Multiple metal sites doped in metal-organic frameworks (MOFs) are essential for their promising application in cascade reactions.However,precision synthesis of tetrametallic MOFs with total coordination and regular sh...Multiple metal sites doped in metal-organic frameworks (MOFs) are essential for their promising application in cascade reactions.However,precision synthesis of tetrametallic MOFs with total coordination and regular shapes is challenging due to the different coordination abilities of four metal ions.Herein,a series of tetrametallic MOFs (t-MOFs) with four regular morphologies is successfully constructed by regulating the metal ratio,amount of morphologic modulating reagent or growth time.The t-MOFs can be flexibly oxidized to afford porous metal oxides (MxCo_(3)O_(4),M=CuZnNi) under air or reduced to carbon-encapsulated CuCoNi under H_(2)/Ar for different reactions to maximize the value-in-use of MOFs.In particular,the t-MOF@MxCo_(3)O_(4) obtained upon the surface oxidation of t-MOF well integrates the Lewis-base sites from MOF core with photothermal oxidation activity from MxCo_(3)O_(4) shell.The hybrid effectively catalyzes the cascade reaction of styrene oxidation coupling Knoevenagel condensation under visible light.Thus,the by-product,benzaldehyde,is successfully converted to easily separated benzylidene malononitrile to finally obtain pure styrene epoxide (SO).In MxCo_(3)O_(4),Ni species afford good photothermal effect,Cu and Co species provide catalytic activity,and Zn species increase SO selectivity.The host-object coordination and the synergy among objects may greatly boost more complex reactions in the future.展开更多
基金supported by the Excellent Youth Foundation of Natural Science Foundation of Shandong Province,China(No.ZR2020YQ08)the National Natural Science Foundation of China(No.22275108).
文摘Multiple metal sites doped in metal-organic frameworks (MOFs) are essential for their promising application in cascade reactions.However,precision synthesis of tetrametallic MOFs with total coordination and regular shapes is challenging due to the different coordination abilities of four metal ions.Herein,a series of tetrametallic MOFs (t-MOFs) with four regular morphologies is successfully constructed by regulating the metal ratio,amount of morphologic modulating reagent or growth time.The t-MOFs can be flexibly oxidized to afford porous metal oxides (MxCo_(3)O_(4),M=CuZnNi) under air or reduced to carbon-encapsulated CuCoNi under H_(2)/Ar for different reactions to maximize the value-in-use of MOFs.In particular,the t-MOF@MxCo_(3)O_(4) obtained upon the surface oxidation of t-MOF well integrates the Lewis-base sites from MOF core with photothermal oxidation activity from MxCo_(3)O_(4) shell.The hybrid effectively catalyzes the cascade reaction of styrene oxidation coupling Knoevenagel condensation under visible light.Thus,the by-product,benzaldehyde,is successfully converted to easily separated benzylidene malononitrile to finally obtain pure styrene epoxide (SO).In MxCo_(3)O_(4),Ni species afford good photothermal effect,Cu and Co species provide catalytic activity,and Zn species increase SO selectivity.The host-object coordination and the synergy among objects may greatly boost more complex reactions in the future.
