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Manzhou Zhu - One of the best experts on this subject based on the ideXlab platform.
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metal Nanoclusters stabilized by selenol ligands
Small, 2019Co-Authors: Xi Kang, Manzhou ZhuAbstract:The past decades have witnessed great advances in controllable synthesis, structure determination, and property investigation of metal Nanoclusters. Selenolated Nanoclusters, a special branch in the nanocluster family, have attracted great interest in these years. The electronegativity and atomic radius of selenium is different from sulfur, and thus the selenolated Nanoclusters are anticipated to display different electronic/geometric structures and distinct chemical/physical properties relative to their thiolated analogues. This review covers the syntheses, structures, and properties of selenolated Nanoclusters (including Au, Ag, Cu, and alloy Nanoclusters). Ligand effects (between SeR and SR) on nanocluster properties, including optical absorption, stability, and electrochemical properties, are disclosed as well. At the end of the review, a scope for improvements and future perspectives of selenolated Nanoclusters is highlighted. The review hopefully opens up new horizons for cluster scientists to synthesize more selenolated Nanoclusters with novel structures and properties. This review is based on publications available up to May 2019.
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of t...
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of the free valence electrons to the interior of the nanocluster. More importantly, the Au1Ag16Cu12 enables the multicomponent A3 coupling reaction at high temperatures, which remarkably shortens the catalytic reaction time from ∼5 h to 3 min. Overall, this work presents a strategy for enhancing the thermal stability of Nanoclusters via centralizing the free valence electrons to the nanocluster kernels.
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tailoring the photoluminescence of atomically precise Nanoclusters
Chemical Society Reviews, 2019Co-Authors: Xi Kang, Manzhou ZhuAbstract:Due to their atomically precise structures and intriguing chemical/physical properties, metal Nanoclusters are an emerging class of modular nanomaterials. Photo-luminescence (PL) is one of their most fascinating properties, due to the plethora of promising PL-based applications, such as chemical sensing, bio-imaging, cell labeling, phototherapy, drug delivery, and so on. However, the PL of most current Nanoclusters is still unsatisfactory-the PL quantum yield (QY) is relatively low (generally lower than 20%), the emission lifetimes are generally in the nanosecond range, and the emitted color is always red (emission wavelengths of above 630 nm). To address these shortcomings, several strategies have been adopted, and are reviewed herein: capped-ligand engineering, metallic kernel alloying, aggregation-induced emission, self-assembly of nanocluster building blocks into cluster-based networks, and adjustments on external environment factors. We further review promising applications of these fluorescent Nanoclusters, with particular focus on their potential to impact the fields of chemical sensing, bio-imaging, and bio-labeling. Finally, scope for improvements and future perspectives of these novel nanomaterials are highlighted as well. Our intended audience is the broader scientific community interested in the fluorescence of metal Nanoclusters, and our review hopefully opens up new horizons for these scientists to manipulate PL properties of Nanoclusters. This review is based on publications available up to December 2018.
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bimetallic au2 cu6 Nanoclusters strong luminescence induced by the aggregation of copper i complexes with gold 0 species
Angewandte Chemie, 2016Co-Authors: Xi Kang, Shuxin Wang, Yongbo Song, Shan Jin, Guodong Sun, Manzhou ZhuAbstract:The concept of aggregation-induced emission (AIE) has been exploited to render non-luminescent Cu(I) SR complexes strongly luminescent. The Cu(I) SR complexes underwent controlled aggregation with Au(0) . Unlike previous AIE methods, our strategy does not require insoluble solutions or cations. X-ray crystallography validated the structure of this highly fluorescent nanocluster: Six thiolated Cu atoms are aggregated by two Au atoms (Au2 Cu6 Nanoclusters). The quantum yield of this nanocluster is 11.7 %. DFT calculations imply that the fluorescence originates from ligand (aryl groups on the phosphine) to metal (Cu(I) ) charge transfer (LMCT). Furthermore, the aggregation is affected by the restriction of intramolecular rotation (RIR), and the high rigidity of the outer ligands enhances the fluorescence of the Au2 Cu6 Nanoclusters. This study thus presents a novel strategy for enhancing the luminescence of metal Nanoclusters (by the aggregation of active metal complexes with inert metal atoms), and also provides fundamental insights into the controllable synthesis of highly luminescent metal Nanoclusters.
