There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of...There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry(LC-MS). Based on the derivatization of C=C bonds with Ph I=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine(PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.展开更多
Asymmetric reduction of the conjugated C=C bonds by the old yellow enzymes(OYEs)presents a promising field in the synthesis of chiral chemicals.Nevertheless,few natural OYEs have been applied in large-scale applicatio...Asymmetric reduction of the conjugated C=C bonds by the old yellow enzymes(OYEs)presents a promising field in the synthesis of chiral chemicals.Nevertheless,few natural OYEs have been applied in large-scale applications due to the requirement of costly NADPH and low operational stability.Herein,a stable and efficient fusion of YqjM from Bacillus subtilis and glucose dehydrogenase(GDH)from Bacillus megaterium was constructed to stereoselectively reduce the conjugated C=C bonds in a self-sufficient continuous process.The effects of the enzyme order and different linkers on the fusions were investigated by structural analysis and all-atom molecular dynamics simulation.The best fusion YqjM_G_GDH gave 98% conversion of 100 mmol/L 2-methylcyclopentenone with an excellent ee value(>99%)in 3 h,while the mixture of individual enzymes only obtained 68% conversion after more than 8 h.The improved substrate conversion of YqjM_G_GDH fusion was probably attributed to the increased flexibility of each fused enzyme and the shortening of the diffusion distance of NADPH regenerated.A one-pot process was designed to purify and immobilize the fusion on the Ni2t-nitrilotriacetic acid functionalized magnetic mesoporous silica nanoflowers.The resulting immobilized biocatalyst not only catalyzed the asymmetric reduction of various α,β-unsaturated ketones(20 mmol/L)continuously with only 50μmol/L NADPt to initiate the whole process,but also retained more than 82%of the initial activity after seven cycles,serving as a good candidate for the industrial applications.展开更多
Improving the efficiency of metal/reducible metal oxide interfacial sites for hydrogenation reactions of unsaturated groups(e.g.,C=C and C=O)is a promising yet challenging endeavor.In our study,we developed a Pd/CeO_(...Improving the efficiency of metal/reducible metal oxide interfacial sites for hydrogenation reactions of unsaturated groups(e.g.,C=C and C=O)is a promising yet challenging endeavor.In our study,we developed a Pd/CeO_(2) catalyst by enhancing the oxygen vacancy(O V)concentration in CeO_(2) through high-temperature treatment.This process led to the formation of an interface structure ideal for supporting the hydrogenation of methyl oleate to methyl stearate.Specifi cally,metal Pd^(0) atoms bonded to the O V in defective CeO_(2) formed Pd^(0)-O v-Ce^(3+)interfacial sites,enabling strong electron transfer from CeO_(2) to Pd.The interfacial sites exhibit a synergistic adsorption eff ect on the reaction substrate.Pd^(0) sites promote the adsorption and activation of C=C bonds,while O V preferably adsorbs C=O bonds,mitigating competition with C=C bonds for Pd^(0) adsorption sites.This synergy ensures rapid C=C bond activation and accelerates the attack of active H*species on the semi-hydrogenated intermediate.As a result,our Pd/CeO_(2)-500 catalyst,enriched with Pd^(0)-O v-Ce^(3+)interfacial sites,dem-onstrated excellent hydrogenation activity at just 30℃.The catalyst achieved a Cis-C18:1 conversion rate of 99.8% and a methyl stearate formation rate of 5.7 mol/(h·g metal).This work revealed the interfacial sites for enhanced hydrogenation reactions and provided ideas for designing highly active hydrogenation catalysts.展开更多
A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition m...A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .展开更多
A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is re...A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.展开更多
The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a p...The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through C-O bond activation. There also ex- ist considerable studies on the catalytic cleavage of C-C bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of C-C bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce Q -Cs polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of C-C bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of C-C bonds can be achieved in biomass.展开更多
