Recent Progress in Pt-Based Catalysts for Oxygen Reduction Reaction北大核心CSCD

One major challenge for a large-scale commercialization of the proton-exchange membrane fuel cells (PEMFCs) technologies that enable a shift to 'zero-emission' personal transportation, is the expensive and unstable Pt catalysts, which are mainly used to catalyze the sluggish kinetics of the oxygen reduction reaction (ORR) occurred on the air electrode of PEMFCs.Many research works have targets to improve the stability of Pt-based catalysts and to construct Pt/transitional metal alloys with low Pt loading amount.Herein, we provide a minireview for the Pt-based ORR catalysts based on our recent work, which covers a brief background introduction, the stability improvement of pure Pt catalysts, the construction of Pt-alloy type catalysts and a future perspective.It is believed that the alloy catalysts with a sophistical structure design at an atomic level owns a promising future prospect. © 2018 Chinese Chemical Society. All rights reserved.     

Recent advances in starch–clay nanocomposites

Biological nanocomposites are a valuable addition to the existing nanocomposite materials and eventually can substitute petroleum-based composite materials in numerous applications due to their inherent advantages such as biodegradability, eco-friendliness, low cost, and easy availability to name a few. Recently, polymer–clay nanocomposites have achieved much more attention due to their enhanced properties such as size dispersion and significant enhancement in physicochemical and mechanical properties in comparison to the pure polymer systems. Among various biopolymers, starch is one of the most abundant natural polymers on the earth and is highly valuable due to its chemical and physical properties. Starch polymer has highly increased potential as an alternative to petroleum-based materials. However, starch cannot be used alone and starch–clay nanocomposite has emerged as a new potential green sustainable material. This article focuses on recent progress in starch-based nanocomposites with particular emphasis on starch–clay nanocomposite preparation, properties, and applications.     

Recent advances in Ni−Al bimetallic catalysis for unreactive bond transformation

Ni-Al bimetallic catalysis proves to be an efficient catalytic strategy for unreactive bond transformations. Recently, chiral bifunctional ligands, especially amphoteric secondary phosphine oxide(SPO) ligand, are used for a more powerful synergistic effect in the bimetal-catalyzed reactions, providing not only milder reaction conditions and higher reactivity but also excellent reaction selectivity. Herein, we give a brief review on the development of Ni-Al bimetallic catalytic system and highlight recent advances in enantioselective Ni-Al bimetallic catalysis for unreactive bond transformation.     

Recent advancements in analytical methods of phosphodiesterase 5 inhibitors and their metabolitesEI北大核心CSCD

磷酸二酯酶5抑制剂(PDE5i)用于治疗勃起功能障碍和肺动脉高压等疾病。因PDE5i类药物种类繁多,理化性质各异,在体内代谢迅速且具有多种代谢途径,故生物样本检验难度大。本文介绍了PDE5i类药物及其代谢物,总结了生物样本中该类物质的沉淀蛋白法、液-液萃取法、固相萃取法和固相微萃取法等前处理方法,综述了高效液相色谱法、液相色谱质谱联用法、荧光光谱法和电化学分析法等检测方法,展望了PDE5i及其代谢物分析的未来发展方向,以期为PDE5i的药物监测和法庭科学毒物检验提供参考。     

Recent advances in catalytic asymmetric Büchner reaction

Büchner reaction, as a unique type of expansive dearomatization, has become a practical strategy for the straightforward assembly of valuable functionalized cycloheptatrienes from ubiquitous aromatic precursors. Although the asymmetric version has been investigated since the early 1990s, enantioselective Büchner reaction is still limited by the catalyst type and substrate scope. This review aims to propose the limitation and possible development direction of this field by summarizing the evolution of catalytic asymmetric Büchner reaction, which is organized on the basis of intra- and intermolecular reactions. Considering the different metal carbene precursors, the reactions are further classified by carbene sources.     

Recent advances in mechanochemical C–H functionalization reactions

The mechanochemical synthesis has provided a greener alternative to solution-based approaches by eliminating the use of organic solvents and reducing the energy consumption. The C–H functionalization is among the most concise and economical synthetic strategies. The combination of the benefits from these two methods provides new opportunities to further increase the efficiency and sustainability of organic synthesis. In this digest, we aim to provide a brief overview of the recent advances in mechanochemical C–H functionalization reactions.     

Recent advances in chemical adsorption and catalytic conversion materials for Li–S batteries

Owing to their low cost, high energy densities, and superior performance compared with that of Li-ion batteries, Li–S batteries have been recognized as very promising next-generation batteries. However, the commercialization of Li–S batteries has been hindered by the insulation of sulfur, significant volume expansion, shuttling of dissolved lithium polysulfides(Li PSs), and more importantly, sluggish conversion of polysulfide intermediates. To overcome these problems, a state-of-the-art strategy is to use sulfur host materials that feature chemical adsorption and electrocatalytic capabilities for Li PS species. In this review, we comprehensively illustrate the latest progress on the rational design and controllable fabrication of materials with chemical adsorbing and binding capabilities for Li PSs and electrocatalytic activities that allow them to accelerate the conversion of Li PSs for Li–S batteries. Moreover, the current essential challenges encountered when designing these materials are summarized, and possible solutions are proposed. We hope that this review could provide some strategies and theoretical guidance for developing novel chemical anchoring and electrocatalytic materials for high-performance Li–S batteries.     

