Binary mixtures of novel sulfoxides and water: intermolecular structure, dynamic properties, thermodynamics, and cluster analysis

Oxidative Dehydrogenative Coupling of Thiols with Alkanes for the Synthesis of Sulfoxides

An oxidative dehydrogenative coupling of thiols with alkanes via direct C(sp³)-H bond functionalization to form a new C-S bond and S═O double bond was developed. The present reaction features the use of readily available reagents and high step- and atom-efficiency, thus providing an efficient access to sulfoxides. A possible mechanism is proposed.

Morphology prediction of 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX) crystal in dimethyl sulfoxide (DMSO) solvent with different models using molecular dynamics simulation

The interface interaction between DMSO solution and HMX crystal was simulated by molecular dynamics (MD) method, and the morphology of HMX in DMSO solvent was predicted through the occupancy model and attachment energy (AE) model. The intramolecular and intermolecular interactions in HMX crystals were dominated by O···H/H···O contacts, accounting for 63.0%. The S value and the adsorption position of DMSO on different crystal planes of HMX have been compared, which showed that (1 0 - 1) has a deep cavity for the adsorption of solvent molecules. The density of DMSO in the z direction of the different planes showed that (0 1 1) has the largest density peak and (0 2 0) has the smallest density peak. The DMSO solvent had an attraction effect with each crystal plane of HMX. The absolute value of E_int was sorted as follows: (1 1 0) > (1 0 1) > (0 2 0) > (1 0 - 1) > (0 1 1). The DMSO solvent affected the attachment energy of each crystal plane of HMX. In our simulation system, the prediction results of the occupancy model were the most consistent with the experimental values.

Breakdown of the Stokes-Einstein relation in supercooled water: the jump-diffusion perspective

Although water is the most ubiquitous liquid it shows many thermodynamic and dynamic anomalies. Some of the anomalies further intensify in the supercooled regime. While many experimental and theoretical studies have focused on the thermodynamic anomalies of supercooled water, fewer studies explored the dynamical anomalies very extensively. This is due to the intricacy of the experimental measurement of the dynamical properties of supercooled water. Violation of the Stokes-Einstein relation (SER), an important relation connecting the diffusion of particles with the viscosity of the medium, is one of the major dynamical anomalies. In absence of experimentally measured viscosity, researchers used to check the validity of SER indirectly using average translational relaxation time or α-relaxation time. Very recently, the viscosity of supercooled water was accurately measured at a wide range of temperatures and pressures. This allowed direct verification of the SER at different temperature-pressure thermodynamic state points. An increasing breakdown of the SER was observed with decreasing temperature. Increasing pressure reduces the extent of breakdown. Although some well-known theories explained the above breakdown, a detailed molecular mechanism was still elusive. Recently, a translational jump-diffusion (TJD) approach has been able to quantitatively explain the breakdown of the SER in pure supercooled water and an aqueous solution of methanol. The objective of this article is to present a detailed and state-of-the-art analysis of the past and present works on the breakdown of SER in supercooled water with a specific focus on the new TJD approach for explaining the breakdown of the SER.

Tunable Porous Electrode Architectures for Enhanced Li-Ion Storage Kinetics in Thick Electrodes

Thick electrodes, although promising toward high-energy battery systems, suffer from restricted lithium-ion transport kinetics due to prolonged diffusion lengths and tortuous transport pathways. Despite the emerging low-tortuosity designs, capacity retention under higher current densities is still limited. Herein, we employ a modified ice-templating method to fabricate low-tortuosity porous electrodes with tunable wall thickness and channel width and systematically investigate the critical impacts of the fine structural parameters on the thick electrode electrochemistry. While the porous electrodes with thick walls show diminished capability under a C-rate larger than 1.5 C, those with thinner walls could maintain ∼70% capacity under 2.5 C. The superior capacity retention is ascribed to the fast diffusion into the thin lamellar walls compared with their thicker counterparts. This study provides deeper insights into structure-affected electrochemistry and opens up new perspective of 3D porous architectural designs for high-energy and high-power electrodes.

Breakdown of the Stokes-Einstein Relation in Supercooled Water/Methanol Binary Mixtures: Explanation Using the Translational Jump-Diffusion Approach

A recent experiment has directly checked the validity of the Stokes-Einstein (SE) relation for pure water, pure methanol, and their binary mixtures of three different compositions at different temperatures. The effect of composition on the nature of breakdown of the SE relation is interesting. While in the majority of the systems, an increasing SE breakdown is observed with decreasing temperature, the breakdown is already significant at higher temperatures for the equimolar mixture. Violations of the SE relation in pure supercooled water at different temperatures and pressures have been previously explained using the translational jump-diffusion (TJD) approach, which provides a fundamental molecular basis, by directly connecting the SE breakdown with jump-diffusion of the molecules. We have used the same TJD approach for explaining the SE breakdown for the methanol/water binary mixtures of compositions studied in the experiment over a wide range of temperatures between 220 K and 300 K. We have understood that the jump-diffusion is the key responsible factor for the SE breakdown. The maximum jump-diffusion contribution gives rise to the early SE breakdown observed for the equimolar mixture observed in the experiment. This study, therefore, provides molecular insight into the SE breakdown for the supercooled water/methanol binary mixture, as found in the experiment.

Nitrosoarene-catalyzed regioselective aromatic C-H sulfinylation with thiols under aerobic conditions

Aromatic amines and (hetero)arenes, such as indoles and pyrroles, are regioselectively sulfinylated under mild aerobic conditions using nitrosoarenes as a redox-catalyst. The nitrosoarene is involved in the electron transfer process with arenes to generate a crucial arene radical cation intermediate for C-H sulfinylation. The present methodology requires no directing group, can be scaled up easily and is applicable for the late-stage functionalization of drug molecules and natural products with high regioselectivity.

Application of the 3D-RISM-KH molecular solvation theory for DMSO as solvent

The molecular solvation theory in the form of the Three-Dimensional Reference Interaction Site Model (3D-RISM) with Kovalenko-Hirata (KH) closure relation is benchmarked for use with dimethyl sulfoxide (DMSO) as solvent for (bio)-chemical simulation within the framework of integral equation formalism. Several force field parameters have been tested to correctly reproduce solvation free energy in DMSO, ion solvation in DMSO, and DMSO coordination prediction. Our findings establish a united atom (UA) type parameterization as the best model of DMSO for use in 3D-RISM-KH theory based calculations.