A special column highlighting young scientists at Institute of Chemistry, Chinese Academy of Sciences (ICCAS)

Just seeing off the BOth anniversary of the Institute of Chemistry, Chinese Academy of Sciences （ICCAS）, we are here with pleasure to conduct A Special Column for Young Scientists at ICCAS published in Chinese Chemistry Letters （CCL） endeavoring to disseminate positive energy of several enthusiastic chemists and spread their recent research to the global scientific community.

Celebrating the 60th Anniversary of Institute of Chemistry,Chinese Academy of Sciences

Institute of Chemistry,Chinese Academy of Sciences(ICCAS)was established in 1956.ICCAS is a multidisciplinary research institute dedicated to the basic research in broad fields of chemical sciences,and to the key development of the innovative high-technology aiming at the imperative national needs and important strategic targets,as well as to the collaborative high-technology applications and transfers.With the development of 60 years,ICCAS has become one of the leading chemistry institutions in China with high international visibility.

Medicinal uses,phytochemistry and pharmacology of Picralima nitida(Apocynaceae) in tropical diseases:A review

Picralima nitida Durand and Hook,(fam.Apocynaceae)is a West African plant with varied applications in African folk medicine.Various parts of the plant have been employed ethnomedicinally as remedy for fever,hypertension,jaundice,dysmenorrheal,gastrointestinal disorders and malaria.In order to reveal its full pharmacological and therapeutic potentials,die present review focuses on the current medicinal uses,phytochemistry,pharmacological and toxicological activities of this species.Literature survey on scientific journals,books as well as electronic sources have shown the isolation of alkaloids,tannins,polyphenols and steroids from different parts of the plant,pharmacological studies revealed that the extract or isolated compounds from this species posses analgesic,anti-inflammatory,hypoglyceamic,hypotensive,antiplasmodial,antimicrobial,antiulcer and antitumorigenic activities.Results from various scientific investigations to date have revealed the potential of the extract from the plant or isolated compounds for use in the treatment and prevention of various kinds of human diseases.However,further studies on the extracts and pure compounds from this species is required to completely assess its phytoc-hemical,pharmacological and toxicological profile as well as the mechanism of action behind these pharmacological activities exhibited by the compounds isolated from this species.

ELECTROCHEMISTRY OF POLYANILINE UNDER LIGHT

The electrochemistry of polyaniline synthesized electrochemically in acidic solution under light irradiation has been studied as a function of the applied potentials, the concentration and acidity of electrolyte as well as pH at applied potentials in the rang+0.40 to-0.5V vs. SCE. It is concluded that under selected experimental conditions the reduced repeat groups in polyaniline are oxidized by air in the dark and that this oxidation process can be strongly photocatalyzed.

Microstructural evolution and micro-mechanical properties of non-isothermal solidified zone in TLP bonded Ni-based superalloy joints

Transient liquid phase(TLP)bonding is a promising process for the joining and repairing of nickel-base superalloys.One of the most important parameters in TLP bonding is the bonding time required for suf-ficient isothermal solidification which prevents the formation of undesirable precipitated phases.In the present work,the effect of bonding time on the microstructure,type,and evolution of precipitates in the non-isothermal solidified zone(NSZ)and their effect on micro-mechanical properties were systemat-ically investigated using multi-scale tests in TLP bonded Mar-M247 superalloy joints with Ni-15.2Cr-3.74B interlayer at 1230℃.For a bonding time of 5 min,dual-phase M_(23)(C,B)_(6)-γ/γ’(where M is a mix-ture of Hf,Ta,Cr,and Ni)with eutectic configuration was formed in NSZ.With the increase in bonding time,the evolution of NSZ microstructure can be summed up as eutectic M_(23)(C,B)_(6)-γ/γ’,semi-striping dual-phase M_(23)(C,B)_(6)-γ/γ’,discontinuously striping M_(23)(C,B)_(6)-γ/γ’,followed by the disintegration of NSZ.As the NSZ counterpart,the isothermal solidified zone(ISZ)is mainly composed ofγ/γ’.Ac-companied by the dissolution of M_(23)(C,B)_(6) in the centerline,the proportion of the ISZ increases greatly until the joints are completely occupied by ISZ.Finally,a bamboo-like structure with domain size of-100μm was formed in the joint centerline,along withγ’reorganized themselves all into cubic shapes and distributed homogeneously.Mechanical property tests demonstrated that in comparison to samples with longer bonding time,the NSZ of the shortest bonding time(5 min)has the highest strength and a subsequent decrease in strength was observed with prolonging the bonding time and post-bond heat treatment.Furthermore,possible solidification/transformation path,segregation behavior,and formation mechanism of NSZ/ISZ evolution were discussed.

