Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promo...Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.展开更多
A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is ver...A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).展开更多
The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy ...The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.展开更多
The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-...The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-mediated[5+2]cycloaddition/decarboxylation cascade was explored and applied without the use of protecting groups,and water as an environmentally friendly solvent contributed to the cascade.The intramolecular[5+2]cycloaddition mechanism,involving oxidation and dearomatization of the flavanol unit as a diene,was proposed and supported by the synthesis of the intermediate.The regioselectivity of the cyclization was found to be dependent on the substitution effects of the stilbene units by the exploration of substrate scope.展开更多
Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performa...Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performance. This study examined the interactive effects of elevated [CO2] and nitrogen supply on the eco-physiological performance of yellow birch. Seedlings were exposed to two [CO2] levels and five nitrogen supply levels for 4 months. Growth parameters such as seedling height and root collar diameter increased with higher nitrogen supply and elevated [CO2], while specific leaf area decreased. [CO2] elevation and increasing nitrogen supply also increased the total and stem, and leaf biomass. The elevated [CO2] increased the stem mass ratio but decreased the root-to-shoot ratio and root mass ratio. However, decreases in nitrogen supply increased root mass ratio and root-to-shoot ratio. The elevated [CO2] increased the maximum rate of Rubisco carboxylation (Vcmax) and photosynthetic electron transport (Jmax), but the effect on Jmax was statistically significant only at the two highest nitrogen supply levels. The results indicate that yellow birch may increase photosynthetic capacity, biomass, and growth in the future when [CO2] is higher.展开更多
Cyclobutanes are distributed widely in a large class of natural products featuring diverse pharmaceutical activities and intricate structural frameworks.The[2+2]cycloaddition is unequivocally the primary and most comm...Cyclobutanes are distributed widely in a large class of natural products featuring diverse pharmaceutical activities and intricate structural frameworks.The[2+2]cycloaddition is unequivocally the primary and most commonly used method for synthesizing cyclobutanes.In this review,we have summarized the application of the[2+2]cycloaddition with different reaction mechanisms in the chemical synthesis of selected cyclobutane-containing natural products over the past decade.展开更多
A new compound, \[Ni(en)\-3\]\-2\[Ni(en)\-2(H\-2O)\-2\]\[As\-6V\-\{15\}O\-\{42\}\]·4H\-2O, was first prepared by hydrothermal synthesis and characterized by elemental analysis, IR, TGA\|DSC, ESR and single crysta...A new compound, \[Ni(en)\-3\]\-2\[Ni(en)\-2(H\-2O)\-2\]\[As\-6V\-\{15\}O\-\{42\}\]·4H\-2O, was first prepared by hydrothermal synthesis and characterized by elemental analysis, IR, TGA\|DSC, ESR and single crystal X\|ray diffraction. Crystal data: monoclinic, space group \%C\-c, a\%=1\^523 6(3) nm, \%b\%=2\^051 8(4) nm, \%c\%=2\^395 9(5) nm, \%β=97\^41(3)°, V\%=7\^427(3) nm\+3, \%Z=4, R=0\^057 0, wR\-2=0\^135 7\%. The polyanion consists of six AsO\-3 pyramids and fifteen VO\-5 pyramids. Counterions are complex ions with octahedral structure, which consist of NH\-2CH\-2CH\-2NH\-2 and Ni\+\{2+\}.展开更多
