In this study,an alkynyl-modified aromatic dicarboxylic acid bifunctional ligand was selected to construct lanthanide compound{[Eu_(4)(ebdc)_(6)(4,4-bpy)_(0.5)(H_(2)O)_(4.5)]·(C_(2)H_(5)OH)_(1.25)(H_(2)O)}_(n)(Eu...In this study,an alkynyl-modified aromatic dicarboxylic acid bifunctional ligand was selected to construct lanthanide compound{[Eu_(4)(ebdc)_(6)(4,4-bpy)_(0.5)(H_(2)O)_(4.5)]·(C_(2)H_(5)OH)_(1.25)(H_(2)O)}_(n)(Eu-MOF,H_(2)ebdc=5-ethynyl-isophthalic acid,4,4-bpy=4,4-bipyridine,MOF=metal-organic framework),of which the uncoordinated alkynyl group would be used to anchor silver nanoclusters(Ag NCs).The Eu-MOF exhibits double emission peaks,located at 492 and 611 nm,respectively,in which the high-energy blue emission is associated with alkynyl-modified ligand while the low-energy red emission belongs to characteristic emission of Eu3+,indicating that ligands can effectively sensitize Eu3+luminescence.The intensity ratio of the dual emission fluorescence peaks of Eu-MOF displays a good linear relationship with temperature,which realizes the detection function in the low temperature region of 75–275 K,the thermal sensitivity reaches 1.5398%·K^(−1).After anchoring the Ag NCs,the high-energy blue emission is significantly quenched,indicating that the Ag NCs are indeed confined into the framework and interact with the alkynyl group,and thus change the overall electronic distribution.This is the first case of anchoring Ag NCs by a luminescent Eu-MOF and studying nanocluster loading by using spectroscopic properties.In addition,the Ag NCs@Eu-MOF also shows a good catalytic activity for cycloaddition reaction from CO_(2)and epoxides.This study not only provides ideas for exploring the changes in optical properties of luminescent MOFs and Ag NCs caused by confinement effect,but also expands their potential applications in various fields.展开更多
It remains a significant challenge to develop a catalyst that merges the advantages of homogeneous and heterogeneous catalysis with high reactivity and great recyclability.Herein,an atomically precise Cu_(6)-NH_(2) na...It remains a significant challenge to develop a catalyst that merges the advantages of homogeneous and heterogeneous catalysis with high reactivity and great recyclability.Herein,an atomically precise Cu_(6)-NH_(2) nanocluster with distorted octahedral Cu_(6) core and NH_(2)-functionalized ligands has been developed as the first homo/heterogeneous catalyst to catalyze the cyclization reaction of propargylic amines with carbon dioxide(CO_(2))under mild conditions.As a homogeneous catalyst,Cu_(6)-NH_(2) shows excellent catalytic activity with high turnover frequency due to highly accessible active sites.The definite coordination geometry and homogeneity nature of active centers make it convenient to investigate the structure–activity relationship at the atomic level through experiments and theory calculations.In addition,the nanocluster exhibits excellent stability,great recrystallizability,and reusability in five catalytic cycles,in which its catalytic performance has no obvious decrease.Moreover,Cu_(6)-NH_(2) incorporates Lewis acid and base sites in metal and ligand,respectively,which can promote catalytic efficiency in a synergistic effect in the absence of any cocatalysts.Importantly,Cu_(6)-NH_(2) can realize direct conversion of CO_(2) in simulated flue gas into oxazolidinones with high efficiency.The metal-ligand cooperative effect and integrated advantages of homogeneous and heterogeneous catalysis would provide new perspectives to achieve advanced metal nanocluster catalysts for CO_(2) conversion.展开更多
基金the National Natural Science Foundation of China(Nos.21975065,U21A20277,21825106,and 22201065).
文摘In this study,an alkynyl-modified aromatic dicarboxylic acid bifunctional ligand was selected to construct lanthanide compound{[Eu_(4)(ebdc)_(6)(4,4-bpy)_(0.5)(H_(2)O)_(4.5)]·(C_(2)H_(5)OH)_(1.25)(H_(2)O)}_(n)(Eu-MOF,H_(2)ebdc=5-ethynyl-isophthalic acid,4,4-bpy=4,4-bipyridine,MOF=metal-organic framework),of which the uncoordinated alkynyl group would be used to anchor silver nanoclusters(Ag NCs).The Eu-MOF exhibits double emission peaks,located at 492 and 611 nm,respectively,in which the high-energy blue emission is associated with alkynyl-modified ligand while the low-energy red emission belongs to characteristic emission of Eu3+,indicating that ligands can effectively sensitize Eu3+luminescence.The intensity ratio of the dual emission fluorescence peaks of Eu-MOF displays a good linear relationship with temperature,which realizes the detection function in the low temperature region of 75–275 K,the thermal sensitivity reaches 1.5398%·K^(−1).After anchoring the Ag NCs,the high-energy blue emission is significantly quenched,indicating that the Ag NCs are indeed confined into the framework and interact with the alkynyl group,and thus change the overall electronic distribution.This is the first case of anchoring Ag NCs by a luminescent Eu-MOF and studying nanocluster loading by using spectroscopic properties.In addition,the Ag NCs@Eu-MOF also shows a good catalytic activity for cycloaddition reaction from CO_(2)and epoxides.This study not only provides ideas for exploring the changes in optical properties of luminescent MOFs and Ag NCs caused by confinement effect,but also expands their potential applications in various fields.
基金financially supported by the National Natural Science Foundation of China(grant nos.92061201,21825106,21771163,and 22371263)the National Key R&D Program of China(grant no.2021YFA1200301)+1 种基金the Natural Science Foundation of Henan Province(grant no.232300421144)the Zhongyuan Thousand Talents(Zhongyuan Scholars)Program of Henan Province(grant no.234000510007).
文摘It remains a significant challenge to develop a catalyst that merges the advantages of homogeneous and heterogeneous catalysis with high reactivity and great recyclability.Herein,an atomically precise Cu_(6)-NH_(2) nanocluster with distorted octahedral Cu_(6) core and NH_(2)-functionalized ligands has been developed as the first homo/heterogeneous catalyst to catalyze the cyclization reaction of propargylic amines with carbon dioxide(CO_(2))under mild conditions.As a homogeneous catalyst,Cu_(6)-NH_(2) shows excellent catalytic activity with high turnover frequency due to highly accessible active sites.The definite coordination geometry and homogeneity nature of active centers make it convenient to investigate the structure–activity relationship at the atomic level through experiments and theory calculations.In addition,the nanocluster exhibits excellent stability,great recrystallizability,and reusability in five catalytic cycles,in which its catalytic performance has no obvious decrease.Moreover,Cu_(6)-NH_(2) incorporates Lewis acid and base sites in metal and ligand,respectively,which can promote catalytic efficiency in a synergistic effect in the absence of any cocatalysts.Importantly,Cu_(6)-NH_(2) can realize direct conversion of CO_(2) in simulated flue gas into oxazolidinones with high efficiency.The metal-ligand cooperative effect and integrated advantages of homogeneous and heterogeneous catalysis would provide new perspectives to achieve advanced metal nanocluster catalysts for CO_(2) conversion.