Rongchao Jin - One of the best experts on this subject based on the ideXlab platform.
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chiral ag 23 nanocluster with open shell electronic structure and helical face centered cubic framework
Nature Communications, 2018Co-Authors: Chao Liu, Hadi Abroshan, Chen Zhang, Hyung J Kim, Rongchao JinAbstract:We report the synthesis and crystal structure of a nanocluster composed of 23 silver atoms capped by 8 phosphine and 18 phenylethanethiolate ligands. X-ray crystallographic analysis reveals that the kernel of the Ag nanocluster adopts a helical face-centered cubic structure with C2 symmetry. The thiolate ligands show two binding patterns with the surface Ag atoms: tri- and tetra-podal types. The tetra-coordination mode of thiolate has not been found in previous Ag Nanoclusters. No counter ion (e.g., Na+ and NO3-) is found in the single-crystal and the absence of such ions is also confirmed by X-ray photoelectron spectroscopy analysis, indicating electrical neutrality of the nanocluster. Interestingly, the nanocluster has an open shell electronic structure (i.e., 23(Ag 5s1)-18(SR) = 5e), as confirmed by electron paramagnetic resonance spectroscopy. Time-dependent density functional theory calculations are performed to correlate the structure and optical absorption/emission spectra of the Ag nanocluster.
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heterogeneous catalysis by gold and gold based bimetal Nanoclusters
Nano Today, 2018Co-Authors: Jianbo Zhao, Rongchao JinAbstract:Abstract Gold and gold-based bimetallic catalysts have shown great potential for many important chemical transformation reactions owing to their good activity and high selectivity under relatively mild conditions. However, elucidating their structure-property relationships remains a major challenge because of size distributions and ill-defined structures (i.e. structural heterogeneity) of conventional nanoparticle catalysts. Recently, controlled synthesis of homogold and gold-based bimetal Nanoclusters with precise atom numbers have been accomplished, and more importantly their atomic structures have been elucidated, which provide new model systems for understanding the catalytic behavior at the atomic level. Due to their ultra-small size, gold and bimetal Nanoclusters exhibit unique properties, which contribute to novel catalysts or precatalysts for many chemical reactions. Herein, we review the recent progress in the catalytic research of atomically precise gold and gold-based bimetal Nanoclusters. Specifically, this review covers the application of Nanoclusters with or without ligands as catalysts for reactions such as selective oxidation, selective hydrogenation, C–C coupling and photocatalysis. Finally, we provide some future perspectives about metal nanocluster catalysis.
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Excited-State Behaviors of M1Au24(SR)18 Nanoclusters: The Number of Valence Electrons Matters
2018Co-Authors: Meng Zhou, Chuanhao Yao, Matthew Y. Sfeir, Tatsuya Higaki, Rongchao JinAbstract:Doping is a quite useful strategy for probing the structure and properties of metal Nanoclusters, but the effect of doping on the photodynamical properties is still not fully understood. Here, we reveal that the number of valence electrons plays a major role in determining the photodynamics of M1Au24(SR)18 Nanoclusters. By carrying out temperature-dependent optical absorption, it is found that Cd doping enhances electron–phonon coupling while Hg doping does not significantly alter the coupling. Moreover, the relaxation dynamics of [M1Au24(SR)18]0 (M = Hg/Cd) Nanoclusters show similar features to that of the negatively charged Au25 nanocluster. Specifically, the 8-electron M1Au24 (M = Cd/Hg) Nanoclusters show a long excited-state lifetime (50−200 ns) and a weak picosecond relaxation, similar to the case of the anionic [Au25]− nanocluster. On the other hand, the non-8-electron MAu24 (M = Pd/Pt) Nanoclusters show much more significant picosecond relaxation and thus much shorter excited-state lifetimes, which resembles the case of neutral [Au25]0. The picosecond relaxation in all six cases can be explained by core–shell charge transfer or relaxation to the surface trap state. These results are of great importance for fundamental understanding of the interplay between the valence electrons and the optical properties of metal Nanoclusters
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Reversible Control of Chemoselectivity in Au38(SR)24 Nanocluster-Catalyzed Transfer Hydrogenation of Nitrobenzaldehyde Derivatives
