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.

用于实现高性能热催化氧化还原反应的二茂铁功能化锆氧簇

The Zr(Ⅳ)ions are easily hydrolyzed to form oxides,which severely limits the discovery of new structures and applications of Zr-based compounds.In this work,three ferrocene(Fc)-functionalized Zr-oxo clusters(ZrOCs),Zr_(9)Fc_(6),Zr_(10)Fc_(6) and Zr_(12)Fc_(8) were synthesized through inhibiting the hydrolysis of Zr(Ⅳ)ions,which show increased nuclearity and regular structural variation.More importantly,these Fc-functionalized ZrOCs were used as heterogeneous catalysts for the transfer hydrogenation of levulinic acid(LA)and phenol oxidation reactions for the first time,and displayed outstanding catalytic activity.In particular,Zr_(12)Fc_(8) with the largest number of Zr active sites and Fc groups can achieve>95% yield for LAto-c-valerolactone within 4 h(130℃)and>98% yield for 2,3,6-trimethylphenol-to-2,3,5-trimethyl-pbenzoquinone within 30 min(80℃),showing the best catalytic performance.Catalytic characterization combined with theory calculations reveal that in the Fc-functionalized ZrOCs,the Zr active sites could serve as substrate adsorption sites,while the Fc groups could act as hydrogen transfer reagent or Fenton reagent,and thus achieve effectively intramolecular metal-ligand synergistic catalysis.This work develops functionalized ZrOCs as catalysts for thermal-triggered redox reactions.

A novel pillared-layer-type porous coordination polymer featuring three-dimensional pore system and high methane storage capacity

Solvothermal reaction of Zn（NO3）2, 4-（1H-pyrazol-4-yl）pyridine （Hpypz） and 1,3,5-benzenetricarboxylic acid （H3btc） in N,N-dimethylacetamide （DMA） produced a new porous coordination polymer [Zns（pypz）4（btc）2] （1）. Single-crystal X-ray diffraction study of 1 showed that deprotonated pypz^- ligands served as 1,2,4-triazolate-like ligands, linking Zn（II） ^＋ ions to form porous two-dimensional （2-D） sql-a layers {Zn（pypz）} , which were further connected by eight-legged pillars {Zn2（btc）4（H2O）2}8- based on the typical paddlewheel dinuclear Zn2（RCOO）4（H20）2 cluster to form a novel type of non-interpenetrated pillared-layer framework with 3-D intersecting pore system and large pore volume. Gas sorption measurements revealed that 1 possesses large BET surface area of 2061 m^2g^-1 and very high methane total uptake of 245 cm^3（STP） cm^-3 at 298 K and 65 bar.