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Pengfei Yan - One of the best experts on this subject based on the ideXlab platform.
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local Coordination Geometry perturbed β diketone dysprosium single ion magnets
Inorganic Chemistry, 2014Co-Authors: Jing Zhu, Changzheng Wang, Fang Luan, Tianqi Liu, Pengfei YanAbstract:A series of three β-diketone mononuclear dysprosium complexes, namely, Dy(TFI)3(H2O)2 (1), Dy(TFI)3(bpy) (2), and [Dy(TFI)3(Phen)]·0.02CHCl3 (3) (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been designed and synthesized. Crystal structure analysis reveals that complexes 1–3 have haveisomorphic structures in which the central Dy(III) ion is eight-coordinated by six oxygen atoms from three TFI ligands and two O/N atoms from auxiliary ligands, forming a distorted bicapped trigonal prismatic Geometry for 1, a distorted dodecahedral Geometry for 2, and a distorted square antiprismatic Geometry for 3, respectively. Magnetic studies indicate that complex 2 with D2d symmetry and 3 with D4d symmetry exhibit slow magnetic relaxation with barrier heights (Ueff/kB) of 48.8 K for 2 and 57.9 K for 3. Strikingly, the relaxation time (τ) of 0.0258 s for 3 is about 20 times that for 2, which is presumably associated with larger rotation of the SAP surroundings for 3. Fu...
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Local Coordination Geometry Perturbed β‑Diketone Dysprosium Single-Ion Magnets
2014Co-Authors: Jing Zhu, Changzheng Wang, Fang Luan, Tianqi Liu, Pengfei YanAbstract:A series of three β-diketone mononuclear dysprosium complexes, namely, Dy(TFI)3(H2O)2 (1), Dy(TFI)3(bpy) (2), and [Dy(TFI)3(Phen)]·0.02CHCl3 (3) (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been designed and synthesized. Crystal structure analysis reveals that complexes 1–3 have haveisomorphic structures in which the central Dy(III) ion is eight-coordinated by six oxygen atoms from three TFI ligands and two O/N atoms from auxiliary ligands, forming a distorted bicapped trigonal prismatic Geometry for 1, a distorted dodecahedral Geometry for 2, and a distorted square antiprismatic Geometry for 3, respectively. Magnetic studies indicate that complex 2 with D2d symmetry and 3 with D4d symmetry exhibit slow magnetic relaxation with barrier heights (Ueff/kB) of 48.8 K for 2 and 57.9 K for 3. Strikingly, the relaxation time (τ) of 0.0258 s for 3 is about 20 times that for 2, which is presumably associated with larger rotation of the SAP surroundings for 3. Further, complexes 2 and 3 exhibit essential magnetic hysteresis loops at 1.8 K. These extend the recent reports of the single-ion magnets (SIMs) of β-diketone mononuclear dysprosium complexes
John H Viles - One of the best experts on this subject based on the ideXlab platform.
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copper binding to the amyloid β aβ peptide associated with alzheimer s disease folding Coordination Geometry ph dependence stoichiometry and affinity of aβ 1 28 insights from a range of complementary spectroscopic techniques
Journal of Biological Chemistry, 2004Co-Authors: Christopher D Syme, Rebecca C Nadal, Stephen E J Rigby, John H VilesAbstract:There is now direct evidence that copper is bound to amyloid-beta peptide (Abeta) in senile plaque of Alzheimer's disease. Copper is also linked with the neurotoxicity of Abeta and free radical damage, and Cu(2+) chelators represent a possible therapy for Alzheimer's disease. We have therefore used a range of complementary spectroscopies to characterize the Coordination of Cu(2+) to Abeta in solution. The mode of copper binding is highly pH-dependent. EPR spectroscopy indicates that both coppers have axial, Type II Coordination Geometry, square-planar or square-pyramidal, with nitrogen and oxygen ligands. Circular dichroism studies indicate that copper chelation causes a structural transition of Abeta. Competition studies with glycine and l-histidine indicate that copper binds to Abeta-(1-28) at pH 7.4 with an affinity of K(a) approximately 10(7) m(-1). (1)H NMR indicates that histidine residues are involved in Cu(2+) Coordination but that Tyr(10) is not. Studies using analogues of Abeta-(1-28) in which each of the histidine residues have been replaced by alanine or in which the N terminus is acetylated suggest that the N terminus and His(13) are crucial for Cu(2+) binding and that His(6) and His(14) are also implicated. Evidence for the link between Alzheimer's disease and Cu(2+) is growing, and our studies have made a significant contribution to understanding the mode of Cu(2+) binding to Abeta in solution.