Synthesis and Modulation of Low-Dimensional Transition Metal Chalcogenide Materials via Atomic Substitution

In recent years,low-dimensional transition metal chalcogenide(TMC)materials have garnered growing research attention due to their superior electronic,optical,and catalytic properties compared to their bulk counterparts.The controllable synthesis and manipulation of these materials are crucial for tailoring their properties and unlocking their full potential in various applications.In this context,the atomic substitution method has emerged as a favorable approach.It involves the replacement of specific atoms within TMC structures with other elements and possesses the capability to regulate the compositions finely,crystal structures,and inherent properties of the resulting materials.In this review,we present a comprehensive overview on various strategies of atomic substitution employed in the synthesis of zero-dimensional,one-dimensional and two-dimensional TMC materials.The effects of substituting elements,substitution ratios,and substitution positions on the structures and morphologies of resulting material are discussed.The enhanced electrocatalytic performance and photovoltaic properties of the obtained materials are also provided,emphasizing the role of atomic substitution in achieving these advancements.Finally,challenges and future prospects in the field of atomic substitution for fabricating low-dimensional TMC materials are summarized.

Synthesis and Photochemistry of Diphenylchlorin and Diphenylbacteriochlorin

Diphenylchlorin (DPC) and diphenylbacteriochlorin (DPBC) were synthesized for the first time from reduction of 5,10-diphenylporphyrin (DPP). As photosensitizers they have sizable absorption in the red region of the visible spectrum. The high yield of DPC.-photosensitized generation Of O-1(2), and the EPR studies in homogenerous solution showed that the photodynamic action of DPP-based photosensitizers may proceed via type I and type II machanisms.

A perspective on energy chemistry of low-temperature lithium metal batteries

Dendrite growth of lithium(Li)metal anode severely hinders its practical application,while the situation becomes more serious at low temperatures due to the sluggish kinetics of Liion diffusion.This perspective is intended to clearly understand the energy chemistry of lowtemperature Li metal batteries(LMBs).The lowtemperature chemistries between LMBs and traditional Liion batteries are firstly compared to figure out the features of the lowtemperature LMBs.Li deposition behaviors at low temperatures are then discussed concerning the variation in Liion diffusion behaviors and solid electrolyte interphase(SEI)features.Subsequently,the strategies to enhance the diffusion kinetics of Li ions and suppress dendrite growth including designing electrolytes and electrode/electrolyte interfaces are analyzed.Finally,conclusions and outlooks are drawn to shed lights on the future design of highperformance lowtemperature LMBs.

Quantum Chemistry Study on Dissociation of Oxalyl Bromide

The multi-bond dissociation dynamics of oxalyl bromide （（BrCO）2） has been investigated by DFT and CIS calculations. Upon the results, conclusion could be drawn that dissociation of C-Br bond of oxalyl bromide at the ground state （So） is of barfierless. After the absorption of a photon, （BrCO）2 is excited to the first excited state and one of its C-Br bonds is broken to yield Br ·＊ and BrCOCO· ＊ free radicals. In addition, BrCOCO · ＊ with high energy is apt to release energy, and ultimately, turns into BrCOCO ·of the ground state. The energy is adequate for BrCOCO· to break down into Br · and 2CO; at the same time the C-C and C-Br bonds of BrCOCO · free radicals dissociate.

