Assessment and Optimization of Configurational-Bias Monte Carlo Particle Swap Strategies for Simulations of Water in the Gibbs Ensemble

Particle swap moves between phases are usually the rate-limiting step for Gibbs ensemble Monte Carlo (GEMC) simulations of fluid phase equilibria at low reduced temperatures because the acceptance probabilities for these moves can become very low for molecules with articulated architecture and/or highly directional interactions. The configurational-bias Monte Carlo (CBMC) technique can greatly increase the acceptance probabilities, but the efficiency of the CBMC algorithm is influenced by multiple parameters. In this work we assess the performance of different CBMC strategies for GEMC simulations using the SPC/E and TIP4P water models at 283, 343, and 473 K, demonstrate that much higher acceptance probabilities can be achieved than previously reported in the literature, and make recommendations for CBMC strategies leading to optimal efficiency

TraPPE-zeo: Transferable Potentials for Phase Equilibria Force Field for All-Silica Zeolites

The transferable potentials for phase equilibria (TraPPE) force field is extended to all-silica zeolites. This novel force field is parametrized to match the experimental adsorption isotherms of <i>n</i>-heptane, propane, carbon dioxide, and ethanol with the Lennard-Jones parameters for sorbate–framework interactions determined in a consistent manner using the Lorentz–Berthelot combining rules as for other parts of the TraPPE force field. The TraPPE-zeo force field allows for accurate predictions for both adsorption and diffusion of alkanes, alcohols, carbon dioxide, and water over a wide range of pressures and temperatures. In order to achieve transferability to a wider range of molecule types, ranging from nonpolar to dipolar and hydrogen-bonding compounds, Lennard-Jones interaction sites and partial charges are placed at both the oxygen and the silicon atoms of the zeolite lattice, which allows for a better balance of dispersive and first-order electrostatic interactions than is achievable with the Lennard-Jones potential used only for the oxygen atoms. The use of the Lorentz–Berthelot combining rules for unlike interactions makes the TraPPE-zeo force field applicable to any sorbate as long as the relevant TraPPE sorbate–sorbate parameters are available. The TraPPE-zeo force field allows for greatly improved predictive power compared to force fields that explicitly tabulate the individual cross-interaction parameters

A Four-Component Cascade C–H Functionalization/Cyclization/Nucleophilic Substitution Reaction To Construct α‑Functionalized Tetrahydro­quinolines by the Strategy of <i>in Situ</i> Directing Group Formation

A four-component cascade C–H functionalization/cyclization/nucleophilic substitution reactions of anilines, carboxylic anhydrides, propenol, and alkohols have been developed by a strategy of <i>in situ</i> directing group formation, affording an efficient and convenient synthesis of α-alkoxyl tetrahydro­quinolines from basic starting materials. A plausible mechanism involving rhodium­(III) catalytic C–H functionalization and double nucleophilic attacks is proposed. The nucleophilicity order of some alcohols is also obtained for the cascade reaction

Suppression of Phase Separation in LiFePO₄ Nanoparticles During Battery Discharge

Using a novel electrochemical phase-field model, we question the common belief that Li_<i>X</i>FePO₄ nanoparticles always separate into Li-rich and Li-poor phases during battery discharge. For small currents, spinodal decomposition or nucleation leads to moving phase boundaries. Above a critical current density (in the Tafel regime), the spinodal disappears, and particles fill homogeneously, which may explain the superior rate capability and long cycle life of nano-LiFePO₄ cathodes

Dehydrogenative Cross-Coupling Reaction by Cooperative Transition-Metal and Brønsted Acid Catalysis for the Synthesis of β‑Quinolinyl α‑Amino Acid Esters

A novel dehydrogenative cross-coupling (DCC) reaction between methylquinoline derivatives and <i>N</i>-aryl glycine esters was developed by a cooperative catalysis of copper salt and Brønsted acid, affording an efficient synthesis of β-quinolinyl α-amino acid esters. A plausible mechanism using a proton to activate the methylquinoline derivative and copper­(II) to activate <i>N</i>-aryl glycine ester has been proposed

Adsorptive Separation of Fructose and Glucose by Metal–Organic Frameworks: Equilibrium, Kinetic, Thermodynamic, and Adsorption Mechanism Studies

