Photoactivation of Silver‐Exchanged Zeolite A

Cremer, Gert De; Antoku, Yasuko; Roeffaers, Maarten; Śliwa, M.; Noyen, Jasper Van; Smout, Steve; Hofkens, Johan; Vos, Dirk De; Sels, Bert F.; Vosch, Tom

doi:10.1002/ange.200704861

Cited by 28 publications

(32 citation statements)

References 32 publications

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“…Although many approaches to the production of uniform, low‐dimensionality nanostructures have been implemented over the years,, fabrication in confined spaces never lost its appeal. In particular, the improvement of synthesis and characterization techniques combined with insight from computational studies fostered this decade's tremendous progress ,…”

Section: Clusters Of Metals or Semiconductors: Organization Of Zero‐dmentioning

confidence: 99%

“…The reversible, stimuli‐induced change of colors of silver zeolites was correlated to ligand‐to‐metal charge transfer transitions from the oxygen atoms of the framework to the vacant 5 s orbital of the Ag ions . In later experiments, individual Ag clusters were activated by a laser beam, producing intense luminescence . Other studies showed that the emission of Li‐substituted silver–loaded zeolite A could be tuned by water: while partially hydrated composites gave a blue emission, a green/yellow color was detected upon full hydration .…”

Section: Clusters Of Metals or Semiconductors: Organization Of Zero‐dmentioning

confidence: 99%

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Supramolecular Organization in Confined Nanospaces

Tabacchi

2018

ChemPhysChem

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Empty spaces are abhorred by nature, which immediately rushes in to fill the void. Humans have learnt pretty well how to make ordered empty nanocontainers, and to get useful products out of them. When such an order is imparted to molecules, new properties may appear, often yielding advanced applications. This review illustrates how the organized void space inherently present in various materials: zeolites, clathrates, mesoporous silica/organosilica, and metal organic frameworks (MOF), for example, can be exploited to create confined, organized, and self-assembled supramolecular structures of low dimensionality. Features of the confining matrices relevant to organization are presented with special focus on molecular-level aspects. Selected examples of confined supramolecular assemblies - from small molecules to quantum dots or luminescent species - are aimed to show the complexity and potential of this approach. Natural confinement (minerals) and hyperconfinement (high pressure) provide further opportunities to understand and master the atomistic-level interactions governing supramolecular organization under nanospace restrictions.

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Section: Clusters Of Metals or Semiconductors: Organization Of Zero‐dmentioning

confidence: 99%

Section: Clusters Of Metals or Semiconductors: Organization Of Zero‐dmentioning

confidence: 99%

Supramolecular Organization in Confined Nanospaces

Tabacchi

2018

ChemPhysChem

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“…Highly luminescent and photostable AgCLs confined within Linde Type A (LTA) and Faujasite (FAU) zeolites have been reported to have a large apparent Stokes shift and a broad emission spectrum spanning a large part of the visible range and leading to potential applications in bio-imaging and photonics 7,8,9,12,13 The luminescent properties in terms of excitation and emission energy, and luminescence quantum yield (QY) are remarkably dependent on the zeolite topology, Ag loading, cocations type (Li, Na, K, Ca), and hydration level. 7,8,9,10,11,13,14,15 For instance, fine tuning of AgCLs in FAU zeolites recently allowed to obtain a luminescence QY close to one by carefully adjusting the mobility of Na cocations and improving the degree of order of the AgCLs inside the FAU topology. 7 In LTA zeolites, partial replacement of the Na co-cations by Li remarkably enhances the luminescence of AgCLs up to 62% QY compared to QY between 2 and 16% for LTA zeolites with single Na, K, and Ca co-cations.…”

Section: Introductionmentioning

confidence: 99%

Structural and Photophysical Characterization of Ag Clusters in LTA Zeolites

et al. 2019

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Ag clusters (AgCLs) confined within Na exchanged-LTA zeolites are studied by X-ray absorption, and steadystate and time-resolved photoluminescence spectroscopies in a coordinated effort to elucidate the photophysical properties and link them to the precise cluster structure. The hydrated sodalite cage contains mostly tetrahedral [Ag 4 (H 2 O) 4 ] clusters located at the center of the sodalite cages, whereas upon dehydration octahedral Ag 6 clusters coordinated with the zeolite framework oxygen (O F) [Ag 6 (O F) 14 ] are formed. TD-DFT and ESR reports suggest that both the Ag 4 and Ag 6 clusters have formally a double positive charge of 2+. Time-resolved spectroscopy shows that at room temperature the emission of the hydrated sample decays with 3.4 ns from a state with the same multiplicity as the ground state. Upon dehydration, the entire excited state dynamics speeds up to 1.2 ps. The microsecond-scale lifetimes observed at 77K suggest the occurrence of two main decay processes for the initially populated singlet state: intersystem crossing and charge transfer. We show that intersystem-crossing yields the formation of a long-lived (409 µs) triplet state 3 P from the 1 P state located at lower energy from which luminescence occurs. There is evidence that when electron transfer takes place, it is followed by electron hole recombination or back electron transfer yielding a relaxed singlet excited state. Upon removal of water ligands the electrostatic field of the framework is enhanced which leads to an increase in the rate constant of charge transfer due to stronger electronic coupling between Ag 6 2+ and trap levels. The dependence of luminescence lifetime on the water content indicates a possible way to speed or delay the electron-hole recombination in a controlled way. ASSOCIATED CONTENT Supporting Information. Detailed discussions, structural properties, steady-state spectra, fs fluorescence upconversion traces, TC-SPC fluorescence decay traces, luminescence decay traces. This material is available free of charge via the Internet at http://pubs.acs.org.

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“…[3][4][5][6][7][8] One such example is the ship-in-a-bottle synthesis of oligoatomic metal clusters in microporous crystalline materials such as metal-organic frameworks and zeolites. [9][10][11][12][13][14][15][16][17][18][19] It has for instance been demonstrated that LTA or FAU-type zeolites exchanged with silver ions become fluorescent after calcination, due to the formation of small clusters, such as Ag 3 n + an Ag 6 m + , in the zeolite cages by an autoreduction process. [20] The electrons necessary for the silver reduction most probably originate from hydration water, which is oxidized to molecular oxygen.…”

mentioning

confidence: 99%

“…A detailed understanding of the involved processes is important since such small clusters, especially when confined in zeolite hosts, have interesting, but so far not well understood, catalytic potential, [22][23][24] as well as data-carrier properties via their luminescent characteristics. [9,25] In this contribution we characterize in situ the spectral evolution of the emission of silver-exchanged zeolites during heat treatment, in order to visualize possible intermediate fluorescent species. Moreover the stability of the emission under different gas atmospheres is investigated.…”

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confidence: 99%

In Situ Observation of the Emission Characteristics of Zeolite‐Hosted Silver Species During Heat Treatment

et al. 2010

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The influence of heat treatment on the evolution of luminescence in silver exchanged zeolites is investigated under controlled atmosphere by using in situ fluorescence microscopy (see figure). The results indicate that the stable yellow Ag3n+ emitter is most efficiently created in a dry zeolite Y host. In zeolite A, the clusters interact with neighboring clusters or with water, decreasing the overall yellow luminescence.

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Photoactivation of Silver‐Exchanged Zeolite A

Cited by 28 publications

References 32 publications

Supramolecular Organization in Confined Nanospaces

Supramolecular Organization in Confined Nanospaces

Structural and Photophysical Characterization of Ag Clusters in LTA Zeolites

In Situ Observation of the Emission Characteristics of Zeolite‐Hosted Silver Species During Heat Treatment

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