In view of the importance of picolinic acid (Pa) in preventing cell growth and arresting cell cycle, attempts were made to design, synthesize and characterize two new Pa based tetradentate ligands (DPPTR and DPPTY) wi...In view of the importance of picolinic acid (Pa) in preventing cell growth and arresting cell cycle, attempts were made to design, synthesize and characterize two new Pa based tetradentate ligands (DPPTR and DPPTY) with a modified procedure. The procedure reported here avoids by-products and provides better yield and purity.展开更多
A new class of iron（II） hydrides based on a tetradentate PSNP ligand were synthesized and fully characterized. All the iron（II） complexes feature a folded PSNP ligand with cis reactive sites. The hydrido iron comp...A new class of iron（II） hydrides based on a tetradentate PSNP ligand were synthesized and fully characterized. All the iron（II） complexes feature a folded PSNP ligand with cis reactive sites. The hydrido iron complex [2 H（NCMe[2_TD$IF]1）]（BF4） is capable of catalyzing aldehyde hydroboration by pinacolborane（HBpin） and with extremely high efficiency at room temperature. Aldehydes with various functional groups are compatible.展开更多
In this research two chromium（II][） and （VI） complexes of tetradentate Schiff bases have been prepared by condensing of salicylaldehyde with 4-methyl 1,2-phenylenediamine. Schiff base complexes of chromium（Ill） ...In this research two chromium（II][） and （VI） complexes of tetradentate Schiff bases have been prepared by condensing of salicylaldehyde with 4-methyl 1,2-phenylenediamine. Schiff base complexes of chromium（Ill） have been employed to design and synthesize polynuclear complexes. So they have played an important role in molecular magnetism. Synthesized complexes were characterized by elemental analysis, IR, molar conductivity and NMR. The free ligands were alsc characterized by 1H, 13C NMR spectra. The 13C NMR and IR spectra of free ligand and the complexes are compared and discussed.展开更多
The new metal complexes of Cu(II), Ni(II) and Co(II) with the new ligand derived from isatine and 1,2-diaminocyclohexane were synthesized and biologically screened. The synthesized complexes and ligand were characteri...The new metal complexes of Cu(II), Ni(II) and Co(II) with the new ligand derived from isatine and 1,2-diaminocyclohexane were synthesized and biologically screened. The synthesized complexes and ligand were characterized by spectroscopic FT-IR, UV-VIS, 1H-NMR and elemental analyses. The ligand and complexes were screened for their antibacterial activities against three different strains, namely E. coli, P. aeruginosa and S. aureus. In particular, the Co(II) and Cu-complexes exhibited excellent antibacterial activities compared to the reference compound.展开更多
Chiral bipyridines represent a class of ligands noted for their distinctive reactivity and stereoselectivity in metal-catalyzed reactions.Herein,we have developed a new class of bifunctional C_(2)-symmetric chiral bip...Chiral bipyridines represent a class of ligands noted for their distinctive reactivity and stereoselectivity in metal-catalyzed reactions.Herein,we have developed a new class of bifunctional C_(2)-symmetric chiral bipyridine-type tetradentate ligands,abbreviated as Bpy-Bisulidines.These crab-shape ligands feature that:(1)bipyridine framework possesses the rich coordination ability with various metal ions;(2)chiral imidazolidine could generate a deep chiral pocket;(3)C_(2)-symmetry could reduce the number of possible transition states;(4)rigid chiral enviroments are close to the metal,and(5)imidazolidine N-H moiety acts as hydrogen-bonding donor.The newly developed chiral Bpy-Bisulidine ligands were successfully applied in Ni(II)-catalyzed asymmetric Friedel-Crafts alkylation reaction and inverse-electron-demand Hetero-Diels-Alder reactions,achieving excellent stereoselectivities.Our work is the first example of bifunctional C_(2)-symmetric chiral imidazolidine-type tetradentate ligands.X-ray crystallographic analysis of the Bpy-Bisulidine-Ni(OTf)_(2)complex,control experiments and linear correlation showed that the catalytically active species was a monomeric catalyst.展开更多
A novel hydrido iridium chloride complex supported by a tetradentate PNCP ligand has been synthesized and characterized.Upon activation with NaOtBu,the PNCP-IrHC1 complex is active for transfer dehydrogenation of cycl...A novel hydrido iridium chloride complex supported by a tetradentate PNCP ligand has been synthesized and characterized.Upon activation with NaOtBu,the PNCP-IrHC1 complex is active for transfer dehydrogenation of cyclic and linear alkanes.展开更多
