Magnetic resonance imaging(MRI)is a non-invasive medical imaging technique that has been widely applied in the clinical diagnosis of diseases across various fields.Currently,there is a dearth of high-performance dual-...Magnetic resonance imaging(MRI)is a non-invasive medical imaging technique that has been widely applied in the clinical diagnosis of diseases across various fields.Currently,there is a dearth of high-performance dual-mode contrast agents that provide precise diagnostic information for complex diseases.In this study,iron oxide-gadolinium nanoparticles(IO-Gd NPs)bridged by hydrophilic ligand ethylenedi-amine tetramethylenephosphonic acid(EDTMP)are designed inspired by Solomon-Bloembergen-Morgan(SBM)theory,where T_(1)and T_(2)relaxivity increase with a reduction in Gd content.In particular,the NPs with minimum Gd content exhibit excellent dual-mode contrast performance(r_(1)=94.42 mM^(−1)s^(−1),r_(2)=343.62 mM^(−1)s^(−1)).The underlying mechanism is that the bridged EDTMP coordinate limits Gd tum-bling and forces Gd^(3+)to expose itself to the surface of the NPs.This provides more opportunities for water molecules to coordinate with Gd^(3+)and significantly enhances proton relaxivity.Moreover,the hy-drophilicity of the ligand enhances the water dispersion stability of the NPs and increases the exchange rate of water protons near the NPs,further enhancing the dual-mode contrast effect.Finally,the biocom-patibility and in vitro/vivo imaging performances of the IO@EDTMP-Gd NPs are systematically evaluated,and the results demonstrate their potential as dual-mode contrast agents.This study provides a new strategy for developing dual-mode MRI contrast agents that can further improve the accuracy of MRI in the diagnosis of complex diseases.展开更多
General guidelines for the design of ligands for the enrichment of rare-earth elements by solid-liquid adsorption are described using coordination chemistry.Relevant properties of ligands include selectivity of metal ...General guidelines for the design of ligands for the enrichment of rare-earth elements by solid-liquid adsorption are described using coordination chemistry.Relevant properties of ligands include selectivity of metal ions based on adjustment of donor atom polarizability,denticity,and the pKarange of the binding sites.The selectivity of solid-phase materials for the enrichment of rare-earth ions by the ligand design guidelines is outlined,with special consideration of additional variable factors including steric hindrance,saturated binding sites,variability in speciation caused by the identity of counterions and ionic strength,and size-exclusivity in ligands stemming from differences in bite angle,preo rganization of ligands,or intraligand interactions.This review analyzes some principles of selectivity of rare-earth elements with ligands organized by donor type from examples collected from reports published between 2009 and 2021.展开更多
Two comparable discrete complexes [CuⅡ（CH3CN）2L2]·2（ClO4） 1 and [CuI2I2L2]·（DMF）2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis（3-pyr...Two comparable discrete complexes [CuⅡ（CH3CN）2L2]·2（ClO4） 1 and [CuI2I2L2]·（DMF）2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis（3-pyridinylmethylthio）-1,3,4-thiadiazole）（L）,respectively.Complex 1 presents a single nuclear structure while 2 has a dimeric structure where two CuI ions are doubly bridged by halide ions in a μ2-fashion.Both discrete molecules were outspreaded into a one-dimensional supramolecular chain via aromatic interactions such as C–H…π and π…π interactions.展开更多
Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and signif...Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.展开更多
基金supported by the National Key R&D Program of China(Nos.2020YFA0710800,2022YFE0124500)the National Natural Science Foundation of China(Nos.32271467,32071364)+1 种基金the Outstanding Postdoctoral Program of Jiangsu Province(No.2022ZB367)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Magnetic resonance imaging(MRI)is a non-invasive medical imaging technique that has been widely applied in the clinical diagnosis of diseases across various fields.Currently,there is a dearth of high-performance dual-mode contrast agents that provide precise diagnostic information for complex diseases.In this study,iron oxide-gadolinium nanoparticles(IO-Gd NPs)bridged by hydrophilic ligand ethylenedi-amine tetramethylenephosphonic acid(EDTMP)are designed inspired by Solomon-Bloembergen-Morgan(SBM)theory,where T_(1)and T_(2)relaxivity increase with a reduction in Gd content.In particular,the NPs with minimum Gd content exhibit excellent dual-mode contrast performance(r_(1)=94.42 mM^(−1)s^(−1),r_(2)=343.62 mM^(−1)s^(−1)).The underlying mechanism is that the bridged EDTMP coordinate limits Gd tum-bling and forces Gd^(3+)to expose itself to the surface of the NPs.This provides more opportunities for water molecules to coordinate with Gd^(3+)and significantly enhances proton relaxivity.Moreover,the hy-drophilicity of the ligand enhances the water dispersion stability of the NPs and increases the exchange rate of water protons near the NPs,further enhancing the dual-mode contrast effect.Finally,the biocom-patibility and in vitro/vivo imaging performances of the IO@EDTMP-Gd NPs are systematically evaluated,and the results demonstrate their potential as dual-mode contrast agents.This study provides a new strategy for developing dual-mode MRI contrast agents that can further improve the accuracy of MRI in the diagnosis of complex diseases.
