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Investigation of Antimony ions doping on crystal structure and enhanced microwave dielectric performance of MgTa_(2)O_(6)ceramics

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Journal of Materiomics 2023年第4期9卷 701-708页

作者： Liang Shi Kui Liu Cheng Liu Dainan Zhang Huaiwu Zhang School of Electronic Science and Engineering University of Electronic Science and Technology of ChinaChengdu610054China State Key Laboratory of Electronic Thin Films and Integrated Devices University of Electronic Science and Technology of ChinaChengdu610054China

Dielectric ceramics are promising in large-scale commercial millimeter-wave communication technology,such as 5G and the upcoming 6G,thanks to their excellent frequency selection characteristics and environmental stability.In this work,various contents of SbeO bonds were introduced into the MgTa_(2)O_(6)lattice using the solid-phase reaction method to investigate the effects on the lattice and microwave dielectric properties.XRD confirms that Sb ions successfully occupy Ta sites in the lattice and cause lattice shrinkage and crystallinity deterioration,which leads to a slight decrease in the quality factor.Furthermore,dft calculations reveal that the doping leads to electron-biased aggregation toward O atoms,causing higher SbeO ionicity,but also attenuates the degree of ionization of Ta and Mg ions,which makes the dielectric constant of the doped samples vary non-monotonically with gradient doping.Satisfactorily,Sb doping substantially enhanced the thermal stability of the ceramics,with TCF values reduced from 36×10^(-6)℃^(-1)to 15×10^(-6)℃^(-1).

关键词： MgTa_(2)O_(6)ceramics Dielectric Raman dft calculation

Activation of peracetic acid by metal-organic frameworks(ZIF-67)for efficient degradation of sulfachloropyridazine

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Chinese Chemical Letters 2022年第6期33卷 3172-3176页

作者： Jun Duan Long Chen Haodong Ji Peishen Li Fan Li Wen Liu The Key Laboratory of Water and Sediment Science Ministry of EducationCollege of Environment Science and EngineeringPeking UniversityBeijing 100871China State Environmental Protection Key Laboratory of All Material Fluxes in River Ecosystems Peking UniversityBeijing 100871China

Peracetic acid(PAA)-based system is becoming an emerging advanced oxidation process(AOP)for effective removal of organic contaminants from water.Various approaches have been tested to activate PAA,while no previous researches reported the application of metal-organic frameworks(MOFs)materials for PAA activation.In this study,zeolitic imidazole framework(ZIF)-67,a representative MOFs,was facile synthesized via direct-mixing method at room temperature,and tested for PAA activation and sulfachloropyridazine(SCP)degradation.The as-synthesized ZIF-67 exhibited excellent performance for PAA activation and SCP degradation with 100%of SCP degraded within 3 min,owing to the specific MOFs structure and abundant Co^(2+) sites.The pseudo-first-order kinetic model was applied to fit the kinetic data,with rate constant k_(1) of ZIF-67 activated PAA system 34.2 and 156.5 times higher than those of conventional Co_(3)O_(4)activated PAA and direct oxidation by PAA.Radical quenching experiments and electron paramagnetic resonance(EPR)analysis indicated that CH_(3)C(O)OO^(·)played a major role in this PAA activation system.Then,the Fukui index based on density functional theory(dft)calculation was used to predict the possible reaction sites of SCP for electrophilic attack by CH_(3)C(O)OO^(·).In addition,the degradation pathway of SCP was proposed based on Fukui index values and intermediates detection,which mainly included the S-N bond cleavage and SO_(2)extrusion and followed by further oxidation,dechlorination,and hydroxylation.Therefore,ZIF-67 activated PAA is a novel strategy and holds strong potential for the removal of emerging organic contaminants(EOCs)from water.

关键词： Peracetic acid activation Metal-organic frameworks Zeolitic imidazole framework(ZIF)-67 Emerging organic contaminants Acetylperoxy radical dft calculation

Constructing low-valent Ni nanoparticles for highly selective CO_(2) reduction

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Chinese Chemical Letters 2022年第1期33卷 424-427页

作者： Kuanda Xu Shisheng Zheng Yang Li Honghao Chu Qi Xiong Zongwei Mei Qinghe Zhao Luyi Yang Shunning Li Feng Pan School of Advanced Materials Peking University Shenzhen Graduate SchoolShenzhen 518055China

The electroreduction of CO_(2)(CO_(2)RR)into value-added chemicals is a sustainable strategy for mitigating global warming and managing the global carbon balance.However,developing an efficient and selective catalyst is still the central challenge.Here,we developed a simple two-step pyrolysis method to confine low-valent Ni-based nanoparticles within nitrogen-doped carbon(Ni-NC).As a result,such Ni-based nanoparticles can effectively reduce CO_(2)to CO,with a maximum CO Faradaic efficiency(FE)of 98%at an overpotential of 0.8 V,as long as good stability.Experimental and the density functional theory(dft)calculation results reveal that low-valent Ni plays a key role in activity and selectivity enhancement.This study presents a new understanding of Ni-based CO_(2)RR,and provides a simple,scalable approach to the synthesis of low-valent catalysts towards efficient CO_(2)RR.