The development of highly active and enantioselective ligands and catalysts for the asymmetric hydrogenation of ketone has been the goal of synthetic chemists for more than fifty years.Herein,a series of ferrocene-bas...The development of highly active and enantioselective ligands and catalysts for the asymmetric hydrogenation of ketone has been the goal of synthetic chemists for more than fifty years.Herein,a series of ferrocene-based tetradentate ligands were developed and applied in Ir-catalysed asymmetric hydrogenation of ketone.The hydrolytic ring-opening of the oxazoline moiety of ligand f-amphox leads to the accidental discovery of a highly efficient and enantioselective tetradentate ligand f-phamidol which showed extraordinarily high reactivity and enantioselectivity(up to 99%yield,up to>99%ee and up to 1,000,000 TON).In addition,two types of other tetradentate ligands f-phamida and f-phamide were also synthesized and evaluated.展开更多
In this work, it is found that 1,8-dihydroxyimino-1,2,7,8-tetraphenyl-3,6-diazocta-2,6-diene(PhdoenH2) could react with nickel(Ⅱ) salt to yield a mononickel complex Ni(Phdoen)(1) with unusual [2N2O]-coordinated mode,...In this work, it is found that 1,8-dihydroxyimino-1,2,7,8-tetraphenyl-3,6-diazocta-2,6-diene(PhdoenH2) could react with nickel(Ⅱ) salt to yield a mononickel complex Ni(Phdoen)(1) with unusual [2N2O]-coordinated mode, while the analogous diimine-dioxime ligands usually form the [4N]-coordinated mode. The novel complex 1 has been carefully characterized by 1H NMR, elemental analysis, and X-ray diffraction structure analysis. The influences of the coordination modes on the structures and redox properties have been further investigated. Theoretical investigations revealed that the different coordination modes were ascribed to the thermodynamic properties of ligands.展开更多
Synthesis and characterization of two novel potentially tetradentate chelating O^N^C ligands： 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid and 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid ethyl ester were fir...Synthesis and characterization of two novel potentially tetradentate chelating O^N^C ligands： 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid and 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid ethyl ester were firstly reported.展开更多
The synthesis and characterization of several hexa – coordinated Ru(II) complexes of the type [Ru(CO)(B)(L)] (B = PPh3/AsPh3/py/pip;L = di-basic tetradentate ligand derived from the condensation of isatin with diamin...The synthesis and characterization of several hexa – coordinated Ru(II) complexes of the type [Ru(CO)(B)(L)] (B = PPh3/AsPh3/py/pip;L = di-basic tetradentate ligand derived from the condensation of isatin with diamines) were reported. IR, electronic, 1H- NMR, 31P-NMR of the complexes are discussed. An octahedral geometry has been tentatively proposed for all these complexes. The new complexes have been tested for the catalytic activity in the reaction of oxidation of alcohols in the presence of N-me- thylmorpholine–N-oxide as co-oxidant. The new complexes were also exhibited antimicrobial investigations.展开更多
The formation of colourless gadolinium complexes (x,y,z), between x gadolinium ions, y ligands and z protons, of some organic acids, has been studied in aqueous solution. In this work we present the results of investi...The formation of colourless gadolinium complexes (x,y,z), between x gadolinium ions, y ligands and z protons, of some organic acids, has been studied in aqueous solution. In this work we present the results of investigations on the interaction of the gadolinium ion (Gd3+) with malic acid (C4H6O5, a-hydroxyl dicarboxylic acid), in dilute aqueous solution for pH values between 5.5 and 7.5. Colourless gadolinium complexes of malate ions have no absorption band UV-visible, the indirect photometric detection (IPD) technique was used and studies have identified a major tri-nuclear complex of malate ion (﹣OOC-CH2-CHOH-COO﹣). The formation of this new colourless complex is derived from three Gd(III) ions that react with two malate ions and two hydronium ions (H3O+), giving for this colourless complex, a (3,2,2) composition and apparent stability constant depends on the acidity of the medium, with logK'322 = 18.88 ± 0.05 at pH = 6.30. To complement previous results and to propose a probable structure for this new complex detected in solution, studies of IR spectroscopy have been conducted to identify the chelation sites for both ligands. The results were analysed and show that this organometallic gadolinium complex, contains two different sites, respectively, two lateral tetradentate mono-nuclear sites and a single central bidentate mono-nuclear site. From these results, the reaction of formation, the stability constant and the probable structure of this new colourless organometallic gadolinium complex are proposed.展开更多
