Co-reporter:Meng Zhou, Chenjie Zeng, Matthew Y. Sfeir, Mircea Cotlet, Kenji Iida, Katsuyuki Nobusada, and Rongchao Jin
The Journal of Physical Chemistry Letters September 7, 2017 Volume 8(Issue 17) pp:4023-4023
Publication Date(Web):August 10, 2017
DOI:10.1021/acs.jpclett.7b01597
Understanding the correlation between the atomic structure and optical properties of gold nanoclusters is essential for exploration of their functionalities and applications involving light harvesting and electron transfer. We report the femto-nanosecond excited state dynamics of a periodic series of face-centered cubic (FCC) gold nanoclusters (including Au28, Au36, Au44, and Au52), which exhibit a set of unique features compared with other similar sized clusters. Molecular-like ultrafast Sn → S1 internal conversions (i.e., radiationless electronic transitions) are observed in the relaxation dynamics of FCC periodic series. Excited-state dynamics with near-HOMO–LUMO gap excitation lacks ultrafast decay component, and only the structural relaxation dominates in the dynamical process, which proves the absence of core–shell relaxation. Interestingly, both the relaxation of the hot carriers and the band-edge carrier recombination become slower as the size increases. The evolution in excited-state properties of this FCC series offers new insight into the structure-dependent properties of metal nanoclusters, which will benefit their optical energy harvesting and photocatalytic applications.
Co-reporter:Zhao Liu, Manzhou Zhu, Xiangming Meng, Guoyong Xu, and Rongchao Jin
The Journal of Physical Chemistry Letters September 1, 2011 Volume 2(Issue 17) pp:
Publication Date(Web):August 4, 2011
DOI:10.1021/jz200925h
We report intermolecular electron transfer between 2,2,6,6-tetramethylpiperidin-1-oxoammonium tetrafluoroborate (TEMPO+BF4–) and thiol-stabilized [Au25(SC2H4Ph)18]−TOA+ (abbreviated as Au25–) nanoclusters. The TEMPO+ cations are generated by single electron oxidation of piperidine aminoxyl radical TEMPO (2,2,6,6-tetramethylpiperidinyl-oxy). Cyclic voltammetry (CV) and electron spin resonance (ESR) explicitly indicate that two consecutive single-electron transfer reactions occur between TEMPO+ cations and Au25– nanoclusters. Nuclear magnetic resonance (1H NMR) analysis demonstrates that the methylene proton resonances of the thiolate ligands can also be used to monitor the redox process. UV–vis spectroscopic analysis reveals the changes in the absorption peaks of Au25 nanoclusters upon consecutive single-electron transfers between the nanoclusters and TEMPO+ cations. The ease of control over the redox process involving TEMPO+ allows the preparation of pure Au25(SC2H4Ph)18+ nanoclusters. The interesting electron-donating properties of Au25(SR)18 clusters may find some promising applications in future studies.Keywords: Au25; electron transfer; gold nanoclusters; oxoammonium cation;
Co-reporter:Jonathan W. Padelford, Meng Zhou, Yuxiang Chen, Rongchao Jin, and Gangli Wang
The Journal of Physical Chemistry C October 5, 2017 Volume 121(Issue 39) pp:21217-21217
Publication Date(Web):September 8, 2017
DOI:10.1021/acs.jpcc.7b07314
Rich and discrete energy states in gold nanoclusters enable different combinations of electronic transitions and correspondingly electrochemical and optical properties for a variety of applications. The impacts on those electronic transitions by the emergence and magnitude/alignment of a band gap and by the contributions from different atomic/molecular orbitals require further study. Au nanoclusters with 130 core Au atoms are of interest in this report because they are at the transition size regime where a small yet well-defined band gap can be resolved along with continuous quantized frontier core orbitals. Here, electrochemical analysis is combined with UV–vis–near infrared optical measurements to unveil previously unresolved electronic transitions. Finite changes in the steady-state optical absorption spectrum are captured by spectroelectrochemistry when the Au nanoclusters are charged to different states via electrolysis. Multiple previously unresolved peaks and valleys as well as isosbestic “points/regions” are observed in the differential spectrum. The detailed spectral features are explained by the respective electronic transitions to those affected energy states. Key features are also well correlated with ultrafast absorption analysis which provides additional insights, such as the lifetime of the corresponding transitions. The experimentally measured energy states and transitions could serve as references for future theoretical study to learn the respective contributions from different atomic orbitals and, importantly, to explore routes to enhance or suppress certain transition so as to modulate the corresponding electrochemical and optical properties for better applications.
Co-reporter:Tatsuya Higaki, Chong Liu, Meng Zhou, Tian-Yi Luo, Nathaniel L. Rosi, and Rongchao Jin
Journal of the American Chemical Society July 26, 2017 Volume 139(Issue 29) pp:9994-9994
Publication Date(Web):June 29, 2017
DOI:10.1021/jacs.7b04678
We report the synthesis and crystal structure determination of a gold nanocluster with 103 gold atoms protected by 2 sulfidos and 41 thiolates (i.e., 2-naphthalenethiolates, S-Nap), denoted as Au103S2(S-Nap)41. The crystallographic analysis reveals that the thiolate ligands on the nanocluster form local tetramers by intracluster interactions of C–H···π and π···π stacking. The herringbone pattern formation via intercluster interactions is also observed, which leads to a linearly connected zigzag pattern in the single crystal. The kernel of the nanocluster is a Marks decahedron of Au79, which is the same as the kernel of the previously reported Au102(pMBA)44 (pMBA = −SPh-p-COOH); this is a surprise given the much bulkier naphthalene-based ligand than pMBA, indicating the robustness of the decahedral structure as well as the 58-electron configuration. Despite the same kernel, the surface structure of Au103 is quite different from that of Au102, indicating the major role of ligands in constructing the surface structure. Other implications from Au103 and Au102 include (i) both nanoclusters show similar HOMO–LUMO gap energy (i.e., Eg ≈ 0.45 eV), indicating the kernel is decisive for Eg while the surface is less critical; and (ii) significant differences are observed in the excited-state lifetimes by transient absorption spectroscopy analysis, revealing the kernel-to-surface relaxation pathway of electron dynamics. Overall, this work demonstrates the ligand-effected modification of the gold–thiolate interface independent of the kernel structure, which in turn allows one to map out the respective roles of kernel and surface in determining the electronic and optical properties of the 58e nanoclusters.
Co-reporter:Yongbo Song, Hadi Abroshan, Jinsong Chai, Xi Kang, Hyung J. Kim, Manzhou Zhu, and Rongchao Jin
Chemistry of Materials April 11, 2017 Volume 29(Issue 7) pp:3055-3055
Publication Date(Web):March 14, 2017
DOI:10.1021/acs.chemmater.7b00058
In this work, we report a new size conversion from [Au25(SePh)18]− to [Au23(SePh)16]− nanoclusters under the reductive condition (NaBH4). This novel transformation induced by only reductant has not been reported before in the field of gold nanocluster. The conversion process is studied via MALDI mass spectrometry, and UV–vis spectroscopy. These results demonstrate that the [Au23(SePh)16]− nanocluster is directly obtained by pulling out two units of “Au-SeR” from the [Au25(SePh)18]− nanocluster, which is similar to the “small molecular” reaction. In order to further understand this novel conversion, DFT calculations were performed, in which, with addition of two H– in the [Au25(SeH)18]− model, two Au atoms will depart from the structure of the [Au25(SeH)18]−, which is consistent with the experimental results. Furthermore, the as-prepared [Au23(SePh)16]− nanoclusters can be converted into [Au25(PET)18]− nanocluster (PET = SCH2CH2Ph) with excess PET under the reductive condition, which is quite remarkable due to a stronger bond of Au–Se in comparison to Au–S of the final product. Interestingly, the number of the PET ligands on the surface of the 25-atoms nanocluster can be controlled by the addition of the reductant. Based on these results, a circularly progressive mechanism of ligand exchange is proposed. This may offer a new approach to synthesis of new gold nanoclusters and also have significant contribution for understanding and further exploration of the mechanism of ligand exchange.