2018Co-Authors: Jianbo Zhao, Yongbo Song, Meng Zhou, Shengli Zhuang, Peng Zhang, David J. Morris, Rongchao JinAbstract:Chemoselective hydrogenation of nitrobenzaldehyde derivatives is one of the important catalytic processes being studied in hydrogenation catalysis. In this work, we report for the first time the catalytic reaction over atomically precise gold nanocluster catalysts (Au25, Au38, Au52, and Au144) using potassium formate as the hydrogen source. A complete selectivity for hydrogenation of the aldehyde group, instead of the nitro group, is obtained. A distinct dependence on the size of nanocluster catalysts is also observed, in which the Au38(SCH2CH2Ph)24 gives rise to the highest catalytic activity. The catalyst also shows good versatility and recyclability. Interestingly, the ligand-off nanocluster changes its catalytic selectivity to the nitro hydrogenation, which is in contrast with the ligand-on catalyst. In addition, the selectivity can be restored by treating the ligand-off nanocluster catalyst with thiol. This reversible control of chemoselectivity is remarkable and may stimulate future work on the exploitation of such Nanoclusters for hydrogenation catalysis with control over selectivity
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Reconstructing the Surface of Gold Nanoclusters by Cadmium Doping
2017Co-Authors: Kelly J. Lambright, Nathaniel L Rosi, Michael G. Taylor, Kristin Kirschbaum, Tian-yi Luo, Jianbo Zhao, Giannis Mpourmpakis, Soumitra Mokashi-punekar, Rongchao JinAbstract:Atomically precise metal Nanoclusters with tailored surface structures are important for both fundamental studies and practical applications. The development of new methods for tailoring the surface structure in a controllable manner has long been sought. In this work, we report surface reconstruction induced by cadmium doping into the [Au23(SR)16]− (R = cyclohexyl) nanocluster, in which two neighboring surface Au atomic sites “coalesce” into one Cd atomic site and, accordingly, a new bimetal nanocluster, [Au19Cd2(SR)16]−, is produced. Interestingly, a Cd(S-Au-S)3 “paw-like” surface motif is observed for the first time in nanocluster structures. In such a motif, the Cd atom acts as a junction which connects three monomeric -S-Au-S- motifs. Density functional theory calculations are performed to understand the two unique Cd locations. Furthermore, we demonstrate different doping modes when the [Au23(SR)16]− nanocluster is doped with different metals (Cu, Ag), including (i) simple substitution and (ii) total structure transformation, as opposed to surface reconstruction for Cd doping. This work greatly expands doping chemistry for tailoring the structures of Nanoclusters and is expected to open new avenues for designing Nanoclusters with novel surface structures using different dopants
Xi Kang - One of the best experts on this subject based on the ideXlab platform.
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metal Nanoclusters stabilized by selenol ligands
Small, 2019Co-Authors: Xi Kang, Manzhou ZhuAbstract:The past decades have witnessed great advances in controllable synthesis, structure determination, and property investigation of metal Nanoclusters. Selenolated Nanoclusters, a special branch in the nanocluster family, have attracted great interest in these years. The electronegativity and atomic radius of selenium is different from sulfur, and thus the selenolated Nanoclusters are anticipated to display different electronic/geometric structures and distinct chemical/physical properties relative to their thiolated analogues. This review covers the syntheses, structures, and properties of selenolated Nanoclusters (including Au, Ag, Cu, and alloy Nanoclusters). Ligand effects (between SeR and SR) on nanocluster properties, including optical absorption, stability, and electrochemical properties, are disclosed as well. At the end of the review, a scope for improvements and future perspectives of selenolated Nanoclusters is highlighted. The review hopefully opens up new horizons for cluster scientists to synthesize more selenolated Nanoclusters with novel structures and properties. This review is based on publications available up to May 2019.
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of t...
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of the free valence electrons to the interior of the nanocluster. More importantly, the Au1Ag16Cu12 enables the multicomponent A3 coupling reaction at high temperatures, which remarkably shortens the catalytic reaction time from ∼5 h to 3 min. Overall, this work presents a strategy for enhancing the thermal stability of Nanoclusters via centralizing the free valence electrons to the nanocluster kernels.