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copper binding to the amyloid beta abeta peptide associated with alzheimer s disease folding Coordination Geometry ph dependence stoichiometry and affinity of abeta 1 28 insights from a range of complementary spectroscopic techniques
Journal of Biological Chemistry, 2004Co-Authors: Christopher D Syme, Rebecca C Nadal, Stephen E J Rigby, John H VilesAbstract:There is now direct evidence that copper is bound to amyloid-beta peptide (Abeta) in senile plaque of Alzheimer's disease. Copper is also linked with the neurotoxicity of Abeta and free radical damage, and Cu(2+) chelators represent a possible therapy for Alzheimer's disease. We have therefore used a range of complementary spectroscopies to characterize the Coordination of Cu(2+) to Abeta in solution. The mode of copper binding is highly pH-dependent. EPR spectroscopy indicates that both coppers have axial, Type II Coordination Geometry, square-planar or square-pyramidal, with nitrogen and oxygen ligands. Circular dichroism studies indicate that copper chelation causes a structural transition of Abeta. Competition studies with glycine and l-histidine indicate that copper binds to Abeta-(1-28) at pH 7.4 with an affinity of K(a) approximately 10(7) m(-1). (1)H NMR indicates that histidine residues are involved in Cu(2+) Coordination but that Tyr(10) is not. Studies using analogues of Abeta-(1-28) in which each of the histidine residues have been replaced by alanine or in which the N terminus is acetylated suggest that the N terminus and His(13) are crucial for Cu(2+) binding and that His(6) and His(14) are also implicated. Evidence for the link between Alzheimer's disease and Cu(2+) is growing, and our studies have made a significant contribution to understanding the mode of Cu(2+) binding to Abeta in solution.
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copper binding to the octarepeats of the prion protein affinity specificity folding and cooperativity insights from circular dichroism
Journal of Biological Chemistry, 2003Co-Authors: Anthony P Garnett, John H VilesAbstract:Abstract The prion protein (PrP) is a Cu2+ binding cell surface glycoprotein. There is increasing evidence that PrP functions as a copper transporter. In addition, strains of prion disease have been linked with copper binding. We present here CD spectroscopic studies of Cu2+ binding to various fragments of the octarepeat region of the prion protein. We show that glycine and l-histidine will successfully compete for all Cu2+ ions bound to the PrP octapeptide region, suggesting Cu2+ coordinates with a lower affinity for PrP than the fm dissociation constant reported previously. We show that each of the octarepeats do not form an isolated Cu2+ binding motif but fold up cooperatively within multiple repeats. In addition to the coordinating histidine side chain residues, we show that the glycine residues and the proline within each octarepeat are also necessary to maintain the Coordination Geometry. The highly conserved octarepeat region in mammals is a hexarepeat in birds that also binds copper but with different Coordination Geometry. Finally, in contrast to other reports, we show that Mn2+ does not bind to the octarepeat region of PrP.
Jinkui Tang - One of the best experts on this subject based on the ideXlab platform.