Co-reporter:Shuo Zhao, Renxi Jin, Hadi Abroshan, Chenjie ZengHui Zhang, Stephen D. House, Eric GottliebHyung J. Kim, Judith C. Yang, Rongchao Jin
Journal of the American Chemical Society 2017 Volume 139(Issue 3) pp:1077-1080
Publication Date(Web):January 9, 2017
DOI:10.1021/jacs.6b12529
Electrocatalytic water splitting to produce hydrogen comprises the hydrogen and oxygen evolution half reactions (HER and OER), with the latter as the bottleneck process. Thus, enhancing the OER performance and understanding the mechanism are critically important. Herein, we report a strategy for OER enhancement by utilizing gold nanoclusters to form cluster/CoSe2 composites; the latter exhibit largely enhanced OER activity in alkaline solutions. The Au25/CoSe2 composite affords a current density of 10 mA cm–2 at small overpotential of ∼0.43 V (cf. CoSe2: ∼0.52 V). The ligand and gold cluster size can also tune the catalytic performance of the composites. Based upon XPS analysis and DFT simulations, we attribute the activity enhancement to electronic interactions between nanocluster and CoSe2, which favors the formation of the important intermediate (OOH) as well as the desorption of oxygen molecules over Aun/CoSe2 composites in the process of water oxidation. Such an atomic level understanding may provide some guidelines for design of OER catalysts.
Co-reporter:Tatsuya Higaki, Chong LiuYuxiang Chen, Shuo Zhao, Chenjie Zeng, Renxi JinShuxin Wang, Nathaniel L. Rosi, Rongchao Jin
The Journal of Physical Chemistry Letters 2017 Volume 8(Issue 4) pp:
Publication Date(Web):February 1, 2017
DOI:10.1021/acs.jpclett.6b03061
Here we report an oxidation-induced transformation of [Au23(S-c-C6H11)16]−TOA+ (S-c-C6H11: cyclohexanethiolate; TOA: tetraoctylammonium) to the [Au28(S-c-C6H11)20]0 nanocluster by H2O2 treatment under ambient conditions. This is the first example of oxidation-induced transformation of one stable size to another with atomic precision. The product was crystallized and analyzed by X-ray crystallography. Further insights into the transformation process were obtained by monitoring the process with optical spectroscopy and also by electrochemical analysis. This work adds a new dimension to the recently established transformation chemistry of nanoclusters that involves size and structure transformations.
Co-reporter:Xi Kang;Meng Zhou;Shuxin Wang;;Guodong Sun;Manzhou Zhu
Chemical Science (2010-Present) 2017 vol. 8(Issue 4) pp:2581-2587
Publication Date(Web):2017/03/28
DOI:10.1039/C6SC05104A
The atomic-structure characterization of alloy nanoclusters (NCs) remains challenging but is crucial in order to understand the synergism and develop new applications based upon the distinct properties of alloy NCs. Herein, we report the synthesis and X-ray crystal structure of the Pt1Ag28(S-Adm)18(PPh3)4 nanocluster with a tetrahedral shape. Pt1Ag28 was synthesized by reacting Pt1Ag24(SPhMe2)18 simultaneously with Adm-SH (1-adamantanethiol) and PPh3 ligands. A tetrahedral structure is found in the metal framework of Pt1Ag28 NC and an overall surface shell (Ag16S18P4), as well as discrete Ag4S6P1 motifs. The Pt1Ag12 kernel adopts a face-centered cubic (FCC) arrangement, which is observed for the first time in alloy nanoclusters in contrast to the commonly observed icosahedral structure of homogold and homosilver NCs. The Pt1Ag28 nanocluster exhibits largely enhanced photoluminescence (quantum yield QY = 4.9%, emission centered at ∼672 nm), whereas the starting material (Pt1Ag24 NC) is only weakly luminescent (QY = 0.1%). Insights into the nearly 50-fold enhancement of luminescence were obtained via the analysis of electronic dynamics. This study demonstrates the atomic-level tailoring of the alloy nanocluster properties by controlling the structure.
Co-reporter:Renxi Jin;Shuo Zhao;Chong Liu;Meng Zhou;Gihan Panapitiya;Yan Xing;Nathaniel L. Rosi;James P. Lewis
Nanoscale (2009-Present) 2017 vol. 9(Issue 48) pp:19183-19190
Publication Date(Web):2017/12/14
DOI:10.1039/C7NR05871C
Doping metal nanoclusters with a second type of metal is a powerful method for tuning the physicochemical properties of nanoclusters at the atomic level and it also provides opportunities for a fundamental understanding of alloying rules as well as new applications. Herein, we have devised a new, one-phase strategy for achieving heavy Ag-doping in Au25(SR)18 nanoclusters. This strategy overcomes the light doping of silver by previous methods. X-ray crystallography together with ESI-MS determined the composition of the product to be [AgxAu25−x(SC6H11)18]− with x ∼ 21. Cryogenic optical spectroscopy (80–300 K) revealed fine features in optical absorption peaks. Interestingly, the heavy doping of silver does not significantly change the electron–phonon coupling strength and the surface phonon frequency. DFT simulations reproduced the experimentally observed trend of electronic structure evolution with Ag doping. We further investigated the electrocatalytic performance of such heavily Ag-doped nanoclusters for oxygen reduction in alkaline solutions. The mass activity of ligand-off [AgxAu25−x(SC6H11)18]− nanoclusters (217.4 A g−1metal) was determined to be higher than that of ligand-on nanoclusters (29.6 A g−1metal) at a potential of −0.3 V (vs. Ag/AgCl). The rotating disk electrode (RDE) studies revealed the tunable kinetic features of the nanoclusters by ligand removal.
Co-reporter:Jacob Good, Paul N. Duchesne, Peng Zhang, William Koshut, Meng Zhou, Rongchao Jin
Catalysis Today 2017 Volume 280, Part 2(Volume 280, Part 2) pp:
Publication Date(Web):1 February 2017
DOI:10.1016/j.cattod.2016.04.016
•A well defined Au38(SR)24/CeO2 nanocatalyst is studied for CO oxidation.•La, Y, Ga, and Sm are doped into CeO2 to modulate the Ce4+/Ce3+ ratio.•Increasing the Ce4+/Ce3+ ratio increases the catalyst activity.•The rate limiting step is identified to be the coordination of lattice oxygen to CO which itself is coordinated by the gold nanocluster.The catalytic oxidation of carbon monoxide to carbon dioxide by gold nanoclusters loaded onto cerium oxide supports is an important reaction that has been increasingly tailored for use in hydrogen fuel cells. It has been known that there are simultaneous mechanisms that involve coordination of both the dioxygen and carbon monoxide to the gold, as well as one in which the dioxygen is contributed in the form of lattice oxygen while the gold still coordinates the carbon monoxide. The latter has been shown to be the more potent, and it is for this reason that modulating the cerium oxide support is of vital interest. The present work provides compelling evidence that the rate-limiting step in this process is the coordination of the lattice oxygen. Exploratory studies of the control or this step via doping the cerium oxide support are also presented.Download high-res image (107KB)Download full-size image
Co-reporter:Dr. Meng Zhou;Dr. Chenjie Zeng;Dr. Yongbo Song;Jonathan W. Padelford; Gangli Wang;Dr. Matthew Y. Sfeir;Tatsuya Higaki; Rongchao Jin
Angewandte Chemie 2017 Volume 129(Issue 51) pp:16475-16479
Publication Date(Web):2017/12/18
DOI:10.1002/ange.201709095
AbstractThe transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.
Co-reporter:Dr. Meng Zhou;Dr. Chenjie Zeng;Dr. Yongbo Song;Jonathan W. Padelford; Gangli Wang;Dr. Matthew Y. Sfeir;Tatsuya Higaki; Rongchao Jin
Angewandte Chemie International Edition 2017 Volume 56(Issue 51) pp:16257-16261
Publication Date(Web):2017/12/18
DOI:10.1002/anie.201709095
AbstractThe transition from molecular to plasmonic behaviour in metal nanoparticles with increasing size remains a central question in nanoscience. We report that the giant 246-gold-atom nanocluster (2.2 nm in gold core diameter) protected by 80 thiolate ligands is surprisingly non-metallic based on UV/Vis and femtosecond transient absorption spectroscopy as well as electrochemical measurements. Specifically, the Au246 nanocluster exhibits multiple excitonic peaks in transient absorption spectra and electron dynamics independent of the pump power, which are in contrast to the behaviour of metallic gold nanoparticles. Moreover, a prominent oscillatory feature with frequency of 0.5 THz can be observed in almost all the probe wavelengths. The phase and amplitude analysis of the oscillation suggests that it arises from the wavepacket motion on the ground state potential energy surface, which also indicates the presence of a small band-gap and thus non-metallic or molecular-like behaviour.
