Metalloenzymes play a crucial role in life,performing myriad functions in aqueous environments in nature.Understanding these systems’structural and functional mimics in water at ambient temperature is essential for d...Metalloenzymes play a crucial role in life,performing myriad functions in aqueous environments in nature.Understanding these systems’structural and functional mimics in water at ambient temperature is essential for developing new catalysts.Inspired by nature,we report here the synthesis of a remarkably stable formal[(L)Cu(Ⅲ)]^(+)(2)species supported by a tetradentate pseudopeptide ligand,which we then characterized by various spectroscopic techniques in water at ambient temperature and using DFT methods.Our experimental and DFT studies indicate that the observed stability is caused by hydrogen bonding of water molecules to the amide moiety of the ligand bound to the formal Cu(Ⅲ)center.The Natural Bonding Orbital(NBO)analysis indicated the best description of the oxidized species to be formal Cu(Ⅲ).The formal Cu(Ⅲ)species(2)could also be prepared by electrochemical oxidation methods in water.The generated species 2 was found to be reactive towards various phenols in H_(2)O:CH_(3)CN(1:1).The ability to stabilize formal Cu(Ⅲ)in water encouraged us to investigate the biological activity of[(L)Cu(Ⅱ)](1)in cancer cell proliferation.Studies of these metalloenzyme mimics in cells indicated that intracellular and extracellular reactive oxygen species(ROS)generation,in turn,selectively prevented the growth of liver cancer cells over other cancer cell lines and normal kidney cells.展开更多
Supercoiled structures with multiple,continuous“figure-eight”conformations,such as complex DNA plectonemes,are ubiquitous and play vital roles in biological systems.In comparison,synthetic smallmolecule supercoils w...Supercoiled structures with multiple,continuous“figure-eight”conformations,such as complex DNA plectonemes,are ubiquitous and play vital roles in biological systems.In comparison,synthetic smallmolecule supercoils with two or more crossings are scarce.Herein,we report a supercoiled plectoneme structure with two crossings assembled by synergistic cation and anion coordination to a heterotopic ligand,which contains an oligourea backbone for sulfate anion coordination and two pyridyl ends for platinum(Ⅱ)ion coordination.The supercoiled structure is confirmed by single-crystal diffraction to be a racemic mixture with positive and negative crossings.Enantiopure supercoils can be induced by adenosine monophosphate or inosine monophosphate binding inside the apical loops,resembling the polymerase encapsulation in bacterial plectonemes that guides DNA and RNA synthesis.展开更多
In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with ...In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with five strongπ-donating ancillary ligands(L^X)to furnish a suite of nine new complexes with the general formula Ir(C^N)_(2)(L^X).Improvements in deep-red photoluminescence quantum yields were accomplished by the incorporation of sterically encumbering substituents onto the ancillary ligand,which can enhance the radiative rate constant(k_(r))and/or reduce the non-radiative rate constant(k_(nr)).Five of the complexes were characterized by X-ray crystallography,and all of them were investigated by in-depth spectroscopic and electrochemical measurements.展开更多
In this work,we study the structural changes of the polar[NH4][Cd(HCOO)3]hybrid perovskite under external hydrostatic pressure.We report a reversible framework rearrangement as a function of pressure characterized by:...In this work,we study the structural changes of the polar[NH4][Cd(HCOO)3]hybrid perovskite under external hydrostatic pressure.We report a reversible framework rearrangement as a function of pressure characterized by:(i)a gradual modification of one formate ligand,which changes its coordination mode from a bridging syn–anti mode at atmospheric pressure(LP-phase)to a chelating-anti mode at high-pressure(HP-phase)and(ii)a change in the coordination of the Cd2+cations from six-coordinated(LP-phase)to hepta-coordinated(HP-phase).Very interestingly,this unprecedented framework arrangement displays a large electrical polarization.For instance,the polarization value observed at p=17.7 GPa is about four times the polarization at atmospheric pressure.Therefore,we report that the external pressure induces a novel framework rearrangement in the polar[NH4][Cd(HCOO)3]hybrid perovskite with enhanced electrical polarization.This structure–property relationship offers new insights for designing novel ferroelectric materials based on pressure-responsive hybrid perovskite materials.展开更多
基金supported by the SERB(CRG/2023/001112 and CRG/2021/004787)CSIR(01(3050)/21/EMR-II and 02(366)/19/EMR-II)+1 种基金DBT(BT/12/IYBA/2019/07)ICMR(AMR/ADHOC/296/2022-ECD-II).
