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Covalently tethering disulfonic acid moieties onto polyoxometalate boosts acid strength and catalytic performance for hydroxyalkylation/alkylation reaction

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Science China Chemistry 2022年第4期65卷 699-709页

作者： Lifei Lian Yubing Liu Xianfeng Yi Hanbin Hu Xiang Chen Hongqiang Li Wei Chen Anming Zheng Yu-Fei Song State key laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China Wuhan Center for magnetic resonance Key Laboratory of Magnetic Resonance in Biological SystemsState Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China

Solid acid catalysts are widely used in the production of various high-value added and industrially important *** the use of organosilicon compounds to modify the vacancy site has been extensively studied,the covalent tethering-SO_(3)H functionalized organosilicon modified polyoxometalates(POMs)has been rarely *** this work,two catalysts(TBA_(4)[SiW_(11)O_(39)(O(SiC_(3)H_(6)SO_(3)H)_(2))](compound 2)and TBA_(4)[SiW_(11)O_(39)(O(SiC_(8)H_(8)SO_(3)H)_(2))](compound 3))were synthesized successfully through covalently grafting different sulfonic acid(-SO_(3)H)groups onto[SiW_(11)O_(39)]^(8−)cluster,*** 2 was achieved by surface grafting and in situ oxidation(3-mercaptopropyl)-trimethoxysilane,while compound 3 was achieved by surface grafting of 2-(4-chlorosulfonylphenyl)*** Brønsted acid strength of compounds 2 and 3 can be demonstrated by different methods including potentiometric titration,pyridine adsorption studies,and the ^(31)P trimethylphosphine oxides(TMPO)nuclear magnetic resonance(NMR).The systematic investigation of the relationship among POM structures,acid strength,and electron density was carried out based on density functional theory(DFT)calculation and experimental results,which revealed that covalent modification of compounds 2 and 3 decreased the electron density of the O-H bond,and promoted the release of H^(+).When applied in hydroxyalkylation/alkylation(HAA)reaction of 2-methylfuran(2-MF)with cyclohexanone,compound 2 exhibited better catalytic performance with conversion of ~93%,monocyclic fuel precursors(1a)yield of 79.9% and selectivity of 85.7% than compound 3,which can be attributed to strong Brønsted acid and the intramolecular hydrogen-bonding interactions between the neighboring -SO_(3)H moieties in compound ***,compound 2 also showed excellent catalytic activity in the HAA reaction of 2-MF with several different aldehydes and ketones(e.g.,furfuraldehyde,5-methylfurfurald

关键词： polyoxometalates sulfonic acid covalent modifications acid catalysis alkylation reaction

Excited-state Intramolecular Proton Transfer Mechanisms of Thiazole-based Chemosensor: a TD-DFT Study

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Chinese Journal of Structural Chemistry 2020年第11期39卷 1933-1940页

作者： CAO Hu LIU Gai-Mei CAI Jia WANG Yan School of Chemistry and Environmental Engineering Hubei Minzu UniversityEnshi 445000China key laboratory of magnetic resonance in biological systems National Center for Magnetic Resonance in WuhanState Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China

The excited-state intramolecular proton transfer(ESIPT) mechanisms of 2-(2-hydroxyphenyl)-4-phenylthiazole(HPT) and 2-(5-bromo-2-hydroxyphenyl)-4-phenylthiazole(BrHPT) have been systematically investigated by density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods, approaching along with the polarizable continuum model(PCM). The calculated primary bond lengths and bond angles demonstrate that HPT and BrHPT can form intramolecular hydrogen bonds in the ground state(S0), which can be significantly strengthened in the first excited state(S1). Our calculated results well reproduce the experimental absorption and emission spectra. Upon addition of F-, the proton can move close to F-and the hydroxy moieties are deprotonated, which cause a red-shift in absorption and a new emission peak in fluorescence emission with the disappearance of the dual fluorescence emission. The calculated Mulliken’s charge distribution and frontier molecular orbitals further demonstrate that the ESIPT processes are more likely to occur in the S1 state. The constructed potential energy curves of the S0 and S1 states confirm that the proton transfer processes are hard to occur in the S0 state due to the high energy barriers. Moreover, much lower energy barriers are found in the S1 state, which proves that the ESIPT processes are more likely to take place in the S1 state. In addition, compound with electron withdrawing(-Br) group might result in much stronger intramolecular hydrogen bond and owns lower energy barrier, which can facilitate the ESIPT processes.