Co-reporter:Qi Li, Michael G. Taylor, Kristin Kirschbaum, Kelly J. Lambright, Xiaofan Zhu, Giannis Mpourmpakis, Rongchao Jin
Journal of Colloid and Interface Science 2017 Volume 505(Volume 505) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jcis.2017.06.049
The synthesis and structure determination of atomically precise alloy nanoclusters have attracted much attention in recent research. Herein, we report a new alloy nanocluster Au24-xAgx(TBBM)20 (x ∼ 1) synthesized via a ligand-exchange-induced size/structure transformation method. Its X-ray structure is obtained successfully and the dopant Ag is found to occupy three special positions in the kernel, rather than equivalently over all the kernel sites. This selective occupancy is interesting and DFT calculation results suggest that the relative oxidation state (rationalized as difference in the charge) of the Ag when doped into the cluster is likely determining the most favorable doping positions. This work provides a new strategy for controlled synthesis of new Au-Ag nanoclusters and also reveals a new scenario for the doping position of Ag atoms in Au-Ag bimetal nanoclusters.Download high-res image (166KB)Download full-size image
Co-reporter:Rongchao Jin, Chenjie Zeng, Meng Zhou, and Yuxiang Chen
Chemical Reviews 2016 Volume 116(Issue 18) pp:10346-10413
Publication Date(Web):September 1, 2016
DOI:10.1021/acs.chemrev.5b00703
Colloidal nanoparticles are being intensely pursued in current nanoscience research. Nanochemists are often frustrated by the well-known fact that no two nanoparticles are the same, which precludes the deep understanding of many fundamental properties of colloidal nanoparticles in which the total structures (core plus surface) must be known. Therefore, controlling nanoparticles with atomic precision and solving their total structures have long been major dreams for nanochemists. Recently, these goals are partially fulfilled in the case of gold nanoparticles, at least in the ultrasmall size regime (1–3 nm in diameter, often called nanoclusters). This review summarizes the major progress in the field, including the principles that permit atomically precise synthesis, new types of atomic structures, and unique physical and chemical properties of atomically precise nanoparticles, as well as exciting opportunities for nanochemists to understand very fundamental science of colloidal nanoparticles (such as the stability, metal–ligand interfacial bonding, ligand assembly on particle surfaces, aesthetic structural patterns, periodicities, and emergence of the metallic state) and to develop a range of potential applications such as in catalysis, biomedicine, sensing, imaging, optics, and energy conversion. Although most of the research activity currently focuses on thiolate-protected gold nanoclusters, important progress has also been achieved in other ligand-protected gold, silver, and bimetal (or alloy) nanoclusters. All of these types of unique nanoparticles will bring unprecedented opportunities, not only in understanding the fundamental questions of nanoparticles but also in opening up new horizons for scientific studies of nanoparticles.
Co-reporter:Yuxiang Chen; Chong Liu; Qing Tang; Chenjie Zeng; Tatsuya Higaki; Anindita Das; De-en Jiang; Nathaniel L. Rosi
Journal of the American Chemical Society 2016 Volume 138(Issue 5) pp:1482-1485
Publication Date(Web):January 21, 2016
DOI:10.1021/jacs.5b12094
Understanding the isomerism phenomenon at the nanoscale is a challenging task because of the prerequisites of precise composition and structural information on nanoparticles. Herein, we report the ligand-induced, thermally reversible isomerization between two thiolate-protected 28-gold-atom nanoclusters, i.e. Au28(S-c-C6H11)20 (where -c-C6H11 = cyclohexyl) and Au28(SPh-tBu)20 (where -Ph-tBu = 4-tert-butylphenyl). The intriguing ligand effect in dictating the stability of the two Au28(SR)20 structures is further investigated via dispersion-corrected density functional theory calculations.
Co-reporter:Chenjie Zeng; Chong Liu; Yuxiang Chen; Nathaniel L. Rosi
Journal of the American Chemical Society 2016 Volume 138(Issue 28) pp:8710-8713
Publication Date(Web):June 29, 2016
DOI:10.1021/jacs.6b04835
Unveiling the ligand binding mode on the crystalline surfaces is important for deciphering the long-standing structural enigma in self-assembled monolayers (SAMs). Here, the binding and patterning structures of thiolates (SR) on the Au(100) crystalline facet are revealed on the basis of the atomic structure of a highly regular, single crystalline Au92(SR)44 nanocrystal. The six exposed facets of this tetragonal nanocrystal give rise to six pieces of “nanoSAMs”. We found that thiolates bind to the planar (100) facets of the nanocrystal via a simple bridge-like mode and are assembled into an overlayer with c(2 × 2) symmetry. The Au–S binding mode and translational symmetry in the kernel and on the surface of the Au92 nanocrystal can be generalized infinitely to construct the bulk two-dimensional SAMs and various tetragonal nanocrystals.
Co-reporter:Man-Bo Li, Shi-Kai Tian, Zhikun Wu, and Rongchao Jin
Chemistry of Materials 2016 Volume 28(Issue 4) pp:1022
Publication Date(Web):February 1, 2016
DOI:10.1021/acs.chemmater.5b04907
Co-reporter:Weili Li, Qingjie Ge, Xiangang Ma, Yuxiang Chen, Manzhou Zhu, Hengyong Xu and Rongchao Jin
Nanoscale 2016 vol. 8(Issue 4) pp:2378-2385
Publication Date(Web):11 Jan 2016
DOI:10.1039/C5NR07498C
We report a new activation method and insight into the catalytic behavior of a CeO2-supported, atomically precise Au144(SR)60 nanocluster catalyst (where thiolate –SR = –SCH2CH2Ph) for CO oxidation. An important finding is that the activation of the catalyst is closely related to the production of active oxygen species on CeO2, rather than ligand removal of the Au144(SR)60 clusters. A mild O2 pretreatment (at 80 °C) can activate the catalyst, and the addition of reductive gases (CO or H2) can enhance the activation effects of O2 pretreatment via a redox cycle in which CO could reduce the surface of CeO2 to produce oxygen vacancies—which then adsorb and activate O2 to produce more active oxygen species. The CO/O2 pulse experiments confirm that CO is adsorbed on the cluster catalyst even with ligands on, and active oxygen species present on the surface of the pretreated catalyst reacts with CO pulses to generate CO2. The Au144(SR)60/CeO2 exhibits high CO oxidation activity at 80 °C without the removal of thiolate ligands. The surface lattice-oxygen of the support CeO2 possibly participates in the oxidation of CO over the Au144(SR)60/CeO2 catalyst.
Co-reporter:Meng Zhou, Huifeng Qian, Matthew Y. Sfeir, Katsuyuki Nobusada and Rongchao Jin
Nanoscale 2016 vol. 8(Issue 13) pp:7163-7171
Publication Date(Web):29 Feb 2016
DOI:10.1039/C6NR01008C
Atomically precise, doped metal clusters are receiving wide research interest due to their synergistic properties dependent on the metal composition. To understand the electronic properties of doped clusters, it is highly desirable to probe the excited state behavior. Here, we report the ultrafast relaxation dynamics of doped M1@Au24(SR)18 (M = Pd, Pt; R = CH2CH2Ph) clusters using femtosecond visible and near infrared transient absorption spectroscopy. Three relaxation components are identified for both mono-doped clusters: (1) sub-picosecond relaxation within the M1Au12 core states; (2) core to shell relaxation in a few picoseconds; and (3) relaxation back to the ground state in more than one nanosecond. Despite similar relaxation pathways for the two doped nanoclusters, the coupling between the metal core and surface ligands is accelerated by over 30% in the case of the Pt dopant compared with the Pd dopant. Compared to Pd doping, the case of Pt doping leads to much more drastic changes in the steady state and transient absorption of the clusters, which indicates that the 5d orbitals of the Pt atom are more strongly mixed with Au 5d and 6s orbitals than the 4d orbitals of the Pd dopant. These results demonstrate that a single foreign atom can lead to entirely different excited state spectral features of the whole cluster compared to the parent Au25(SR)18 cluster. The detailed excited state dynamics of atomically precise Pd/Pt doped gold clusters help further understand their properties and benefit the development of energy-related applications.
