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 wor...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.展开更多
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),Z...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.展开更多
Due to the overconsumption of fossil fuels,humanity is facing a series of energy and environmental problems[1,2].Utilizing renewable and clean energy instead of fossil fuels in chemical production has become a hot top...Due to the overconsumption of fossil fuels,humanity is facing a series of energy and environmental problems[1,2].Utilizing renewable and clean energy instead of fossil fuels in chemical production has become a hot topic[3].Solar energy is the most abundant source of energy on Earth.Therefore,using solar energy for chemical synthesis has attracted much attention from researchers,which can convert organic compounds or environmental pollutants into high-value-added chemicals[4].Under illumination,photoelectrons and holes of catalysts can undergo reduction and oxidation reactions.However,in most cases,it can only utilize photogenerated electrons or holes,which causes undesired energy loss[5].Additional oxidizing or reducing agents are often required,which increases the economic cost and environmental pollution.In some photocatalytic systems,however,the catalyst can utilize both photogenerated electrons and holes to achieve an overall reaction[6].Due to uncontrollable reverse reactions(e.g.,oxygen reduction reaction in overall water splitting or carbon dioxide reduction reactions),the products may be converted back to feedstock,thus limiting the reaction efficiency[7].If the oxidation and reduction products can be one-pot converted into higher-value compounds,the problem can be solved[8].展开更多
AMI semi-empirical method was used to optimize the barbituric acid derivatives substituted with glucosyl B1-5 （series B）, and the thiobarbituric acid derivatives substituted with glucosyl T1-5 （series T）. Based on...AMI semi-empirical method was used to optimize the barbituric acid derivatives substituted with glucosyl B1-5 （series B）, and the thiobarbituric acid derivatives substituted with glucosyl T1-5 （series T）. Based on the optimized structures, INDO/CI method was adopted to calculate the electronic spectra. Meanwhile, the second-order nonlinear optical （NLO） coefficients βμ were calculated with the sum-over-state （SOS） formula. The results show that when the number of glucosyl units was increased, ｜βμ｜ values of the barbituric and thiobarbituric acid derivatives were both enhanced, especially for thiobarbituric acid derivatives. It indicates that non-conjugated substituted group could also improve NLO properties of materials when the number of repeated units was increased. Additionally, the absorption bands appearing in UV area are consistent with the proper change of the number of glucosyl units, and consequently it can be concluded that the high transparencies of all systems were scarcely varied.展开更多
基金supported by the National Natural Science Foundation of China(22225109,92061101,22071109,and 22101089)the Top Youth Project of Guangdong Province Pearl River Talents Program(2021QN02L617)+2 种基金the Excellent Youth Foundation of Jiangsu Provincial Natural Science Foundation(BK20211593)the Open Fund of Energy and Materials Chemistry Joint Laboratory of South China Normal University and Guangzhou Tinci Materials Technology(SCNU-TINCI-202204)Guangdong Provincial Basic and Applied Basic Research Foundation(2023A1515030097 and 2020A1515110836).
文摘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.
基金supported by the National Key R&D Program of China(2023YFA1507204)the National Natural Science Foundation of China(22271104,22225109,22071109,and 22201046)+3 种基金the Excellent Youth Foundation of Jiangsu Natural Science Foundation(BK20211593)Young Top Talents of Pearl River Talent Program of Guangdong Province(2021QN02L617)Guangdong Basic and Applied Basic Research Foundation(2023A1515030097)the Open Fund of Energy and Materials Chemistry Joint Laboratory of South China Normal University and Guangzhou Tinci Materials Technology(SCNU-TINCI-202204).
文摘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.
基金supported by the National Key R&D Program of China(2023YFA1507204)the National Natural Science Foundation of China(22225109,22201082,22301084,and 22301086)+1 种基金the GuangDong Basic and Applied Basic Research Foundation(2021A1515110429 and 2024A1515010768)project funded by China Postdoctoral Science Foundation(2022M721216 and 2023T160235).
文摘Due to the overconsumption of fossil fuels,humanity is facing a series of energy and environmental problems[1,2].Utilizing renewable and clean energy instead of fossil fuels in chemical production has become a hot topic[3].Solar energy is the most abundant source of energy on Earth.Therefore,using solar energy for chemical synthesis has attracted much attention from researchers,which can convert organic compounds or environmental pollutants into high-value-added chemicals[4].Under illumination,photoelectrons and holes of catalysts can undergo reduction and oxidation reactions.However,in most cases,it can only utilize photogenerated electrons or holes,which causes undesired energy loss[5].Additional oxidizing or reducing agents are often required,which increases the economic cost and environmental pollution.In some photocatalytic systems,however,the catalyst can utilize both photogenerated electrons and holes to achieve an overall reaction[6].Due to uncontrollable reverse reactions(e.g.,oxygen reduction reaction in overall water splitting or carbon dioxide reduction reactions),the products may be converted back to feedstock,thus limiting the reaction efficiency[7].If the oxidation and reduction products can be one-pot converted into higher-value compounds,the problem can be solved[8].
基金Project supported bythe National Natural Science Foundation of China （No.20162005）, and the Trans-century Programme Foundation for the Talents by the State Education Commission of China （No. [2001]3）.
文摘AMI semi-empirical method was used to optimize the barbituric acid derivatives substituted with glucosyl B1-5 （series B）, and the thiobarbituric acid derivatives substituted with glucosyl T1-5 （series T）. Based on the optimized structures, INDO/CI method was adopted to calculate the electronic spectra. Meanwhile, the second-order nonlinear optical （NLO） coefficients βμ were calculated with the sum-over-state （SOS） formula. The results show that when the number of glucosyl units was increased, ｜βμ｜ values of the barbituric and thiobarbituric acid derivatives were both enhanced, especially for thiobarbituric acid derivatives. It indicates that non-conjugated substituted group could also improve NLO properties of materials when the number of repeated units was increased. Additionally, the absorption bands appearing in UV area are consistent with the proper change of the number of glucosyl units, and consequently it can be concluded that the high transparencies of all systems were scarcely varied.