关键词： density functional theory ESIPT 2-(2-hydroxy-phenyl)-4-phenylthiazole potential energy curves

Computational Insights into the Excited State Intramolecular Proton Transfer Reactions in Ortho-hydroxylated Oxazolines

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Chinese Journal of Structural Chemistry 2021年第5期40卷 540-548,527页

作者： LIU Gai-Mei MA Wei-Jia WANG Yan YANG Yan SONG Xin-Jian School of Chemistry and Environmental Engineering Hubei Minzu UniversityEnshi 445000China key laboratory of magnetic resonance in biological systems National Center for Magnetic Resonance in WuhanState Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsChinese Academy of SciencesWuhan 430071China

Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-ol(DDOP-C_(6)H_(5)) and 4-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-3-hydroxy-benzonitrile(DDOP-CN), have been systematically explored by density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods. Two stable configurations(enol and keto forms) are found in the ground states(S_(0)) for all the compounds while the enol form only exists in the first excited states(S_(1)) for the compound modified with electron donating group(-C_(6)H_(5)). In addition, the calculated absorption and emission spectra of the compounds are in good agreements with the experiments. Infrared vibrational spectra at the hydrogen bond groups demonstrate that the intramolecular hydrogen bond O(1)-H(2)···N(3) in DDOP-C_(6)H_(5) is strengthened in the S_(1) states, while the frontier molecular orbitals further reveal that the ESIPT reactions are more likely to occur in the S_(1) states for all the compounds. Besides, the proton transfer potential energy curves show that the enol forms can barely convert into keto forms in the S_(0) states because of the high energy barriers. Meanwhile, intramolecular proton transfer of all the compounds could occur in S_(1) states. The ESIPT reactions of the ortho-hydroxylated oxazolines are barrierless processes for unsubstituted DDOP and electron withdrawing substituted DDOP-CN, while the electron donating substituted DDOP-C_(6)H_(5) has a small barrier, so the electron donating is unfavorable to the ESIPT reactions of ortho-hydroxylated oxazolines.

关键词： excited-state intramolecular proton transfer electron donating group ortho-hydroxylated oxazolines potential energy curves

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Brain structural plasticity in rats subjected to early binocular enucleation characterized by high resolution anatomical magnetic resonance imaging and diffusion tensor imaging

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magnetic resonance Letters 2023年第1期3卷 14-21,I0002页

作者： Xuxia Wang Fuchun Lin Yan Kang Hao Lei Center for Brain Science State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsNational Center for Magnetic Resonance in WuhanKey Laboratory of Magnetic Resonance in Biological SystemsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430071China

Visual deprivation leads to structural neuroplasticity in the blind subjects,including gray matter(GM)and white matter(WM)atrophy and alterations in structural *** rat model of binocular enucleation(BE)is a frequently used animal model for studying brain plasticity induced by early *** few neuroimaging studies have been performed on this model to investigate whether or not the BE rats have image phenotypes similar to or comparable to,those observed in the early blind *** current study aimed to assess brain structural plasticity in BE rats using anatomical magnetic resonance imaging(MRI)and diffusion tensor imaging(DTI).The results demonstrated that early BE at postnatal day 4(P4)caused almost complete degeneration of optic nerve(ON)and optic chiasma(OCH),atrophy in a number of visual and non-visual structures,including optic tract(OT),dorsal lateral geniculate nucleus(DLG)and corpus callosum(CC).The BE rats also exhibited impairments of WM microstructural integrity in the OT,and reduction of structural connectivity between the normal-appearing visual cortex(VC)and somatosensory/motor cortices at 4 months of age,likely as manifestations of deafferentationinduced *** structural neuroplasticity in BE rats observable to structural MRI parallels largely with what has been reported in blind subjects,suggesting that longitudinal neuroimaging studies on animal models of sensory deprivation can provide insights into how the brain changes its wiring and function during development/adaption in response to the lack of sensory stimuli.