Co-reporter:Qi Li, Shuxin Wang, Kristin Kirschbaum, Kelly J. Lambright, Anindita Das and Rongchao Jin
Chemical Communications 2016 vol. 52(Issue 29) pp:5194-5197
Publication Date(Web):10 Mar 2016
DOI:10.1039/C6CC01243D
We report a method for heavy doping of the Au25(SR)18 nanocluster (where R = C6H11) with silver through the Ag(I)–thiolate complex induced size/structure transformation of Au23(SR)16− into Au25–xAgx(SR)18−. X-ray crystallographic analysis revealed that Ag dopants are distributed not only in the icosahedral core but also in the surface staple motifs; the latter was not achieved in earlier studies of alloy Au25–xAgx nanoclusters.
Co-reporter:Chenjie Zeng;Yuxiang Chen;Kristin Kirschbaum;Kelly J. Lambright
Science 2016 Vol 354( Iss 6319) pp:
Publication Date(Web):23 Dec 2016
DOI:10.1126/science.aak9750
Probing packing rules
The crystals of a well-defined ligand-covered gold nanoparticle can reveal how packing into a lattice happens. Zeng et al. synthesized nanoparticles with a 246-atom gold core surrounded by 80 4-methylbenzenethiol ligands. These nearly spherical nanoparticles did not pack into a cubic arrangement but instead formed a lower-symmetry monoclinic structure. A hierarchy of interparticle ligand interactions controlled the packing, including sets of chiral packing arrangements that reversed between layers.
Science, this issue p. 1580
Co-reporter:Tatsuya Higaki;Chong Liu;Chenjie Zeng;Renxi Jin;Yuxiang Chen; Nathaniel L. Rosi; Rongchao Jin
Angewandte Chemie 2016 Volume 128( Issue 23) pp:6806-6809
Publication Date(Web):
DOI:10.1002/ange.201601947
Abstract
We report the X-ray structure of a gold nanocluster with 30 gold atoms protected by 18 1-adamantanethiolate ligands (formulated as Au30(S-Adm)18). This nanocluster exhibits a threefold rotationally symmetrical, hexagonal-close-packed (HCP) Au18 kernel protected by six dimeric Au2(SR)3 staple motifs. This new structure is distinctly different from the previously reported Au30S(S-tBu)18 nanocluster protected by 18 tert-butylthiolate ligands and one sulfido ligand with a face-centered cubic (FCC) Au22 kernel. The Au30(S-Adm)18 nanocluster has an anomalous solubility (it is only soluble in benzene but not in other common solvents). This work demonstrates a ligand-based strategy for controlling nanocluster structure and also provides a method for the discovery of possibly overlooked clusters because of their anomalous solubility.
Co-reporter:Tatsuya Higaki;Chong Liu;Chenjie Zeng;Renxi Jin;Yuxiang Chen; Nathaniel L. Rosi; Rongchao Jin
Angewandte Chemie International Edition 2016 Volume 55( Issue 23) pp:6694-6697
Publication Date(Web):
DOI:10.1002/anie.201601947
Abstract
We report the X-ray structure of a gold nanocluster with 30 gold atoms protected by 18 1-adamantanethiolate ligands (formulated as Au30(S-Adm)18). This nanocluster exhibits a threefold rotationally symmetrical, hexagonal-close-packed (HCP) Au18 kernel protected by six dimeric Au2(SR)3 staple motifs. This new structure is distinctly different from the previously reported Au30S(S-tBu)18 nanocluster protected by 18 tert-butylthiolate ligands and one sulfido ligand with a face-centered cubic (FCC) Au22 kernel. The Au30(S-Adm)18 nanocluster has an anomalous solubility (it is only soluble in benzene but not in other common solvents). This work demonstrates a ligand-based strategy for controlling nanocluster structure and also provides a method for the discovery of possibly overlooked clusters because of their anomalous solubility.
Co-reporter:E. Hussain, I. Majeed, M. Amtiaz Nadeem, A. Badshah, Yuxiang Chen, M. Arif Nadeem, and Rongchao Jin
The Journal of Physical Chemistry C 2016 Volume 120(Issue 31) pp:17205-17213
Publication Date(Web):July 28, 2016
DOI:10.1021/acs.jpcc.6b04695
Here we demonstrate a new strategy of boosting the photocatalytic activity of titania (P25) for photocatalytic H2 production from the water splitting reaction by depositing palladium/strontium nanoparticles, forming Pd/Sr-NPs@P25. The Pd/Sr-NPs are in situ prepared on the surface of P25. The effects of Pd and Sr in the photocatalytic reactions are further revealed. Strontium in the form of strontium oxide promotes electron transfer from the semiconductor surface to palladium nanoparticles by increasing the Fermi level of the P25 support. The structural and morphological characterizations of the Pd/Sr-NPs nanocomposite are carried out using UV–vis DRS, XRD, TEM, and XPS techniques, based upon which the mechanistic insights are discussed.
Co-reporter:Shuo Zhao, Anindita Das, Hui Zhang, Renxi Jin, Yongbo Song, Rongchao Jin
Progress in Natural Science: Materials International 2016 Volume 26(Issue 5) pp:483-486
Publication Date(Web):October 2016
DOI:10.1016/j.pnsc.2016.08.009
A trio of thiolate-protected atomically precise gold nanoclusters, [Au23(S-c-C6H11)16]–, Au24(SCH2pHtBu)20 and [Au25(SCH2CH2pH)18]–, are utilized as catalysts for 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP). Despite nearly identical sizes (~1 nm), the three nanoclusters possess distinctly different atomic packing structures and surface ligand binding modes, which contribute to different catalytic performance. The [Au23(S-c-C6H11)16]– nanocluster shows the highest activity with a kinetic rate constant of 0.0370 s−1, which is higher than those of Au24(SCH2pHtBu)20 (0.0090 s−1) and [Au25(SCH2CH2pH)18]– (0.0242 s−1). Such a trio of gold nanoclusters indicate that the atomic packing mode and electronic structure play a crucial role in determining their catalytic performance.