Stereochemistry Control in Direct 1α-Hydroxylation of 5,6-trans-Vitamin D_(3) by Solid Support

A solid-phase synthesis of 1α-hydroxylation of 5,6-trans-vitamin D3 8 is described.The solid phase resin acts as a special protecting group, which gives a higher stereoselectivity in oxidation step than classical protecting groups. The stereochemistry control is favored by using high crosslinkage polymer support in a poor solvent. This work may be of benefit to the synthesis of vitamin D system.

Room Temperature Synthesis of Vertically Aligned Amorphous Ultrathin NiCo-LDH Nanosheets Bifunctional Flexible Supercapacitor Electrodes

Developing a simple scalable method to fabricate electrodes with high capacity and wide voltage range is desired for the real use of electrochemical supercapacitors.Herein,we synthesized amorphous NiCo-LDH nanosheets vertically aligned on activated carbon cloth substrate,which was in situ transformed from Co-metal-organic framework materials nano-columns by a simple ion exchange process at room temperature.Due to the amorphous and vertically aligned ultrathin structure of NiCo-LDH,the NiCo-LDH/activated carbon cloth composites present high areal capacities of 3770 and 1480 mF cm^(-2)as cathode and anode at 2 mA cm^(-2),and 79.5%and 80%capacity have been preserved at 50 mA cm^(-2).In the meantime,they all showed excellent cycling performance with negligible change after>10000 cycles.By fabricating them into an asymmetric supercapacitor,the device achieves high energy densities(5.61 mWh cm^(-2)and 0.352 mW cm^(-3)).This work provides an innovative strategy for simplifying the design of supercapacitors as well as providing a new understanding of improving the rate capabilities/cycling stability of NiCo-LDH materials.

Synthesis, Electrochemistry and Antitumor Activity of 1’H, 3’H(Me)-spiro-[(aza)benzimidazoline-2’, 3-(1,2-diferrocenylcyclopropenes)], 2-(1,2-Diferrocenylvinyl)benz- and Azabenzimidazoles

A new method of synthesis of 2-(1,2-diferrocenylvinyl)benz- and azabenzimidazoles (3a-f), (4a-f) and 1’H,3’H(Me)-spiro-[(aza)benzimidazoline-2’,3-(1,2-diferrocenylcyclopropenes)] (5a-f) via reactions of diferrocenyl(methylsulfanyl)cyclopropenylium iodide (1) with aromatic o-diamines (2a-f) in the presence of Et3N (80°C - 82°C) is described. The structures of the resultant compounds are established using IR, 1H and 13C NMR spectroscopy, mass spectrometry and elemental analysis. The structure of one compound, cis-2-(1,2-diferrocenylvinyl)-1-methylbenzimidazole (3b), is confirmed by X-ray diffraction analysis. The electrochemical properties of compounds 3a, 3b, 3d and 5f are investigated using cyclic square wave voltammetry. Two electrochemical processes (I-II), attributed to oxidation of the ferrocene moieties, and the values of E0’(I), E0’(II), DE0’(II-I) and comporportionation constant Kcom are reported. The bioactivities of seven compounds 3a, 3c-f, 5d, 5f are evaluated. Compound 5f is the most active compound with a modest cytotoxic activity against six human cancer cell lines: U-251 (glioma), PC-3 (prostate cancer), K-562 (leukemia), HCT-15 (colon cancer), MCF-7 (breast cancer) and SKLU-1 (lung cancer).

Carboxylates as green corrosion inhibitors of magnesium alloy for biomedical application

The efficiency of the green inhibitors(sodium salts of fumarate,glycolate and gluconate)in suppressing corrosion of the structural MA8 magnesium alloy(Mg–Mn–Ce)and the biomedical Mg–0.8Ca alloy was studied using the hydrogen evolution measurements,mass loss test,EIS,PDP,SVET/SIET.The analysis of the morphology,chemical composition,and growth kinetic of corrosion films formed in 0.9 wt%NaCl solution with and without corrosion inhibitors was carried out.The most compact surface film with the smallest thickness was formed in a saline solution with sodium fumarate.The Mg alloy samples exhibited the highest polarization resistance,the lowest localized electrochemical activity,and the lowest corrosion rate in saline with the addition of sodium fumarate and sodium glycolate.The efficiency of the applied inhibitors was up to 81%.The model of the corrosion mechanism based on the sorption of molecules of organic inhibitors is proposed.The results show the high compatibility of the used inhibitors with the calcium-phosphate PEO-matrix,indicating the possibility of forming a self-healing coating by means of these active substances.

