Photochemical and photophysical properties of tetranuclear and hexanuclear clusters of metals with d10 and s2 electronic configurations

Ford, Peter C.; Vogler, Arnd

doi:10.1021/ar00028a013

Cited by 512 publications

(264 citation statements)

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“…The luminescence properties of inorganic tetra-and hexanuclear Cu(I) clusters and similar clusters in Cu(I)-MTs have been reported (26,43,44,46). Although the Cu(I) 6 clusters exhibit only a single low energy band at ϳ700 nm, high and low energy bands at ϳ430 and 620 nm are observed in the luminescence spectra of Cu(I) 4 clusters.…”

Section: Characterization Of Cu(i)znmt-3 Species By Cu(i)mentioning

confidence: 57%

“…However in polynuclear Cu(I) complexes, including the Cu(I) 8 MT-1 complex, which exhibit relatively short Cu...Cu distances (Ͻ2.8 Å) an intramolecular d 10 -d 10 interaction of adjacent Cu(I) ions leads to a number of excited states with a largely metal character. These weak low energy bands have been assigned to formally spin forbidden 3d 3 4s metal cluster-centered (CC) transitions (42)(43)(44)(45). Thus, the occurrence of similar transitions in Cu(I) 4 Zn 4 MT-3 suggest the presence of a Cu(I) 4 -thiolate cluster.…”

Section: Formation and Stability Of Cuznmt-3 In Air-mentioning

confidence: 99%

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Redox Silencing of Copper in Metal-linked Neurodegenerative Disorders

Meloni

Faller

Vašák

2007

Journal of Biological Chemistry

116

159

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Dysregulation of copper and zinc homeostasis in the brain plays a critical role in Alzheimer disease (AD). Copper binding to amyloid-␤ peptide (A␤) is linked with the neurotoxicity of A␤and free radical damage. Metallothionein-3 (MT-3) is a small cysteine-and metal-rich protein expressed in the brain and found down-regulated in AD. This protein occurs intra-and extracellularly, and it plays an important role in the metabolism of zinc and copper. In cell cultures Zn 7 MT-3, by an unknown mechanism, protects neurons from the toxicity of A␤. We have, therefore, used a range of complementary spectroscopic and biochemical methods to characterize the interaction of Zn 7 MT-3 with free Cu 2؉ ions. We show that Zn 7 MT-3 scavenges free Cu Essential transition metals like copper and zinc play a critical role in neurobiology. The homeostasis of both metals is tightly regulated and essential for brain physiology (1). In vitro evidence suggests that in physiological conditions micromolar concentrations of zinc and copper are actively released from neurons during neurotransmission processes into pre-and postsynaptic clefts. However, at present it is not known whether the released copper is present in a chemically exchangeable form (2). Dysregulated metal metabolism (zinc and copper) occurs in neurodegenerative disorders such as Alzheimer (3, 4), Parkinson (5), and prion (6) diseases. In these diseases increased extracellular copper concentrations and free-radical production have been found. There is now direct evidence that copper is bound to amyloid-␤ peptide (A␤) 2 in senile plaque of Alzheimer disease (AD) (7). Copper is also linked with the neurotoxicity of A␤ and free radical damage (8).Because of its redox-active nature (Cu ϩ /Cu 2ϩ ), its reactivity with molecular oxygen (O 2 ) generates the reactive oxygen species (ROS) such as superoxide, hydrogen peroxide, and hydroxyl radicals (9, 10). The redox cycling of copper requires its reduction by biological components, including ascorbate, which actively accumulates in the brain at concentrations between 0.5 and 10 mM (11). Hence, copper chelation and its redox-silencing may represent critical events in preventing the progression of neurodegenerative diseases. In recent years a metal chelation therapy has emerged as a promising tool to attenuate abnormal metal-protein interactions that lead to increased free-radical toxicity (10).The natural metal chelator metallothionein-3 (MT-3), also known as the growth inhibitory factor, is a small non-inducible cysteine-and metal-rich protein mainly expressed in the brain. In the brain its expression was found in zinc-enriched neurons. Like other mammalian metallothioneins (MTs), MT-3 binds with a high affinity essential monovalent and divalent d 10 metal ions Cu(I) and Zn(II). Recently, the interaction of Zn 7 MT-3 with the small-GTPase Rab3a, which is strictly linked to the exo-endocytotic cycle of synaptic vesicles, has been demonstrated. It has been suggested that Zn 7 MT-3 actively participates in synaptic cycle of zinc vesicles...

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Section: Characterization Of Cu(i)znmt-3 Species By Cu(i)mentioning

confidence: 57%

Section: Formation and Stability Of Cuznmt-3 In Air-mentioning

confidence: 99%

Redox Silencing of Copper in Metal-linked Neurodegenerative Disorders

Meloni

Faller

Vašák

2007

Journal of Biological Chemistry

116

159

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“…10 When reduced to copper(I) state they can additionally provide long-lived electronically excited states, and exhibit intense luminescence. [11][12][13] The redox potential of acyclic and macrocyclic Schiff base complexes has deserved a strong interest since it seems to be directly related to some of the biologically important properties of this type of compounds. Mostly, Schiff-base copper complexes have been intensively investigated as enzyme mimics by their dioxygen binding ability, and catalytic activity in oxidative processes.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic characterization of schiff base-copper complexes immobilized in smectite clays

Dias¹,

Kinouti²,

Constantino³

et al. 2010

Quím. Nova

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Recebido em 5/7/10; aceito em 17/9/10; publicado na web em 25/10/10 Herein, the immobilization of some Schiff base-copper(II) complexes in smectite clays is described as a strategy for the heterogenization of homogeneous catalysts. The obtained materials were characterized by spectroscopic techniques, mostly UV/Vis, EPR, XANES and luminescence spectroscopy. SWy-2 and synthetic Laponite clays were used for the immobilization of two different complexes that have previously shown catalytic activity in the dismutation of superoxide radicals, and disproportionation of hydrogen peroxide. The obtained results indicated the occurrence of an intriguing intramolecular redox process involving copper and the imine ligand at the surface of the clays. These studies are supported by computational calculations.

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“…In the emitting excited state the electronic structure should be similar to that of the ground-state trimers M, (M= alkali, Cu, Ag, and Au) which were the subject of numerous studies [ 3-51. Moreover, the electron configuration of mercury in the Hg$+ cation is formally intermediate between thatofHg(0) (dios2) andHg(II) (d"s'). The emission behavior of d'Os* and dl" cluster complexes [ 6,7] including those of Hg(II) [8] has been studied in some detail quite recently. Finally, the nature of electronically excited Hg!+ is also of interest with regard to the photochemical activity of mercury cluster compounds.…”

Section: Introductionmentioning

confidence: 99%