Enantioselective cis-dihydroxylation of alkenes represents an ideal route to synthesize enantioenriched syn-2,3-dihydroxy esters that are important structural motifs in numerous biologically and pharmaceutically relev...Enantioselective cis-dihydroxylation of alkenes represents an ideal route to synthesize enantioenriched syn-2,3-dihydroxy esters that are important structural motifs in numerous biologically and pharmaceutically relevant molecules.Bioinspired nonheme iron-catalyzed enantioselective cis-dihydroxylation meets the requirement of the modern synthetic chemistry from the atomic economy,green chemistry,and sustainable development perspectives.However,nonheme iron-catalyzed enantioselective cis-dihydroxylation is much underdeveloped because of the formidable challenges of controlling chemo-and enantioselectivities and product selectivity caused by the competitive epoxidation,cis-dihydroxylation,and overoxidation reactions.Herein,we disclose the fabrication of a biologically inspired nonheme iron complex-catalyzed enantioselective cis-dihydroxylation of multisubstituted acrylates using hydrogen peroxide(H_(2)O_(2))as the terminal oxidant by controlling the non-ligating or weakly ligating counterions of iron(Ⅱ)complexes,demonstrating a dramatic counteranion effect on the enantioselective cisdihydroxylation of olefins by H_(2)O_(2) catalyzed by nonheme iron complexes.A range of structurally disparate alkenes were transformed to the corresponding syn-2,3-dihydroxy esters in practically useful yields with exquisite chemo-and enantioselectivities(up to 99% ee).Given the mild and benign nature of this biologically inspired oxidation system as well as the ubiquity and synthetic utility of enantioenriched syn-2,3-dihydroxy esters as pharmaceuticals candidates and natural products,we expect that this strategy could serve as a promising complement to the well-known Sharpless asymmetric dihydroxylation,which is the chemical reaction of an alkene with OsO_(4) to produce a vicinal diol.展开更多
文摘In view of the importance of picolinic acid (Pa) in preventing cell growth and arresting cell cycle, attempts were made to design, synthesize and characterize two new Pa based tetradentate ligands (DPPTR and DPPTY) with a modified procedure. The procedure reported here avoids by-products and provides better yield and purity.
基金financial support from the "1000 Youth Talents Plan"the National Natural Science Foundation of China (Nos. 21402107, 91427303)the Natural Science Foundation of Shandong Province (Nos. ZR2014M011)
文摘A new class of iron（II） hydrides based on a tetradentate PSNP ligand were synthesized and fully characterized. All the iron（II） complexes feature a folded PSNP ligand with cis reactive sites. The hydrido iron complex [2 H（NCMe[2_TD$IF]1）]（BF4） is capable of catalyzing aldehyde hydroboration by pinacolborane（HBpin） and with extremely high efficiency at room temperature. Aldehydes with various functional groups are compatible.
文摘In this research two chromium（II][） and （VI） complexes of tetradentate Schiff bases have been prepared by condensing of salicylaldehyde with 4-methyl 1,2-phenylenediamine. Schiff base complexes of chromium（Ill） have been employed to design and synthesize polynuclear complexes. So they have played an important role in molecular magnetism. Synthesized complexes were characterized by elemental analysis, IR, molar conductivity and NMR. The free ligands were alsc characterized by 1H, 13C NMR spectra. The 13C NMR and IR spectra of free ligand and the complexes are compared and discussed.
文摘The new metal complexes of Cu(II), Ni(II) and Co(II) with the new ligand derived from isatine and 1,2-diaminocyclohexane were synthesized and biologically screened. The synthesized complexes and ligand were characterized by spectroscopic FT-IR, UV-VIS, 1H-NMR and elemental analyses. The ligand and complexes were screened for their antibacterial activities against three different strains, namely E. coli, P. aeruginosa and S. aureus. In particular, the Co(II) and Cu-complexes exhibited excellent antibacterial activities compared to the reference compound.
