Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold i...Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.展开更多
The present study reports large room-temperature ferromagnetism in Co and Tb co-doped GaN films and further investigates the correlation between the doping concentration and the magnetic moment.X-ray photoelectron spe...The present study reports large room-temperature ferromagnetism in Co and Tb co-doped GaN films and further investigates the correlation between the doping concentration and the magnetic moment.X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD)measurements confirm that most of the dopants are incorporated into the GaN lattice.Photoluminescence(PL)and Raman spectra results reveal that post-annealing repaired most of lattice defects induced by ion implantation.The ZFC/FC curves show a blocked phase related to Co precipitates in Co single-doped GaN system and this phase is suppressed by the incorporation of Tb ions in the co-doped GaN systems.Although the magnetic properties were enhanced with the co-implantation of Co and Tb ions,the magnetic moment introduced by each ion slightly decreased with increasing Tb concentration.Density functional theory(DFT)calculations suggest that a high doping concentration of Tb atoms leads to the antiferromagnetic phase in the nearest position between Co and Tb ions.Appropriate co-doping with Co and Tb ions in GaN favors the development of enhanced ferromagnetism with no secondary phase.Our study not only offers valuable insights for understanding the magnetic characteristics of co-doped GaN,but also highlights the viability of developing room-temperature diluted magnetic semiconductors by appropriately co-doping TM and RE elements.展开更多
基金National Natural Science Foundation of China(Nos.22001177,22203023)Guangdong Pearl River Talent Program(no.2021QN020268)+3 种基金the Natural Science Foundation of Guangdong Province(Nos.2024A1515012381,2022A1515011859)Shenzhen Bay Laboratory Startup Fund(No.S201100003)Major Program of Shenzhen Bay Laboratory(No.S211101001-4)Shenzhen Bay Qihang Fellow Program(No.QH23001)for generous financial support.
文摘Chiral aryl cyclohex-3-en ether scaffold is widely present in bioactive natural products and drugs.The exploitation of efficient and enantioselective methods for the construction of aryl cyclohex-3-en ether scaffold is significant.Herein we disclose a chiral N,N’-dioxide/Lewis acid complex-catalyzed asymmetric inverse-electron-demand Diels-Alder(IEDDA)reaction using electron-deficient 3-carboalkoxyl-2-pyrones and less electron-enriched aryl enol ethers as reactants.A wide range of non-and 1,2-disubstituted acyclic aryl enol ethers are applicable to deliver diverse chiral bridged bicyclic lactones in high yields and stereoselectivities(up to 96%yield,>20:1 dr,97:3 er).The bridged bicyclic lactone core can be easily converted into chiral aryl cyclohex-3-en ether scaffold.Notably,DFT calculations revealed a stepwise and endo mechanism to explain the high enantioselectivity controlled by the cooperative effect of the steric factors and the dispersion interactions between ligands and enol ethers.
基金financially supported by the National Natural Science Foundation of China(Nos.12275027,11875088,12205016,61474142 and 61974162)the Young Elite Scientists Sponsorship Program by CAST(No.2023QNRC001)the Fund of Innovation Center of Radiation Application(No.KFZC2021020801).
文摘The present study reports large room-temperature ferromagnetism in Co and Tb co-doped GaN films and further investigates the correlation between the doping concentration and the magnetic moment.X-ray photoelectron spectroscopy(XPS)and X-ray diffraction(XRD)measurements confirm that most of the dopants are incorporated into the GaN lattice.Photoluminescence(PL)and Raman spectra results reveal that post-annealing repaired most of lattice defects induced by ion implantation.The ZFC/FC curves show a blocked phase related to Co precipitates in Co single-doped GaN system and this phase is suppressed by the incorporation of Tb ions in the co-doped GaN systems.Although the magnetic properties were enhanced with the co-implantation of Co and Tb ions,the magnetic moment introduced by each ion slightly decreased with increasing Tb concentration.Density functional theory(DFT)calculations suggest that a high doping concentration of Tb atoms leads to the antiferromagnetic phase in the nearest position between Co and Tb ions.Appropriate co-doping with Co and Tb ions in GaN favors the development of enhanced ferromagnetism with no secondary phase.Our study not only offers valuable insights for understanding the magnetic characteristics of co-doped GaN,but also highlights the viability of developing room-temperature diluted magnetic semiconductors by appropriately co-doping TM and RE elements.
