Simple and Efficient Separation of Atomically Precise Noble Metal Clusters

Ghosh, Atanu; Hassinen, Jukka; Pulkkinen, Petri; Tenhu, Heikki; Ras, Robin H. A.; Pradeep, Thalappil

doi:10.1021/ac503165t

Cited by 70 publications

(55 citation statements)

References 38 publications

(86 reference statements)

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“…Parent Au 25 SBB 18 emits primarily in the NIR region (see Figure S1C) with a peak maximum at 1030 nm (black thin line in Figure 1B) while the red-emitting cluster showed an emission maximum at 737 nm (red thick line) with a concomitant loss of NIR emission. 58 It is important to have pure QCs in order to determine their molecularity using mass spectrometric techniques. This was much higher than that of parent Au 25 SBB 18 clusters (0.04%) and that reported for other organic thiolate ligand protected Au 25 clusters.…”

Section: Resultsmentioning

confidence: 99%

Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification

et al. 2015

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An efficient method to enhance visible luminescence in a visibly non-luminescent organic-soluble 4-(tert butyl)benzyl mercaptan (SBB)-stabilized Au25 cluster has been developed. This method relies mainly on enhancing the surface charge density on the cluster by creating an additional shell of thiolate on the cluster surface, which enhances visible luminescence. The viability of this method has been demonstrated by imparting red luminescence to various ligand-protected quantum clusters (QCs), observable to the naked eye. The bright red luminescent material derived from Au25SBB18 clusters was characterized using UV-vis and luminescence spectroscopy, TEM, SEM/EDS, XPS, TG, ESI and MALDI mass spectrometry, which collectively proposed an uncommon molecular formula of Au29SBB24S, suggested to be due to different stapler motifs protecting the Au25 core. The critical role of temperature on the emergence of luminescence in QCs has been studied. The restoration of the surface ligand shell on the Au25 cluster and subsequent physicochemical modification to the cluster were probed by various mass spectral and spectroscopic techniques. Our results provide fundamental insights into the ligand characteristics determining luminescence in QCs.

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Section: Resultsmentioning

confidence: 99%

Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification

et al. 2015

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“…One possible reason is that different ion species possess various reduction potentials and coordination natures. One hour later, the four reactions were stopped by the addition of excessive petroleum ether, the as-obtained precipitates were collected and thoroughly washed with methanol, then used for thin-layer chromatography (TLC) analyses 42,43 (CH 2 Cl 2 -petroleum ether as developing solvent). To unravel this question, we tested the reaction between the anion Au 25 (PET) 18 À (N(C 8 H 17 ) 4 + as the counter ion) and four different silver ion precursors.…”

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confidence: 99%

Ion-precursor and ion-dose dependent anti-galvanic reduction

et al. 2015

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Controlling alloy nanoparticles with atomic monodispersity is challenging, and the recently revealed anti-galvanic reduction (AGR) provides a unique solution to this challenge. Herein we demonstrate that AGR is ion-precursor and ion-dose dependent, which offers novel strategies to tune the composition, structure and properties of nanoparticles by varying the ion-precursor and ion-dose in the AGR reaction.

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“…Au 20 , Au 22 , Au 24 , Au 25 , Au 38 , etc.) with thiolate ligands or stabilized by protein templates (Ghosh et al 2014) have been synthesized, and their electronic and optical properties have been studied.…”

Section: The Cluster Structures and Their Stabilitymentioning

confidence: 99%

Molecular-Size Fluorescence Emitters

Demchenko

2015

Introduction to Fluorescence Sensing

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A variety of fluorescent and luminescent materials in the form of molecules, their complexes and nanoparticles are available for implementation as response units into sensing and imaging technologies and we discuss their general properties that are essential for these applications. Organic dyes were the first and remain to be the most popular emitters used with these purposes. Their labeling and responsive properties are overviewed. Natural fluorescent proteins and their engineered analogues incorporate organic fluorophores that are synthesized spontaneously from the polypeptide chain inside the living cells without the need of their intrusion, as the gene products. They resulted in revolutionary advancement in cell imaging and show good prospects in sensing and reporting on cellular processes. Organic heterocyclic compounds can incorporate metal ions generating long-living luminescence. Moreover, noble metal particles of a very small size exhibit unique light-absorbing and fluorescent emission properties. In this Chapter we focus on these types of fluorophores that possess subnanometer dimensions and display single type of absorption-emission cycle. The more complex nanostructures and nanocomposites will be overviewed in Chaps. 5 and 6 that follow. Fluorophores and Their Characteristics General Properties of Fluorescent DyesIn view of tremendous diversity of structures, chemical reactivities and spectroscopic properties, one needs certain practically useful criteria for the dye selection for the purpose of sensing and imaging. They can be formulated in the form of spectroscopic parameters that have to be optimized. It is the parameter describing the ability of molecule to absorb light at a particular wavelength. The absorbance E measured at any wavelength on spectrophotometer is proportional to the dye concentration c (in mol/l) and the light path length in a sample l (in cm). In this relation, ε plays the role of coefficient of proportionality, so that E = εcl. The value of molar absorbance is obtained by purifying and drying the dye, dissolving it at low concentration and measuring E on a spectrophotometer. The broadly used term extinction includes absorbance and light scattering. Absorbance is a unique characteristic of a molecule under certain environmental conditions. In general, the bigger the fluorophore size, the greater is the probability that the photon will be absorbed.The value of ε max at the maximum of absorption band is the common characteristic of the light-absorbing power of the dye. The dye 'brightness' that determines the absolute sensitivity of fluorescence detection (Wetzl et al. 2003) is the product of molar absorbance and quantum yield, Φ. The absorbance is related to optical cross-section and for organic dyes, ε max varies from ca. 10 3 l mol −1 cm −1 for small dyes, such as coumarins to ca. 10 5 l mol −1 cm −1 for larger fluorophores such as cyanines and phthalocyanines (Lavis and Raines 2008). It should be selected as high as possible, but the limiting factor is the fluorophore size. Us...

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Simple and Efficient Separation of Atomically Precise Noble Metal Clusters

Cited by 70 publications

References 38 publications

Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification

Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification

Ion-precursor and ion-dose dependent anti-galvanic reduction

Molecular-Size Fluorescence Emitters

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Simple and Efficient Separation of Atomically Precise Noble Metal Clusters

Cited by 70 publications

References 38 publications

Efficient red luminescence from organic-soluble Au25 clusters by ligand structure modification

Efficient red luminescence from organic-soluble Au25 clusters by ligand structure modification

Ion-precursor and ion-dose dependent anti-galvanic reduction

Molecular-Size Fluorescence Emitters

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Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification

Efficient red luminescence from organic-soluble Au₂₅ clusters by ligand structure modification