锆/铪氧簇中硫原子导向的金属-配体协同高效催化胺氧化反应

The performance applications(e.g.,photocatalysis)of zirconium(Zr)and hafnium(Hf)based complexes are greatly hindered by the limited development of their structures and the relatively inert metal reactivity.In this work,we constructed two ultrastable Zr/Hf-based clusters(Zr_(9)-TC4A and Hf_(9)-TC4A)using hydrophobic 4-tert-butylthiacalix[4]arene(H4TC4A)ligands,in which unsaturated coordinated sulfur(S)atoms on the TC4A^(4-)ligand can generate strong metal–ligand synergy with nearby active metal Zr/Hf sites.As a result,these two functionalized H4TC4A ligands modified Zr/Hf-oxo clusters,as catalysts for the amine oxidation reaction,exhibited excellent catalytic activity,achieving very high substrate conversion(>99%)and product selectivity(>90%).Combining comparative experiments and theoretical calculations,we found that these Zr/Hf-based cluster catalysts accomplish efficient amine oxidation reactions through synergistic effect between metals and ligands:(i)The photocatalytic benzylamine(BA)oxidation reaction was achieved by the synergistic effect of the dual active sites,in which,the naked S sites on the TC4A^(4-)ligand oxidize the BA by photogenerated hole and oxygen molecules are reduced by photogenerated electrons on the metal active sites;(ii)in the aniline oxidation reaction,aniline was adsorbed by the bare S sites on ligands to be closer to metal active sites and then oxidized by the oxygen-containing radicals activated by the metal sites,thus completing the catalytic reaction under the synergistic catalytic effect of the proximity metal–ligand.In this work,the Zr/Hf-based complexes applied in the oxidation of organic amines have been realized using active S atom-directed metal–ligand synergistic catalysis and have demonstrated very high reactivity.

Implanting Built-In Electric Field in Heterometallic Phthalocyanine Covalent Organic Frameworks for Light-Assisted CO_(2)Electroreduction

A strategy that enables introducing bimetallic active sites is desired for the exploration of light-sensitive covalent organic framework(COF)-based electrocatalysts in light-assisted CO_(2)electroreduction.Here,salphen-pockets have been implanted into phthalocyanine(Pc)-based COFs through the elaborate design of structural struts;the produced NiPc-DFP-M COFs(M=Ni and Co)possess the advantages of controllable bimetallic centers with different coordination environments,outstanding light sensitivity,and built-in electric-field effects that can be successfully applied in light-assisted CO_(2)electroreduction.Notably,the optimal heterometallic NiPc-DFP-Co COF presents a∼100%Faradic efficiency for CO formation(FECO)in a wide potential range of−0.7 to−1.1 V and∼70%energy efficiency(−0.7 V)under light-irradiation,which is superior to mono-and homometallic COFs and under dark conditions.The high performance can be ascribed to the synergistic effect of the NiPc and Co-salphen pockets that can largely reduce the rate-determining energy-barrier and enhance the electron density to boost the light-assisted activity as supported by density functional theory calculations.A series of bimetallic Pc-based NiPc-DFP-M COF(M=Ni and Co)with integrated salphen-pockets and NiPc units have been synthesized and successfully applied in efficient light-assisted CO_(2)electroreduction.

Selective Generation of Electroreduction C_(1)-C_(2)Products Through Self-Regulation of Catalytically Active Cu Sites on the Same Coordination Cluster Catalyst

Well-defined crystalline coordination compound catalysts have showcased distinct advantages in the regulation of the species and selectivity of electrocatalytic CO_(2)reduction products.However,the systematic study of the crystal-facet effect of crystalline coordination compounds on the performance of electrocatalytic CO_(2)reduction has not yet been reported.Herein,a stable hexanuclear copper cluster(Cu6)catalyst model system is designed and synthesized.By effectively regulating the growth size(micro-nano size)and morphology of the Cu6 single crystal,Cu6(P)with the main(100)facet,Cu6(H)with the main(100)and(001)facets,and Cu6(S)with the main(001)facet are obtained.From Cu6(P)via Cu6(H)to Cu6(S),there is a shift from the predominantly exposed(100)facet(involving two non-adjacent active Cu sites)to the(001)facet(involving three adjacent active Cu sites),which directly affects the adsorption direction of the key*CO intermediate and the potential of C-C coupling,thus enabling effective regulation of the selectivity of C1(CO and CH4)and C2(C2H4)reduction products.This work provides an essential molecular model system and a novel design perspective for the systematic study of the crystalfacet effect of coordination compounds on the species and selectivity of CO_(2)reduction reaction products.

Insight into hexanuclear peroxotantalum complexes:synthesis,characterization,and efficient catalyst for amidation reaction

Polyoxometalates(POMs),large oxoanions of the group 5 and 6 elements,attract attention due to their use as oxidation-stable catalysts and ligands.Different from the well-known V,Mo,and W POMs,the group V POMs of Ta assemble and are stable only in highly alkaline solution rather than acidic solution.In this paper,we successfully synthesized and structurally characterized two unprecedented peroxotantalum-containing clusters,KNa_(2)[HSe_(2)(TaO_(2))_(6)(OH)_(4)(H_(2)O)_(2)O_(13)]·15H_(2)O(1)and Cs_(2)K_(1.5)Na_(1.5)[Se_(4)(TaO_(2))_(6)(OH)_(3)O_(18)]·17H_(2)O(2),which comprises a 6-peroxo-6-tantalum core stabilized by two and four selenite centers,respectively.The simple,one-pot synthesis of 1 and 2 involving addition of sodium selenite into the acidified hexatantalate aqueous solution in the presence of hydrogen peroxide could represent a general procedure for incorporating heteroatoms into peroxo-polyoxotantalate species,thus opening new possibilities for this emergent branch of polyoxotantalate chemistry.Moreover,the catalytic properties of these two compounds were investigated using succinic anhydride and phenylamine as the model substrate,and compound 2 presents excellent catalytic activity in the amidation reactions of anhydrides and amines.