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capture of cesium ions with Nanoclusters effects on inter and intramolecular assembly
Chemistry of Materials, 2019Co-Authors: Xi Kang, Qianqin Yuan, Shuxin WangAbstract:The capture of cations with Nanoclusters is a flourishing area in the nanocluster science due to their effects on both molecular chemistry and supramolecular chemistry. The capture of Cs+ is most concerned in this field for its capability of controlling the synthesis and assembly of Nanoclusters. However, the atomically precise interaction between Cs+ ions and Nanoclusters remains mysterious. In this paper, we report the first X-ray crystal structure of a Cs+-captured nanocluster, formulated as Cs3Ag29(SSR)12(DMF)x (x = 5, 6; SSR, 1,3-benzene dithiol). The capture of Cs+ with Ag29(SSR)12(PPh3)4 peels the PPh3 ligands off from the nanocluster surface, giving rise to Cs3Ag29(SSR)12(DMF)x. The Cs+–cluster interactions not only alter the geometric structure of the Ag29(SSR)12 kernel but also assemble Ag29(SSR)12 clusters into one-dimensional, cluster-based lines. Remarkable differences have been observed by comparing the optical properties of the Cs3Ag29(SSR)12(DMF)x nanocluster in solutions or in crystallize...
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tailoring the photoluminescence of atomically precise Nanoclusters
Chemical Society Reviews, 2019Co-Authors: Xi Kang, Manzhou ZhuAbstract:Due to their atomically precise structures and intriguing chemical/physical properties, metal Nanoclusters are an emerging class of modular nanomaterials. Photo-luminescence (PL) is one of their most fascinating properties, due to the plethora of promising PL-based applications, such as chemical sensing, bio-imaging, cell labeling, phototherapy, drug delivery, and so on. However, the PL of most current Nanoclusters is still unsatisfactory-the PL quantum yield (QY) is relatively low (generally lower than 20%), the emission lifetimes are generally in the nanosecond range, and the emitted color is always red (emission wavelengths of above 630 nm). To address these shortcomings, several strategies have been adopted, and are reviewed herein: capped-ligand engineering, metallic kernel alloying, aggregation-induced emission, self-assembly of nanocluster building blocks into cluster-based networks, and adjustments on external environment factors. We further review promising applications of these fluorescent Nanoclusters, with particular focus on their potential to impact the fields of chemical sensing, bio-imaging, and bio-labeling. Finally, scope for improvements and future perspectives of these novel nanomaterials are highlighted as well. Our intended audience is the broader scientific community interested in the fluorescence of metal Nanoclusters, and our review hopefully opens up new horizons for these scientists to manipulate PL properties of Nanoclusters. This review is based on publications available up to December 2018.
Richard G Finke - One of the best experts on this subject based on the ideXlab platform.
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supersensitivity of transition metal nanoparticle formation to initial precursor concentration and reaction temperature understanding its origins
Journal of Nanoscience and Nanotechnology, 2008Co-Authors: Lisa S Ott, Richard G FinkeAbstract:A supersensitivity of the formation and stabilization of transition-metal Nanoclusters to the initial nanocluster concentration and temperature synthesis conditions is reported, then probed, herein for the specific case of prototype Ir(O)n Nanoclusters prepared from the organometallic precursor [Bu4N]5Na3[(1,5-COD)Ir x P2W15Nb3O62] by reduction with H2 in propylene carbonate solvent. Fully isolable, redissolvable, near-monodisperse (i.e., < or = +/- 15% size distribution) and thus excellent Ir(O)n Nanoclusters are formed using low temperature (22 degrees C) and moderate precursor concentration (1.2 mM) in propylene carbonate solvent. However, inferior, polydisperse (+/- 40% size distribution), non-redispersable Nanoclusters are formed at the seemingly only moderately different conditions of 38 degrees C higher temperature (i.e., 60 degrees C) and 5-fold lower precursor concentration (0.24 mM). Investigation of this supersensitivity to the nanocluster synthesis conditions reveals that it derives from the dissociation of (1,5-COD)Ir(solvent)2+ from the P2W15Nb3O62(9-) polyanionic ligand/ stabilizer, subsequently resulting in a too fast, kinetically uncontrolled reduction of the quickly reduced (1,5-COD)Ir(solvent)2+ as the cause of the inferior synthesis of polydisperse, non-isolable, non-redissolvable Nanoclusters. The results are significant in that they illustrate that understanding the mechanism of nanocluster formation, and then performing the nanocluster synthesis under kinetically carefully controlled, understood conditions, is necessary for the formation of superior Nanoclusters in this, and by implication probably many other, cases.
