Molecular Electron-Transfer Properties of Au<sub>38</sub> Clusters

Antonello, Sabrina; Holm, Anne I. S.; Instuli, Emanuele; Maran, Flavio

doi:10.1021/ja071191+

Cited by 85 publications

(161 citation statements)

References 22 publications

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“…It was later found with these systems that tremendous optical limiting and time-resolved optical properties [31][32][33] could be obtained as well as new ideas for catalysis. [9][10][11][12][13][14][15] Highly stable systems, such as gold, became a major focus for new nanosystem synthesis. 34,35 The search for even smaller gold particles made in this regard was reported by Crooks et al, 36,37 Chandler et al 38,39 and Dickson et al 7 utilizing the dendrimer capture approach with PAMAM.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

et al. 2010

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Monolayer-protected metal nanoclusters (MPCs) were investigated to probe their fundamental excitation and emission properties. In particular, gold MPCs were probed by steady-state and time-resolved spectroscopic measurements; the results were used to examine the mechanism of emission in relation to the excited states in these systems. In steady-state measurements, the photoluminescence of gold clusters in the range of 25 to 140 atoms was considerably stronger relative to larger particle analogues. The increase in emission efficiency (for Au 25 , Au 55 , and Au 140 on the order of 10 -5) over bulk gold may arise from a different mechanism of photoluminescence, as suggested by measurements on larger gold spheres and rods. Results of fluorescence upconversion found considerably longer lifetimes for smaller gold particles than for larger particles. Measurements of the femtosecond transient absorption of the smaller clusters suggested dramatically different behavior than what was observed for larger particles. These results, combined with the result of a new bleach band in the transient absorption signal (which is presumably due to an unforeseen ground state absorption), suggest that quantum size effects and associated discrete molecular-like state structure play a key role in enhanced visible fluorescence of small clusters.

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Section: Introductionmentioning

confidence: 99%

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

et al. 2010

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“…These conditions might also lead to redox processes involving disulfide and AusS bonds. [32][33][34][35] Indeed, the irreversible oxidation peak at 0.90 V observed for alkanetetrathiols is attributed to oxidation of thiol groups, leading to the formation of disulfide linkages. 36 It was also reported that dissociation of dimethyl disulfide (CH 3 SSCH 3 ) adsorbed on the Au(111) surface can be accomplished by applying a voltage of ∼1.4 V. 37 Existence of disulfide bonds has long been a controversy for alkanethiols and dialkyl disulfides adsorbed on gold surfaces.…”

Section: Introductionmentioning

confidence: 99%

Electron Transport through Cyclic Disulfide Molecular Junctions with Two Different Adsorption States at the Contact: A Density Functional Theory Study

Jang

Goddard

2008

J. Phys. Chem. C

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1,2-Dithiolane is a promising anchor group for attaching molecules to metal electrodes in molecular junction devices. This five-membered cyclic disulfide adsorbs on Au surfaces either in a cyclic fashion (with its disulfide bond intact, via molecular adsorption) or in an acyclic fashion (with its disulfide bond broken, via dissociative adsorption). Our density functional theory calculations show that the dissociative adsorption is slightly preferred, but both are stable. We also report nonequilibrium Green's function calculations showing that molecular junctions of cyclic and acyclic 1,2-dithiolanes sandwiched between two gold electrodes exhibit essentially the same insulating current-voltage characteristics at moderate bias voltages, despite the significant difference in their states of adsorption.

