Theoretical Study of Ethanethiol Adsorption on HZSM-5 Zeolite

The density functional theory and the cluster model methods have been employed to investigate the interactions between ethanethiol and HZSM-5 zeolites. Molecular complexes formed by the adsorption of ethanethiol on silanol H3SiOH with two coordination forms, model Bronsted acid sites of zeolite cluster H3Si(OH)Al(OH)2SiH3 interaction with ethanethiol, aluminum species adsorbed ethanethiol have been comparatively studied. Full optimization and frequency analysis of all cluster models have been carried out using B3LYP hybrid method at 3-21G basis level for hydrogen atoms and 6-31G(d) basis set level for silicon, aluminum, oxygen, carbon, and sulfur atoms. The structures and energy changes of different coordination forms of H3Si(OH)Al(OH)2SiH3-ethanethiol, silanol-ethanethiol and Al(OH)3-ethanethiol have been studied. The calculated results showed the nature of interactions was van der Waals force as exhibited by not much change in geometric structures and properties. The preference order of ethanethiol adsorbed on HZSM-5 zeolite may be residual aluminum species, bridging hydroxyl groups and silanol OH groups from the adsorption heat. The adsorbed models of protonized ethanethiol on bridging hydroxyl OH groups and linear hydrogen bonded ethanethiol on bridging OH groups suggested in literature might not exist as revealed by this theoretical calculation. Possible adsorption models were obtained for the first time.     

Dynamic coating of a capillary with room-temperature ionic liquids for the separation of amino acids and acid drugs by capillary electrophoresis

A room-temperature ionic liquid (IL), 1-ethyl-3-methyl-imidazolium tetrafluoroborate (1E-3MI-TFB), used for the coating of a silica capillary enables one to reduce or invert the electroosmotic flow (EOF) in capillary zone electrophoresis. Excellent separations of amino acids and ary lalkanoic acids were obtained. Such separations could not be obtained in a naked capillary in the presence of the cationic surfactants cetyltrimethylammonium bromide (CTAB) or polycationic polymer hexadimethrine bromide (HDB). The results indicate that 1E-3MI-TFB not only modulates the EOF but also acts as a discriminator. Further experiments indicate that the interaction between hydrogen at C-2 carbon of IL and acid drugs plays an important role in the separation. The text was submitted by the authors in English.     

Thermal degradation kinetics of polyimide containing 2,6-benzobisoxazole units

A novel polyimide (PI) based on 2,6-bis(p-aminophenyl)-benzo[1,2-d;5,4-d′]bisoxazole has been synthesized via a conventional two-stage procedure with bis(ether anhydrides) (HQDPA). The intermediate poly(amic acid) had inherent viscosities of 1.70 dl/g and could be thermally converted into light yellow polyimide film. The resulted polyimide showed excellent thermal stability, and the glass transition temperatures (T_g) were above 283 °C, the 5% weight loss temperature of the polymer was at 572 °C in N₂. The thermal degradation of the polyimide was studied by thermogravimetric analysis (TGA) in order to determine the actual reaction mechanisms of the decomposition process. The activation energy of the solid-state process was determined using Flynn-Wall-Ozawa method, which does not require knowledge of the reaction mechanism, which resulted to be 361.36 kJ/mol. The activation energy of different mechanism models and pre-exponential factor (A) were determined by Coats-Redfern method. Compared with the value obtained from the Ozawa method, the actual reaction mechanism obeyed nucleation and growth model, Avrami-Erofeev function (A₃) with integral form g(X) = [−ln(1−X)]³.     

Anion and Additive Effects on the Structure of Mercury(II) Halides Complexes with Tripodal Ligand

The metal complexes [Hg₂(tbim)₂Br₄]·2DMF ( 1 ) and [Hg₂(tbim)I₄]·1.5DMF ( 2 ) were prepared by reactions of 1,3,5‐tris(benzimidazol‐1‐ylmethyl)‐2,4,6‐trimethylbenzene (tbim) with HgBr₂, HgI₂, respectively, and [Hg₂(tbim)I₄]·0.5(FeCp₂)·H₂O ( 3 ) was obtained by the same method with addition of ferrocene (FeCp₂) as additive. Their structures were determined by X‐ray crystallographic analyses. Complex 1 has a macrocyclic binuclear structure with one benzimidazole arm of the ligand free of coordination and the binuclear units are further connected by C‐H···N hydrogen bonds to give an infinite zigzag chain. Complexes 2 and 3 have a 2D network structure in which tbim serves as a tridentate ligand. The results showed that the halides of bromide and iodide have remarkable impact on the structure of the complexes. The FeCp₂ molecules are trapped in the voids of framework 3 .     