关键词： Blindness Brain Structural plasticity MRI Rats

Detection of a temporal salient object benefits from visual stimulus-specific adaptation in avian midbrain inhibitory nucleus

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Integrative Zoology 2024年第2期19卷 288-306页

作者： Jiangtao WANG Xiaoping RAO Shuman HUANG Zhizhong WANG Xiaoke NIU Minjie ZHU Songwei WANG Li SHI Department of Automation Zhengzhou University School of Electrical EngineeringZhengzhouChina State key laboratory of magnetic resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in WuhanKey Laboratory of Magnetic Resonance in Biological SystemsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhanChina Department of Automation Tsinghua UniversityBeijingChina

Food and predators are the most noteworthy objects for the basic survival of wild animals,and both are often deviant in both spatial and temporal domains and quickly attract an animal’s *** stimulus-specific adaptation(SSA)is considered a potential neural basis of salient sound detection in the temporal domain,related research on visual SSA is limited and its relationship with temporal saliency is *** avian nucleus isthmi pars magnocellularis(Imc),which is central to midbrain selective attention network,is an ideal site to investigate the neural correlate of visual SSA and detection of a salient object in the time ***,the constant order paradigm was applied to explore the visual SSA in the Imc of *** results showed that the firing rates of Imc neurons gradually decrease with repetitions of motion in the same direction,but recover when a motion in a deviant direction is presented,implying visual SSA to the direction of a moving ***,enhanced response for an object moving in other directions that were not presented ever in the paradigm is also *** verify the neural mechanism underlying these phenomena,we introduced a neural computation model involving a recoverable synaptic change with a“center-surround”pattern to reproduce the visual SSA and temporal saliency for the moving *** results suggest that the Imc produces visual SSA to motion direction,allowing temporal salient object detection,which may facilitate the detection of the sudden appearance of a predator.

关键词： adaptation attention model pigeon saliency

Targeted Catalytic Cracking to Olefins(TCO):Reaction Mechanism,Production Scheme,and Process Perspectives

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Engineering 2023年第11期30卷 100-109页

作者： Youhao Xu Yanfen Zuo Wenjie Yang Xingtian Shu Wei Chen Anmin Zheng Research Institute of Petroleum Processing SinopecBeijing 100083China Economics and Development Research Institute SinopecBeijing 100029China State key laboratory of magnetic resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in WuhanKey Laboratory of Magnetic Resonance in Biological SystemsWuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China

Light olefins are important organic building blocks in the chemicals *** main low-carbon olefin production methods,such as catalytic cracking and steam cracking,have considerable room for improvement in their utilization of *** review provides a thorough overview of recent studies on catalytic cracking,steam cracking,and the conversion of crude oil *** maximize the production of light olefins and reduce carbon emissions,the perceived benefits of various technologies are *** olefin generation and conversion as a link to expand upstream and downstream processes,a targeted catalytic cracking to olefins(TCO)process is proposed to meet current demands for the transformation of oil refining into chemical *** main innovations of this process include a multiple feedstock supply,the development of medium-sized catalysts,and a diameter-transformed fluidizedbed reactor with different feeding *** combination with other chemical processes,TCO is expected to play a critical role in enabling petroleum refining and chemical processes to achieve low carbon dioxide emissions.

