Engineering the Charge-Transfer State to Facilitate Spin–Orbit Charge Transfer Intersystem Crossing in Spirobis[anthracene]diones

Spiro conjugation has been proposed to dictate the efficiency of charge transfer, which could directly affect the spin–orbit charge transfer intersystem crossing (SOCT-ISC) process. However, this process has yet to be exemplified. Herein, we prepared three spirobis[anthracene]diones, in which two benzophenone moieties are locked in close proximity and differentially functionalized to fine-tune the charge transfer state. Its feasibility for SOCT-ISC was theoretically predicted, then experimentally evaluated. Through fine-tuning the spiro conjugation coupling and varying the solvent dielectric constants, ISC rate constants were engineered to vary in a dynamic range of three orders of magnitude, from 7.8×10⁸ s⁻¹ to 1.0×10¹¹ s⁻¹, which is the highest ISC rate reported for SOCT-ISC system to our knowledge. Our findings substantiate the key factors for effective SOCT-ISC and offer a new avenue for the rational design of heavy atom free triplet sensitizers.     

Ultrastable Perovskite–Zeolite Composite Enabled by Encapsulation and In Situ Passivation

Metal halide perovskites have been widely applied in optoelectronic fields, but their poor stability hinders their actual applications. A perovskite–zeolite composite was synthesized via in situ growth in air from aluminophosphate AlPO-5 zeolite crystals and perovskite nanocrystals. The zeolite matrix provides quantum confinement for perovskite nanocrystals, achieving efficient green emission, and it passivates the defects of perovskite by H-bonding interaction, which leads to a longer lifetime compared to bulk perovskite film. Furthermore, the AlPO-5 zeolite also acts as a protection shield and enables ultrahigh stability of perovskite nanocrystals under 150 °C heat stress, under a 15-month long-term ambient exposure, and even in water for more than 2 weeks, respectively. The strategy of in situ passivation and encapsulation for the perovskite@AlPO-5 composite was amenable to a range of perovskites, from MA- to Cs-based perovskites. Benefiting from high stability and photoluminescence performance, the composite exhibits great potential to be virtually applied in light-emitting diodes (LEDs) and backlight displays.     

用作锂离子电池负极的FeS2微球的制备及性能

以氯化亚铁和硫代硫酸钠为原料, 采用水热法一步合成了由FeS₂纳米片堆积的FeS₂微球. 通过调控铁源与硫源的摩尔比及水热合成时间, 并结合X射线衍射(XRD)和扫描电子显微镜(SEM)表征结果推测了FeS₂的生长机理, 筛选出最优条件以提升其电化学性能. 电化学测试结果表明, 在500 mA/g的电流密度条件下, 材料的首次放电/充电容量可分别达到905和800 mA·h·g ^-1, 首次库伦效率达到88.4%; 在2000 mA/g的大电流密度条件下, 500次放电/充电循环后依然稳定保持350 mA·h·g ^-1的可逆容量.     

可拉伸超韧水凝胶的制备和应用

综述了可拉伸超韧水凝胶的设计原理及其在组织工程和柔性电子器件领域的应用. 通过将网络结构层次、 化学结构、 增韧机制与宏观力学性能相结合, 重点讨论了单网络水凝胶、 双网络水凝胶、 纳米复合水凝胶及其它水凝胶等可拉伸超韧水凝胶的研究进展, 并总结和展望了新思路和新方向.     

Ag-Y/MIL-101吸附剂的制备及其吸附脱硫性能

通过银、钇双金属改性制备了Ag-Y/MIL-101吸附剂,并对Ag-Y/MIL-101进行了X射线衍射(XRD)、电镜(SEMEDS)、比表面积(BET)和热重(TG-DTG)表征。考察了Ag-Y/M IL-101金属负载顺序、金属负载浓度、金属溶液用量、负载时间对脱硫性能的影响,优化了吸附脱硫条件。结果表明,金属改性得到的Ag-Y/MIL-101保持了MIL-101的晶格结构。与M IL-101相比,Ag-Y/MIL-101的比表面积和孔容均有所下降。适宜Ag-Y/MIL-101的制备条件为:先负载银后负载钇,银离子和钇离子的负载浓度均为30 mmol/L,金属溶液用量均为1 mL,负载时间为8 h。适宜Ag-Y/MIL-101的吸附脱硫条件为:吸附剂用量0.05 g,模拟油为10 mL,吸附温度为60℃,吸附时间为8 h。在此条件下,Ag-Y/MIL-101对噻吩的吸附量达到21.7 mg/g。Ag能显著提高MIL-101的吸附硫容,Y能显著提高MIL-101的吸附选择性,因此,Ag-Y/MIL-101吸附剂中Ag和Y的协同作用使其拥有比MIL-101更高的硫容和噻吩脱硫选择性。     

The miracle role of lattice imperfections in benzene alkylation with methanol over mordenite

Mordenite (MOR) has demonstrated potential as a catalyst for alkylation due to high variability, intrinsic porosity, and outstanding stability. However, the contact probability of benzene and methanol has been limited by typical layered structures of MOR and there is no connection between layers. Here, we report the preparedness of H-MOR via a sequential post-treatment method based on a commercial MOR. H-MOR sample had appeared lattice imperfections inferred from characterization means. The samples were tested with benezene methylation reaction. Results show that the high conversion of benzene and the high selectivity of toluene were obtained from the miracle role of lattice imperfections in the H-MOR sample. Sequentially, based on the study of all catalyst structure and physical properties, a plausible reaction mechanism for the selectivity of the desired toluene was proposed.     