Co-reporter:Rongchao Jin
Progress in Natural Science: Materials International 2016 Volume 26(Issue 5) pp:427
Publication Date(Web):October 2016
DOI:10.1016/j.pnsc.2016.10.001
Co-reporter:Qi Li, Tian-Yi Luo, Meng Zhou, Hadi Abroshan, Jingchun Huang, Hyung J. Kim, Nathaniel L. Rosi, Zhengzhong Shao, and Rongchao Jin
ACS Nano 2016 Volume 10(Issue 9) pp:8385
Publication Date(Web):August 22, 2016
DOI:10.1021/acsnano.6b03113
Silicon nanoparticles (NPs) have been widely accepted as an alternative material for typical quantum dots and commercial organic dyes in light-emitting and bioimaging applications owing to silicon’s intrinsic merits of least toxicity, low cost, and high abundance. However, to date, how to improve Si nanoparticle photoluminescence (PL) performance (such as ultrahigh quantum yield, sharp emission peak, high stability) is still a major issue. Herein, we report surface nitrogen-capped Si NPs with PL quantum yield up to 90% and narrow PL bandwidth (full width at half-maximum (fwhm) ≈ 40 nm), which can compete with commercial dyes and typical quantum dots. Comprehensive studies have been conducted to unveil the influence of particle size, structure, and amount of surface ligand on the PL of Si NPs. Especially, a general ligand-structure-based PL energy law for surface nitrogen-capped Si NPs is identified in both experimental and theoretical analyses, and the underlying PL mechanisms are further discussed.Keywords: narrow bandwidth; PL energy law; quantum dots; silicon nanoparticles; ultrabright fluorescence
Co-reporter:Gao Li, Hadi Abroshan, Chong Liu, Shuo Zhuo, Zhimin Li, Yan Xie, Hyung J. Kim, Nathaniel L. Rosi, and Rongchao Jin
ACS Nano 2016 Volume 10(Issue 8) pp:7998
Publication Date(Web):July 21, 2016
DOI:10.1021/acsnano.6b03964
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 reaction between 4-methyl-iodobenzene and 4-nitro-iodobenzene. Results show that the activity and selectivity of the catalysts are largely influenced by the chemical nature of the protecting thiolate ligands. This study highlights that the aromatic ligands not only lead to a higher conversion in catalytic reaction but also markedly increase the yield of the heterocoupling product (4-methyl-4′-nitro-1,1′-biphenyl). Through a combined approach of experiment and theory, this study sheds light on the structure–activity relationships of the Au25 nanoclusters and also offers guidelines for tailoring nanocluster properties by ligand engineering for specific applications.Keywords: Au25; gold; ligand effects; nanoclusters; Ullmann coupling
Co-reporter:Yuxiang Chen, Chenjie Zeng, Douglas R. Kauffman, and Rongchao Jin
Nano Letters 2015 Volume 15(Issue 5) pp:3603-3609
Publication Date(Web):April 27, 2015
DOI:10.1021/acs.nanolett.5b01122
Toward controlling the magic sizes of atomically precise gold nanoclusters, herein we have devised a new strategy by exploring the para-, meta-, ortho-methylbenzenethiol (MBT) for successful preparation of pure Au130(p-MBT)50, Au104(m-MBT)41 and Au40(o-MBT)24 nanoclusters. The decreasing size sequence is in line with the increasing hindrance of the methyl group to the interfacial Au–S bond. That the subtle change of ligand structure can result in drastically different magic sizes under otherwise similar reaction conditions is indeed for the first time observed in the synthesis of thiolate-protected gold nanoclusters. These nanoclusters are highly stable as they are synthesized under harsh size-focusing conditions at 80–90 °C in the presence of excess thiol and air (i.e., without exclusion of oxygen).
Co-reporter:Yuxiang Chen; Chenjie Zeng; Chong Liu; Kristin Kirschbaum; Chakicherla Gayathri; Roberto R. Gil; Nathaniel L. Rosi
Journal of the American Chemical Society 2015 Volume 137(Issue 32) pp:10076-10079
Publication Date(Web):August 5, 2015
DOI:10.1021/jacs.5b05378
We report the structure determination of a large gold nanocluster formulated as Au130(p-MBT)50, where p-MBT is 4-methylbenzenethiolate. The nanocluster is constructed in a four-shell manner, with 55 gold atoms assembled into a two-shell Ino decahedron. The surface is protected exclusively by –S–Au–S– staple motifs, which self-organize into five ripple-like stripes on the surface of the barrel-shaped Au105 kernel. The Au130(p-MBT)50 can be viewed as an elongated version of the Au102(SR)44. Comparison of the Au130(p-MBT)50 structure with the recently discovered icosahedral Au133(p-TBBT)52 nanocluster (where p-TBBT = 4-tert-butylbenzenethiolate) reveals an interesting phenomenon that a subtle ligand effect in the para-position of benzenethiolate can significantly affect the gold atom packing structure, i.e. from the 5-fold twinned Au55 decahedron to 20-fold twinned Au55 icosahedron.
Co-reporter:Gao Li; Hadi Abroshan; Yuxiang Chen; Rongchao Jin;Hyung J. Kim
Journal of the American Chemical Society 2015 Volume 137(Issue 45) pp:14295-14304
Publication Date(Web):October 26, 2015
DOI:10.1021/jacs.5b07716
The catalytic activity of Au25(SR)18 nanoclusters (R = C2H4Ph) for the aldehyde hydrogenation reaction in the presence of a base, e.g., ammonia or pyridine, and transition-metal ions Mz+, such as Cu+, Cu2+, Ni2+ and Co2+, as a Lewis acid is studied. The addition of a Lewis acid is found to significantly promote the catalytic activity of Au25(SR)18/CeO2 in the hydrogenation of benzaldehyde and a number of its derivatives. Matrix-assisted laser desorption ionization (MALDI) and electrospray ionization (ESI) mass spectrometry in conjunction with UV–vis spectroscopy confirm the generation of new species, Au25-n(SR)18-n (n = 1–4), in the presence of a Lewis acid. The pathways for the speciation of Au24(SR)17 from its parent Au25(SR)18 nanocluster as well as its structure are investigated via the density functional theory (DFT) method. The adsorption of Mz+ onto a thiolate ligand “—SR—” of Au25(SR)18, followed by a stepwise detachment of “—SR—” and a gold atom bonded to “—SR—” (thus an “Au-SR” unit) is found to be the most likely mechanism for the Au24(SR)17 generation. This in turn exposes the Au13-core of Au24(SR)17 to reactants, providing an active site for the catalytic hydrogenation. DFT calculations indicate that Mz+ is also capable of adsorbing onto the Au13-core surface, producing a possible active metal site of a different kind to catalyze the aldehyde hydrogenation reaction. This study suggests, for the first time, that species with an open metal site like adducts [nanoparticle-M](z-1)+ or fragments Au25-n(SR)18-n function as the catalysts rather than the intact Au25(SR)18.
Co-reporter:Man-Bo Li, Shi-Kai Tian, Zhikun Wu and Rongchao Jin
Chemical Communications 2015 vol. 51(Issue 21) pp:4433-4436
Publication Date(Web):06 Feb 2015
DOI:10.1039/C4CC08830A
A new nanocluster of atomic precision, Au44(SC2H4Ph)32, is obtained by an oxidation–decomposition–recombination (ODR) process from Au25(SC2H4Ph)18 under mild conditions with high yield (75%). Among the investigated gold nanoclusters, Au44(SC2H4Ph)32 exhibits the highest catalytic activity for the reduction of 4-nitrophenol, especially at low temperature, indicating that the catalytic properties of gold nanoclusters are not only size-dependent, but also structure-sensitive.
Co-reporter:Chao Liu;Tao Li;Dr. Gao Li; Katsuyuki Nobusada;Chenjie Zeng; Guangsheng Pang; Nathaniel L. Rosi; Rongchao Jin
Angewandte Chemie International Edition 2015 Volume 54( Issue 34) pp:9826-9829
Publication Date(Web):
DOI:10.1002/anie.201502667
Abstract
The structure of nanoparticles plays a critical role in dictating their material properties. Gold is well known to adopt face-centered cubic (fcc) structure. Herein we report the first observation of a body-centered cubic (bcc) gold nanocluster composed of 38 gold atoms protected by 20 adamantanethiolate ligands and two sulfido atoms ([Au38S2(SR)20], where R=C10H15) as revealed by single-crystal X-ray crystallography. This bcc structure is in striking contrast with the fcc structure of bulk gold and conventional Au nanoparticles, as well as the bi-icosahedral structure of [Au38(SCH2CH2Ph)24]. The bcc nanocluster has a distinct HOMO–LUMO gap of ca. 1.5 eV, much larger than the gap (0.9 eV) of the bi-icosahedral [Au38(SCH2CH2Ph)24]. The unique structure of the bcc gold nanocluster may be promising in catalytic applications.
