Chiral Adaptive Induction of an Achiral Cucurbit[8]uril-Based Supramolecular Organic Framework by Dipeptides in Water

Chiral induction by natural biomolecules can reveal the indispensable role of chiral structures in life and can be used to develop the chirality-sensing biomolecular recognition. Here, we present the synthesis and characterization of an achiral supramolecular organic framework ( SOF-1 ) constructed from cucurbit[8]uril (CB[8]) and hexaphenylbenzene (HPB) derivative ( 1 ) in water. Due to the propeller-like rotational chiral conformation of HPB units and the specific recognition properties of CB[8], SOF-1 demonstrates chiral adaptive induction in water when interacting with the N-terminal Trp-/Phe-containing dipeptides including L-TrpX and L-PheX (X is an amino acid residue), respectively, exhibiting contrasting circular dichroism (CD) and circularly polarized luminescence (CPL) spectra. Consequently, SOF-1 has been developed as a supramolecular host and chiroptical sensor capable of recognizing and distinguishing the sequence-opposite Trp-/Phe-containing dipeptide pairs including L-TrpX/L-XTrp and L-PheX/L-XPhe based on the sequence-selective CD responses.     

Enhanced Metal-Support Interactions Boost the Electrocatalytic Water Splitting of Supported Ruthenium Nanoparticles on a Ni3N/NiO Heterojunction at Industrial Current Density

Developing highly efficient and stable hydrogen production catalysts for electrochemical water splitting (EWS) at industrial current densities remains a great challenge. Herein, we proposed a heterostructure-induced-strategy to optimize the metal-support interaction (MSI) and the EWS activity of Ru-Ni₃N/NiO. Density functional theory (DFT) calculations firstly predicted that the Ni₃N/NiO-heterostructures can improve the structural stability, electronic distributions, and orbital coupling of Ru-Ni₃N/NiO compared to Ru-Ni₃N and Ru-NiO, which accordingly decreases energy barriers and increases the electroactivity for EWS. As a proof-of-concept, the Ru-Ni₃N/NiO catalyst with a 2D Ni₃N/NiO-heterostructures nanosheet array, uniformly dispersed Ru nanoparticles, and strong MSI, was successfully constructed in the experiment, which exhibited excellent HER and OER activity with overpotentials of 190 mV and 385 mV at 1000 mA cm⁻², respectively. Furthermore, the Ru-Ni₃N/NiO-based EWS device can realize an industrial current density (1000 mA cm⁻²) at 1.74 V and 1.80 V under alkaline pure water and seawater conditions, respectively. Additionally, it also achieves a high durability of 1000 h (@ 500 mA cm⁻²) in alkaline pure water.     

Understanding the Role of Fluorine Groups in Passivating Defects for Perovskite Solar Cells

Introducing fluorine (F) groups into a passivator plays an important role in enhancing the defect passivation effect for the perovskite film, which is usually attributed to the direct interaction of F and defect states. However, the interaction between electronegative F and electron-rich passivation groups in the same molecule, which may influence the passivation effect, is ignored. We herein report that such interactions can vary the electron cloud distribution around the passivation groups and thus changing their coordination with defect sites. By comparing two fluorinated molecules, heptafluorobutylamine (HFBM) and heptafluorobutyric acid (HFBA), we find that the F/−NH₂ interaction in HFBM is stronger than the F/−COOH one in HFBA, inducing weaker passivation ability of HFBM than HFBA. Accordingly, HFBA-based perovskite solar cells (PSCs) provide an efficiency of 24.70 % with excellent long-term stability. Moreover, the efficiency of a large-area perovskite module (14.0 cm²) based on HFBA reaches 21.13 %. Our work offers an insight into understanding an unaware role of the F group in impacting the passivation effect for the perovskite film.     

Inter-Metal Interaction of Dual-Atom Catalysts in Heterogeneous Catalysis

Dual-atom catalysts (DACs) have been a new frontier in heterogeneous catalysis due to their unique intrinsic properties. The synergy between dual atoms provides flexible active sites, promising to enhance performance and even catalyze more complex reactions. However, precisely regulating active site structure and uncovering dual-atom metal interaction remain grand challenges. In this review, we clarify the significance of the inter-metal interaction of DACs based on the understanding of active center structures. Three diatomic configurations are elaborated, including isolated dual single-atom, N/O-bridged dual-atom, and direct dual-metal bonding interaction. Subsequently, the up-to-date progress in heterogeneous oxidation reactions, hydrogenation/dehydrogenation reactions, electrocatalytic reactions, and photocatalytic reactions are summarized. The structure-activity relationship between DACs and catalytic performance is then discussed at an atomic level. Finally, the challenges and future directions to engineer the structure of DACs are discussed. This review will offer new prospects for the rational design of efficient DACs toward heterogeneous catalysis.     