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modulating magnetic dynamics of dy2 system through the Coordination Geometry and magnetic interaction
Inorganic Chemistry, 2013Co-Authors: Peng Zhang, Jinkui TangAbstract:Two new dinuclear dysprosium compounds, [Dy-2(HL1)(2)(PhCOO)(2)(CH3OH)(2)(CH3OH)(2)] (1) and [Dy-2(L-2)(2)(NO3)(2)center dot(CH3OH)(2)]center dot 2CH(3)OH center dot 4H(2)O (2), have been assembled through applying two ligands with different Coordination pockets. The different features of ligands H3L1 and H2L2 result in the distinct Coordination Geometry of the metal ions in their respective structures. The Dy ions of complexes 1 and 2 were linked by the alkoxide- and hydrazone-O, and display the hula hoop-like and the broken hula hoop-like Coordination Geometry, respectively. Consequently, these two compounds show distinct magnetic properties. Complex 1 behaves as a single molecule magnet (SMM) with rather slow quantum tunneling rate (tau > 274 ms), while no SMM behavior was observed for complex 2. In addition, the comparison of the structural parameters among the similar Dy-2 SMMs with hula hoop-like Geometry reveals the significant role played by Coordination Geometry and magnetic interaction in modulating the relaxation dynamics of SMMs.
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modulating magnetic dynamics of dy2 system through the Coordination Geometry and magnetic interaction
Inorganic Chemistry, 2013Co-Authors: Peng Zhang, Li Zhang, Shuangyan Lin, Shufang Xue, Jinkui TangAbstract:Two new dinuclear dysprosium compounds, [Dy2(HL1)2(PhCOO)2(CH3OH)2] (1) and [Dy2(L2)2(NO3)2(CH3OH)2]·2CH3OH·4H2O (2), have been assembled through applying two ligands with different Coordination pockets. The different features of ligands H3L1 and H2L2 result in the distinct Coordination Geometry of the metal ions in their respective structures. The Dy ions of complexes 1 and 2 were linked by the alkoxide- and hydrazone-O, and display the hula hoop-like and the broken hula hoop-like Coordination Geometry, respectively. Consequently, these two compounds show distinct magnetic properties. Complex 1 behaves as a single molecule magnet (SMM) with rather slow quantum tunneling rate (τ > 274 ms), while no SMM behavior was observed for complex 2. In addition, the comparison of the structural parameters among the similar Dy2 SMMs with hula hoop-like Geometry reveals the significant role played by Coordination Geometry and magnetic interaction in modulating the relaxation dynamics of SMMs.
Jing Zhu - One of the best experts on this subject based on the ideXlab platform.
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local Coordination Geometry perturbed β diketone dysprosium single ion magnets
Inorganic Chemistry, 2014Co-Authors: Jing Zhu, Changzheng Wang, Fang Luan, Tianqi Liu, Pengfei YanAbstract:A series of three β-diketone mononuclear dysprosium complexes, namely, Dy(TFI)3(H2O)2 (1), Dy(TFI)3(bpy) (2), and [Dy(TFI)3(Phen)]·0.02CHCl3 (3) (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been designed and synthesized. Crystal structure analysis reveals that complexes 1–3 have haveisomorphic structures in which the central Dy(III) ion is eight-coordinated by six oxygen atoms from three TFI ligands and two O/N atoms from auxiliary ligands, forming a distorted bicapped trigonal prismatic Geometry for 1, a distorted dodecahedral Geometry for 2, and a distorted square antiprismatic Geometry for 3, respectively. Magnetic studies indicate that complex 2 with D2d symmetry and 3 with D4d symmetry exhibit slow magnetic relaxation with barrier heights (Ueff/kB) of 48.8 K for 2 and 57.9 K for 3. Strikingly, the relaxation time (τ) of 0.0258 s for 3 is about 20 times that for 2, which is presumably associated with larger rotation of the SAP surroundings for 3. Fu...