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transition metal nanocluster stabilization for catalysis a critical review of ranking methods and putative stabilizers
Coordination Chemistry Reviews, 2007Co-Authors: Lisa S Ott, Richard G FinkeAbstract:Abstract A significant problem in the burgeoning transition-metal nanocluster literature is the myriad of proposed, putative stabilizers. A main objective of the present contribution is to provide a critical review of the methods for, and current rankings of, claimed transition-metal nanocluster stabilizers, with a focus on catalytically active Nanoclusters. Following a brief introduction to the literature methods for evaluating colloidal stabilizers (methods which are 41 and 105 years old), the need for modern methods to measure nanocluster stability via agglomeration kinetics is presented. Discussed next is the one presently available method for evaluating additives (i.e., putative stabilizers) for the formation and stabilization of transition-metal Nanoclusters, the so-called 5 criteria method; this is followed by a scheme presenting established nanocluster stabilization modes. Next, a table of 48 prototype examples of established and novel nanocluster stabilizers is presented, followed by a discussion of each stabilization mode with selected, representative examples. One conclusion of this review is that it is clear that reliable, quantitative studies ranking claimed nanocluster stabilizers, and understanding of how they work, are just now appearing. A second conclusion is that given the lack of quantitative methods to measure stability and thereby rank stabilizers, it follows that much of the information regarding nanocluster stabilization is not on firm ground. This first review of transition-metal nanocluster stabilizers is just the initial step towards achieving the overall goal of simplifying the “dizzying variety” of claimed nanocluster stabilizers into a preferred, small set of solvents and stabilizers en route to high stability, high catalytic activity Nanoclusters.
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nanocluster formation and stabilization fundamental studies ranking commonly employed anionic stabilizers via the development then application of five comparative criteria
Journal of the American Chemical Society, 2002Co-Authors: Saim Ozkar, Richard G FinkeAbstract:To start, a brief introduction is provided on the importance of transition-metal Nanoclusters, on the need to develop and then apply methods to rank the nanocluster formation and then stabilizing abilities of commonly employed anions, solvents, cations, and polymers, and on the somewhat confused literature of nanocluster stabilization. The fundamental importance of surface-adsorbed anions in transition-metal nanocluster stabilization is noted, the reason the present studies begin with a study of nanocluster-stabilizing anions. Next, five criteria, as well as the associated experimental methods, are developed to evaluate the efficacy of nanocluster stabilizing agents. The criteria are of fundamental significance in that they allow the separation of stabilizing agent effects on nanocluster formation from those on nanocluster stabilization. The results from applying the five criteria to four commonly employed anions lead to the first "anion series" of relative nanocluster-formation and stabilizing abilities, at least for the Ir(0) Nanoclusters examined and by the following five criteria: [(P(2)W(15)Nb(3)O(61))(2)O](16-) (a Brphinsted-basic polyoxoanion) > C(6)H(5)O(7)(3-) (citrate trianion) > [-CH(2)-CH(CO(2))-](n)(n-) (polyacrylate) approximately Cl(-). In addition to the needed methods and the first anion series, six other (8 total) conclusions are reached, important insights in an area previously lacking hard information about which anions are the better choices for nanocluster formation and stabilization. The results are also of significance in establishing polyoxoanions, notably highly charged and basic polyoxoanions such as [(P(2)W(15)Nb(3)O(61))(2)O](16)(-), as the present "Gold Standards" among currently known nanocluster stabilizing anions, and according to the above five criteria. Such standards provide a reference point for future work aspiring to develop even better nanocluster stabilizing anions, solvents, cations, and polymers or their combinations.
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a review of modern transition metal Nanoclusters their synthesis characterization and applications in catalysis
Journal of Molecular Catalysis A-chemical, 1999Co-Authors: John Davis Aiken, Richard G FinkeAbstract:A literature review of modern transition-metal Nanoclusters, with an emphasis on those Nanoclusters which are catalytically active, is presented in two parts. Part One presents background information on transition-metal Nanoclusters, including an overview of common synthetic routes, a description of how Nanoclusters are stabilized, and a brief summary of the multiple characterization techniques used (and the type of information that they can provide). In Part Two, five specific nanocluster case studies are presented, case studies which compare and contrast the syntheses, characterization approaches, and catalytic applications of transition-metal Nanoclusters.
