pH-sensitive wettability of polystyrene-b-poly（4-vinylpyridine） （PS-b-P4VP） self assembled films, exhibiting superoleophobicity under water and hydrophilicity at low pH value, and oleophobicity under water and hyd...pH-sensitive wettability of polystyrene-b-poly（4-vinylpyridine） （PS-b-P4VP） self assembled films, exhibiting superoleophobicity under water and hydrophilicity at low pH value, and oleophobicity under water and hydrophobicity at neutral condition, has been realized. The wettability properties resulted from the surface topological and chemical transition, which were confirmed by in situ AFM measurements under water at different pH. At low pH, P4VP chains, which were confined in the hexagonal-packed nanodomains, got protonated into a swollen state, while at high pH, P4VP chains were deprotonated into a collapsed state. The reversible protonation/deprotonation procedure on the molecular scale leads to surface topological and chemical transition, thereby pH-sensitive wettability.展开更多
Densely functionalized chiral nitrogen-containing heterocycles are ubiquitous in bioactive synthetic compounds and natural products.Herein,we report a nickel(Ni)-catalyzed enantioselective desymmetrizing aza-Heck cycl...Densely functionalized chiral nitrogen-containing heterocycles are ubiquitous in bioactive synthetic compounds and natural products.Herein,we report a nickel(Ni)-catalyzed enantioselective desymmetrizing aza-Heck cyclization of oxime esters with a commercially available chiral pyridinebis(oxazoline)(pybox)ligand.This reaction proceeds under mild reaction conditions,tolerates various functional groups,and leads to chiral 2-substituted-3,7a-dihydro-3aH-indoles.展开更多
基金financially supported by the National Natural Science Foundation of China(No.21204002)Specialized Research Fund for the Doctoral Program of Higher Education(No.20111102120050)+1 种基金Program for New Century Excellent Talents in Universities(2010)the Fundamental Research Funds for the Central Universities
文摘pH-sensitive wettability of polystyrene-b-poly（4-vinylpyridine） （PS-b-P4VP） self assembled films, exhibiting superoleophobicity under water and hydrophilicity at low pH value, and oleophobicity under water and hydrophobicity at neutral condition, has been realized. The wettability properties resulted from the surface topological and chemical transition, which were confirmed by in situ AFM measurements under water at different pH. At low pH, P4VP chains, which were confined in the hexagonal-packed nanodomains, got protonated into a swollen state, while at high pH, P4VP chains were deprotonated into a collapsed state. The reversible protonation/deprotonation procedure on the molecular scale leads to surface topological and chemical transition, thereby pH-sensitive wettability.
基金The authors are grateful for financial support from the Chinese Academy of Science(grant no.XDB20020000)the National Natural Science Foundation of China(no.21933004)+2 种基金the Shenzhen STIC(nos.JCYJ20170412150507046 and JCYJ20170412150343516)the Shenzhen San-Ming Project(no.SZSM201809085)fellowship from the International Postdoctoral Exchange Fellowship Program(no.2020014 to H.C.Shen).
文摘Densely functionalized chiral nitrogen-containing heterocycles are ubiquitous in bioactive synthetic compounds and natural products.Herein,we report a nickel(Ni)-catalyzed enantioselective desymmetrizing aza-Heck cyclization of oxime esters with a commercially available chiral pyridinebis(oxazoline)(pybox)ligand.This reaction proceeds under mild reaction conditions,tolerates various functional groups,and leads to chiral 2-substituted-3,7a-dihydro-3aH-indoles.