Sixty Years of Chemistry at CAS

As one of the fundamental and key disciplines of natural sciences, chemistry deals with the properties, composition, structure, transformation and applications of substances.It could be further divided into several branches, such as inorganic chemistry, organic chemistry, physical chemistry, polymer chemistry, analytical chemistry and chemical engineering.In recent years, many new branches and fields have emerged amide the continuous development of chemistry and its interdisciplinary research with mathematics, physics, astronomy, earth science, biology, medical science, materials science, and environmental science.

Effect of Ta_(2)O_(5)nanoparticles on bioactivity,composition,structure,in vitro and in vivo behavior of PEO coatings on Mg-alloy

The present study investigates the physical and chemical characteristics,behavior in vitro and in vivo,and biocompatibility of coatings containing Ta_(2)O_(5),which are obtained by plasma electrolytic oxidation(PEO)on MA8 magnesium alloy.The obtained coatings demonstrate in vivo biocompatibility and in vitro bioactivity.Compared to the base PEO coating,the layers containing Ta_(2)O_(5)facilitate the development of apatite in simulated body fluid,suggesting that the inclusion of nanoparticles improves bioactivity of the coatings.It was found that incorporation of Ta_(2)O_(5)nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in vivo.Based on in vivo studies,these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen evolution.The results obtained in the present study concluded biocompatibility,tissue integration of the PEO coatings containing Ta_(2)O_(5)nanoparticles making them a promising protective layer for biodegradable magnesium implants.

Effect of Low pH on Forming Process of Desulfurization Gypsum Composite Boards Strengthened by Melamine-formaldehyde Resin

Through exploring the effects of low pH on the composite system of desulfurization gypsum(DG)enhanced by melamine-formaldehyde resin(MF),it is found that the inducing of sulfate-ion,in contrast to chloride and oxalate ions,favors the longitudinal growth of the crystalline form of the hydration product,which was relatively simple and had the highest length to width(L/D)ratio.At the same time,MF can also improve L/D ratio of gypsum hydration products,which favors the formation of hydrated whiskers.Finally,in a composite system composed of hemihydrate gypsum,MF,and glass fibers,when dilute sulfuric acid was used to regulate pH=3-4,the tight binding formed among the components of the composite system compared to pH=5-6.The hydration product of gypsum adheres tightly to glass fiber surface and produces a good cross-linking and binding effect with MF.The flexural strength,compressive strength,elastic modulus,and water absorption of the desulphurized gypsum composite board is 22.7 MPa,39.8 MPa,5608 MPa,and 1.8%,respectively.

Effect of the anionic composition of sulfolane based electrolytes on the performances of lithium-sulfur batteries

In lithium-sulfur batteries,cell design,specifically electrolyte design,has a key impact on the battery performance.The effect of lithium salt anion donor number(DN)(DN[PF_(6)]^(-)=2.5,DN[N(SO_(2)CF_(3))_(2)]^(-)=5.4,DN[ClO_(4)]^(-)=8.4,DN[SO_(3)CF_(3)]^(-)=16.9,and DN[NO_(3)]^(-)=21.1)on the patterns of lithium-sulfur batteries and lithium metal electrode performances with sulfola ne-based electrolytes is investigated.An increase in DN of lithium salt anions leads to an increase in the depth and rate of electrochemical reduction of sulfur and long-chain lithium polysulfides and to a decrease in those for medium-and short-chain lithium polysulfides.DN of lithium salt anions has weak effect on the discharge capacity of lithium-sulfur batteries and the Coulomb efficiency during cycling,with the exception of LiSO_(3)CF_(3)and LiNO_(3).An increase in DN of lithium salt anions leads to an increase in the cycling duration of lithium metal anodes and to a decrease in the presence of lithium polysulfides.In sulfolane solutions of LiNO_(3)and LiSO_(3)CF_(3),lithium polysulfides do not affect the cycling duration of lithium metal anodes.