基金the financial support from the NSFC(22361009)Guizhou Provincial Basic Research Program(GCC[2023]078,ZK[2023]043,ZK[2024]374).
文摘Chiral bipyridines represent a class of ligands noted for their distinctive reactivity and stereoselectivity in metal-catalyzed reactions.Herein,we have developed a new class of bifunctional C_(2)-symmetric chiral bipyridine-type tetradentate ligands,abbreviated as Bpy-Bisulidines.These crab-shape ligands feature that:(1)bipyridine framework possesses the rich coordination ability with various metal ions;(2)chiral imidazolidine could generate a deep chiral pocket;(3)C_(2)-symmetry could reduce the number of possible transition states;(4)rigid chiral enviroments are close to the metal,and(5)imidazolidine N-H moiety acts as hydrogen-bonding donor.The newly developed chiral Bpy-Bisulidine ligands were successfully applied in Ni(II)-catalyzed asymmetric Friedel-Crafts alkylation reaction and inverse-electron-demand Hetero-Diels-Alder reactions,achieving excellent stereoselectivities.Our work is the first example of bifunctional C_(2)-symmetric chiral imidazolidine-type tetradentate ligands.X-ray crystallographic analysis of the Bpy-Bisulidine-Ni(OTf)_(2)complex,control experiments and linear correlation showed that the catalytically active species was a monomeric catalyst.
基金financially supported by the National Basic Research Program of China(2015CB856600)the National Natural Science Foundation of China(21422209,21432011,21421091)
文摘A novel hydrido iridium chloride complex supported by a tetradentate PNCP ligand has been synthesized and characterized.Upon activation with NaOtBu,the PNCP-IrHC1 complex is active for transfer dehydrogenation of cyclic and linear alkanes.
基金X.Zhang is indebted to the National Key R&D Program of China(No.2021YFA1500201)the Shenzhen Science and Technology Innovation Committee(SSTIC)(No.KQTD2015071710315717)+5 种基金Stable Support Plan Program of Shenzhen Natural Science Fund(No.20200925161222002)Key-Area Research and Development Program of Guangdong Province(No.2020B010188001)Innovative Team of Universities in Guangdong Province(No.2020KCXTD016)National Natural Science Foundation of China(No.21991113)G.Q.Chen gratefully acknowledges the National Natural Science Foundation of China(Nos.21901107 and 22171129)SSTIC(No.JCYJ20210324104202007)for financial support.
文摘The development of highly active and enantioselective ligands and catalysts for the asymmetric hydrogenation of ketone has been the goal of synthetic chemists for more than fifty years.Herein,a series of ferrocene-based tetradentate ligands were developed and applied in Ir-catalysed asymmetric hydrogenation of ketone.The hydrolytic ring-opening of the oxazoline moiety of ligand f-amphox leads to the accidental discovery of a highly efficient and enantioselective tetradentate ligand f-phamidol which showed extraordinarily high reactivity and enantioselectivity(up to 99%yield,up to>99%ee and up to 1,000,000 TON).In addition,two types of other tetradentate ligands f-phamida and f-phamide were also synthesized and evaluated.
基金the Natural Science Foundation of China(21773184 and 21671158)。
文摘In this work, it is found that 1,8-dihydroxyimino-1,2,7,8-tetraphenyl-3,6-diazocta-2,6-diene(PhdoenH2) could react with nickel(Ⅱ) salt to yield a mononickel complex Ni(Phdoen)(1) with unusual [2N2O]-coordinated mode, while the analogous diimine-dioxime ligands usually form the [4N]-coordinated mode. The novel complex 1 has been carefully characterized by 1H NMR, elemental analysis, and X-ray diffraction structure analysis. The influences of the coordination modes on the structures and redox properties have been further investigated. Theoretical investigations revealed that the different coordination modes were ascribed to the thermodynamic properties of ligands.
基金supported by the National Natural Science Foundation of China(No.50273045,90210033,50463001).
