In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthe...In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthesized.Then,the NHC precursor compounds were reacted with PdCl2 and Pd(Ⅱ)-NHC complexes[(4a—4c)]were obtained.The synthesized NHC precursors(3a-3c)and Pd(Ⅱ)-NHC complexes(4a—4c)were characterized by different spectroscopic methods.The antibacterial activities of these products were measured against bacteria and fungus with the disc diffusion method.Pd(Ⅱ)-NHC complexes had higher antibacterial activity than the NHC precursors.The synthesized compounds showed antimicrobial activity with different properties from each other.In vitro biological activities of salts and metal complexes on selected bacteria were determined by the broth dilution method based on Clinical and Laboratory Standards Institute guidelines.1,3-Bis-(2-hydroxyethyl)imidazolinium bromide and 3-(2-ethoxy-2-oxoethyl)-1-(3-aminopropyl)-^(1)H-imidazole-3-ium bromide had activity against Escherichia coli.展开更多
Bioorthogonal reactions can take place in biological environments without interfering with biochemical processes.In this study,Pd(PPh_(3))_(2)Cl_(2)was used as a bioorthogonal catalyst to in situ transform the stable ...Bioorthogonal reactions can take place in biological environments without interfering with biochemical processes.In this study,Pd(PPh_(3))_(2)Cl_(2)was used as a bioorthogonal catalyst to in situ transform the stable N-heterocyclic carbene(NHC)-gold(Ⅰ)-alkyne complex 5 to its active species which can effectively inhibit thioredoxin reductase(TrxR)and exhibit significant anticancer bioactivity in hepatocellular carcinoma(HCC).展开更多
The bis-benzimidazolium salt bis[2-（N-ethylbenzimidazoliumyl）ethyl]amine hexafluorophosphate（LH2·（PF6）2） and its N-heterocyclic carbene silver（Ⅰ） complex[L2Ag3]（PF6）3（1）have been prepared and charact...The bis-benzimidazolium salt bis[2-（N-ethylbenzimidazoliumyl）ethyl]amine hexafluorophosphate（LH2·（PF6）2） and its N-heterocyclic carbene silver（Ⅰ） complex[L2Ag3]（PF6）3（1）have been prepared and characterized.In complex 1,a trinuclear silver（Ⅰ） architecture is formed by two tridentate ligands and three silver（I） atoms,in which one 12- and two 7-membered rings are contained.In the crystal packing of 1,1D chain and 2D supramolecular layer are formed via intermolecular weak interactions,including π…π interactions and C-H…π contacts.Additionally,the fluorescence emission spectra of LH2-（PF6）2 and 1 are described.展开更多
As a renewable biomass-based compound with wide applications in food additives,fine chemical synthesis and fuels,γ-valerolactone(GVL)has attached much attention.While,pyrrolidones are widely used in pharmaceutical,ag...As a renewable biomass-based compound with wide applications in food additives,fine chemical synthesis and fuels,γ-valerolactone(GVL)has attached much attention.While,pyrrolidones are widely used in pharmaceutical,agrochemical,material industrial and other chemical production.In this research,we demonstrated transformations of biomass-based ethyl levulinate(EL)into GVL and pyrrolidones by using heterogeneous catalysts(CNT-Ru-1)with N-heterocyclic carbene ruthenium(NHC-Ru)complex grafted on multi-walled carbon nanotube(CNT).The Ru catalyst showed high efficiency on EL hydrogenation to GVL with both EL conversion and GVL yield exceeding 99%.Moreover,the Ru catalyst readily promoted reductive amination of EL in the presence of various amines for pyrrolidone synthesis.Finally,the Ru catalyst was also applicable to hydrogenation of various carbonyl compounds for the synthesis of the corresponding alcohols with excellent catalytic performance.The research provides insight for heterogenizing the homogeneous noble metal-based catalysts with high catalytic active for biomass-based transformations.展开更多
Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was foun...Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was found that 1,3 bis(2,4,6 trimethylphenyl) imidazolium chloride (IMesHCl) Pd 2(dba) 3 catalytic system has the highest activity to obtain phenyl malononitrile among the imidazolium salts. The substituted iodoarenes reacted with malononitrile anions by using the catalytic system to give cross coupling products in yields from 50% to 96%.展开更多