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Local Coordination Geometry Perturbed β‑Diketone Dysprosium Single-Ion Magnets
2014Co-Authors: Jing Zhu, Changzheng Wang, Fang Luan, Tianqi Liu, Pengfei YanAbstract:A series of three β-diketone mononuclear dysprosium complexes, namely, Dy(TFI)3(H2O)2 (1), Dy(TFI)3(bpy) (2), and [Dy(TFI)3(Phen)]·0.02CHCl3 (3) (TFI = 2-(2,2,2-trifluoroethyl)-1-indone, bpy = 2,2′-bipyridine, phen = 1,10-phenanthroline) have been designed and synthesized. Crystal structure analysis reveals that complexes 1–3 have haveisomorphic structures in which the central Dy(III) ion is eight-coordinated by six oxygen atoms from three TFI ligands and two O/N atoms from auxiliary ligands, forming a distorted bicapped trigonal prismatic Geometry for 1, a distorted dodecahedral Geometry for 2, and a distorted square antiprismatic Geometry for 3, respectively. Magnetic studies indicate that complex 2 with D2d symmetry and 3 with D4d symmetry exhibit slow magnetic relaxation with barrier heights (Ueff/kB) of 48.8 K for 2 and 57.9 K for 3. Strikingly, the relaxation time (τ) of 0.0258 s for 3 is about 20 times that for 2, which is presumably associated with larger rotation of the SAP surroundings for 3. Further, complexes 2 and 3 exhibit essential magnetic hysteresis loops at 1.8 K. These extend the recent reports of the single-ion magnets (SIMs) of β-diketone mononuclear dysprosium complexes
Peng Zhang - One of the best experts on this subject based on the ideXlab platform.
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modulating magnetic dynamics of dy2 system through the Coordination Geometry and magnetic interaction
Inorganic Chemistry, 2013Co-Authors: Peng Zhang, Jinkui TangAbstract:Two new dinuclear dysprosium compounds, [Dy-2(HL1)(2)(PhCOO)(2)(CH3OH)(2)(CH3OH)(2)] (1) and [Dy-2(L-2)(2)(NO3)(2)center dot(CH3OH)(2)]center dot 2CH(3)OH center dot 4H(2)O (2), have been assembled through applying two ligands with different Coordination pockets. The different features of ligands H3L1 and H2L2 result in the distinct Coordination Geometry of the metal ions in their respective structures. The Dy ions of complexes 1 and 2 were linked by the alkoxide- and hydrazone-O, and display the hula hoop-like and the broken hula hoop-like Coordination Geometry, respectively. Consequently, these two compounds show distinct magnetic properties. Complex 1 behaves as a single molecule magnet (SMM) with rather slow quantum tunneling rate (tau > 274 ms), while no SMM behavior was observed for complex 2. In addition, the comparison of the structural parameters among the similar Dy-2 SMMs with hula hoop-like Geometry reveals the significant role played by Coordination Geometry and magnetic interaction in modulating the relaxation dynamics of SMMs.
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modulating magnetic dynamics of dy2 system through the Coordination Geometry and magnetic interaction
Inorganic Chemistry, 2013Co-Authors: Peng Zhang, Li Zhang, Shuangyan Lin, Shufang Xue, Jinkui TangAbstract:Two new dinuclear dysprosium compounds, [Dy2(HL1)2(PhCOO)2(CH3OH)2] (1) and [Dy2(L2)2(NO3)2(CH3OH)2]·2CH3OH·4H2O (2), have been assembled through applying two ligands with different Coordination pockets. The different features of ligands H3L1 and H2L2 result in the distinct Coordination Geometry of the metal ions in their respective structures. The Dy ions of complexes 1 and 2 were linked by the alkoxide- and hydrazone-O, and display the hula hoop-like and the broken hula hoop-like Coordination Geometry, respectively. Consequently, these two compounds show distinct magnetic properties. Complex 1 behaves as a single molecule magnet (SMM) with rather slow quantum tunneling rate (τ > 274 ms), while no SMM behavior was observed for complex 2. In addition, the comparison of the structural parameters among the similar Dy2 SMMs with hula hoop-like Geometry reveals the significant role played by Coordination Geometry and magnetic interaction in modulating the relaxation dynamics of SMMs.