关键词： Light olefins Steam cracking Catalytic cracking TCO process Oil processing revolution

Solid-state NMR for metal-containing zeolites:from active sites to reaction mechanism

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Frontiers of Chemical Science and Engineering 2020年第2期14卷 159-187页

作者： Xingling Zhao Jun Xu Feng Deng National Center for magnetic resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsCAS Key Laboratory of Magnetic Resonance in Biological SystemsWuhan Institute of Physics and MathematicsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430071China University of Chinese Academy of Sciences Beijing 100049China Wuhan National laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

Metal-containing zeolite catalysts have found a wide range of applications in heterogeneous *** understand the nature of metal active sites and the reaction mechanism over such catalysts is of great importance for the establishment of structure-activity *** advanced solid-state NMR(SSNMR)spectroscopy is robust in the study of zeolites and zeolite-catalyzed *** this review,we summarize recent developments and applications of SSNMR for exploring the structure and property of active sites in metal-containing ***,detailed information on host-guest interactions in the relevant zeolite catalysis obtained by SSNMR is also ***,we highlight the mechanistic understanding of catalytic reactions on metal-containing zeolites based on the observation of key surface species and active intermediates.

关键词： metal-containing zeolites solid-state NMR active site host-guest interaction reaction mechanism

NMR assignments and characterization of the DNA-binding domain of Arabidopsis transcription factor WRKY11--Dedicated to Professor Xiuwen Han on the occasion of her 80th birthday

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magnetic resonance Letters 2021年第2期1卷 112-120页

作者： Jiannan Wang Yaling Lin Qinjun Zhu Jingfeng Zhang Maili Liu Yunfei Hu State key laboratory of magnetic resonance and Atomic and Molecular Physics Wuhan National Laboratory for OptoelectronicsNational Center for Magnetic Resonance in WuhanKey Laboratory of Magnetic Resonance in Biological SystemsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan430071China University of Chinese Academy of Sciences Beijing100049China

The WRKY proteins are a family of plant-specific transcription factors(TFs)that are widely involved in plant development and anti-stress *** WRKY11(AtWRKY11)functions in regulating plant defense against abiotic stress and belongs to the Ild subgroup of WRKY *** herein report the expres sion,purification and preliminary structural characterization of AtWRKY11 DNA-binding domain(DBD)using solution NMR Almost complete backbone chemical shift assignments of AtWRKY11-DBD have been *** shift-based secondary structure analysis suggests that AtWRKY11-DBD may exhibit local conformational diferences from the X-ray structure of the C-terminal WRKY domain of AtWRKY1,particularly in the β1 and β5 *** current study provides the basis for further structural and interactional studies.

关键词： Transcription factor WRKY DNA-Binding domain W-box Nuclear magnetic resonance(NMR) Protein-DNA interaction

Fluorescence characterization of the thermal stability of collagen mimic peptides

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Chinese Chemical Letters 2017年第5期28卷 963-967页

作者： Xiu-Xia Sun Jun Fan Yan-Nan Hou Shuo Liang Yu-Ping Zhang Jian-Xi Xiao State key laboratory of Applied Organic Chemistry Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu ProvinceCollege of Chemistry and Chemical EngineeringLanzhou University key laboratory of magnetic resonance in biological systems State Key Laboratory of Magnetic Resonance and Atomic and Molecular PhysicsWuhan Institute of Physics and MathematicsChinese Academy of Sciences

The thermal stability of triple helical structure plays a critical role in collagen biosynthesis,function and *** technique was utilized to characterize the thermal stability of synthetic collagen mimic *** spectroscopy is widely used with easy access all around the world because of its inexpensive instrumentation,low operation cost,easy operation,and high *** we have developed an alternative fluorescence method to detect the thermal stability of collagen mimic *** have demonstrated that fluorescence spectroscopy could measure the thermal stability of collagen mimic peptides with low concentrations under different *** highly sensitive fluorescence self-quenching assay will greatly expedite the studies of sequence-dependent properties of collagen mimic peptides,and it has great potential in the application of determining the thermal stability of triple helix systems such as collagens,collectins,adiponectin,macrophage scavenger and C1q.

关键词： Collagen Peptides Thermal stability Fluorescence Triple helix