suggest that amines containing side chains with the ethyl group, along with a single hydroxyl group, and cyclic structures, are especially active for CO capture.

Structure to Property: Chemical Element Embeddings for Predicting Electronic Properties of Crystals.

We present a new general-purpose machine learning model that is able to predict a variety of crystal properties, including Fermi level energy and band gap, as well as spectral ones such as electronic densities of states. The model is based on atomic representations that enable it to effectively capture complex information about each atom and its surrounding environment in a crystal. The accuracy achieved for band gaps exceeds results previously published.

A polarizable valence electron density based force field for high-energy interactions between atoms and molecules.

High-accuracy molecular force field models suited for hot gases and plasmas are not as abundant as those geared toward ambient pressure and temperature conditions. Here, we present an improved version of our previous electron-density based force field model that can now account for polarization effects by adjusting the atomic valence electron contributions to match ab initio calculated Mulliken partial charges. Using a slightly modified version of the Hohenberg-Kohn theorem, we also include an improved theoretical formulation of our model when applied to systems with degenerate ground states.

Theoretical study of fructose adsorption and conversion to trioses on metal-organic frameworks.

The conversion of chemically modified biomass into more valuable chemicals has recently gained significant attention from industry. In this study, we investigate the adsorption of fructose and its conversion into two trioses, glyceraldehyde (GLA) and dihydroxyacetone (DHA), on metal-organic frameworks using density functional theory calculations. The reaction mechanism proceeds through two main steps: first, the opening of the fructose ring; second, the retro-aldol fragmentation, which is favored over intramolecular hydrogen shifts.

Investigation of the Suzuki-Miyaura cross-coupling reaction on a palladium H-beta zeolite with DFT calculations.

Metal or metal cluster-doped zeolites catalyse a wide variety of reactions. In this work, a coupling reaction between bromobenzene and phenylboronic acid to yield biphenyl with the Pd-H-Beta zeolite catalyst was investigated with density functional theory (DFT) calculations. Utilizing a model system with tetrahedral Pd clusters within the H-Beta zeolite, it was demonstrated that the catalyst exhibited notable reactivity by effectively reducing the activation energy barrier for the reaction.

Combined Experimental and Theoretical Study of the Synthesis of 5,7-Dihydroxy-4-methylcoumarin via a Pechmann Condensation in the Presence of UiO-66-SOH Catalysts.

An efficient synthesis of 5,7-dihydroxy-4-methylcoumarin from phloroglucinol with ethyl acetoacetate in the UiO-66-SOH metal-organic framework is reported. The potential of UiO-66-SOH as a solid catalyst was determined through optimized-condition experiments and quantum molecular calculations. The optimal conditions for the synthesis of 5,7-dihydroxy-4-methylcoumarin with UiO-66-SOH were as follows: phloroglucinol/ethyl acetoacetate molar ratio = 1:1.

Coordination polymer-forming liquid Cu(2-isopropylimidazolate).

The structure of the melt state of one-dimensional (1D) coordination polymer crystal Cu(isopropylimidazolate) (melting temperature = 143 °C) was characterized by DSC, variable temperature PXRD, solid-state NMR (SSNMR), viscoelastic measurements, XAS, and DFT-AIMD calculations. These analyses suggested "coordination polymer-forming liquid" formation with preserved coordination bonds above . Variable chain configurations and moderate cohesive interaction in adjacent chains are the keys to the rarely observed polymer-forming liquid.

Microcracking of Ni-rich layered oxide does not occur at single crystal primary particles even abused at 4.7 V.

There is a controversial issue based on the particle cracking of the Ni-rich layered oxide cathode materials whether it occurs at the primary particles or the grain boundary. Herein, we found that the microcracking of NMC811 does not occur at single crystalline primary particles even abused at a severe upper cell voltage of 4.7 V having a lot of gas evolution since the single-crystal NMC811 has superior mechanical stability.

Sensing the Positions in CCl and CHCl from Cl Formation upon Molecular Reduction.

The geometrical effect of chlorine atom positions in polyatomic molecules after capturing a low-energy electron is shown to be a prevalent mechanism yielding Cl. In this work, we investigated hexachlorobenzene reduction in electron transfer experiments to determine the role of chlorine atom positions around the aromatic ring, and compared our results with those using -, - and -dichlorobenzene molecules. This was achieved by combining gas-phase experiments to determine the reaction threshold by means of mass spectrometry together with quantum chemical calculations.

