Rapid Reduction of [CuII(Sarcophagine)]2+ Ion and Elimination of Cu1 From the Cage: A Pulse Radiolysis Study

Creaser, I. I.; Harrowfield, J. M.; Lawrance, G. A.; Mulac, William A.; Sangster, David F.; Sargeson, Alan M.; Schmidt, Klaus; Sullivan, James C.

doi:10.1080/00958979109408266

Cited by 12 publications

(7 citation statements)

References 5 publications

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“…[30,32] However, reduction to Cu I or zero-valent Cu leads to immediate complex dissociation. [36] Indeed, only the expandedcavity hexaamine cage complex [Cu(Me 5 -tricosane)] 2 + (Scheme 1) exhibits quasireversible Cu II/I electrochemistry and makes it unique among the copper cage complexes in this respect. [31] Great interest in understanding the Cu chemistry of polyamines stems from their extensive use as catalysts in "living" radical polymerization.…”

Section: Introductionmentioning

confidence: 99%

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions

Bell

Bernhardt

Gahan

et al. 2010

Chemistry A European J

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The potentially hexadentate mixed-donor cage ligand 1-methyl-8-amino-3,13,16-trithia-6,10,19-triazabicyclo[6.6.6]eicosane (AMME-N(3)S(3)sar; sar=sarcophagine) displays variable coordination modes in a complex with copper(II). In the absence of coordinating anions, the ligand adopts a conventional hexadentate N(3)S(3) binding mode in the complex [Cu(AMME-N(3)S(3)sar)](ClO(4))(2) that is typical of cage ligands. This structure was determined by X-ray crystallography and solution spectroscopy (EPR and NIR UV/Vis). However, in the presence of bromide ions in DMSO, clean conversion to a five-coordinate bromido complex [Cu(AMME-N(3)S(3)sar)Br](+) is observed that features a novel tetradentate (N(2)S(2))-coordinated form of the cage ligand. This copper(II) complex has also been characterized by X-ray crystallography and solution spectroscopy. The mechanism of the reversible interconversion between the six- and five-coordinated copper(II) complexes has been studied and the reaction has been resolved into two steps; the rate of the first is linearly dependent on bromide ion concentration and the second is bromide independent. Electrochemistry of both [Cu(AMME-N(3)S(3)sar)](2+) and [Cu(AMME-N(3)S(3)sar)Br](+) in DMSO shows that upon reduction to the monovalent state, they share a common five-coordinated form in which the ligand is bound to copper in a tetradentate form exclusively, regardless of whether a six- or five-coordinated copper(II) complex is the precursor.

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Section: Introductionmentioning

confidence: 99%

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions

Bell

Bernhardt

Gahan

et al. 2010

Chemistry A European J

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“…For instance, the complex [Cu(diAMsar)] 2+ (Scheme ) is remarkably resistant to acid‐promoted demetalation 30. 32 However, reduction to Cu I or zero‐valent Cu leads to immediate complex dissociation 36. Indeed, only the expanded‐cavity hexaamine cage complex [Cu(Me 5 ‐tricosane)] 2+ (Scheme ) exhibits quasireversible Cu II/I electrochemistry and makes it unique among the copper cage complexes in this respect 31…”

Section: Introductionmentioning

confidence: 99%

Dissection of Human Tropoelastin: Solution Structure, Dynamics and Self‐Assembly of the Exon 5 Peptide

Bochicchio

Floquet

Pepe

et al. 2004

Chemistry A European J

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The elastic properties of elastin have essentially been discussed in terms of dominant entropic components, with questions still remaining about whether the basic mechanism is compatible with the classical theory of rubber elasticity. A better understanding of the structure-function relationships in terms of the protein's elastic properties remains an important goal in elastin science. Recently, we succeeded in the exon-by-exon synthesis of all polypeptide sequences encoded by the so-called hydrophobic exons and almost all of the cross-linking exons of human tropoelastin. Among these, the peptide encoded by exon 5 (PGGLAGAGLGA) has been extensively studied by classical spectroscopic methods, such as CD and NMR spectroscopy, and by molecular dynamics simulations. The results obtained clearly evidenced a large flexibility of the polypeptide chain, which oscillates between rather extended conformations, such as PPII, and folded ones, such as beta turns. At the supramolecular level, we obtained evidence by TEM that shows that the peptide encoded by exon 5 is able to self-assemble in fibrillar structures, a result indicating that the "information" for self-assembly is also contained within a small domain of tropoelastin.

