Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 colu...Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 columns. The structures were elucidated by spectral analysis. Results Thirteen compounds were isolated and their structures were identified as （-）-syringaresinol （1）, syringaresinol-4-O-β-D-glucopyranoside （2）, syringaresinol-4,4′-bis-O-β-D-glucopyranoside （3）, （±）-catechin （4）, catechin-3-O- β-D-glucopyranoside （5）, catechin-5-O-β-D-glucopyranoside （6）, 1,3-bis-（4-hydroxy-3,5-dimethoxyphenyl）-1,3-propanediol （7）, （R）-（＋）-chaulmoogric acid （8）, friedelin （9）, uracile （10）, benzoic acid （11）, vaniUic acid （12）, and 4-hydroxybenzoic acid （13）. Conclusion All the compounds described above were isolated from this genus for the first time.展开更多
A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate （MPC） as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane （HDU） from 1,6- bex...A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate （MPC） as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane （HDU） from 1,6- bexametbylene diamine （HDA）. The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the metboxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate （DMC） with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key spedes for reaction coupling. Higher MPC concentration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium pbenoxide was more suitable to prepare HHDU through reaction coupling. A yield of HDU as high as 98.3% could be reached under the optimal conditions of mPhONa/mDMC = 0.027 and nDMC/nHDa = 8/1 at 90 ℃ in 2 h.展开更多
Researchers from the CAS Key Laboratory of Quantum Information,University of Science and Technology of China have just achieved a significant progress in quantum key distribution research.Based on the self-developed a...Researchers from the CAS Key Laboratory of Quantum Information,University of Science and Technology of China have just achieved a significant progress in quantum key distribution research.Based on the self-developed active switching technology,they successfully conducted the world's longest-more than 90km-round-robin differential phase shift(RRDPS)quantum key distribution experiment.展开更多
To investigate the chemical components from the stems of Casearia velutina Bl.,the constituents were isolated by repeated chromatography with silica gel,Sephadex LH-20,and ODS columns.The structures were elucidated by...To investigate the chemical components from the stems of Casearia velutina Bl.,the constituents were isolated by repeated chromatography with silica gel,Sephadex LH-20,and ODS columns.The structures were elucidated by spectroscopic analysis.Eleven triterpenoids and its glycosides were isolated from the crude extract of C.velutina,and their structures were identified as friedelin-2,3-lactone（1）,friedelane（2）,epifriedelanol（3）,friedelin（4）,2α,3α,19α-trihydroxy-urs-12-en-28-oic acid（5）,2α,3β,19α-trihydroxy-urs-12-en-28-oic acid（6）,2α,3α,23-trihydroxy-urs-12-en-28-oic acid（7）,2α,3α,23-trihydroxy-olean-12-en-28-oic acid（8）,2α,3α,19α,23-tetrahydroxy-urs-12-en-28-oic acid（9）,2α,3α,19α,23-tetrahydroxy-urs-12-en-28-oic acid-28-O-β-D-glucopyranosyl ester（10）,and 3β,19α-dihydroxy-urs-12-en-28-oic acid 3-O-α-L-arabinopyranoside（11）.All the compounds described above were isolated from this species for the first time.Compound 1 is a rarely occurred seco-friedelolactone in Flacourtiaceae.展开更多
When our knowledge of a field accumulates to a certain level,we are bound to see the rise of one or more great scientists.They will make a series of grand discoveries/breakthroughs and push the discipline into an '...When our knowledge of a field accumulates to a certain level,we are bound to see the rise of one or more great scientists.They will make a series of grand discoveries/breakthroughs and push the discipline into an 'age of grand discoveries'.Mathematics,geography,physics and chemistry have all experienced their ages of grand discoveries;and in life sciences,the age of grand discoveries has appeared countless times since the 16th century.Thanks to the ever-changing development of molecular biology over the past 50 years,contemporary life science is once again approaching its breaking point and the trigger for this is most likely to be 'lifeomics'.At the end of the 20th century,genomics wrote out the 'script of life';proteomics decoded the script;and RNAomics,glycomics and metabolomics came into bloom.These 'omics',with their unique epistemology and methodology,quickly became the thrust of life sciences,pushing the discipline to new high.Lifeomics,which encompasses all omics,has taken shape and is now signalling the dawn of a new era,the age of grand discoveries.展开更多