The complex （Ind）NiBr（1,3-bisbenzylimidazol-2-ylidene） （Ind = indenyl） 1 has been prepared in ca. 65% yield via the reaction of （Ind）2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at...The complex （Ind）NiBr（1,3-bisbenzylimidazol-2-ylidene） （Ind = indenyl） 1 has been prepared in ca. 65% yield via the reaction of （Ind）2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072（1）, b = 11.264（2）, c = 14.541（3）°A, α = 102.21（3）,β = 93.44（3）,γ = 90.81（3）°, V = 1129.7（4）°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F（000） = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections （I〉 2σ（I））. The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane.展开更多
Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modific...Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modifications to the ligand framework is investigated across the catalyst series,which includes a non-macrocyclic derivative(1-Co)and 16-(2-Co)and 15-(3-Co)membered macrocycles.A structure-activity relationship is demonstrated,in which the macrocyclic complexes have greater activity compared to their non-macrocyclic counterpart with the most rigid catalyst,supported by the 15-membered macrocycle,performing best overall.Indeed,3-Co catalyzes H2 evolution from aqueous pH 4 acetate buffer with a Faradaic efficiency of 97%at a low overpotential of 330 mV.Mechanistic studies are consistent with formation of a cobalt-hydride species that is subsequently protonated to evolve H2 via a heterolytic pathway.展开更多
While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed...While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.展开更多
基金supported by the Trakya University Research Fund(No.TUBAP-2014-106)。
文摘In this study,firstly,3-bromopropanenitrile(2a),ethyl bromoacetate(2b),and 2-bromoethan-1-amine(2c)were added to 5,6-dimethylbenzimidazole(1)and symmetrically-connected N-heterocyclic carbenes(NHC)[(3a-3c)]were synthesized.Then,the NHC precursor compounds were reacted with PdCl2 and Pd(Ⅱ)-NHC complexes[(4a—4c)]were obtained.The synthesized NHC precursors(3a-3c)and Pd(Ⅱ)-NHC complexes(4a—4c)were characterized by different spectroscopic methods.The antibacterial activities of these products were measured against bacteria and fungus with the disc diffusion method.Pd(Ⅱ)-NHC complexes had higher antibacterial activity than the NHC precursors.The synthesized compounds showed antimicrobial activity with different properties from each other.In vitro biological activities of salts and metal complexes on selected bacteria were determined by the broth dilution method based on Clinical and Laboratory Standards Institute guidelines.1,3-Bis-(2-hydroxyethyl)imidazolinium bromide and 3-(2-ethoxy-2-oxoethyl)-1-(3-aminopropyl)-^(1)H-imidazole-3-ium bromide had activity against Escherichia coli.
基金the financial supports of the National Natural Science Foundation of China(Nos.82173684 and 82204181)Nanjing University of Chinese Medicine National Natural Science Foundation of China Counterpart Funding(No.XPT82204181)+5 种基金General Project of Basic Science in Colleges and Universities of Jiangsu Province(No.21KJB350007)Jiangsu Provincial Health Commission(No.Z2021057)the Open Project of Chinese Materia Medica First Class Discipline of Nanjing University of Chinese Medicine(No.2020YLXK010)the Priority Academic Program Development of Jiangsu Higher Education Institutions(Integration of Chinese and Western Medicine)the experimental support from the Experiment Center for Science and Technology,Nanjing University of Chinese Medicinefinancially supported by the“Innovative and Entrepreneurial Team”Program of Jiangsu Province(2020)。
文摘Bioorthogonal reactions can take place in biological environments without interfering with biochemical processes.In this study,Pd(PPh_(3))_(2)Cl_(2)was used as a bioorthogonal catalyst to in situ transform the stable N-heterocyclic carbene(NHC)-gold(Ⅰ)-alkyne complex 5 to its active species which can effectively inhibit thioredoxin reductase(TrxR)and exhibit significant anticancer bioactivity in hepatocellular carcinoma(HCC).
基金supported by the National Natural Science Foundation of China(No.21172172)Tianjin Natural Science Foundation(No.11JCZDJC22000)the Program for Innovative Research Team in University of Tianjin(TD12-5038)
文摘The bis-benzimidazolium salt bis[2-（N-ethylbenzimidazoliumyl）ethyl]amine hexafluorophosphate（LH2·（PF6）2） and its N-heterocyclic carbene silver（Ⅰ） complex[L2Ag3]（PF6）3（1）have been prepared and characterized.In complex 1,a trinuclear silver（Ⅰ） architecture is formed by two tridentate ligands and three silver（I） atoms,in which one 12- and two 7-membered rings are contained.In the crystal packing of 1,1D chain and 2D supramolecular layer are formed via intermolecular weak interactions,including π…π interactions and C-H…π contacts.Additionally,the fluorescence emission spectra of LH2-（PF6）2 and 1 are described.