利用光谱法和分子对接技术研究4-乙基-2-甲氧基苯酚与人血清白蛋白之间的相互作用

4-乙基-2-甲氧基苯酚是一种被广泛应用的食品添加剂,但它也具有一定的毒性,为了探究4-乙基-2-甲氧基苯酚对人体的影响,将多种光谱技术与分子模拟等技术结合起来对4-乙基-2-甲氧基苯酚与人血清白蛋白Human Serum Albumin(HSA)之间的相互作用进行了较全面的研究。紫外吸收光谱的结果说明,4-乙基-2-甲氧基苯酚与人血清白蛋白之间形成了新的复合物。荧光光谱的结果说明了4-乙基-2-甲氧基苯酚的存在,可以增加人血清白蛋白的荧光强度。通过15 nm的同步荧光光谱同时结合荧光增强效应方程可以计算出4-乙基-2-甲氧基苯酚与人血清白蛋白之间的结合常数,且它们之间的结合常数随着温度的升高而减小。热力学参数表明,4-乙基-2-甲氧基苯酚主要靠氢键和疏水作用力与人血清白蛋白结合在一起。同步荧光光谱、三维荧光光谱和圆二色光谱的结果说明人血清白蛋白的构象会随着4-乙基-2-甲氧基苯酚的作用而发生一定的变化。分子对接得到结果说明4-乙基-2-甲氧基苯酚键合在人血清白蛋白的IB区域。     

高阶效应对超短艾里-高斯脉冲相互作用的影响

本文运用分步傅里叶变换,对满足高阶耦合非线性薛定谔方程的超短艾里脉冲与超短高斯脉冲,利用MATLAB数值模拟了在高阶效应下两脉冲相互作用后的演化过程以及时域上的强度变化。结果表明：负三阶色散效应使超短脉冲相互作用能传输更远距离;正三阶色散效应会减慢超短脉冲相互作用的传输。自陡峭效应通过孤子分裂现象的形式使超短脉冲相互作用产生时域位移,内拉曼效应可以将超短脉冲相互作用的能量由前沿处转移到后沿处。     

Ultrasonic and DFT study of intermolecular association through hydrogen bonding in aqueous solutions of glycerol

The experimental measurements of density, viscosity and ultrasonic velocity of aqueous glycerol solutions were carried out as functions of concentration (0.1 ≤ m [mol kg^− 1] ≤ 1.0) and temperature (303.15 ≤ T [K] ≤323.15). The isentropic compressibility (β_s), acoustic impedance (Z), hydration number (H_n), intermolecular free length (L_f), classical sound absorption (α/f²)_class and shear relaxation time (τ) were calculated by using the measured data. These parameters have been interpreted in terms of solute–solvent interactions. The quantum chemical calculations were performed to study the hydrogen bonding in interacting complex formed between glycerol and water molecules. Computations have been done by using Density Functional Theory (DFT) method at B3LYP/6–31 + g(d) level of theory to study the equilibrium structure of glycerol, glycerol–water interacting complex and vibrational frequencies. The solution phase study was carried out using Onsager's reaction field model in water solvent. The computed vibrational frequencies are in good agreement with the main features of the experimental spectrum when four water molecules are considered explicitly with glycerol. The interaction energy (E_total), hydrogen bond lengths and dipole moment (µ_m) of the interacting complex are also presented and discussed with in the light of solute–solvent interactions.     

YK-1活性炭平衡储氢特性分析

文中基于氢在椰壳活性炭YK-1上的平衡吸附数据,以探寻氢在碳基材料上适宜存储条件为目的,研究吸附氢分子间相互作用能随储存系统温度、压力、表面遮盖率的变化规律。首先,依据容积法的原理,在温度区间113K—293K、压力范围0—13MPa测试氢在YK-1椰壳活性炭上的吸附等温线。其次,应用格子理论推导通用吸附等温方程,通过等温方程的线性标绘确定氢分子在吸附表面的最大浓度,并由氢分子在活性炭典型吸附空间内受到的壁面作用势函数迭代求解氢分子受到的壁面作用势,进而获得与各吸附平衡态对应的氢分子间相互作用能。最后,根据氢分子间作用能随温度、表面遮盖率等的变化关系,分析氢分子在此活性炭上吸附的特点。     

微扰变分法对光折变空间孤子相互作用的研究

利用微扰变分法研究了光折变屏蔽孤子的相干相互作用,得出了光折变空间屏蔽孤子在晶体中同相相互作用时发生第一次碰撞的位置和碰撞周期解析表达式,并对孤子同相和反相相互作用的物理机制进行了分析.研究结果表明:当两孤子尾部交叠时就会发生相互作用,相互作用力的大小与孤子的相对强度、相对间距以及晶体外加电场的大小有关.孤子的相对强度越大、相对间距越小以及晶体外加电场越强,孤子间相互作用力越大;相互作用力的性质与初始相位差有关,同相相互吸引,反相相互排斥.