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“…These half-wave potentials were roughly estimated to be 0.825 and 0.900 V, respectively. Note that Au 25 2+ is known to be unstable, 20 leading to a smaller current for the following oxidation. For Au 25 + the potential difference between the first oxidation (eq 4) and third reduction (eq 3) peaks gives an estimation on the HOMO-LUMO energy gap of 1.558 eV after charging correction.…”

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confidence: 99%

Interrogating Near-Infrared Electrogenerated Chemiluminescence of Au₂₅(SC₂H₄Ph)₁₈⁺ Clusters

et al. 2012

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The electrochemistry, near-infrared photoluminescence (NIR-PL) spectroscopy, and electrogenerated chemiluminescence (ECL) of Au 25 (SC 2 H 4 Ph) 18 + -C 6 F 5 CO 2 − (Au 25 + ) clusters were investigated. For the first time, NIR-ECL emission was observed in both annihilation and coreactant paths. Our newly developed spooling spectroscopy was employed during the ECL evolution and devolution processes along with explicit NIR-PL spectroscopy to elucidate light generation mechanisms. It was discovered that the electronic relaxation of the Au 25 − excited state to the ground state plays a key role in giving off ECL at 893 nm, while intermediate, strong, and weak NIR-PL emissions at 719/820, 857, and 1080 nm can be attributed to the excited states higher than the HOMO-LUMO gap, across the HOMO-LUMO gap, and of semirings, respectively. T he optical properties of nanostructures such as silicon nanocrystals (NCs), 1 carbon quantum dots, 2 and gold nanoparticles (NPs) 3 are attractive to many researchers because of their potential applications. 4 Among a variety of gold NPs, Au 25 L 18 clusters have been the focus of recent investigations due to their molecule-like (1.1 nm in diameter) behavior, monodispersed synthesis protocols, 5 and unique optical, 6 electrochemical, 7 and structural portfolio. 8 A Au 25 cluster consists of an icosahedral Au 13 core and six semi-rings containing -Au-S-Au-S-. 6g,9 Murray et al. 3 and Jin et al. 10 pioneered studies exploring the various properties of Au 25 , for instance, observing the difference in photoluminescence (PL) by changing the combination of protecting ligands and electropositivity. 11 These studies showed that the origins of the clusters' optical properties are dependent on the charge and protecting ligand's functionalities. 10a Zhu et al. and Chen et al. demonstrated that Au clusters protected by bovine serum albumin (BSA) can also be utilized in analytical detection methods based on spectroscopic properties of the Au-BSA cluster. 12 Of the stable charged states of Au 25 L 18 z (z = −1, 0, and +1), the −1 form is the most studied, although recent synthetic protocols have allowed the isolation and investigation of the 0 and +1 states. The different charged states induce various properties on the gold clusters that have been probed by 1 H NMR, 13 PL, 10a and electron paramagnetic resonance spectroscopy. 14 Electrogenerated chemiluminescence (ECL) is the process in which electrogenerated radicals form excited species emitting light without the need of an external light source. 15 Advantages of ECL include simultaneous generation of radical cations and anions and the control of electrode potentials that drive light emission processes. ECL has great potential in biological applications such as detection in immunoassays, food and water testing, trace metal determination, sensors, and biomolecules. 15 Our motivation is to explore ECL of various compounds 2b,c,16 toward applications in biosensors and bioanalytical chemistry.Herein, we report the ECL of Au 25 in the near-infrared (NI...

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Molecular Electron-Transfer Properties of Au₃₈ Clusters

Cited by 85 publications

References 22 publications

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

Electron Transport through Cyclic Disulfide Molecular Junctions with Two Different Adsorption States at the Contact: A Density Functional Theory Study

Interrogating Near-Infrared Electrogenerated Chemiluminescence of Au₂₅(SC₂H₄Ph)₁₈⁺ Clusters

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Molecular Electron-Transfer Properties of Au38 Clusters

Cited by 85 publications

References 22 publications

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

Ultrafast Optical Study of Small Gold Monolayer Protected Clusters: A Closer Look at Emission

Electron Transport through Cyclic Disulfide Molecular Junctions with Two Different Adsorption States at the Contact: A Density Functional Theory Study

Interrogating Near-Infrared Electrogenerated Chemiluminescence of Au25(SC2H4Ph)18+ Clusters

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Molecular Electron-Transfer Properties of Au₃₈ Clusters

Interrogating Near-Infrared Electrogenerated Chemiluminescence of Au₂₅(SC₂H₄Ph)₁₈⁺ Clusters