Highly delocalized Cu(I)/Cu(II); a copper-copper bond?

Harding, Charlie; McKee, Vickie; Nelson, Jane

doi:10.1021/ja00025a050

Cited by 118 publications

(84 citation statements)

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“…Keywords: conducting materials · coordination chemistry · dynamic covalent chemistry · self-assembly calculations and electrochemical measurements indicate that the highest-energy electrons of our four-copper chain are delocalized across all four copper ions, which suggests that previous reports [9,10] of electronic delocalization between partially oxidized pairs of copper ions (Cu 2 3 + centers) are likely to form the basis of a more general class of electronically delocalized Cu n [n + 1] + chains. Such structures may thus be of use as electrically conductive materials.…”

Section: Introductionmentioning

confidence: 62%

“…The electronic delocalization between copper ions, predicted to underlie the conductivity of these structures, could thus be considered as a generalization of the mixed-valence behavior previously observed in dicopper structures (originally by McKee and Nelson in cryptands, [9] and more recently by Jeffery et al [10] in helicates). The aqueous self-assembly technique used to prepare 2 could therefore lead to a novel means of creating electrical connections within electronic devices.…”

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confidence: 86%

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Helicate Extension as a Route to Molecular Wires

Schultz

Biaso

Shahi

et al. 2008

Chemistry A European J

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We describe the preparation of a helicate containing four closely spaced, linearly arrayed copper(I) ions. This product may be prepared either directly by mixing copper(I) with a set of precursor amine and aldehyde subcomponents, or indirectly through the dimerization of a dicopper(I) helicate upon addition of 1,2-phenylenediamine. A notable feature of this helicate is that its length is not limited by the lengths of its precursor subcomponents: each of the two ligands wrapped around the four copper(I) centers contains one diamine, two dialdehyde, and two monoamine residues. This work thus paves the way for the preparation of longer oligo- and polymeric structures. DFT calculations and electrochemical measurements indicate a high degree of electronic delocalization among the metal ions forming the cores of the structures described herein, which may therefore be described as molecular wires

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Section: Introductionmentioning

confidence: 62%

mentioning

confidence: 86%

Helicate Extension as a Route to Molecular Wires

Schultz

Biaso

Shahi

et al. 2008

Chemistry A European J

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“…The chemical possibility of a copper-copper bonded structure has been raised by the recent preparation of azacryptand model compounds that provide heaxaimine and octaamine ligands for a novel dinuclear copper cation, Cu:+ (Harding et al, 1991;Barr et al, 1993). This cation is a class IIIA mixed valence dimer (Robin and Day, 1967), [Cu( + 1.5)-Cu( + 1.5)], containing a single unpaired electron and having a metal-metal bond length of ~0 .…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic and Mutagenesis Studies on the Cu_A Centre from The Cytochrome‐c Oxidase Complex of Paracoccus Denitrificans

Farrar

Lappalainen

Zumft

et al. 1995

European Journal of Biochemistry

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Cytochrome-c oxidase contains an unusual copper centre (Cu,) located in subunit 11. This centre mediates one-electron transfer from cytochrome c to low-spin heme a. Recent spectroscopic and biochemical studies have shown that this centre is a valence delocalised dinuclear [Cu( + 1.5)-Cu( + 1 S)] centre.We have measured the absorption, EPR and variable-temperature magnetic circular dichroism spectra of the CUA-binding domain isolated from Paracoccus denitrificans cytochrome aa3. The EPR spectrum showed the following signals: gll = 2.18; g = 2.03. gll exhibited a seven-line hyperfine splitting pattern, with an intensity ratio showing that the single unpaired electron interacted equally with two copper nuclei. The magnetic circular dichroism spectrum was identical to those from Cu, in bovine heart cytochromec oxidase and centre A of nitrous-oxide reductase, showing the close structural similarity between the three centres. To identify the ligands of Cu,, all the conserved putative ligands in the l? denitrificans Cu, domain were substituted. Only five residues, Cys244, Cys248, His209, His252, and Met255, were required for correct assembly of the Cu, centre. Replacement of Met255 caused protein misfolding. Hence, methionine may have a structural role for the folding of the protein rather than being a CuA ligand. Given that both copper ions must have identical coordination geometries, the number of possible structures is limited. Two models are proposed: one involves the thiolate side-chains of Cys244 and Cys248 bridging a pair of copper ions with one histidine coordinating each copper ion, and the other has terminal ligation of each copper ion by one cysteine and one histidine residue. In both models, the metal-metal distance can be sufficiently short to permit direct d-orbital overlap of the copper ions. The magnetic circular dichroism transitions at 475 nm and 525 nm are assigned to thiolate-to-copper charge-transfer processes polarised perpendicular to one another, although the magnetic circular dichroism intensities show that the excited states were heavily mixed with copper &orbitals. These intensities can be interpreted in the thiolate bridged model in terms of transitions within a Cu2(SR), rhomb. In the model involving terminal cysteine ligation, exciton coupling of two thiolate-to-copper charge-transfer transitions of similar energy, polarised along the Cu-S bonds, would contribute two transitions perpendicular to one another. This requires that the cysteine ligands have a cis orientation relative to one another. The spectral properties of the H252N variant (histidine at position 252 replaced by asparagine) and the high-pH form of l? denitrzjicuns Cu, were similar, showing that one copper ion had lost one histidine ligand in the latter form. The dimer was converted into a valence trapped [Cu(+l)-Cu(+2)] state, which may retain the metal-metal interaction.

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“…Recently, structural studies of Schiff base cryptands as free ligands and as transition metal complexes have been reported (Smith et al, 1993;Harding, McKee & Nelson, 1991;Hunter, Nelson, Harding, McCann & McKee, 1990;Jazwinski et al, 1987). In an attempt to synthesize metal complexes of L1, the cobalt, (I), and copper, (II), complexes were isolated.…”

Section: -Carboxymentioning

confidence: 99%

2-Carboxy-9-dihydroxymethyl-1,10-phenanthroline Complexes of Cobalt(II) and Copper(II)

Sabel¹,

Thompson²,

Butcher³

et al. 1996

Acta Crystallogr C

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Highly delocalized Cu(I)/Cu(II); a copper-copper bond?

Cited by 118 publications

References 0 publications

Helicate Extension as a Route to Molecular Wires

Helicate Extension as a Route to Molecular Wires

Spectroscopic and Mutagenesis Studies on the Cu_A Centre from The Cytochrome‐c Oxidase Complex of Paracoccus Denitrificans

2-Carboxy-9-dihydroxymethyl-1,10-phenanthroline Complexes of Cobalt(II) and Copper(II)

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Highly delocalized Cu(I)/Cu(II); a copper-copper bond?

Cited by 118 publications

References 0 publications

Helicate Extension as a Route to Molecular Wires

Helicate Extension as a Route to Molecular Wires

Spectroscopic and Mutagenesis Studies on the CuA Centre from The Cytochrome‐c Oxidase Complex of Paracoccus Denitrificans

2-Carboxy-9-dihydroxymethyl-1,10-phenanthroline Complexes of Cobalt(II) and Copper(II)

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Spectroscopic and Mutagenesis Studies on the Cu_A Centre from The Cytochrome‐c Oxidase Complex of Paracoccus Denitrificans