关键词： CO_(2)reduction reaction Ni-based catalysts Electrocatalytic selectivity Low-valent catalyst dft calculation

Natural scaffolds-inspired synthesis of CF_(3)-substituted macrolides enabled by Rh-catalyzed C–H alkylation macrocyclization

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Chinese Chemical Letters 2022年第4期33卷 2015-2020页

作者： Tongyu Bi Yi Xu Xin Xu Bixi Tang Qing Yang Yi Zang Zhenyang Lin Jia Li Weibo Yang Chinese Academy of Sciences Key Laboratory of Receptor Research Shanghai Institute of Materia Medica(SIMM)Chinese Academy of SciencesShanghai 201203China University of Chinese Academy of Sciences Beijing 100049China Department of Chemistry The Hong Kong University of Science and TechnologyHong KongChina School of Pharmaceutical Science and Technology Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China Open Studio for Druggability Research of Marine Natural Products Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266237China

The development of innovative strategies and methods to provide natural product-like macrocycles not accessible by biosynthesis, but endowed with novel bioactivities and simplified structure, is highly desirable. Inspired by the key scaffolds of rapamycin and FR252921, herein, we report a Rh(III)-catalyzed C–H alkylation macrocyclization, which enables access to CF_(3)-substituted macrolides. dft calculations reveal that the chemoselectivity between C–H alkylation and olefination macrocyclization was highly controllable. Moreover, the unique CF_(3)-substituted macrolides showed potent anti-inflammation activities against TNF-α, IL-6 and CCL2 m RNA expression.

关键词： Rh-catalyzed C–H alkylation Late stage macrocyclization dft calculation Anti-inflammation

Theoretical Measurements of Quantitative Effects Caused by Spectator Ligands on Palladium-catalyzed C−H Activation

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Chinese Journal of Structural Chemistry 2022年第3期41卷 19-29,I0007页

作者：马晓思周永柱张磊 Department of Chemistry School of ScienceTianjin Chengjian UniversityTianjin 300384China School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China

Ligands can definitely influence C−H activation at the metal center.A ligand not directly participating in the reaction is called a spectator ligand.We attempt to quantitatively characterize the effects of diverse spectator ligands on C−H activation at palladium.We designed a model palladium catalyst and selected an array of spectator ligands,such as methoxyl,amide,methyl,phenyl,cyanide,fluorine,chlorine,and several neutral ligands,and performed density functional theory calculations on the mechanism and energetics of C−H activation reactions of benzene with different catalysts.Univalent ligands have substantially larger effects than neutral ligands,and stronglyσ-donating ligands(e.g.,methyl and phenyl)severely hinder the C−H activation in progress.A ligand trans to the reaction site influences C−H activation more than that cis to the reaction site,indicating electronic effects to be at work.For example,the existence of a methyl ligand raises the barrier height of C−H activation by 6.4 or 14.4 kcal/mol when it is placed at the position cis or trans to the C−H activation site.The effects of poorlyσ-donating ligands are not significant and similar to those of theκ1-acetate ligand.Someσ-donating andπ-accepting ligands,such as cyanide and isonitrile,hinder the C−H activation trans to them but appear to facilitate the C−H activation cis to them.On the basis of molecular orbital analyses,a chemical model is proposed to understand the observed ligand effects.Lastly,the conclusions are applied to explain the plausible mechanism of the dehydrogenative Heck coupling.

关键词： C−H activation ligand effect palladium catalyst reaction mechanism dft calculation

[Cd(Sn_(9))_(2)]^(6-) and[Cd(Ni@Sn_(9))_(2)]^(6-):Reactivity and coordination chemistry of empty and Ni-centered[Sn_(9)]^(4-) Zintl ions

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Chinese Chemical Letters 2023年第1期34卷 523-526页

作者： Ya-Nan Yang Lei Qiao Zhong-Ming Sun State Key Laboratory of Elemento-Organic Chemistry Tianjin Key Lab of Rare Earth Materials and ApplicationsSchool of Material Science and EngineeringNankai UniversityTianjin 300350China