Two copper complexes with a new multi sulfur 1,2 dithiolene ligand, C (C=tetrabutylammonium, n Bu4N+; tetraphenylphosphonium, Ph4P+; cddt = 4a, 6, 7, 7a 5H cyclopenta 1,4 dithiin 2,3 dithiolate) have been synthesized ...Two copper complexes with a new multi sulfur 1,2 dithiolene ligand, C (C=tetrabutylammonium, n Bu4N+; tetraphenylphosphonium, Ph4P+; cddt = 4a, 6, 7, 7a 5H cyclopenta 1,4 dithiin 2,3 dithiolate) have been synthesized and characterized by electrochemical studies, IR, EA, etc. The structure of (Ph4P) was determined by single crystal X ray analysis. The complex was crystallized in the triclinic, space group with the cell dimensions a=10.460(2)?, b=13.000(3)?,c=16.270(3)?, α=86.68(3)°,β= 71.92(3)°,γ=66.66(3)° and Z=2. R1=0.0548, wR2=0.1358 for 6786 independent reflections. The four S atoms surround the Cu atom core is a square planar environment.展开更多
基金the support from National Key R&D Program of China (2021YFC2103704)the National Natural Science Foundation of China (22222808)+4 种基金the Natural Science Foundation of Shandong Province (ZR2023QB152)the Youth Innovation Team Plan of Shandong Province (2022KJ270)the China National Postdoctoral Program for Innovative Talents (BX20240251)the Aeronautical Science Foundation of China (2023Z073048003)the Haihe Laboratory of Sustainable Chemical Transformations。
文摘Photoinduced[2+2]cycloaddition of biomass-derived cycloolefin is a promising approach to synthesize high-energy bio-fuels,however,the conversion efficiency and selectivity are still low.Herein,we provide an acid-promoted photocycloaddition approach to synthesize a new kind of spiral fuel from biomass-derived cyclohexanone (CHOE) and camphene (CPE).BrΦnsted acids show higher catalytic activity than Lewis acids,and acetic acid (HOAc) possesses the best catalytic performance,with CHOE conversion up to 99.1%.Meanwhile,the HOAc-catalytic effect has been confirmed for[2+2]photocycloaddition of other biomass-derived ketenes and olefins.The catalytic mechanism and dynamics have been investigated,and show that HOAc can bond with C=O groups of CHOE to form H–CHOE complex,which leads to higher light adsorption and longer triplet lifetime.Meanwhile,H–CHOE complex reduces the energy gap between CHOE LUMO and CPE HOMO,shortens the distance of ring-forming atoms,and then decreases the energy barrier (from 103.3 kcal mol^(-1)to 95.8 kcal mol^(-1)) of rate-limiting step.After hydrodeoxygenation,the targeted bio-spiral fuel shows high density of 0.992 g cm^(-3),high neat heat of combustion of 41.89 MJ L^(-1),low kinetic viscosity of 5.69 mm^(2)s^(-1)at 20℃,which is very promising to serve as high-performance aerospace fuel.
文摘A visible-light-promoted[1+2]cycloaddition of gem-difluoroalkenes with aryl diazo esters provides an efficient and important route to 1,1-difluorocyclopropanes.The reaction conditions are mild,and the operation is very simple.A number of diazo esters and gem-difluoroalkenes are suitable for this reaction(36 examples),providing the desired products in good yields with excellent diastereoselectivity(>20∶1).
基金financially supported by the National Natural Science Foundation of China(Nos.22371240 and 22361132535)Xiamen University for the financial support。
文摘The[2+2]photopolymerization of bisolefinic monomers is an important method for the synthesis of polymeric materials.However,these processes are usually carried out in solid states under the irradiation of high-energy UV light,while the corresponding[2+2]polymerization in solution has proved to be inefficient due to the lack of preassembly of the monomers.Herein,we demonstrate that the[2+2]polymerization of p-phenylenediacrylate monomers can be achieved in solution under visible light by employing energy transfer catalysis with 2,2'-methoxythioxanthone as a photocatalyst.Because no preassembly is required,this solution polymerization is applicable to p-phenylenediacrylate monomers with different ester groups,affording a series of cyclobutane-imbedded full-carbon chain polymers with high thermal stability,good solubility,and processibility.In addition,by virtue of the reversibility of the photo[2+2]cycloaddition,this[2+2]photopolymerization product can also undergo depolymerization to lower molecular weight polymers,suggesting the potential of this class of photopolymerization in the development of closed-loop chemical recyclable polymers.