Recent advances of Pd-π-allyl zwitterions in cycloaddition reactions

Palladium-catalyzed cycloaddition reactions via Pd-π-allyl zwitterions have been established as significant synthetic transformations to enable numerous carbon- or heterocycles compounds that are key constituents of various biologically active natural products and pharmaceuticals. In addition to the well-known Pd-π-allyl zwitterions, including palladium-trimethylenemethane and Pd-1,3/1,4-zwitterions, chemists have recently discovered new applications of several long ago reported but less-studied Pd-π-allyl zwitterions, which can straightforwardly and efficiently construct novel cyclic architectures. Meanwhile, some impressive newly designed zwitterions have been also developed. Those zwitterions are diverse and can serve as transient and highly reactive intermediates for the subsequent cyclization with various acceptors. In this review, we highlight recent advances in applications of these two types of zwitterions in the synthesis of complex polycyclics and medium-sized cyclic compounds.     

引言北大核心CSCD

食品安全事关人民群众身体健康和生命安全,事关经济健康发展与社会和谐稳定。优异的分离分析技术是保障食品安全的重要手段,食品基质复杂,目标物种类繁多,且含量水平低,加之近年来食品安全有害物隐蔽性越来越强,通过化学性修饰等手段使目标物的形态多样等,给食品安全分离分析带来极大的挑战。     

引言北大核心CSCD

灵敏、可靠地检测复杂样品中痕量、超痕量目标物对分析测量学提出了巨大挑战,目前市场上虽已有诸多智能化的现代分析检测仪器,但考虑到复杂的样品基底及目标组分的低含量,在进行仪器分析检测前,需进行有效的样品制备,以降低复杂样品基底的干扰,提高检测准确性,同时对目标组分进行富集,从而改善检测灵敏度。可以说,样品制备过程是整个分析过程中最为重要和耗时的步骤,影响着分析结果的准确性和可靠性。     

Recent advances on small-molecule fluorophores with emission beyond 1000 nm for better molecular imaging in vivo

In the second near-infrared channel(NIR-II, 1000–1700 nm), organic and inorganic fluorophores are designed with superior chemical/optical properties to provide real-time information with deeper penetration depth and higher resolution owing to the innate lower light scattering and absorption of the NIR-II imaging than conventional optical imaging. Among them, the small-molecule based fluorophores have been highlighted due to their desirable biocompatibility and favorable pharmacokinetics. In this review, we introduced the latest research progress of the rational design of small-molecule NIR-II fluorophores and their impressively biological applications including the NIR-II signal imaging,multimodal imaging and theranostic.     

Research progress in mass spectrometry analysis for samples containing non-volatile saltsEI北大核心CSCD

It’s still a challenge for mass spectrometers （MS） to analyze samples in non-volatile salts systems. On the one hand, non-volatile salts are easy to crystallize, which will seriously contaminate and clog the transmission system of mass spectrometry, such as capillaries, ion transfer tubes, sampling cones, etc., thus the analysis results can be affected and the MS can be damaged. On the other hand, non-volatile salts always bring ion suppression, which significantly reduces the signal intensity of the analytes. At the same time, the mass spectrum will be dominated by a large number of salt cluster peaks, interfering with the discrimination of charge state. Recently, different methods have been developed to solve above two problems. This article reviewed the present research progress of mass spectrometry analysis for salt-containing samples, focusing on the role of conventional ion source modification and ambientionization mass spectrometry in the analysis of salt-containing samples. Pretreatment methods were also summarized briefly. Finally, the development tendency of mass spectrometry analysis for salt containing samples is predicted and prospected. © 2023, Youke Publishing Co.,Ltd. All rights reserved.     

Recent advances in C–S bond construction to synthesize sulfone

Sulfone is prevalent in natural products and has been widely used in organic chemistry. Among the approaches of installing sulfonyl group, sulfonylation starting from stable and environmentally friendly sulfonyl sources is promising and attractive. Diverse mild sulfonyl sources such as DABSO, inorganic metal salts, sulfinic acids/salts, and sulfonyl hydrazides have been applied to construct sulfone. In this review, recent advances for the sulfonylation under transition metal catalysis and metal-free conditions are summarized.     

Advances in chromatographic analysis of ginsenosidesEI北大核心CSCD

Ginsenosides possess pharmacological activities such as anti-aging,cardiovascular protection,and improving immunity. However,the detection and analysis of ginsenosides commonly suffer from the problem of low sensitivity owing to the complex matrix and low content of ginsenosides. Chromatographic technology was often used to detect ginsenosides owing to the advantages of high accuracy,high sensitivity,good reproducibility and low sample consumption,etc. In this review,the application of chromatographic analysis technologies in ginsenosides detection was summarized. First of all,accuracy of test results for the ginsenosides can be effectively improved by using high performance liquid chromatography（HPLC）combined with various detectors. Secondly,the combination of HPLC with mass spectrometry can be utilized for qualitative and quantitative analysis of ginsenosides, as well as other fields, such as metabonomics, pharmacokinetics, intestinal microorganisms and quality control. Moreover,the application of gas chromatography in analysis of ginsenosides was reviewed. Briefly,with the continuous development of chromatographic technology,the degree of accuracy for ginsenosides detection was effectively improved,which is beneficial to realize the effective analysis of ginsenosides. © 2023, Youke Publishing Co., Ltd. All rights reserved.