Approaches to Improving Selectivity During Photoelectrochemical Transformation of Small Molecules

Photoelectrochemical (PEC) small-molecule oxidation can selectively transform substrates into high-value-added fine chemicals and increase the rate of cathode hydrogen evolution. Nevertheless, achieving high-selectivity PEC oxidation of small molecules to produce specific products is a very challenging task. In general, selectivity can be improved by changing the surface catalyticsites of the photoanode and modulating the interfacial environments of the reactions. Herein, recent advances in approaches to improving selective PEC oxidation of small molecules are introduced. We first briefly discuss the basic concept and fundamentals of small-molecule PEC oxidation. The reported approaches to improving the performance of selective PEC oxidation of small molecules are highlighted from two aspects: (1) changing the surface properties of photoanodes by selecting suitable materials or modifying the photoanodes and (2) mediating the oxidation reactions using redox mediators. The PEC oxidation mechanism of these studies is emphasized. We also discuss the challenges in this research direction and offer a perspective on the further development of selective PEC-based small-molecule transformation.

Alleviating the sluggish kinetics of all-solid-state batteries via cathode single-crystallization and multi-functional interface modification

The application of Li-rich Mn-based cathodes, the most promising candidates for high-energy-density Liion batteries, in all-solid-state batteries can further enhance the safety and stability of battery systems.However, the utilization of high-capacity Li-rich cathodes has been limited by sluggish kinetics and severe interfacial issues in all-solid-state batteries. Here, a multi-functional interface modification strategy involving dispersed submicron single-crystal structure and multi-functional surface modification layer obtained through in-situ interfacial chemical reactions was designed to improve the electrochemical performance of Li-rich Mn-based cathodes in all-solid-state batteries. The design of submicron single-crystal structure promotes the interface contact between the cathode particles and the solid-state electrolyte,and thus constructs a more complete ion and electron conductive network in the composite cathode.Furthermore, the Li-gradient layer and the lithium molybdate coating layer constructed on the surface of single-crystal Li-rich particles accelerate the transport of Li ions at the interface, suppress the side reactions between cathodes and electrolyte, and inhibit the oxygen release on the cathode surface. The optimized Li-rich cathode materials exhibit excellent electrochemical performance in halide all-solid-state batteries. This study emphasizes the vital importance of reaction kinetics and interfacial stability of Lirich cathodes in all-solid-state batteries and provides a facile modification strategy to enhance the electrochemical performance of all-solid-state batteries based on Li-rich cathodes.

Introducing hydroxyl groups to tailor the d-band center of Ir atom through side anchoring for boosted ORR and HER

Tuning the coordination atoms of central metal is an effective means to improve the electrocatalytic activity of atomic catalysts.Herein,iridium(Ir) is proposed to be asymmetrically anchored by sp-N and pyridinic N of hydrogen-substituted graphdiyne(HsGDY),and coordinated with OH as an Ir atomic catalyst(Ir_(1)-N-HsGDY).The electron structures,especially the d-band center of Ir atom,are optimized by these specific coordination atoms.Thus,the as-synthesized Ir_(1)-N-HsGDY exhibits excellent electrocatalytic performances for oxygen reduction and hydrogen evolution reactions in both acidic and alkaline media.Benefiting from the unique structure of HsGDY,IrN_(2)(OH)_(3) has been developed and demonstrated to act as the active site in these electrochemical reactions.All those indicate the fresh role of the sp-N in graphdiyne in producing a new anchor way and contributing to promote the electrocatalytic activity,showing a new strategy to design novel electrochemical catalysts.