Understanding the interactions between lithium polysulfides and anchoring materials in advanced lithium-sulfur batteries using density functional theory.

Lithium-sulfur batteries (LSBs) are promising energy storage devices because of their high theoretical capacity and energy density. However, the "shuttle" effect in lithium polysulfides (LiPSs) is an unresolved issue that can hinder their practical commercial application. Research on LSBs has focused on finding appropriate materials that suppress this effect by efficiently anchoring the LiPSs intermediates.

Metal triflate formation of C-C phenolic compounds by the simultaneous C-O breaking and C-C coupling of benzyl phenyl ether.

Catalytic pathways to produce high carbon number compounds from benzyl phenyl ether require multiple steps to break the aryl etheric carbon-oxygen bonds; these steps are followed by energy-intensive processes to remove oxygen atoms and/or carbon-carbon coupling. Here, we show an upgrading strategy to transform benzyl phenyl ether into large phenolic (C-C) compounds by a one-step C-O breaking and C-C coupling catalyzed by metal triflates under a mild condition (100 °C and 1 bar). Hafnium triflate was the most selective for the desired products.

Adsorption and dehydration of ethanol on isomorphously B, Al, and Ga substituted H-ZSM-5 zeolite: an embedded ONIOM study.

Dehydration reactions are important in the petroleum and petrochemical industries, especially for the feedstock production. In this work, the catalytic activity of zeolites with different acidities for the dehydration of ethanol to ethylene and diethylether is investigated by density functional calculations on cluster models of three isomorphous B, Al, and Ga substituted H-ZSM-5 zeolites. Both unimolecular and bimolecular mechanisms are investigated.

Electronic structure and reactivity of tirapazamine as a radiosensitizer.

Tirapazamine (TP) has been shown to enhance the cytotoxic effects of ionizing radiation in hypoxic cells, thus making it a candidate for a radiosensitizer. This selective behavior is often directly linked to the abundance of O. In this paper, we study the electronic properties of TP in vacuum, micro-hydrated from one up to three molecules of water and embedded in a continuum of water.

Density Functional Investigation of the Conversion of Furfural to Furfuryl Alcohol by Reaction with -Propanol over UiO-66 Metal-Organic Framework.

Carbonyl C═O bond reduction via catalytic transfer hydrogenation (CTH) is one of the essential processes for biomass conversion to valuable chemicals and fuels. Here, we investigate the CTH of furfural to furfuryl alcohol with -propanol on UiO-66 metal-organic frameworks using density functional theory calculations and linear scaling relations. Initially, the reaction over two defect sites presented on Zr-UiO-66, namely, dehydrated and hydrated sites, have been compared.

Effects of single and double active sites of Cu oxide clusters over the MFI zeolite for direct conversion of methane to methanol: DFT calculations.

In this work, we investigate the effect of various species of Cu oxide clusters including single and double active sites incorporated in the MFI zeolite framework for the direct conversion of methane to methanol. An M06-2X density functional calculation is employed to fine-tune the suitable number and species of active sites and to provide insights into the effect of the active sites on the reaction mechanism of methane to methanol. Two models, single and double active sites of Cu oxide clusters, have been chosen, in which the single active site of Cu oxide clusters, (mono(μ-oxo)dicopper(ii)), is located at the Al1'-Al12' pair ([Cu(μ-O)Cu]2+@Al1'-Al12'/MFI) or at the Al6-Al7 pair ([Cu(μ-O)Cu]2+@Al6-Al7/MFI) in the MFI framework.

Effect of Intercalants inside Birnessite-Type Manganese Oxide Nanosheets for Sensor Applications.

Hydrazine is a common reducing agent widely used in many industrial and chemical applications; however, its high toxicity causes severe human diseases even at low concentrations. To detect traces of hydrazine released into the environment, a robust sensor with high sensitivity and accuracy is required. An electrochemical sensor is favored for hydrazine detection owing to its ability to detect a small amount of hydrazine without derivatization.

Chiral Macroporous MOF Surfaces for Electroassisted Enantioselective Adsorption and Separation.