The humilith series of lignite, longflame coal, gas coal, fat coal, coking coal, lean coal, meagre coal and anthracite are measured by FIR1600 infrared spectrophotometer. The variation curve between the infrared absor...The humilith series of lignite, longflame coal, gas coal, fat coal, coking coal, lean coal, meagre coal and anthracite are measured by FIR1600 infrared spectrophotometer. The variation curve between the infrared absorption wave number of aromaticring C--C bond of vitrinite and its reflectance values are gained, which shows the shift of infrared absorption wave number of aromaticring C--C bond of humic coals towards lower wave number with the increase of coalification. It is believed that the coal rank of humilith series can be determined and more evolutional information about coal composition and structure can be obtained by the infrared spectroscopic method.展开更多
3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formati...3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.22074111, 22004093 and 22004092)the National Key Research and Development Program of China (No.2021YFC2700700)the support of the start-up funds of Wuhan University and the National Youth Talents Plan of China。
文摘There is a close relationship between the biological functions of lipids and their structures, and various isomers greatly increases the complexity of lipid structures. The C=C bond location and sn-position are two of the essential attributes that determine the structures of unsaturated lipids. However, simultaneous identification of both attributes remains challenging. Here, we develop a visible-light-activated aziridination reaction system, which enables the dual-resolving of the C=C bond location and sn-position isomerism of in lipids when combines with liquid chromatography-mass spectrometry(LC-MS). Based on the derivatization of C=C bonds with Ph I=NTs, their location in lipids could be easily identified by tandem MS. Especially, the sn-position isomers of unsaturated phosphatidylcholine(PC) can be separated and quantified by LC-MS after the derivatization. By using the proposed method, the significant changes of the sn-position isomers ratios of PC in mouse brain ischemia were revealed. This study offers a powerful tool for deep lipid structural biology.
基金financially supported by the National Key Research and Development Program of China(No.2021YFC2104100)the National Natural Science Foundation of China(Nos.21901058,22178083 and 22078081)+3 种基金the Hebei Key Research and Development Project(Nos.21372805D,21372804D and 20372802D)the Science and Technology Research Project of Hebei Higher Education(No.ZD2019045)the Natural Science Foundation of Hebei province(Nos.B2019202216,B2017202056 and C2019208174)the Natural Science Foundation of Tianjin City(No.20JCYBJC00530).
文摘Asymmetric reduction of the conjugated C=C bonds by the old yellow enzymes(OYEs)presents a promising field in the synthesis of chiral chemicals.Nevertheless,few natural OYEs have been applied in large-scale applications due to the requirement of costly NADPH and low operational stability.Herein,a stable and efficient fusion of YqjM from Bacillus subtilis and glucose dehydrogenase(GDH)from Bacillus megaterium was constructed to stereoselectively reduce the conjugated C=C bonds in a self-sufficient continuous process.The effects of the enzyme order and different linkers on the fusions were investigated by structural analysis and all-atom molecular dynamics simulation.The best fusion YqjM_G_GDH gave 98% conversion of 100 mmol/L 2-methylcyclopentenone with an excellent ee value(>99%)in 3 h,while the mixture of individual enzymes only obtained 68% conversion after more than 8 h.The improved substrate conversion of YqjM_G_GDH fusion was probably attributed to the increased flexibility of each fused enzyme and the shortening of the diffusion distance of NADPH regenerated.A one-pot process was designed to purify and immobilize the fusion on the Ni2t-nitrilotriacetic acid functionalized magnetic mesoporous silica nanoflowers.The resulting immobilized biocatalyst not only catalyzed the asymmetric reduction of various α,β-unsaturated ketones(20 mmol/L)continuously with only 50μmol/L NADPt to initiate the whole process,but also retained more than 82%of the initial activity after seven cycles,serving as a good candidate for the industrial applications.
基金This work was supported by the National Key Research and Development Program of China(No.2023YFB4203800).