Hadi Abroshan - One of the best experts on this subject based on the ideXlab platform.
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of t...
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free valence electron centralization strategy for preparing ultrastable Nanoclusters and their catalytic application
Inorganic Chemistry, 2019Co-Authors: Xi Kang, Shuxin Wang, Hadi Abroshan, Manzhou ZhuAbstract:Metal Nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver Nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag Nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag Nanoclusters highly stable. The stability of Ag29(SSR)12(PPh3)4 (SSR: benzene-1,3-dithiol) was controllably enhanced by stepwisely alloying the Ag29 nanocluster to Ag17Cu12(SSR)12(PPh3)4 and Au1Ag16Cu12(SSR)12(PPh3)4. Specifically, the trimetallic Au1Ag16Cu12 is ultrastable even at 175 °C, which is close to the nanocluster decomposition temperature. The structures of Ag17Cu12 and Au1Ag16Cu12 Nanoclusters are determined by single-crystal X-ray diffraction. Furthermore, a combination of X-ray photoelectron spectroscopy measurements and density functional theory calculations demonstrates that the enhanced stability is induced by the centralization of the free valence electrons to the interior of the nanocluster. More importantly, the Au1Ag16Cu12 enables the multicomponent A3 coupling reaction at high temperatures, which remarkably shortens the catalytic reaction time from ∼5 h to 3 min. Overall, this work presents a strategy for enhancing the thermal stability of Nanoclusters via centralizing the free valence electrons to the nanocluster kernels.
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chiral ag 23 nanocluster with open shell electronic structure and helical face centered cubic framework
Nature Communications, 2018Co-Authors: Chao Liu, Hadi Abroshan, Chen Zhang, Hyung J Kim, Rongchao JinAbstract:We report the synthesis and crystal structure of a nanocluster composed of 23 silver atoms capped by 8 phosphine and 18 phenylethanethiolate ligands. X-ray crystallographic analysis reveals that the kernel of the Ag nanocluster adopts a helical face-centered cubic structure with C2 symmetry. The thiolate ligands show two binding patterns with the surface Ag atoms: tri- and tetra-podal types. The tetra-coordination mode of thiolate has not been found in previous Ag Nanoclusters. No counter ion (e.g., Na+ and NO3-) is found in the single-crystal and the absence of such ions is also confirmed by X-ray photoelectron spectroscopy analysis, indicating electrical neutrality of the nanocluster. Interestingly, the nanocluster has an open shell electronic structure (i.e., 23(Ag 5s1)-18(SR) = 5e), as confirmed by electron paramagnetic resonance spectroscopy. Time-dependent density functional theory calculations are performed to correlate the structure and optical absorption/emission spectra of the Ag nanocluster.
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tailoring the electronic and catalytic properties of au25 Nanoclusters via ligand engineering
ACS Nano, 2016Co-Authors: Gao Li, Hadi Abroshan, Shuo Zhuo, Zhimin Li, Nathaniel L RosiAbstract:To explore the electronic and catalytic properties of Nanoclusters, here we report an aromatic-thiolate-protected gold nanocluster, [Au25(SNap)18]− [TOA]+, where SNap = 1-naphthalenethiolate and TOA = tetraoctylammonium. It exhibits distinct differences in electronic and catalytic properties in comparison with the previously reported [Au25(SCH2CH2Ph)18]−, albeit their skeletons (i.e., Au25S18 framework) are similar. A red shift by ∼10 nm in the HOMO–LUMO electronic absorption peak wavelength is observed for the aromatic-thiolate-protected nanocluster, which is attributed to its dilated Au13 kernel. The unsupported [Au25(SNap)18]− Nanoclusters show high thermal and antioxidation stabilities (e.g., at 80 °C in the present of O2, excess H2O2, or TBHP) due to the effects of aromatic ligands on stabilization of the nanocluster’s frontier orbitals (HOMO and LUMO). Furthermore, the catalytic activity of the supported Au25(SR)18/CeO2 (R = Nap, Ph, CH2CH2Ph, and n-C6H13) is examined in the Ullmann heterocoupling r...