基金the financial support from the National Natural Science Foundation of China(U1810111,51872124 and21676116)Natural Science Foundation of Guangdong Province,China(2018B030311010)+1 种基金the Fundamental Research Funds for the Central Universities(21617431)Key Laboratory of Biomass Chemical Engineering of Ministry of Education,Zhejiang University(2018BCE002)
文摘As a renewable biomass-based compound with wide applications in food additives,fine chemical synthesis and fuels,γ-valerolactone(GVL)has attached much attention.While,pyrrolidones are widely used in pharmaceutical,agrochemical,material industrial and other chemical production.In this research,we demonstrated transformations of biomass-based ethyl levulinate(EL)into GVL and pyrrolidones by using heterogeneous catalysts(CNT-Ru-1)with N-heterocyclic carbene ruthenium(NHC-Ru)complex grafted on multi-walled carbon nanotube(CNT).The Ru catalyst showed high efficiency on EL hydrogenation to GVL with both EL conversion and GVL yield exceeding 99%.Moreover,the Ru catalyst readily promoted reductive amination of EL in the presence of various amines for pyrrolidone synthesis.Finally,the Ru catalyst was also applicable to hydrogenation of various carbonyl compounds for the synthesis of the corresponding alcohols with excellent catalytic performance.The research provides insight for heterogenizing the homogeneous noble metal-based catalysts with high catalytic active for biomass-based transformations.
文摘Eight N heterocyclic carbenes (NHC), generated in situ from their imidazolium salts, as ligands of palladium complexes were used for the catalytic coupling of iodobenzene with malononitrile anion. It was found that 1,3 bis(2,4,6 trimethylphenyl) imidazolium chloride (IMesHCl) Pd 2(dba) 3 catalytic system has the highest activity to obtain phenyl malononitrile among the imidazolium salts. The substituted iodoarenes reacted with malononitrile anions by using the catalytic system to give cross coupling products in yields from 50% to 96%.
基金This work was supported by the National Natural Science Foundation of China (No. 20272040) and the Key Lab. of Organic Synthesis of Jiangsu Province
文摘The complex （Ind）NiBr（1,3-bisbenzylimidazol-2-ylidene） （Ind = indenyl） 1 has been prepared in ca. 65% yield via the reaction of （Ind）2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072（1）, b = 11.264（2）, c = 14.541（3）°A, α = 102.21（3）,β = 93.44（3）,γ = 90.81（3）°, V = 1129.7（4）°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F（000） = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections （I〉 2σ（I））. The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane.
文摘Three cobalt complexes bearing tunable,redox-active bipyridyl N-heterocyclic carbene(NHC)-based ligands have been studied for electrocatalytic hydrogen evolution from aqueous solutions.The effect of structural modifications to the ligand framework is investigated across the catalyst series,which includes a non-macrocyclic derivative(1-Co)and 16-(2-Co)and 15-(3-Co)membered macrocycles.A structure-activity relationship is demonstrated,in which the macrocyclic complexes have greater activity compared to their non-macrocyclic counterpart with the most rigid catalyst,supported by the 15-membered macrocycle,performing best overall.Indeed,3-Co catalyzes H2 evolution from aqueous pH 4 acetate buffer with a Faradaic efficiency of 97%at a low overpotential of 330 mV.Mechanistic studies are consistent with formation of a cobalt-hydride species that is subsequently protonated to evolve H2 via a heterolytic pathway.
基金financial support from the National Natural Science Foundation of China (No. 22001248)the Fundamental Research Funds for the Central Universities and the University of the Chinese Academy of Sciences
文摘While N-alkenoxypyridinium salts are widely used for the synthesis ofα-functionalized ketones via umpolung strategy,such approaches are usually limited to special nucleophiles at high temperatures.Herein,we developed an alternative photoinduced N-heterocyclic carbene(NHC)-mediated functionalization of N-alkenoxypyridinium salts with various nucleophiles,including tetramethylammonium azide,secondary amines,aryl and alkyl thiols,and even the challenging C(sp^(3))-nucleophiles,under mild conditions.A cascade radical-radical coupling/nucleophilic substitution sequence was proposed,wherein the NHC enabled the formation of a photoactive electron donor-acceptor complex forα-iodo ketone synthesis.