Co-reporter:Chenjie Zeng; Yuxiang Chen; Anindita Das
The Journal of Physical Chemistry Letters 2015 Volume 6(Issue 15) pp:2976-2986
Publication Date(Web):July 9, 2015
DOI:10.1021/acs.jpclett.5b01150
Controlling nanoparticles with atomic precision has long been a major dream of nanochemists. This dream has first been realized in the case of gold nanoparticles. We previously discussed a size-focusing methodology for the syntheses of atomically precise gold nanoclusters protected by thiolate ligands (referred to as Aun(SR)m, where n and m represent the exact numbers of gold atoms and surface ligands). This methodology led to molecularly pure nanoclusters such as Au25(SR)18, Au38(SR)24, Au144(SR)60, and many others in recent work. In this Perspective article, we shall further discuss a new methodology for controlling the size and structure of nanoclusters through ligand-exchange-induced transformation of Aun(SR)m nanoclusters. Notable examples include the transformations of Au25(SR)18 to Au28(SR′)20, Au38(SR)24 to Au36(SR′)24, and Au144(SR)60 to Au133(SR′)52. Total structures of the new nanoclusters have also been attained. The transformation processes are remarkable and resemble the organic transformation chemistry. We have also achieved mechanistic understanding on the transformation process, and a disproportionation mechanism has been for the first time identified. This new methodology (i.e., ligand-exchange-induced size/structure transformation, LEIST for short) has not only demonstrated the important role of thiolate ligand in the transformation chemistry of clusters but also paved the way for creating an expanded “library” of Aun(SR)m nanoclusters for exploration of their magic sizes, structures, properties, and applications.
Co-reporter:Gao Li
The Journal of Physical Chemistry C 2015 Volume 119(Issue 20) pp:11143-11147
Publication Date(Web):February 6, 2015
DOI:10.1021/jp511930n
We report the chemoselective hydrogenation of 4-nitrobenaldehyde to 4-nitrobenzyl alcohol using the unsupported Au spherical nanoparticle and nanorod catalysts at 80 °C in water. A ∼100% selectivity for the 4-nitrobenzyl alcohol product was obtained when the hydrogenation reaction was catalyzed by the unsupported gold catalysts. The Au nanorod catalysts exhibited an aspect-ratio dependent reactivity and generally performed much better than the Au spherical nanoparticle catalyst. The Au nanorod catalysts showed excellent recyclability in the chemoselective hydrogenation (>99% conversion and 100% selectivity after 5 cycles).
Co-reporter:Chenjie Zeng;Yuxiang Chen;Chong Liu;Nathaniel L. Rosi;Katsuyuki Nobusada
Science Advances 2015 Volume 1(Issue 9) pp:e1500425
Publication Date(Web):09 Oct 2015
DOI:10.1126/sciadv.1500425
Structures of gold clusters resemble the benzene and DNA molecules and reveal a “supermolecule” origin of the magic-sized clusters.
Co-reporter:Renxi Jin, Chong Liu, Shuo Zhao, Anindita Das, Hongzhu Xing, Chakicherla Gayathri, Yan Xing, Nathaniel L. Rosi, Roberto R. Gil, and Rongchao Jin
ACS Nano 2015 Volume 9(Issue 8) pp:8530
Publication Date(Web):July 27, 2015
DOI:10.1021/acsnano.5b03524
The [Au37(PPh3)10(SR)10X2]+ nanocluster (where SR = thiolate and X = Cl/Br) was theoretically predicted in 2007, but since then, there has been no experimental success in the synthesis and structure determination. Herein, we report a kinetically controlled, selective synthesis of [Au37(PPh3)10(SC2H4Ph)10X2]+ (counterion: Cl– or Br–) with its crystal structure characterized by X-ray crystallography. This nanocluster shows a rod-like structure assembled from three icosahedral Au13 units in a linear fashion, consistent with the earlier prediction. The optical absorption and the electrochemical and catalytic properties are investigated. The successful synthesis of this new nanocluster allows us to gain insight into the size, structure, and property evolution of gold nanoclusters that are based upon the assembly of icosahedral units (i.e., cluster of clusters). Some interesting trends are identified in the evolution from the monoicosahedral [Au13(PPh3)10X2]3+ to the bi-icosahedral [Au25(PPh3)10(SC2H4Ph)5X2]2+ and to the tri-icosahedral [Au37(PPh3)10(SC2H4Ph)10X2]+ nanocluster, which also points to the possibility of achieving even longer rod nanoclusters based upon assembly of icosahedral building blocks.Keywords: Au37 nanocluster; clusters of clusters; CO oxidation; mixed ligands; structure evolution;
Co-reporter:Chao Liu;Tao Li;Dr. Gao Li; Katsuyuki Nobusada;Chenjie Zeng; Guangsheng Pang; Nathaniel L. Rosi; Rongchao Jin
Angewandte Chemie 2015 Volume 127( Issue 34) pp:9964-9967
Publication Date(Web):
DOI:10.1002/ange.201502667
Abstract
The structure of nanoparticles plays a critical role in dictating their material properties. Gold is well known to adopt face-centered cubic (fcc) structure. Herein we report the first observation of a body-centered cubic (bcc) gold nanocluster composed of 38 gold atoms protected by 20 adamantanethiolate ligands and two sulfido atoms ([Au38S2(SR)20], where R=C10H15) as revealed by single-crystal X-ray crystallography. This bcc structure is in striking contrast with the fcc structure of bulk gold and conventional Au nanoparticles, as well as the bi-icosahedral structure of [Au38(SCH2CH2Ph)24]. The bcc nanocluster has a distinct HOMO–LUMO gap of ca. 1.5 eV, much larger than the gap (0.9 eV) of the bi-icosahedral [Au38(SCH2CH2Ph)24]. The unique structure of the bcc gold nanocluster may be promising in catalytic applications.
Co-reporter:Chenjie Zeng;Yuxiang Chen;Kristin Kirschbaum;Kannatassen Appavoo;Matthew Y. Sfeir
Science Advances 2015 Volume 1(Issue 2) pp:e1500045
Publication Date(Web):20 Mar 2015
DOI:10.1126/sciadv.1500045
X-ray crystallography unravels molecular self-assembly and structural ordering on the curved surface of the largest gold nanoparticle, consisting of 133 atoms.
Co-reporter:Changlin Yu;Gao Li;Santosh Kumar;Kai Yang
Advanced Materials 2014 Volume 26( Issue 6) pp:892-898
Publication Date(Web):
DOI:10.1002/adma.201304173
Co-reporter:Gao Li ; Chenjie Zeng
Journal of the American Chemical Society 2014 Volume 136(Issue 9) pp:3673-3679
Publication Date(Web):February 25, 2014
DOI:10.1021/ja500121v
We report the synthesis and catalytic application of thermally robust gold nanoclusters formulated as Au99(SPh)42. The formula was determined by electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry in conjunction with thermogravimetric analysis. The optical spectrum of Au99(SPh)42 nanoclusters shows absorption peaks at ∼920 nm (1.35 eV), 730 nm (1.70 eV), 600 nm (2.07 eV), 490 nm (2.53 eV), and 400 nm (3.1 eV) in contrast to conventional gold nanoparticles, which exhibit a plasmon resonance band at 520 nm (for spherical particles). The ceria-supported Au99(SPh)42 nanoclusters were utilized as a catalyst for chemoselective hydrogenation of nitrobenzaldehyde to nitrobenzyl alcohol in water using H2 gas as the hydrogen source. The selective hydrogenation of the aldehyde group catalyzed by nanoclusters is a surprise because conventional nanogold catalysts instead give rise to the product resulting from reduction of the nitro group. The Au99(SPh)42/CeO2 catalyst gives high catalytic activity for a range of nitrobenzaldehyde derivatives and also shows excellent recyclability due to its thermal robustness. We further tested the size-dependent catalytic performance of Au25(SPh)18 and Au36(SPh)24 nanoclusters, and on the basis of their crystal structures we propose a molecular adsorption site for nitrobenzaldehyde. The nanocluster material is expected to find wide application in catalytic reactions.
Co-reporter:Gao Li
Journal of the American Chemical Society 2014 Volume 136(Issue 32) pp:11347-11354
Publication Date(Web):July 30, 2014
DOI:10.1021/ja503724j
We report high catalytic activity of ultrasmall spherical Au25(SC2H4Ph)18 and rod-shaped Au25(PPh3)10(C≡CPh)5X2 (X = Br, Cl) nanoclusters supported on oxides for the semihydrogenation of terminal alkynes into alkenes with >99% conversion of alkynes and ∼100% selectivity for alkenes. In contrast, internal alkynes cannot be catalyzed by such “ligand-on” Au25 catalysts; however, with “ligand-off” Au25 catalysts the internal alkynes can undergo semihydrogenation to yield Z-alkenes, similar to conventional gold nanoparticle catalysts. On the basis of the results, a unique activation pathway of terminal alkynes by “ligand-on” gold nanoclusters is identified, which should follow a deprotonation activation pathway via a R′—C≡C—[AunLm] (where L represents the protecting ligands on the cluster), in contrast with the activation mechanism on conventional gold nanocatalysts. This new activation mode is supported by observing the incorporation of deprotonated —C≡CPh as ligands on rod-shaped Au25(PPh3)10(C≡CPh)5X2 nanoclusters under conditions similar to the catalytic reaction and by detecting the R′—C≡C—[Aun(SC2H4Ph)m] via FT-IR spectroscopy.