β微管蛋白中紫杉醇(Taxol)结合腔的性质分析

采用多拷贝同时搜寻法(MCSS), 并结合现有微管抑制剂的SAR及3D-QSAR对β微管蛋白中Taxol(紫杉醇)结合腔的性质进行了分析. 结构研究结果表明, Taxol结合腔以疏水性质为主, 并指出官能团分布的具体位置: 在Phe270上方(Leu361-Pro272-Leu273-Leu228之间)的弧形区域、Asp26羧基下方及其与Glu22羧基之间、M-loop的中部, 以及Asp224内侧且靠近Arg276的胍基的位置. 而Asp224的内侧又是新提出的结合位点. 研究结果符合现有微管抑制剂的SAR, 为现有抗肿瘤药物的结构改造以及小分子微管抑制剂设计提供了理论依据.     

Competitive adsorption of Pb2+, Cu2+, and Cd2+ ions on microporous titanosilicate ETS-10

In the present study, the competitive adsorption characteristics of binary and ternary heavy metal ions Pb2+, Cu2+, and Cd2+ on microporous titanosilicate ETS-10 were investigated in batch systems. Pure microporous titanosilicate ETS-10 was synthesized with P25 as the Ti source and characterized by the techniques of X-ray diffraction (XRD), field emission-scanning electron microscope (FESEM), nitrogen adsorption, and zeta-potential. Equilibrium and kinetic adsorption data showed that ETS-10 displays a high selectivity toward one metal in a two-component or a three-component system with an affinity order of Pb2+ > Cd2+ > Cu2+. The equilibrium behaviors of heavy metals species with stronger affinity toward ETS-10 can be described by the Langmuir equation while the adsorption kinetics of the metals can be well fitted to a pseudo-second-order (PSO) model.     

双功能型嵌入镍纳米颗粒的碳棱柱状微米棒电极用于电化学甲醇氧化助力的节能产氢

With the rapid development of human society, clean energy forms are imperative to sustain the normal operations of various mechanical and electrical facilities under a cozy environment. Hydrogen is considered among the most promising clean energy sources for the future. Recently, electrochemical water splitting has been considered as one of the most efficient approaches to harvest hydrogen energy, which generates only non-pollutant water on combustion. However, the sluggish anodic oxygen evolution reaction significantly restricts the efficiency of water splitting and requires a relatively high cell voltage to drive the electrolysis. Therefore, seeking a thermodynamically favorable anodic reaction to replace the sluggish oxygen evolution reaction by utilizing highly active bifunctional electrocatalysts for the anodic reaction and hydrogen evolution are crucial for achieving energy-efficient hydrogen production for industrial applications. Nevertheless, it is known that the oxygen evolution reaction can be replaced with other useful and thermodynamically favorable reactions to reduce the electrolysis voltage for realizing energy-efficient hydrogen production. Therefore, in this study, we present a bifunctional nickel nanoparticle-embedded carbon (Ni@C) prism-like microrod electrocatalyst synthesized via a two-step method involving the synthesis of a precursor metal-organic framework-74 and subsequent carbonization treatment for methanol oxidation and hydrogen evolution. The interfacial structure consisting of a nickel and carbon skeleton was realized via in situ carbonization. However, the dispersed nickel nanoparticles do not easily aggregate owing to the partition by the surrounding carbon as it would sufficiently expose the active Ni sites to the electrolytes, ensuring fast charge transfer between the catalyst and electrolytes by accelerating the electrochemical kinetics. In the anodic methanol oxidation, the products were detected as carbon dioxide and formate with faradaic efficiencies of 36.2% and 62.5%, respectively, at an applied potential of 1.55 V. Meanwhile, the Ni@C microrod catalyst demonstrated high activity and durability (2.7% current decay after 12 h of continuous operation) toward methanol oxidation, which demonstrates that methanol oxidation precedes oxidation under voltage forces. Notably, the bifunctional catalyst not only exhibits excellent performance toward methanol oxidation but also yields a low overpotential of 155 mV to drive 10 mA∙cm⁻² toward hydrogen evolution in 1.0 mol∙L⁻¹ KOH aqueous solution with 0.5 mol∙L⁻¹ methanol at room temperature, which guarantees the hydrogen production efficiency. More importantly, the constructed two-electrode electrolyzer produced a current density of 10 mA∙cm⁻² at a low cell voltage of 1.6 V, which decreased by 240 mV after replacing the oxygen evolution reaction with methanol oxidation.     

