Self-Assembly of a Copper-Ligating Dendrimer that Provides a New Non-Heme Metalloprotein Mimic:  “Dendrimer Effects” on Stability of the Bis(<i>μ</i>-oxo)dicopper(III) Core

Enomoto, Masashi; Aida, Takuzo

doi:10.1021/ja982282x

Cited by 116 publications

(72 citation statements)

References 22 publications

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“…It is well known that multiple copper ions bound within a spherical dendrimer have been used for O 2 binding, [11] and the copper-ion dendrimer could react with oxygen to form bridged copper complexes. [12] Moreover, a dendritic microenvironment leading to modification of optical, [13] redox [14] or catalytic [15] properties of the metal ions encapsulated in a dendritic matrix, and the electron-transfer kinetics in such a system, become significantly slower-a feature that also is observed in redox-active proteins. [16] Poly(propylene imine) (PPI) dendrimers, as well as other dendrimers, can form complexes with different metal ions.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Poly(propylene imine)–Copper Dendromesogenic Complexes: An EPR Study

et al. 2006

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Copper(II) complexes formed by coordination of the Cu(II) ion with liquid-crystalline poly(propylene imine) dendrimer ligand (L) of the first (complex 1) and second (complex 2) generations with various Cu(II) contents (x = Cu/L) have been studied by electron paramagnetic resonance (EPR) spectroscopy. The existence of a redox-active blue complex 1 (x = 1.9) and the copper(II) nitrate electron transfer associated with the valence tautomerism are revealed for the first time in copper-based dendrimers. It has been shown that the electronic structure of the blue complex 1 (x = 1.9) is adequately described as a mixed-valence dimer containing d9- and diamagnetic d10-configurated copper ions, and an antiferromagnetically coupled NO3* radical arising on the nitrate-bridged counter ligand. The activation energy value found for the electron transfer is about 0.35 meV, which indicates a low-energy charge dynamic. The ability of the blue and green complexes 1 (x = 1.9) dissolved in isotropic solvents to orient themselves in the magnetic field was revealed by EPR spectroscopy. The degree of orientation of the molecular z axis (S(z)) of these complexes in the magnetic field differs, depending on the type of copper(II)-complexing site in the dendrimer ligand, and can reach 0.76, which is close to S(z) = 1 (completely aligned system). A combination of magnetic and orientational parameters indicates an NO4 environment of the Cu(II) ion in green complex 1 (x = 1.9), and confirms the chain structure with intermolecular Cu(II)-NO3-Cu(II) bridges between Cu(II) centres in columns.

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Section: Introductionmentioning

confidence: 99%

Magnetic Properties of Poly(propylene imine)–Copper Dendromesogenic Complexes: An EPR Study

et al. 2006

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“…[48] However, there have only been a few reports on metal-complexation-induced conformational changes in dendritic ligands. [49][50][51] Aida et al have reported on mechanistic aspects of the formation of dendritic dinuclear iron(iii) complexes. [49,50] In their work on iron-sulfur core dendrimers, Gorman et al [52,53] related core encapsulation to the primary dendrimer structure and conformation.…”

Section: Introductionmentioning

confidence: 99%

“…[49][50][51] Aida et al have reported on mechanistic aspects of the formation of dendritic dinuclear iron(iii) complexes. [49,50] In their work on iron-sulfur core dendrimers, Gorman et al [52,53] related core encapsulation to the primary dendrimer structure and conformation. Recently, Vçgtle et al [51] have reported on dendritic ligands containing a cyclam core.…”

Section: Introductionmentioning

confidence: 99%

Metal‐Induced Chiral Folding of Depsipeptide Dendrimers

Buschhaus¹,

Hampel²,

Hirsch³

2005

Chemistry A European J

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The synthesis and metal complexation of chiral depsipeptide dendrimers 3 and 7 containing an ethylenediaminetetraacetic acid (EDTA) ester‐derived core is reported. The EDTA ester cavity of these dendrimers selectively complexes Zn2+ and Cu2+ ions leading to diastereoselective folding. To elucidate the coordination motif in the resulting “foldamers” of 3‐ZnCl2, 7‐ZnCl2, 3‐CuCl2, and 7‐CuCl2, the coordination behavior of the tetramethyl ester of EDTA (8) has been investigated as a model case. The corresponding complexes 8‐ZnCl2 and 8‐CuCl2 have been structurally characterized by 1H NMR spectroscopy and X‐ray analysis. The complexes involve the inherently chiral octahedral cis‐α coordination motif, in which 8 serves as a tetradentate ligand. In the case of the ZnII complex 8‐ZnCl2, both Δcis‐α(S,S,λ) and Λcis‐α(R,R,λ) stereoisomers were found in the unit cell. For the CuII complex 8‐CuCl2, only one stereoisomer, namely Δcis‐α(S,S,λ) was found in the crystal under investigation. 1H NMR spectroscopy has shown that the same coordination motif is diastereoselectively formed in the chiral Zn2+ dendrimers 3‐ZnCl2 and 7‐ZnCl2. Likewise, the calculated CD spectrum of the Δcis‐α(S,S,λ) stereoisomer of the model complex 8‐CuCl2 shows good agreement with the experimental spectrum of the CuII dendrimers 3‐CuCl2 and 7‐CuCl2, allowing assignment of the absolute configurations of the preferred foldamers as Λcis‐α(R,R,λ) for 3‐CuCl2 and Δcis‐α(S,S,λ) for 7‐CuCl2. This work represents the first example of metal‐complexation‐mediated diastereoselective folding of chiral dendrimers with known absolute configuration.

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“…However, dendrons can also encourage the spontaneous formation of metal clusters. In a particularly noteworthy example, Enomoto and Aida reported a 'Fréchet-type' dendrimer with a triazacyclononane ligand at the core [52]. Two of these dendritic ligands assemble around a bis(µ-oxo)dicopper(III) core to generate a supramolecular dendrimer containing two copper ions and bound oxygen ( Figure 20).…”

Section: 5mentioning

confidence: 99%

Self-assembly using dendritic building blocks—towards controllable nanomaterials

Smith

Hirst

Love

et al. 2005

Progress in Polymer Science

177

100

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Self-Assembly of a Copper-Ligating Dendrimer that Provides a New Non-Heme Metalloprotein Mimic: “Dendrimer Effects” on Stability of the Bis(μ-oxo)dicopper(III) Core

Cited by 116 publications

References 22 publications

Magnetic Properties of Poly(propylene imine)–Copper Dendromesogenic Complexes: An EPR Study

Magnetic Properties of Poly(propylene imine)–Copper Dendromesogenic Complexes: An EPR Study

Metal‐Induced Chiral Folding of Depsipeptide Dendrimers

Self-assembly using dendritic building blocks—towards controllable nanomaterials

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