Co-reporter:Gao Li, De-en Jiang, Santosh Kumar, Yuxiang Chen, and Rongchao Jin
ACS Catalysis 2014 Volume 4(Issue 8) pp:2463
Publication Date(Web):June 26, 2014
DOI:10.1021/cs500533h
We investigate the catalytic properties of water-soluble Aun(SG)m nanocluster catalysts (H-SG = glutathione) of different sizes, including Au15(SG)13, Au18(SG)14, Au25(SG)18, Au38(SG)24, and captopril-capped Au25(Capt)18 nanoclusters. These Aun(SR)m nanoclusters (SR represents thiolate generally) are used as homogeneous catalysts (i.e., without supports) in the chemoselective hydrogenation of 4-nitrobenzaldehyde (4-NO2PhCHO) to 4-nitrobenzyl alcohol (4-NO2PhCH2OH) with ∼100% selectivity in water using H2 gas (20 bar) as the hydrogen source. These nanocluster catalysts, except Au18(SG)14, remain intact after the catalytic reaction, evidenced by UV–vis spectra, which are characteristic of nanoclusters of each size and thus serve as spectroscopic “fingerprints”. We observe a drastic size dependence and steric effect of protecting ligands on the gold nanocluster catalysts in the hydrogenation reaction. Density functional theory (DFT) modeling of the 4-nitrobenzaldehyde adsorption shows that both the -CHO and -NO2 groups closely interact with the S-Au-S staples on the gold nanocluster surface. The adsorptions of the 4-nitrobenzaldehyde molecule on the four different sized Aun(SR)m nanoclusters are moderately strong and similar in strength. The DFT results suggest that the catalytic activity of the Aun(SR)m nanoclusters is primarily determined by the surface area of the Au nanocluster, consistent with the observed trend of the conversion of 4-nitrobenzaldehyde versus the cluster size. Overall, this work offers molecular insight into the hydrogenation of 4-nitrobenzaldehyde and the catalytically active site structure on gold nanocluster catalysts.Keywords: Au nanocluster; chemoselective; hydrogenation; size dependence; water-soluble
Co-reporter:Hideya Kawasaki, Santosh Kumar, Gao Li, Chenjie Zeng, Douglas R. Kauffman, Junya Yoshimoto, Yasuhiko Iwasaki, and Rongchao Jin
Chemistry of Materials 2014 Volume 26(Issue 9) pp:2777
Publication Date(Web):April 22, 2014
DOI:10.1021/cm500260z
The generation of highly reactive singlet oxygen (1O2) is of major importance for a variety of applications such as photodynamic therapy (PDT) for cancer treatment, water treatment, catalytic oxidation, and others. Herein, we demonstrate that 1O2 can be efficiently produced through the direct photosensitization by Au25(SR)18– clusters (H−SR = phenylethanethiol or captopril) without using conventional organic photosensitizers under visible/near-IR (532, 650, and 808 nm) irradiation. 1O2 was successfully detected by direct observation of the characteristic 1O2 emission around 1276 nm as well as three different 1O2-selective probes. Water-soluble Au25(captopril)18– clusters were explored for cytocompatibility and photodynamic activity toward cancer cells. In addition, selective catalytic oxidation of organic sulfide to sulfoxide by 1O2 was demonstrated on the photoexcited Au25(SC2H4Ph)18– clusters. It is suggested that the optical gap of Au25(SR)18 clusters (∼1.3 eV) being larger than the energy of 1O2 (0.97 eV) allows for the efficient energy transfer to 3O2. In addition, the long lifetime of the electronic excited states of Au25(SR)18 and the well-defined O2 adsorption sites are the key factors that promote energy transfer from Au25(SR)18– to molecular oxygen, thus facilitating the formation of 1O2. Finally, neutral Au25(SR)180 can also produce 1O2 as efficiently as does the anionic Au25(SR)18−.
Co-reporter:Anindita Das, Tao Li, Gao Li, Katsuyuki Nobusada, Chenjie Zeng, Nathaniel L. Rosi and Rongchao Jin
Nanoscale 2014 vol. 6(Issue 12) pp:6458-6462
Publication Date(Web):09 May 2014
DOI:10.1039/C4NR01350F
Solving the total structures of gold nanoclusters is of critical importance for understanding their electronic, optical and catalytic properties. Herein, we report the X-ray structure of a charge-neutral Au24(SCH2Ph-tBu)20 nanocluster. This structure features a bi-tetrahedral Au8 kernel protected by four tetrameric staple-like motifs. Electronic structure analysis is further carried out and the optical absorption spectrum is interpreted. The Au24(SCH2Ph-tBu)20, Au23(S-c-C6H11)16 and Au25(SCH2CH2Ph)18 nanoclusters constitute the first crystallographically characterized “trio”.
Co-reporter:Chenjie Zeng, Yuxiang Chen, Gao Li and Rongchao Jin
Chemical Communications 2014 vol. 50(Issue 1) pp:55-57
Publication Date(Web):05 Nov 2013
DOI:10.1039/C3CC47089J
We report the synthesis of a Au44(SR)28 nanocluster (SR = 4-tert-butylbenzenethiolate). Based on the structural rules learned from the known Au28(SR)20 and Au36(SR)24 structures, we propose a plausible structure for Au44(SR)28, which is predicted to comprise a six-interpenetrating cuboctahedral Au36 kernel protected by four dimeric staples and sixteen bridging thiolates, i.e. Au36[Au2(SR)3]4(SR)16.
Co-reporter:Chao Liu, Gao Li, Douglas R. Kauffman, Guangsheng Pang, Rongchao Jin
Journal of Colloid and Interface Science 2014 Volume 423() pp:123-128
Publication Date(Web):1 June 2014
DOI:10.1016/j.jcis.2014.02.022
•A synthetic method for ultrasmall Pt nanoparticles (∼1 nm) is developed.•Compared to bulk Pt, structural relaxation is observed in the Pt nanoparticles.•The Pt 4f core level energy shifts positively by +1 eV compared with bulk Pt.We report the synthesis of ligand-protected, ultrasmall Pt nanoparticles of ∼1 nm size via a one-phase wet chemical method. Using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS), we determined the mass of the nanoparticles to be ∼8 kDa. Characterization of the Pt nanoparticles was further carried out by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), optical absorption spectroscopy, and X-ray photoelectron spectroscopy (XPS). Interestingly, we observed a large structural relaxation in the 8 kDa nanoparticles (i.e. lattice parameter elongation by +10%) compared to bulk platinum. XPS analysis revealed a positive shift of Pt 4f core level energy by approximately +1 eV compared with bulk Pt, indicating charge transfer from Pt to S atom of the thiolate ligand on the particle. Compared to bulk Pt, the 5d band of Pt nanoparticles is narrower and shifts to higher binding energy. Overall, the ∼1 nm ultrasmall Pt nanoparticles exhibit quite distinct differences in electronic and structural properties compared to their larger counterparts and bulk Pt.