The development of surfaces with chiral features is a fascinating challenge for modern materials science, especially when they are used for chiral separation technologies. In this contribution, the design of hierarchically structured chiral macroporous zeolitic imidazolate framework-8 (ZIF-8) electrodes is presented. They are elaborated by an electrochemical deposition-dissolution technique based on the electrodeposition of metal through a colloidal crystal template, followed by controlled electrooxidation.

Dehydrogenation of ethanol to acetaldehyde with nitrous oxide over the metal-organic framework NU-1000: a density functional theory study.

The conversion of ethanol to more valuable hydrocarbon compounds receives great attention in chemical industries because it could diminish the dependency on petroleum as raw material. We investigate the catalytic performance of Fe-supported MOF NU-1000 for the dehydrogenation of ethanol to acetaldehyde with nitrous oxide (N2O) by deriving the relevant reaction profiles with density functional theory calculations. In the proposed mechanism, the activation barrier of the rate-determining step is almost four times lower in the presence of N2O than without it.

Nanocavity effects of various zeolite frameworks on n-pentane cracking to light olefins: combination studies of DFT calculations and experiments.

Better control of the product selectivity of light olefins (e.g., ethylene and propylene) obtained from the n-pentane catalytic cracking process has attracted considerable attention from both scientific and petrochemical industrial points of view.

Theoretical study of methane adsorption and C─H bond activation over Fe-embedded graphene: Effect of external electric field.

The effect of an external electric field (EF) on the methane adsorption and its activation on iron-embedded graphene (Fe-GPs) are investigated by using the M06-L density functional method. The EF is applied in the perpendicular direction to the graphene in the range of -0.015 to +0.

Phenol Tautomerization Catalyzed by Acid-Base Pairs in Lewis Acidic Beta Zeolites: A Computational Study.

We investigate the tautomerization of phenol catalyzed by acid-base active pair sites in Lewis acidic Beta zeolites by means of density functional calculations using the M06-L functional. An analysis of the catalytic mechanism shows that hafnium on the Beta zeolite causes the strongest absorption of phenol compared to zirconium, tin, and germanium. This can be rationalized by the highest delocalization of electron density between the Lewis site and the oxygen of phenol which can in turn be quantified by the perturbative E stabilization energy.

Computational study of the carbonyl-ene reaction between formaldehyde and propylene encapsulated in coordinatively unsaturated metal-organic frameworks M(btc) (M = Fe, Co, Ni, Cu and Zn).

The carbonyl-ene reaction between encapsulated formaldehyde and propylene over the coordinatively unsaturated metal-organic frameworks M3(btc)2 (M = Fe, Co, Ni, Cu and Zn) has been investigated by means of density functional calculations. Zn3(btc)2 adsorbs formaldehyde strongest due to electron delocalization between Zn and the oxygen atom of the reactant molecule. The reaction is proposed to proceed in a single step involving proton transfer and carbon-carbon bond formation.

Insights into the reaction mechanism of n-hexane dehydroaromatization to benzene over gallium embedded HZSM-5: effect of H incorporated on active sites.

The catalytic dehydroaromatization of alkanes to aromatics has attracted considerable attention from the scientific community, because it can be used for the upgrading of low-cost alkanes into high added-value aromatics, such as benzene, toluene, and xylene (BTX). In this context, we report the reaction mechanism of n-hexane dehydroaromatization to benzene over two different reduced gallium species embedded in HZSM-5, including univalent Ga+ embedded in HZSM-5 (Ga/HZSM-5) and dihydrido gallium complex (GaH2+) embedded in HZSM-5 (GaH2/HZSM-5) by using the M06-2X/6-31G(d,p) level of calculation. The reaction proceeds by following two main steps: (i) the dehydrogenation of hexane to haxa-1,3,5-triene; (ii) the dehydroaromatization of haxa-1,3,5-triene to benzene.

Novel Hybrid Energy Conversion and Storage Cell with Photovoltaic and Supercapacitor Effects in Ionic Liquid Electrolyte.

A single hybrid energy conversion and storage (HECS) cell of alpha-cobalt hydroxide (α-Co(OH)) in ionic liquid was fabricated and operated under light illumination. The α-Co(OH), which is unstable in an aqueous electrolyte (i.e.