基金financial surpport from the CAMS Innovation Fund for Medical Sciences(CIFMS,No.2021-I2M-1-028)supported by Biomedical High Performance Computing Platform,Chinese Academy of Medical Sciences。
文摘The first synthesis of flavanostilbenes with a 2-cyclohepten-1-one core was carried out by applying an effective strategy in three steps from abundant polymerized flavanol resources.A key regio-and stereoselective Cu-mediated[5+2]cycloaddition/decarboxylation cascade was explored and applied without the use of protecting groups,and water as an environmentally friendly solvent contributed to the cascade.The intramolecular[5+2]cycloaddition mechanism,involving oxidation and dearomatization of the flavanol unit as a diene,was proposed and supported by the synthesis of the intermediate.The regioselectivity of the cyclization was found to be dependent on the substitution effects of the stilbene units by the exploration of substrate scope.
文摘Climate change impacts soil nitrogen, influencing plant responses to elevated atmospheric [CO2]. Understanding the interaction between nitrogen supply and elevated [CO2] is crucial for predicting plant future performance. This study examined the interactive effects of elevated [CO2] and nitrogen supply on the eco-physiological performance of yellow birch. Seedlings were exposed to two [CO2] levels and five nitrogen supply levels for 4 months. Growth parameters such as seedling height and root collar diameter increased with higher nitrogen supply and elevated [CO2], while specific leaf area decreased. [CO2] elevation and increasing nitrogen supply also increased the total and stem, and leaf biomass. The elevated [CO2] increased the stem mass ratio but decreased the root-to-shoot ratio and root mass ratio. However, decreases in nitrogen supply increased root mass ratio and root-to-shoot ratio. The elevated [CO2] increased the maximum rate of Rubisco carboxylation (Vcmax) and photosynthetic electron transport (Jmax), but the effect on Jmax was statistically significant only at the two highest nitrogen supply levels. The results indicate that yellow birch may increase photosynthetic capacity, biomass, and growth in the future when [CO2] is higher.
基金financially supported by the National Science Fund for Distinguished Young Scholars(82325047)Second Tibetan Plateau Scientific Expedition and Research(STEP)program(2019QZKK0502)NSFC-Joint Foundation of Yunnan Province(U2002221).
文摘Cyclobutanes are distributed widely in a large class of natural products featuring diverse pharmaceutical activities and intricate structural frameworks.The[2+2]cycloaddition is unequivocally the primary and most commonly used method for synthesizing cyclobutanes.In this review,we have summarized the application of the[2+2]cycloaddition with different reaction mechanisms in the chemical synthesis of selected cyclobutane-containing natural products over the past decade.
文摘A new compound, \[Ni(en)\-3\]\-2\[Ni(en)\-2(H\-2O)\-2\]\[As\-6V\-\{15\}O\-\{42\}\]·4H\-2O, was first prepared by hydrothermal synthesis and characterized by elemental analysis, IR, TGA\|DSC, ESR and single crystal X\|ray diffraction. Crystal data: monoclinic, space group \%C\-c, a\%=1\^523 6(3) nm, \%b\%=2\^051 8(4) nm, \%c\%=2\^395 9(5) nm, \%β=97\^41(3)°, V\%=7\^427(3) nm\+3, \%Z=4, R=0\^057 0, wR\-2=0\^135 7\%. The polyanion consists of six AsO\-3 pyramids and fifteen VO\-5 pyramids. Counterions are complex ions with octahedral structure, which consist of NH\-2CH\-2CH\-2NH\-2 and Ni\+\{2+\}.
文摘Two copper complexes with a new multi sulfur 1,2 dithiolene ligand, C (C=tetrabutylammonium, n Bu4N+; tetraphenylphosphonium, Ph4P+; cddt = 4a, 6, 7, 7a 5H cyclopenta 1,4 dithiin 2,3 dithiolate) have been synthesized and characterized by electrochemical studies, IR, EA, etc. The structure of (Ph4P) was determined by single crystal X ray analysis. The complex was crystallized in the triclinic, space group with the cell dimensions a=10.460(2)?, b=13.000(3)?,c=16.270(3)?, α=86.68(3)°,β= 71.92(3)°,γ=66.66(3)° and Z=2. R1=0.0548, wR2=0.1358 for 6786 independent reflections. The four S atoms surround the Cu atom core is a square planar environment.