Metal-reinforced sulfonic-acid-modified zirconia for the removal of trace olefins from aromatics

Metal-reinforced sulfonic-acid-modified zirconia catalysts were successfully prepared and used to remove trace olefins from aromatics in a fixed-bed reactor. Catalysts were characterized by ICP-OES, N₂ adsorption–desorption, X-ray diffraction, thermogravimetric analysis (TGA), and pyridine-FTIR spectroscopy. Different metals and calcination temperatures had great influence on the catalytic activity. Alumina-reinforced sulfated zirconia exhibited outstanding catalytic performance, stable regeneration activity, and giant surface area, and are promising in industrial catalysis. TGA showed that the decomposition of methyl could be attributed to Brønsted acid sites, and pyridine-FTIR spectroscopy proved the weak Brønsted sites on these synthesized metal-reinforced sulfated zirconia. Also, a relation between the reaction rate and weak Brønsted acid density is proposed.     

Single-Molecule Magnetism in Dy2 Cluster Based on a Schiff Base Ligand

Two dinuclear Ln^III-based clusters, namely [Dy₂L₂(NO₃)₂(DME)₄] ( 1 ) and [Gd₂L₂(NO₃)₂(DME)₄] ( 2 ) [H₂L = (E)-2-((2-hydroxybenzylidene)amino)phenol] were obtained under hydrothermal condition. Two Ln^III ions are bridged by two phenolic hydroxyl oxygen atoms, and the distances of them are 3.829 Å (Dy1–Dy1A) and 3.860 Å (Gd1–Gd1A). Two Dy1–O–Dy1A and Gd1–O–Gd1A angles are 109.4° and 109.8°, respectively. Magnetic studies reveal a weak antiferromagnetic interaction between Gd ions in complex 2 , and single-molecule magnet behavior for 1 with U_eff = 49.9 K and τ₀ = 1.54 × 10^–6 s.     

Effect of ammonia,ammonia-water,and sulfuric acid on the HO2 + HO2 → H2O2 + 3O2 reaction in troposphere: Competition between stepwise and one-step mechanisms

A detailed theoretical study on the reaction mechanisms for the formations of H₂O₂ + ³O₂ from the self-reaction of HO₂ radicals under the effect of NH₃, H₃N···H₂O, and H₂SO₄ catalysts was performed using the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ method. The rate constant was computed using canonical variational transition state theory (CVT) with small curvature tunneling (SCT). Our results indicate that NH₃-, H₃N···H₂O-, and H₂SO₄-catalyzed reactions could proceed through both one-step and stepwise routes. Calculated rate constants show that the catalyzed routes in the presence of the three catalysts all prefer stepwise pathways. Compared to the catalytic efficiency of H₂O, the efficiencies of NH₃, H₃N···H₂O, and H₂SO₄ are much lower due to their smaller relative concentrations. The present results have provided a definitive example of how basic and acidic catalysts influence the atmospheric reaction of HO₂ + HO₂ → H₂O₂ + ³O₂. These results further encourage one to consider the effects of basic and acidic catalysts on the related atmospheric reactions. Thus, the present investigation should have broad implications in the gas-phase reactions of the atmosphere.     

Substrate-Induced Dimerization Assembly of Chiral Macrocycle Catalysts toward Cooperative Asymmetric Catalysis

An artificial system of substrate-induced dimerization assembly of chiral macrocycle catalysts enables a highly cooperative hydrogen-bonding activation network for efficient enantioselective transformation. These macrocycles contain two thiourea and two chiral diamine moieties and dimerize with sulfate to form a sandwich-like assembly. The macrocycles then adopt an extended conformation and reciprocally complement the hydrogen-bonding interaction sites. Inspired by the guest-induced dynamic assembly, these macrocycles catalyze the decarboxylative Mannich reaction of cyclic aldimines containing a sulfamate heading group. The imine substrate can be activated toward nucleophilic attack of β-ketoacid by a cooperative hydrogen-bonding network enabled by sulfamate-induced dimerization assembly of the macrocycle catalysts. Highly efficient (>95 % yield in most cases) and enantioselective (up to 97.5:2.5 er) transformation of a variety of substrates using only 5 mol % macrocycle was achieved.