文摘Synthesis and characterization of two novel potentially tetradentate chelating O^N^C ligands： 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid and 2-（2-hydroxyphenyl）-6-p-tolylisonicotinic acid ethyl ester were firstly reported.
文摘The synthesis and characterization of several hexa – coordinated Ru(II) complexes of the type [Ru(CO)(B)(L)] (B = PPh3/AsPh3/py/pip;L = di-basic tetradentate ligand derived from the condensation of isatin with diamines) were reported. IR, electronic, 1H- NMR, 31P-NMR of the complexes are discussed. An octahedral geometry has been tentatively proposed for all these complexes. The new complexes have been tested for the catalytic activity in the reaction of oxidation of alcohols in the presence of N-me- thylmorpholine–N-oxide as co-oxidant. The new complexes were also exhibited antimicrobial investigations.
文摘The formation of colourless gadolinium complexes (x,y,z), between x gadolinium ions, y ligands and z protons, of some organic acids, has been studied in aqueous solution. In this work we present the results of investigations on the interaction of the gadolinium ion (Gd3+) with malic acid (C4H6O5, a-hydroxyl dicarboxylic acid), in dilute aqueous solution for pH values between 5.5 and 7.5. Colourless gadolinium complexes of malate ions have no absorption band UV-visible, the indirect photometric detection (IPD) technique was used and studies have identified a major tri-nuclear complex of malate ion (﹣OOC-CH2-CHOH-COO﹣). The formation of this new colourless complex is derived from three Gd(III) ions that react with two malate ions and two hydronium ions (H3O+), giving for this colourless complex, a (3,2,2) composition and apparent stability constant depends on the acidity of the medium, with logK'322 = 18.88 ± 0.05 at pH = 6.30. To complement previous results and to propose a probable structure for this new complex detected in solution, studies of IR spectroscopy have been conducted to identify the chelation sites for both ligands. The results were analysed and show that this organometallic gadolinium complex, contains two different sites, respectively, two lateral tetradentate mono-nuclear sites and a single central bidentate mono-nuclear site. From these results, the reaction of formation, the stability constant and the probable structure of this new colourless organometallic gadolinium complex are proposed.
基金the National Natural Science Foundation of China(no.21771087 to B.W and no.21703080 to J.C)the NSF of Shandong Province(no.ZR2020YQ10 to B.W)+1 种基金Taishan Scholar Program of Shandong Province(no.tsqn201812078 to B.W.)the NRF of Korea(no.NRF-2021R1A3B1076539 to W.N.and no.NRF-2020R1I1A1A01074630 to Y.-M.L.).
文摘Enantioselective cis-dihydroxylation of alkenes represents an ideal route to synthesize enantioenriched syn-2,3-dihydroxy esters that are important structural motifs in numerous biologically and pharmaceutically relevant molecules.Bioinspired nonheme iron-catalyzed enantioselective cis-dihydroxylation meets the requirement of the modern synthetic chemistry from the atomic economy,green chemistry,and sustainable development perspectives.However,nonheme iron-catalyzed enantioselective cis-dihydroxylation is much underdeveloped because of the formidable challenges of controlling chemo-and enantioselectivities and product selectivity caused by the competitive epoxidation,cis-dihydroxylation,and overoxidation reactions.Herein,we disclose the fabrication of a biologically inspired nonheme iron complex-catalyzed enantioselective cis-dihydroxylation of multisubstituted acrylates using hydrogen peroxide(H_(2)O_(2))as the terminal oxidant by controlling the non-ligating or weakly ligating counterions of iron(Ⅱ)complexes,demonstrating a dramatic counteranion effect on the enantioselective cisdihydroxylation of olefins by H_(2)O_(2) catalyzed by nonheme iron complexes.A range of structurally disparate alkenes were transformed to the corresponding syn-2,3-dihydroxy esters in practically useful yields with exquisite chemo-and enantioselectivities(up to 99% ee).Given the mild and benign nature of this biologically inspired oxidation system as well as the ubiquity and synthetic utility of enantioenriched syn-2,3-dihydroxy esters as pharmaceuticals candidates and natural products,we expect that this strategy could serve as a promising complement to the well-known Sharpless asymmetric dihydroxylation,which is the chemical reaction of an alkene with OsO_(4) to produce a vicinal diol.