To investigate the reactivity of homoatomic clusters[E_(9)]^(4-)(E=Si-Pb)and intermetalloid clusters[M@E_(9)]^(q-),the reactions of the Zintl anions[Sn_(9)]^(4-) and[Ni@Sn_(9)]^(4-) with the CdMes_(2)(Mes=Mesitylene)in the presence of 2.2.2-crypt were carried out.Two new compounds[K(2.2.2-crypt)]_(6)[(Sn_(9))Cd(Sn_(9))]·en(1)and[K(2.2.2-crypt)]_(6)[(Ni@Sn_(9))Cd(Ni@Sn_(9))]·en(2)were afforded.Both 1 and 2 were characterized by single-crystal X-ray diffraction,energy dispersive X-ray(EDX),and electrospray ionization mass spectrometry(ESI-MS),and can be viewed as two[Sn_(9)]^(4-)or[Ni@Sn_(9)]^(4-)subunits bridged by Cd ion in an η^(3):η^(3) coordination mode.Quantum chemical calculations reveal the relationships between the geometries and electronic structures of clusters 2a,[Ni_(3)Ge_(18)]^(4-)and[Cu_(4)@Sn_(18)]^(4-).Further electron localization technique(Ad NDP method)was performed to explain chemical bonding patterns of 1a.

关键词： Heterometallic complexes Sn cluster Zintl anions dft calculation Electronic structure

Control of meta-selectivity in the Ir-catalyzed aromatic C-H borylation directed by hydrogen bond interaction:A combined computational and experimental study

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Chinese Chemical Letters 2023年第5期34卷 263-267页

作者： Wenju Chang Yajun Wang Yu Chen Jiawei Ma Yong Liang State Key Laboratory of Coordination Chemistry Jiangsu Key Laboratory of Advanced Organic MaterialsChemistry and Biomedicine Innovation CenterSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

The origin of regioselectivity in meta-selective C-H borylation of benzamides directed by hydrogen bond interaction between ligand and substrate is elucidated through combined computational and experimental studies.We discover that a non-directed pathway,in which the urea moiety in ligand recognizes the O atom in Bpin instead of substrate,competes with the directed pathway and erodes the meta-selectivity.The non-directed pathway is sensitive to steric repulsion between Bpin and urea,and thus can be impeded by introducing a bulky substituent into the urea moiety.Accordingly,we optimize the ligand and improve the meta-selectivity in the Ir-catalyzed C-H borylation of some previously reported unsuccessful arenes.

关键词： Meta-C-H borylation Regioselectivity dft calculation Ligand design Hydrogen bond

Electroreduction NO to NH_(3)over single metal atom anchored on pyrrole type defective graphene:A dft study

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Chinese Chemical Letters 2023年第5期34卷 571-575页

作者： Jiazhi Wang Kai Li Qi Hao Dongxue Liu Xinbo Zhang State Key Laboratory of Rare Earth Resource Utilization Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China Hefei 230026China Key Laboratory of Automobile Materials Ministry of EducationJilin UniversityChangchun 130022China

Electrochemical is considered an attractive approach to recycling the pollution NO(NORR)and producing the valuable NH_(3),which could simultaneously solve the two challenging problems,i.e.,NO removal and NH_(3)synthesis.Current research efforts focus less on NORR due to the lack of effective catalysts.Herein,based on dft calculation,we try to explore effective pyrrole-type TM-N_(4)(TM=V,Cr,Mn,Fe,Co,Ni,Cu,Ru,Rh,Ta)catalysts for achieving the direct NORR.Among the investigated systems,Fe-N_(4)exhibits excellent catalytic activity and high NH_(3)selectivity.Moreover,the free energy of adsorption of N*has been proposed as a descriptor to predict and screen the effective TM-N_(4)catalyst for NORR and the crystal orbital halmilton populations(COHP)is used to describe the intrinsic relationship between metal atoms and the adsorption free energy of N^(*)intermediate.This work has provided a theoretical picture of TM-N4catalyzing NO to NH_(3),which will establish guidelines for the rational design of NORR catalysts and other electrochemical reactions.

关键词： dft calculation Pyrrole-type Descriptor NORR COHP

Self-assemblies of TTF derivatives with fluorinated phenyls and pyridine group

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Chinese Chemical Letters 2022年第2期33卷 1100-1104页

作者： Jianghua Fang Xiaoyang Zhu Wendi Luo Jianxun Shi Lejia Wang Bin Tu Qingdao Zeng Xunwen Xiao College of Material Science and Chemical Engineering Ningbo University of TechnologyNingbo 315211China CAS Key Laboratory of Standardization and Measurement for Nanotechnology CAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology(NCNST)Beijing 100190China Zhejiang Pharmaceutical College Ningbo 315100China

The self-assembly characteristics of tetrathiafulvalene(TTF) derivatives molecules 1-3 at the 1-phenyloctane/HOPG(HOPG = highly oriented pyrolytic graphite) interface had been carefully studied by scanning tunneling microscopy(STM) method. The number of F atoms on the phenyl group had significantly affected the self-assembly structures. High-resolution STM images make clear the different assembly structures between the molecules 1-3, which attribute to the different F atom numbers and pyridine group in the molecule. Density functional theory(dft) calculations have been performed to reveal the formation mechanism.

关键词： TTF Self-assembly STM dft calculation Hydrogen bonds