基金Project supported by the U.S.Army Engineer Research and Development Center (W912HZ-21-2-0048)。
文摘General guidelines for the design of ligands for the enrichment of rare-earth elements by solid-liquid adsorption are described using coordination chemistry.Relevant properties of ligands include selectivity of metal ions based on adjustment of donor atom polarizability,denticity,and the pKarange of the binding sites.The selectivity of solid-phase materials for the enrichment of rare-earth ions by the ligand design guidelines is outlined,with special consideration of additional variable factors including steric hindrance,saturated binding sites,variability in speciation caused by the identity of counterions and ionic strength,and size-exclusivity in ligands stemming from differences in bite angle,preo rganization of ligands,or intraligand interactions.This review analyzes some principles of selectivity of rare-earth elements with ligands organized by donor type from examples collected from reports published between 2009 and 2021.
基金Supported by the National Natural Science Foundation of China (Nos 20801004/B01, 20871016/B0101, 10876002/A06)the 111 Project (B07012)Excellent Young Scholars Research Fund of Beijing Institute of Technology (No 2006Y0715)
文摘Two comparable discrete complexes [CuⅡ（CH3CN）2L2]·2（ClO4） 1 and [CuI2I2L2]·（DMF）2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis（3-pyridinylmethylthio）-1,3,4-thiadiazole）（L）,respectively.Complex 1 presents a single nuclear structure while 2 has a dimeric structure where two CuI ions are doubly bridged by halide ions in a μ2-fashion.Both discrete molecules were outspreaded into a one-dimensional supramolecular chain via aromatic interactions such as C–H…π and π…π interactions.
基金supported by the National Natural Science Foundation of China(92261203,22101116,22033005 and 21971106)Key Laboratory of Rare Earth Chemistry of Guangdong Higher Education Institutes(2022KSYS006)+2 种基金the Stable Support Plan Program of Shenzhen Natural Science Fund(20200925161141006),Shenzhen Fundamental Research Program(JCYJ20220530115001002)Postdoctoral Scientific Research Fund for staying at(coming to)Shenzhen(K21217520)The calculations were performed with SUSTech supercomputer and were supported by Guangdong Provincial Key Laboratory of Catalysis(No.2020B121201002).
文摘Coordination chemistry of rare-earth elements has been dominated by the+3 oxidation state.Complexes with higher-valence lanthanide ions are synthetically challenging but are of fundamental research interest and significance as advanced molecular materials.Herein,four tetravalent terbium complexes(2-5)of the common formula[Tb(OSiPh3)4L](L=ethylene glycol dimethyl ether(DME),2,2’-bipyridine(bpy),2,2’-bipyrimidine(bpym),and 1,10-phenanthroline(phen))are reported.Crystallographic analyses reveal in each of these complexes a hexacoordinate Tb(IV)ion situated in a distorted octahedral coordination environment formed by four triphenylsi-loxido ligands and a bidentate chelating ligand.The use of chelating ligands enhances the stability of the resulting complexes over their THF solvate precursor.More significantly,the aromatic N-chelating ligands have been found to tune effectively the electronic structures of the complexes,as evidenced by the sizable potential shifts observed for the quasi-reversible redox Tb(IV/III)process and by the changes in their absorption spectra.The experimental findings are augmented with quantum theoretical calculations in which the ligandπ-donation to the 5d orbitals of the Tb(IV)center is found to be primarily responsible for stability enhancement and the corresponding changes of physical properties observed.Magnetic measurements and results from electron paramagnetic resonance studies produced small absolute values of zero-field splittings of these complexes,ranging from 0.1071(22)to 1.1484(112)cm-1 and comparable to the values reported for analogous Tb(IV)complexes.