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“…In the diaminosarcophagine ligand of Co(diAMsar), the acidity of its fully protonated primary amine groups is strikingly higher than that of the conjugated acids of typical organic amines, which is due to the electrostatic influence of the Co(III) center. 29,30 Co-sarcophagine compounds which a Estimated standard deviations are given in parentheses. b Equivalent isotropic U defined as one-third of the trace of the orthogonalized Uij tensor.…”

Section: Discussionmentioning

confidence: 99%

“…p K a Determinations. In the diaminosarcophagine ligand of Co(diAMsar), the acidity of its fully protonated primary amine groups is strikingly higher than that of the conjugated acids of typical organic amines, which is due to the electrostatic influence of the Co(III) center. , Co−sarcophagine compounds which have an imidazole moiety attached to the cage via the primary amines have been prepared in our group. In these complexes, the p K a 's of the imidazolium groups were lowered relative to imidazole itself, although these changes in p K a were less extreme than those for the fully protonated parent primary amines of Co(diAMsar).…”

Section: Discussionmentioning

confidence: 99%

Synthesis and Characterization of Cobalt-Cage Complexes with Pendant Phenol Groups

1996

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The synthesis and characterization of four compounds formed from the reductive amination of m- and o-hydroxybenzaldehyde to (1,8-diamino-3,6,10,13,16,19-hexaazabicyclo[6.6.6]eicosane)cobalt(III) are presented. These compounds are the mono- and dialkylated derivatives of the starting cobalt complex. The X-ray crystal structures of each compound, as its fully protonated chloride salt, have been obtained and are reported. The pK(a)'s of the compounds were determined by nonlinear least-squares analysis of data from potentiometric titrations and UV/vis spectrophotometry. The K(a)'s of the phenol groups of the compounds are reduced by roughly 1 order of magnitude compared to their analogous organic phenols. In the solid state, the compounds with one pendant phenol group (2, 4) are yellow and adopt the ob(3) conformation of their ethylene diamine rings in their crystal structures, while the compounds with two pendant phenol groups (3, 5) are orange and have the lel(3) conformation in their crystal structures. Solid-state reflectance UV/vis spectroscopy confirms these structural differences. In water, all four compounds form orange solutions and adopt the lel(3) conformation, as indicated by comparison of UV/vis spectroscopy and cyclic voltammetry properties with the literature.

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Rapid Reduction of [Cu^II(Sarcophagine)]²⁺ Ion and Elimination of Cu¹ From the Cage: A Pulse Radiolysis Study

Cited by 12 publications

References 5 publications

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions

Dissection of Human Tropoelastin: Solution Structure, Dynamics and Self‐Assembly of the Exon 5 Peptide

Synthesis and Characterization of Cobalt-Cage Complexes with Pendant Phenol Groups

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Rapid Reduction of [CuII(Sarcophagine)]2+ Ion and Elimination of Cu1 From the Cage: A Pulse Radiolysis Study

Cited by 12 publications

References 5 publications

Copper(II) Complexes of a Hexadentate Mixed‐Donor N3S3 Macrobicyclic Cage: Facile Rearrangements and Interconversions

Copper(II) Complexes of a Hexadentate Mixed‐Donor N3S3 Macrobicyclic Cage: Facile Rearrangements and Interconversions

Dissection of Human Tropoelastin: Solution Structure, Dynamics and Self‐Assembly of the Exon 5 Peptide

Synthesis and Characterization of Cobalt-Cage Complexes with Pendant Phenol Groups

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Product

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Rapid Reduction of [Cu^II(Sarcophagine)]²⁺ Ion and Elimination of Cu¹ From the Cage: A Pulse Radiolysis Study

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions

Copper(II) Complexes of a Hexadentate Mixed‐Donor N₃S₃ Macrobicyclic Cage: Facile Rearrangements and Interconversions