The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavag...The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavage under physiological conditions but also function as monomer or initiator participants in polymer science. The homo-polymerization of enediynes through the Bergman cyclization to fabricate conjugated polymers is a fascinating strategy due to the advantages of facial operation, high efficiency, tailored structure, and catalyst-free operation. Moreover, conjugated polymers generated through the Bergman cyclization show many remarkable properties, such as excellent thermal stability, good solubility, and processability, which enables these polymers to be further manufactured into carbon-rich materials. Recent times have seen extensive efforts devoted to the application of the Bergman cyclization in polymer science and materials chemistry. A variety of synthetic strategies have been developed to fabricate structurally unique materials via the Bergman cyclization, including the fabrication of rod-like polymers with polyester, dendrimers and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and the construction of carbon nanomembranes with different morphologies. Future developments involving the Bergman cyclization in polymer science, probably by altering the reaction mechanism to precisely control the microstructure of polymeric products, are also proposed in this review article.展开更多
Synthetic macrocycles, a typical type of building block for molecular recognition and self-assembly, are crucial to supramolecular chemistry and materials science. Since 2008, a new generation of synthetic macrocyclic...Synthetic macrocycles, a typical type of building block for molecular recognition and self-assembly, are crucial to supramolecular chemistry and materials science. Since 2008, a new generation of synthetic macrocyclic hosts, pillarenes and their abundant derivatives, which consist of hydroquinone units linked by methylene bridges at 2,5-positions, have been the focus of much research. Numerous studies on their host-guest properties and the fabrication of supramolecular assemblies have demon- strated that pillarenes and their derivatives possess many advantages that facilitate their applications in many research fields. Herein we summarize and classitfy the applications of pillarenes in terms of artificial transmembrane channels, controlled delivery systems, dispersion of carbon hybrid materials, extraction and absorption, liquid crystals, metal-organic frameworks, sensing and detection, stabilization of nanoparticles （Au/Ag/CdTe）, and other typical biological applications. We also provide an overview of future developments in pillarene chemistry.展开更多
基金Program for Changjiang Scholar and InnovativeTeam in Peking University (Grant number: 985-2-063-112).
文摘Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 columns. The structures were elucidated by spectral analysis. Results Thirteen compounds were isolated and their structures were identified as （-）-syringaresinol （1）, syringaresinol-4-O-β-D-glucopyranoside （2）, syringaresinol-4,4′-bis-O-β-D-glucopyranoside （3）, （±）-catechin （4）, catechin-3-O- β-D-glucopyranoside （5）, catechin-5-O-β-D-glucopyranoside （6）, 1,3-bis-（4-hydroxy-3,5-dimethoxyphenyl）-1,3-propanediol （7）, （R）-（＋）-chaulmoogric acid （8）, friedelin （9）, uracile （10）, benzoic acid （11）, vaniUic acid （12）, and 4-hydroxybenzoic acid （13）. Conclusion All the compounds described above were isolated from this genus for the first time.
基金Supported by the National Natural Science Foundation of China(21276126,21306089)the Jiangsu Province Higher Education Natural Science Foundation(09KJA530004,13KJB530006)
文摘A reaction coupling system of transesterification and methoxycarbonylation with methyl phenyl carbonate （MPC） as intermediate was established to efficiently prepare 1,6-hexamethylene diurethane （HDU） from 1,6- bexametbylene diamine （HDA）. The feasibility of the system was explored using the thermodynamics analysis, the reaction mechanism and the experiment results. The optimal reaction was carried out to get higher HDU yield. The thermodynamic analysis showed that the metboxycarbonylation of HDA with MPC, the Gibbs free energy of which was negative, was a spontaneous process. Furthermore, the equilibrium constant of the methoxycarbonylation of HDA with MPC was much greater than that of the transesterification of dimethyl carbonate （DMC） with phenol, so the reaction coupling could be realized under mild conditions. The reaction mechanism analysis indicated that phenoxy anion was the key spedes for reaction coupling. Higher MPC concentration was detected when sodium phenoxide was used as transesterification reactant with DMC, since the phenoxy anion of sodium phenoxide could be dissociated more easily. Sodium pbenoxide was more suitable to prepare HHDU through reaction coupling. A yield of HDU as high as 98.3% could be reached under the optimal conditions of mPhONa/mDMC = 0.027 and nDMC/nHDa = 8/1 at 90 ℃ in 2 h.
文摘Researchers from the CAS Key Laboratory of Quantum Information,University of Science and Technology of China have just achieved a significant progress in quantum key distribution research.Based on the self-developed active switching technology,they successfully conducted the world's longest-more than 90km-round-robin differential phase shift(RRDPS)quantum key distribution experiment.