In this work, seven metal–organic frameworks [ZIF-8, MIL-53­(Cr), MIL-96­(Al), MIL-100­(Cr), MIL-100­(Fe), MIL-101­(Cr), and UiO-66 ] were applied for adsorptive separation of fructose–glucose mixture. UiO-66 exhibited better performance in adsorption capacity and selective adsorption of fructose. The adsorptive process with UiO-66 was further investigated in detail including kinetic, isotherm, and adsorption mechanisms. The rate-determining step analysis based on film diffusion and intraparticle diffusion model suggested that the adsorption process was controlled by multiple steps, which fitted the pseudo-second-order model. The Freundlich model was fitting better than the Langmuir model, which indicated multilayer adsorption on heterogeneous surface. The thermodynamic parameters (Δ<i>G</i>, Δ<i>H</i>, and Δ<i><i>S</i></i>) were calculated, indicating that adsorption process on UiO-66 was an endothermic and entropy increment process. UiO-66 can be a promising adsorbent for adsorptive separation of fructose and glucose

Isobaric Vapor–Liquid Equilibrium Data for the Binary System of Water + 2‑Methylpyridine at 101.3, 60.0, and 20.0 kPa

Isobaric vapor–liquid equilibrium (VLE) data for the binary system of water + 2-methylpyridine were determined by using Fisher VLE 602 equipment at 101.3, 60.0, and 20.0 kPa to assist with the design of the separation process by distillation. All of the binary data at different pressures were considered to be thermodynamically consistent according to Wisniak’s area and point test. The results showed that the binary system at all three pressures formed the minimum boiling azeotropes and exhibited a positive deviation from Raoult’s law. The binary VLE data were correlated by using NRTL-HOC, UNIQUAC-HOC, and Wilson-HOC models with minor deviations, and the result showed that all three models were in good agreement with the experimental data. The azeotropic temperatures and compositions at 101.3, 60.0, and 20.0 kPa were determined by the NRTL-HOC model, respectively, which showed that the azeotropic composition of 2-methylpyridine tended to decrease with the decline in system pressure

Transient Polarization and Dendrite Initiation Dynamics in Ceramic Electrolytes

Solid-state electrolytes combined with lithium-metal anodes have the potential to improve the energy density of lithium-ion batteries. However, soft Li metal can still penetrate these stiff electrolytes above a critical current density (CCD). Prevailing methods to determine CCD suffer inconsistencies due to void formations after repeated stripping and plating, leaving significant variations in reported data. Here, we combine one-way linear sweep voltammetry (LSV) with electrochemical impedance spectroscopy (EIS) to uncover the existence of significant polarization in ceramic electrolytes, which can fully relax even without stacking pressure. At high scan rates, LSV experiments showed metal penetration with a diverging transient current, similar to CCD values. However, at a lowered scan rate, the transient current reaches a maximum, suggesting a dynamic electrochemical limiting mechanism. The results and analysis of many consistent samples suggest that polarization of mobile charge carriers preceding the maximum current is critical for accurately understanding dendrite penetration in ceramic electrolytes

Cascade C–H Functionalization/Amidation Reaction for Synthesis of Azepinone Derivatives

A cascade C–H functionalization/amidation reaction of aminobiaryls with diazomalonates has been developed under rhodium catalysis, affording new azepinone derivatives in moderate to excellent yields

Deconstructing Hydrogen-Bond Networks in Confined Nanoporous Materials: Implications for Alcohol–Water Separation

Essential topological indices of the hydrogen-bond networks of water, methanol, ethanol, and their binary mixtures adsorbed in microporous silicalite-1 (a hydrophobic zeolite with potential application for biofuel processing) are analyzed and compared to their bulk liquid counterparts. These include the geodesic distribution (the shortest H-bond pathways between molecular vertices), the average length, the geodesic index, the orientation and distance of the adsorbate to the interior of the zeolite, and the sorbate–sorbate and sorbate–sorbent distributions of H-bonds. In combination, they describe how the H-bond networks are altered when going from the bulk to the confined silicalite-1 environment. The speciation of the adsorbed compounds is quantified in terms of their network connectivity, revealing that pure water has a high probability of forming long, contiguous H-bonded chains in silicalite-1 at high loading, while alcohols form small dimeric/trimeric clusters. The extent to which the H-bond network of binary water–alcohol systems is altered relative to either unary system is quantified, demonstrating an enhanced interconnectivity that is reflected in the tendency of individual H₂O molecules to become co-adsorbed with alcohol clusters in the zeolite framework. Selectivity for the alcohol over water diminishes with increasing alcohol loading as the H-bonded clusters serve as favorable adsorption sites for H₂O