Highly efficient non-doped blue fluorescent OLEDs with low efficiency roll-off based on hybridized local and charge transfer excited state emitters

Designing a donor–acceptor (D–A) molecule with a hybridized local and charge transfer (HLCT) excited state is a very effective strategy for producing an organic light-emitting diode (OLED) with a high exciton utilization efficiency and external quantum efficiency. Herein, a novel twisting D–π–A fluorescent molecule (triphenylamine–anthracene–phenanthroimidazole; TPAAnPI) is designed and synthesized. The excited state properties of the TPAAnPI investigated through photophysical experiments and density functional theory (DFT) analysis reveal that its fluorescence is due to the HLCT excited state. The optimized non-doped blue OLED using TPAAnPI as a light-emitting layer exhibits a novel blue emission with an electroluminescence (EL) peak at 470 nm, corresponding to the Commission International de L''Eclairage (CIE) coordinates of (0.15, 0.22). A fabricated device termed Device II exhibits a maximum current efficiency of 18.09 cd A⁻¹, power efficiency of 12.35 lm W⁻¹, luminescence of ≈29 900 cd cm⁻², and external quantum efficiency (EQE) of 11.47%, corresponding to a high exciton utilization efficiency of 91%. Its EQE remains as high as 9.70% at a luminescence of 1000 cd m⁻² with a low efficiency roll-off of 15%. These results are among the best for HLCT blue-emitting materials involved in non-doped blue fluorescent OLEDs. The performance of Device II highlights a great industrial application potential for the TPAAnPI molecule.

A new pure fluorescent blue HLCT-emitter was designed and synthesized. Highly efficient non-doped blue OLEDs with low efficiency roll-off were achieved.     

One-step preparation of branched PEG functionalized AIE-active luminescent polymeric nanoprobes

The synthesis of amphiphilic aggregation-induced emission(AIE) dyes based organic nanoparticles has recently attracted increasing attention in the biomedical fields. These AIE dyes based nanoparticles could effectively overcome the aggregation caused quenching effect of conventional organic dyes, making them promising candidates for fabrication of ultrabright organic luminescent nanomaterials. In this work, AIE-active luminescent polymeric nanoparticles(4-NH_2-PEG-TPE-E LPNs) were facilely fabricated through Michael addition reaction between tetraphenylethene acrylate(TPE-E) and 4-arm-poly(ethylene glycol)-amine(4-NH_2-PEG) in rather mild ambient. The 4-NH_2-PEG can not only endow these AIE-active LPNs good water dispersibility, but also provide functional groups for further conjugation reaction. The size, morphology and luminescent properties of 4-NH_2-PEG-TPE-E LPNs were characterized by a series of techniques in detail. Results suggested that these AIE-active LPNs showed spherical morphology with diameter about 100–200 nm. The obtained 4-NH_2-PEG-TPE-E LPNs display high water dispersibility and strong fluorescence intensity because of their self assembly and AIE properties of TPE-E.Biological evaluation results demonstrated that 4-NH_2-PEG-TPE-E LPNs showed negative toxicity toward cancer cells and good fluorescent imaging performance. All of these features make 4-NH_2-PEG-TPE-E LPNs promising candidates for biological imaging and therapeutic applications.     

Seed‐Mediated Synthesis of Gold Tetrahedra in High Purity and with Tunable,Well‐Controlled Sizes

We report a facile synthesis of Au tetrahedra in high purity and with tunable, well‐controlled sizes via seed‐mediated growth. The success of this synthesis relies on the use of single‐crystal, spherical Au nanocrystals as the seeds and manipulation of the reaction kinetics to induce an unsymmetrical growth pattern for the seeds. In particular, the dropwise addition of a precursor solution with a syringe pump, assisted by cetyltrimethylammonium chloride and bromide at appropriate concentrations, was found to be critical to the formation of Au tetrahedra in high purity. Their sizes could be readily tuned in the range of 30–60 nm by simply varying the amount of precursor added to the reaction solution. The current strategy not only enables the synthesis of Au tetrahedra with tunable and controlled sizes but also provides a facile and versatile approach to reducing the symmetry of nanocrystals made of a face‐centered cubic lattice.