基金Changjiang Scholar and Innovative Team in University (Grant No. 985-2-063-112)
文摘To investigate the chemical components from the stems of Casearia velutina Bl.,the constituents were isolated by repeated chromatography with silica gel,Sephadex LH-20,and ODS columns.The structures were elucidated by spectroscopic analysis.Eleven triterpenoids and its glycosides were isolated from the crude extract of C.velutina,and their structures were identified as friedelin-2,3-lactone（1）,friedelane（2）,epifriedelanol（3）,friedelin（4）,2α,3α,19α-trihydroxy-urs-12-en-28-oic acid（5）,2α,3β,19α-trihydroxy-urs-12-en-28-oic acid（6）,2α,3α,23-trihydroxy-urs-12-en-28-oic acid（7）,2α,3α,23-trihydroxy-olean-12-en-28-oic acid（8）,2α,3α,19α,23-tetrahydroxy-urs-12-en-28-oic acid（9）,2α,3α,19α,23-tetrahydroxy-urs-12-en-28-oic acid-28-O-β-D-glucopyranosyl ester（10）,and 3β,19α-dihydroxy-urs-12-en-28-oic acid 3-O-α-L-arabinopyranoside（11）.All the compounds described above were isolated from this species for the first time.Compound 1 is a rarely occurred seco-friedelolactone in Flacourtiaceae.
基金funded by China-Australia Joint Science and Technology Commission (2010DFA31260)China-Canada Joint Health Research Initiative (81010064)
文摘When our knowledge of a field accumulates to a certain level,we are bound to see the rise of one or more great scientists.They will make a series of grand discoveries/breakthroughs and push the discipline into an 'age of grand discoveries'.Mathematics,geography,physics and chemistry have all experienced their ages of grand discoveries;and in life sciences,the age of grand discoveries has appeared countless times since the 16th century.Thanks to the ever-changing development of molecular biology over the past 50 years,contemporary life science is once again approaching its breaking point and the trigger for this is most likely to be 'lifeomics'.At the end of the 20th century,genomics wrote out the 'script of life';proteomics decoded the script;and RNAomics,glycomics and metabolomics came into bloom.These 'omics',with their unique epistemology and methodology,quickly became the thrust of life sciences,pushing the discipline to new high.Lifeomics,which encompasses all omics,has taken shape and is now signalling the dawn of a new era,the age of grand discoveries.
基金supported by the National Natural Science Foundation of China(21474027,91023008,20874026,20704013)Shanghai Shuguang Project(07SG33)+1 种基金New Century Excellent Talents in University,Ph D Programs Foundation of Ministry of Education of China,Shanghai Leading Academic Discipline Project(B502)the"Eastern Scholar Professorship"support from Shanghai Local Government
文摘The Bergman cyclization has strongly impacted on a number of fields including pharmaceutics, synthetic chemistry, and material science. The diradical intermediates stemmed from enediynes can not only cause DNA cleavage under physiological conditions but also function as monomer or initiator participants in polymer science. The homo-polymerization of enediynes through the Bergman cyclization to fabricate conjugated polymers is a fascinating strategy due to the advantages of facial operation, high efficiency, tailored structure, and catalyst-free operation. Moreover, conjugated polymers generated through the Bergman cyclization show many remarkable properties, such as excellent thermal stability, good solubility, and processability, which enables these polymers to be further manufactured into carbon-rich materials. Recent times have seen extensive efforts devoted to the application of the Bergman cyclization in polymer science and materials chemistry. A variety of synthetic strategies have been developed to fabricate structurally unique materials via the Bergman cyclization, including the fabrication of rod-like polymers with polyester, dendrimers and chiral imide side chains, functionalization of carbon nanomaterials by surface-grafting conjugated polymers, formation of nanoparticles by intramolecular collapse of single polymer chains, and the construction of carbon nanomembranes with different morphologies. Future developments involving the Bergman cyclization in polymer science, probably by altering the reaction mechanism to precisely control the microstructure of polymeric products, are also proposed in this review article.
基金supported by the National Natural Science Foundation of China(21272093)the Research Fund for the Doctoral Program of Higher Education of China(20120061120117)the Innovation Program of the State Key Laboratory of Supramolecular Structure and Materials at Jilin University
文摘Synthetic macrocycles, a typical type of building block for molecular recognition and self-assembly, are crucial to supramolecular chemistry and materials science. Since 2008, a new generation of synthetic macrocyclic hosts, pillarenes and their abundant derivatives, which consist of hydroquinone units linked by methylene bridges at 2,5-positions, have been the focus of much research. Numerous studies on their host-guest properties and the fabrication of supramolecular assemblies have demon- strated that pillarenes and their derivatives possess many advantages that facilitate their applications in many research fields. Herein we summarize and classitfy the applications of pillarenes in terms of artificial transmembrane channels, controlled delivery systems, dispersion of carbon hybrid materials, extraction and absorption, liquid crystals, metal-organic frameworks, sensing and detection, stabilization of nanoparticles （Au/Ag/CdTe）, and other typical biological applications. We also provide an overview of future developments in pillarene chemistry.
