A Co_(12)coordination cage with a cuboctahedral architecture,and incorporating a mixture of tritopic(facecapping)and ditopic(edge-bridging)ligands,shows strong vip binding of large aromatic fluorophores(fluorescein ...A Co_(12)coordination cage with a cuboctahedral architecture,and incorporating a mixture of tritopic(facecapping)and ditopic(edge-bridging)ligands,shows strong vip binding of large aromatic fluorophores(fluorescein and its derivatives 6-carboxyfluorescein and Eosin-Y)with 1:1 binding constants in water in the range log K=6.7-7.9;its large central cavity(>1000Å^(3))facilitates binding of much larger vips than was possible with the smaller Co_(8)cage that we have reported previously.vip binding is accompanied by catalysed reactions of bound vips because the high positive charge on the cage surface(24+)also attracts anions,allowing the organic vips and anionic reaction partners to be co-located,resulting for example in cage-catalysed hydrolysis of phosphate esters(the insecticides Me-paraoxon and Et-paraoxon)and conversion of diacetyl fluorescein to fluorescein.In addition,we demonstrate a new type of cage-based catalysis which relies on the redox activity of the Co(Ⅱ)/Co(Ⅲ)couple in the cage to activate the peroxymonosulfate(PMS)anion by converting it to the highly reactive SO_(4)^(·−)radical ion,which bleaches cavity-bound fluorescein by complete oxidation.This is an example of an‘advanced oxidation process’in which the host cage not only brings the fluorescein and the PMS together via orthogonal hydrophobic and electrostatic interactions,but also provides redox activation of the PMS via a Co(Ⅱ)/Co(Ⅲ)couple,with the cage taking an active role in the catalytic process rather than acting simply as a passive reaction vessel.展开更多
基金University of Warwick(UK)for financial support via a Warwick/Monash Alliance accelerator grant involving X.Z.the Development and Promotion of Science and Technology Talents Project,Thailand,for a PhD studentship to B.S.
文摘A Co_(12)coordination cage with a cuboctahedral architecture,and incorporating a mixture of tritopic(facecapping)and ditopic(edge-bridging)ligands,shows strong vip binding of large aromatic fluorophores(fluorescein and its derivatives 6-carboxyfluorescein and Eosin-Y)with 1:1 binding constants in water in the range log K=6.7-7.9;its large central cavity(>1000Å^(3))facilitates binding of much larger vips than was possible with the smaller Co_(8)cage that we have reported previously.vip binding is accompanied by catalysed reactions of bound vips because the high positive charge on the cage surface(24+)also attracts anions,allowing the organic vips and anionic reaction partners to be co-located,resulting for example in cage-catalysed hydrolysis of phosphate esters(the insecticides Me-paraoxon and Et-paraoxon)and conversion of diacetyl fluorescein to fluorescein.In addition,we demonstrate a new type of cage-based catalysis which relies on the redox activity of the Co(Ⅱ)/Co(Ⅲ)couple in the cage to activate the peroxymonosulfate(PMS)anion by converting it to the highly reactive SO_(4)^(·−)radical ion,which bleaches cavity-bound fluorescein by complete oxidation.This is an example of an‘advanced oxidation process’in which the host cage not only brings the fluorescein and the PMS together via orthogonal hydrophobic and electrostatic interactions,but also provides redox activation of the PMS via a Co(Ⅱ)/Co(Ⅲ)couple,with the cage taking an active role in the catalytic process rather than acting simply as a passive reaction vessel.