文摘Metalloenzymes play a crucial role in life,performing myriad functions in aqueous environments in nature.Understanding these systems’structural and functional mimics in water at ambient temperature is essential for developing new catalysts.Inspired by nature,we report here the synthesis of a remarkably stable formal[(L)Cu(Ⅲ)]^(+)(2)species supported by a tetradentate pseudopeptide ligand,which we then characterized by various spectroscopic techniques in water at ambient temperature and using DFT methods.Our experimental and DFT studies indicate that the observed stability is caused by hydrogen bonding of water molecules to the amide moiety of the ligand bound to the formal Cu(Ⅲ)center.The Natural Bonding Orbital(NBO)analysis indicated the best description of the oxidized species to be formal Cu(Ⅲ).The formal Cu(Ⅲ)species(2)could also be prepared by electrochemical oxidation methods in water.The generated species 2 was found to be reactive towards various phenols in H_(2)O:CH_(3)CN(1:1).The ability to stabilize formal Cu(Ⅲ)in water encouraged us to investigate the biological activity of[(L)Cu(Ⅱ)](1)in cancer cell proliferation.Studies of these metalloenzyme mimics in cells indicated that intracellular and extracellular reactive oxygen species(ROS)generation,in turn,selectively prevented the growth of liver cancer cells over other cancer cell lines and normal kidney cells.
基金supported by the National Natural Science Foundation of China(22101024 and 22171023)the Beijing Municipal Natural Science Foundation(2222025).
文摘Supercoiled structures with multiple,continuous“figure-eight”conformations,such as complex DNA plectonemes,are ubiquitous and play vital roles in biological systems.In comparison,synthetic smallmolecule supercoils with two or more crossings are scarce.Herein,we report a supercoiled plectoneme structure with two crossings assembled by synergistic cation and anion coordination to a heterotopic ligand,which contains an oligourea backbone for sulfate anion coordination and two pyridyl ends for platinum(Ⅱ)ion coordination.The supercoiled structure is confirmed by single-crystal diffraction to be a racemic mixture with positive and negative crossings.Enantiopure supercoils can be induced by adenosine monophosphate or inosine monophosphate binding inside the apical loops,resembling the polymerase encapsulation in bacterial plectonemes that guides DNA and RNA synthesis.
基金the National Science Foundation(CHE-1846831)the Welch Foundation(grant no.E-1887)for funding this research.
文摘In this work,we describe bis-cyclometalated iridium complexes with efficient deep-red luminescence.Two different cyclometalating(C^N)ligands-1-phenylisoquinoline(piq)and 2-(2-pyridyl)benzothiophene(btp)-are used with five strongπ-donating ancillary ligands(L^X)to furnish a suite of nine new complexes with the general formula Ir(C^N)_(2)(L^X).Improvements in deep-red photoluminescence quantum yields were accomplished by the incorporation of sterically encumbering substituents onto the ancillary ligand,which can enhance the radiative rate constant(k_(r))and/or reduce the non-radiative rate constant(k_(nr)).Five of the complexes were characterized by X-ray crystallography,and all of them were investigated by in-depth spectroscopic and electrochemical measurements.
基金supported by the Ministerio de Economía y Competitividad(MINECO)and EU-FEDER under the projects[CSD2007-00045,CTQ2015-67755-C2-1-R and MAT2017-86453-R]Ministerio de Ciencia,Innovación y Universidades(MICINN)and EU-FEDER under the project PGC2018-094814-B-C21Xunta de Galicia under the project ED431C2018/39.
文摘In this work,we study the structural changes of the polar[NH4][Cd(HCOO)3]hybrid perovskite under external hydrostatic pressure.We report a reversible framework rearrangement as a function of pressure characterized by:(i)a gradual modification of one formate ligand,which changes its coordination mode from a bridging syn–anti mode at atmospheric pressure(LP-phase)to a chelating-anti mode at high-pressure(HP-phase)and(ii)a change in the coordination of the Cd2+cations from six-coordinated(LP-phase)to hepta-coordinated(HP-phase).Very interestingly,this unprecedented framework arrangement displays a large electrical polarization.For instance,the polarization value observed at p=17.7 GPa is about four times the polarization at atmospheric pressure.Therefore,we report that the external pressure induces a novel framework rearrangement in the polar[NH4][Cd(HCOO)3]hybrid perovskite with enhanced electrical polarization.This structure–property relationship offers new insights for designing novel ferroelectric materials based on pressure-responsive hybrid perovskite materials.
