Unraveling the catalytic performance of RuO2(1 1 0) for highly-selective ethylene production from methane at low temperature: Insights from first-principles and microkinetic simulations.

Despite significant progress in low-temperature methane (CH4) activation, commercial viability, specifically obtaining high yields of C1/C2 products, remains a challenge. High desorption energy (>2 eV) and overoxidation of the target products are key limitations in CH4 utilization. Herein, we employ first-principles density functional theory (DFT) and microkinetics simulations to investigate the CH4 activation and the feasibility of its conversion to ethylene (C2H4) on the RuO2 (1 1 0) surface. The CH activation and CH4 dehydrogenation processes are thoroughly investigated, with a particular focus on the diffusion of surface intermediates. The results show that the RuO2 (1 1 0) surface exhibits high reactivity in CH4 activation (Ea = 0.60 eV), with CH3 and CH2 are the predominant species, and CH2 being the most mobile intermediate on the surface. Consequently, self-coupling of CH2* species via CC coupling occurs more readily, yielding C2H4, a potential raw material for the chemical industry. More importantly, we demonstrate that the produced C2H4 can easily desorb under mild conditions due to its low desorption energy of 0.97 eV. Microkinetic simulations based on the DFT energetics indicate that CH4 activation can occur at temperatures below 200 K, and C2H4 can be desorbed at room temperature. Further, the selectivity analysis predicts that C2H4 is the major product at low temperatures (300-450 K) with 100 % selectivity, then competes with formaldehyde at intermediate temperatures in the CH4 conversion over RuO2 (1 1 0) surface. The present findings suggest that the RuO2 (1 1 0) surface is a potential catalyst for facilitating ethylene production under mild conditions.

The use of multicomponent reactions in the development of bis-boronic acids for the detection of ß-sialic acid.

Sialic acid (SA) is a naturally occurring monosaccharide found in glycoproteins and glycolipids. Changes in the expression of SA are associated with several diseases; thus, the detection of SA is of great significance for biological research, cancer diagnosis, and treatment. Boronic acid analogs have emerged as a promising tool for detecting sugars such as SA due to its reversible covalent bonding ability. In this study, 11 bis-boronic acid compounds and 2 mono-boronic acid compounds were synthesized via a highly efficient Ugi-4CR strategy. The synthesized compounds were subjected to affinity fluorescence binding experiments to evaluate their binding capability to SA. Compound A1 was shown to have a promising binding constant of 2602 ± 100 M-1 at pH = 6.0. Density Functional Theory (DFT) calculations examining the binding modes between A1 and SA indicated that the position of the boronic acid functional group was strongly correlated with its interaction with SA's α-hydroxy acid unit. The DFT calculations were consistent with the observations from the fluorescence experiments, demonstrating that the number and relative positions of the boronic acid functional groups are critical factors in enhancing the binding affinity to SA. DFT calculations of both S and R configuration of A1 indicated that the effect of the S/R configuration of A1 on its binding with ß-sialic acid was insignificant as the Ugi-4CR generated racemic products. A fluorine atom was incorporated into the R2 substituent of A1 as an electron-withdrawing group to produce A5, which possessed a significantly higher capability to bind to SA (Keq = 7015 ± 5 M-1 at pH = 6.0). Finally, A1 and A5 were shown to possess exceptional binding selectivity toward ß-sialic acid under pH of 6.0 and 6.5 while preferring to bind with glucose, fructose, and galactose under pH of 7.0 and 7.5.

Theoretical study of the reductive decomposition of ethylene sulfite: a film-forming electrolyte additive in lithium ion batteries.

The role of ethylene sulfite (ES) as an electrolyte additive for lithium ion batteries is explained by investigating the one- and two-electron reductive decomposition of ES and (ES)Li(+)(PC)(n) (n = 0-2), both in vacuum and solvent, with the aid of high-level density functional theory calculations. The open-chain radical, which is formed as a result of reduction of ES in solvent without first being coordinated with Li(+), is further stabilized by a dissolved lithium ion. The resulting more stable intermediate releases a somewhat large amount of energy, which is utilized in the formation of a subsequent radical anion. On the basis of the study on the reductive decomposition of ES, (ES)Li(+)(PC), and (ES)Li(+)(PC)(2), the major products that are responsible for the formation of a protective solid electrolyte interphase film are Li(2)SO(3), (CH(2)OSO(2)Li)(2), CH(3)CH(OSO(2)Li)CH(2)OCO(2)Li, and ROSO(2)Li.

Barrierless proton transfer within short protonated peptides in the presence of water bridges. A density functional theory study.

We have used density functional theory at the B3LYP/6-31++G(d,p) level of theory to investigate proton transfer in protonated N(2)-acetyl-N(1)-methylglycinamide and N-acetylglycyl-N(1)-methylglycinamide with multiwater assistance and to determine the structures and energies of the most important minima and transition states corresponding to the proton-transfer pathways. We propose mechanisms for proton transfer between adjacent and nonadjacent carbonyl oxygen atoms with water bridge assistance. The presence of a two-water bridge connected to the two carbonyl oxygen atoms provides a proton-transfer mechanism having such a low-barrier that the excess proton is almost freely mobile.

Carbon-carbon bond cleavage in the photoionization of ethanol and 1-propanol clusters.

Tunable VUV laser was used to initiate the ion-molecule reactions in the clusters of ethanol and 1-propanol by photoionization in the region between 10.49 to 10.08 eV. Ionic products were detected by the time-of-flight mass spectrometer. In addition to the protonated clusters from proton transfer reactions, the products corresponding to beta carbon-carbon bond cleavage were found to be one of the major products for small sizes of clusters. A comparison with photoionization of methanol clusters and the results of ab initio calculation has been made.