文摘Improving the efficiency of metal/reducible metal oxide interfacial sites for hydrogenation reactions of unsaturated groups(e.g.,C=C and C=O)is a promising yet challenging endeavor.In our study,we developed a Pd/CeO_(2) catalyst by enhancing the oxygen vacancy(O V)concentration in CeO_(2) through high-temperature treatment.This process led to the formation of an interface structure ideal for supporting the hydrogenation of methyl oleate to methyl stearate.Specifi cally,metal Pd^(0) atoms bonded to the O V in defective CeO_(2) formed Pd^(0)-O v-Ce^(3+)interfacial sites,enabling strong electron transfer from CeO_(2) to Pd.The interfacial sites exhibit a synergistic adsorption eff ect on the reaction substrate.Pd^(0) sites promote the adsorption and activation of C=C bonds,while O V preferably adsorbs C=O bonds,mitigating competition with C=C bonds for Pd^(0) adsorption sites.This synergy ensures rapid C=C bond activation and accelerates the attack of active H*species on the semi-hydrogenated intermediate.As a result,our Pd/CeO_(2)-500 catalyst,enriched with Pd^(0)-O v-Ce^(3+)interfacial sites,dem-onstrated excellent hydrogenation activity at just 30℃.The catalyst achieved a Cis-C18:1 conversion rate of 99.8% and a methyl stearate formation rate of 5.7 mol/(h·g metal).This work revealed the interfacial sites for enhanced hydrogenation reactions and provided ideas for designing highly active hydrogenation catalysts.
文摘A new and simple route for the synthesis of α,β-unsaturated ketones via cleavage of the C-C(O)C single bond of monoalkylated β-diketone has been described. The reaction was catalyzed by copper, a cheap transition metal in a weakly basic medium (K<sub>3</sub>PO<sub>4</sub>) at room temperature. To carry out this study, we first had to synthesize the monoalkylated β-diketones 1. Afterwards, α,β-unsaturated ketones 2 were obtained with high yields around 80%. Finally, all the products were characterized by 1H NMR, 13C NMR, and HRMS spectra. .
基金the National Natural Science Foundation of China (No. 29772012)
文摘A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.
基金supported by the National Natural Science Foundation of China (21173172 and 21473141)the Research Fund for the Doctorial Program of Higher Education (No. 20130121130001)the Program for Innovative Research Team in University (No. IRT_14R31)
文摘The catalytic transformation of cellulose, the major component of abundant and renewable lignocellulosic biomass, into building-block chemicals is a key to establishing sustainable chemical processes. Cellulose is a polymer of glucose and a lot research effort has been devoted to the conversion of cellulose to six-carbon platform compounds such as glucose and glucose derivatives through C-O bond activation. There also ex- ist considerable studies on the catalytic cleavage of C-C bonds in biomass for the production of high-value chemicals, in particular polyols and organic acids such as ethylene glycol and lactic acid. This review article highlights recent advances in the development of new catalytic systems and new strategies for the selective cleavage of C-C bonds in cellulose and its derived carbohydrates under inert, reductive and oxidative atmospheres to produce Q -Cs polyols and organic acids. The key factors that influence the catalytic performance will be clarified to provide insights for the design of more efficient catalysts for the transformation of cellulose with precise cleavage of C-C bonds to high-value chemicals. The reaction mechanisms will also be discussed to understand deeply how the selective cleavage of C-C bonds can be achieved in biomass.
文摘The humilith series of lignite, longflame coal, gas coal, fat coal, coking coal, lean coal, meagre coal and anthracite are measured by FIR1600 infrared spectrophotometer. The variation curve between the infrared absorption wave number of aromaticring C--C bond of vitrinite and its reflectance values are gained, which shows the shift of infrared absorption wave number of aromaticring C--C bond of humic coals towards lower wave number with the increase of coalification. It is believed that the coal rank of humilith series can be determined and more evolutional information about coal composition and structure can be obtained by the infrared spectroscopic method.
文摘3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.