Co-reporter:Anindita Das, Chong Liu, Chenjie Zeng, Gao Li, Tao Li, Nathaniel L. Rosi, and Rongchao Jin
The Journal of Physical Chemistry A 2014 Volume 118(Issue 37) pp:8264-8269
Publication Date(Web):March 12, 2014
DOI:10.1021/jp501073a
Thiolato-protected gold nanoclusters have acquired wide applications; however, on the fundamental science end there is still a lack of deep understanding of their high stability. Recent success in transforming the highly robust biicosahedral Au38(SCH2CH2Ph)24 nanocluster into an extremely stable tetrahedral Au36(SPh-tBu)24 nanocluster raises an important question: Is the transformation due to the bulkiness effect of SPh-tBu or the electronic conjugation effect of the aromatic ligand as opposed to the nonaromatic SCH2CH2Ph? Toward this goal, we report our success in the crystallization of a nonaromatic thiolato-protected Au36(SC5H9)24 nanocluster (where, SC5H9 = cyclopentanethiolato). Comparison of Au36(SC5H9)24 with the aromatic thiolato-protected Au36(SPh-tBu)24 nanocluster rules out the thought that the face-centered cubic, tetrahedral structure of Au36(SPh-tBu)24 is dictated by the aromatic ligand; it also reveals that the electronic conjugation effect in aromatic ligand makes the S–C bond shorter and stronger, and this affects the S–Au bonds, resulting in a larger separation between the staple motifs and the inner Au28 kernel. Overall, this work sheds some light on the major question of the specific roles of thiol ligand in determining the cluster size and structure.
Co-reporter:Shuxin Wang;Xiangming Meng;Anindita Das;Tao Li;Yongbo Song;Tiantian Cao;Xiuyi Zhu; Manzhou Zhu; Rongchao Jin
Angewandte Chemie International Edition 2014 Volume 53( Issue 9) pp:2376-2380
Publication Date(Web):
DOI:10.1002/anie.201307480
Abstract
The rod-shaped Au25 nanocluster possesses a low photoluminescence quantum yield (QY=0.1 %) and hence is not of practical use in bioimaging and related applications. Herein, we show that substituting silver atoms for gold in the 25-atom matrix can drastically enhance the photoluminescence. The obtained AgxAu25−x (x=1–13) nanoclusters exhibit high quantum yield (QY=40.1 %), which is in striking contrast with the normally weakly luminescent AgxAu25−x species (x=1–12, QY=0.21 %). X-ray crystallography further determines the substitution sites of Ag atoms in the AgxAu25−x cluster through partial occupancy analysis, which provides further insight into the mechanism of photoluminescence enhancement.
Co-reporter:Anindita Das ; Tao Li ; Katsuyuki Nobusada ; Chenjie Zeng ; Nathaniel L. Rosi
Journal of the American Chemical Society 2013 Volume 135(Issue 49) pp:18264-18267
Publication Date(Web):November 25, 2013
DOI:10.1021/ja409177s
We report the X-ray structure of a cyclohexanethiolate-capped [Au23(SR)16]− nanocluster (counterion: tetraoctylammonium, TOA+). The structure comprises a cuboctahedron-based bipyramidal Au15 kernel, which is protected by two staple-like trimeric Au3(SR)4 motifs, two monomeric Au(SR)2 and four plain bridging SR ligands. Electronic structure analysis reveals nonsuperatomic feature of [Au23(SR)16]− and confirms the Au15 kernel and surface motifs. The Au15 kernel and trimeric staple motif are unprecedented and offer new insight in understanding the structure evolution of gold nanoclusters.
Co-reporter:Chenjie Zeng ; Tao Li ; Anindita Das ; Nathaniel L. Rosi
Journal of the American Chemical Society 2013 Volume 135(Issue 27) pp:10011-10013
Publication Date(Web):July 1, 2013
DOI:10.1021/ja404058q
We report the crystal structure of a new nanocluster formulated as Au28(TBBT)20, where TBBT = 4-tert-butylbenzenethiolate. It exhibits a rod-like Au20 kernel consisting of two interpenetrating cuboctahedra. The kernel is protected by four dimeric “staples” (-SR-Au-SR-Au-SR-) and eight bridging thiolates (-SR-). The unit cell of Au28(TBBT)20 single crystals contains a pair of enantiomers. The origin of chirality is primarily rooted in the rotating arrangement of the four dimeric staples as well as the arrangement of the bridging thiolates (quasi-D2 symmetry). The enantiomers were separated by chiral HPLC and characterized by circular dichroism spectroscopy.
Co-reporter:Xiaotao Nie, Chenjie Zeng, Xiangang Ma, Huifeng Qian, Qingjie Ge, Hengyong Xu and Rongchao Jin
Nanoscale 2013 vol. 5(Issue 13) pp:5912-5918
Publication Date(Web):24 May 2013
DOI:10.1039/C3NR00970J
The catalytic properties of atomically precise, thiolate-protected Au38(SR)24 (R = CH2CH2Ph) nanoclusters supported on CeO2 were investigated for CO oxidation in a fixed bed quartz reactor. Oxygen (O2) thermal pretreatment of Au38(SR)24/CeO2 at a temperature between 100 and 175 °C largely enhanced the catalytic activity, while pretreatment at higher temperatures (>200 °C) for removing thiolate instead gave rise to a somewhat lower activity than that for 175 °C pretreatment, and the ligand-off clusters were also found to be less stable. The CO conversion in the case of wet feed-gas (i.e. the presence of H2O vapor) was appreciably higher than the case of dry feed-gas when the reaction temperature was kept relatively low (between 60 and 80 °C), and interestingly the ligand-on and ligand-off catalysts exhibited opposite response to water vapor. Finally, we discussed some insights into the catalytic reaction involving the well-defined gold nanocluster catalyst.
Co-reporter:Chao Liu, Gao Li, Guangsheng Pang and Rongchao Jin
RSC Advances 2013 vol. 3(Issue 25) pp:9778-9784
Publication Date(Web):16 May 2013
DOI:10.1039/C3RA40775F
Despite the recent advances in size-controlled synthesis of thiolate-protected Aun(SR)m nanoclusters, understanding the growth mechanism of nanoclusters still significantly lags behind. In this work, we report an important finding that the reaction medium plays a major role in influencing the final cluster size. Specifically, we focus on the one-phase synthetic process that leads to predominant formation of Au25(SR)18 or Au144(SR)60—two ubiquitous nanoclusters in nanocluster synthesis. When THF, acetone or ethyl acetate was used as the reaction solvent, we found that Au25 was formed as the major product, while in methanol or acetonitrile, predominant Au144 and some larger nanoparticles were formed. We mapped out some details of the underlying growth mechanism of nanoclusters, in which the reaction medium was found to affect the Au(I) intermediate (i.e. size and aggregation state), which subsequently affects the final size of gold nanoclusters. The obtained insight into the growth of nanoclusters is expected to contribute to the development of new synthetic strategies.
Co-reporter:Changlin Yu, Gao Li, Santosh Kumar, Hideya Kawasaki, and Rongchao Jin
The Journal of Physical Chemistry Letters 2013 Volume 4(Issue 17) pp:2847-2852
Publication Date(Web):August 13, 2013
DOI:10.1021/jz401447w
We report the visible light photocatalytic properties of a composite material consisting of Au25(SR)18 nanoclusters (R:CH2CH2Ph) and TiO2 nanocrystals. The effects of Au25(SR)18 nanoclusters on the photocatalytic activity of TiO2 nanocrystals were evaluated in the reaction of photocatalytic degradation of methyl orange. The loading of Au25(SR)18 nanoclusters onto TiO2 results in strong visible light absorption by the composite and, more importantly, a 1.6 times increase in visible light photocatalytic activity. Furthermore, the Au25(SR)18/TiO2 composite nanostructure exhibits high stability in recycling tests. The Au25(SR)18 nanolusters dispersed on the TiO2 surface can act as a small-band-gap semiconductor to absorb visible light, giving rise to electron–hole separation and producing singlet oxygen (1O2). Both the generated hydroxyl radicals (HO•) and 1O2 are rationalized to be responsible for the decomposition of the dye.Keywords: Au25(SR)18 nanoclusters; nanocrystalline TiO2; optical absorption; stability; visible light photocatalytic activity;
Co-reporter:Meng Zhou, Silvije Vdović, Saran Long, Manzhou Zhu, Linyin Yan, Yingying Wang, Yingli Niu, Xuefei Wang, Qianjin Guo, Rongchao Jin, and Andong Xia
The Journal of Physical Chemistry A 2013 Volume 117(Issue 40) pp:10294-10303
Publication Date(Web):September 17, 2013
DOI:10.1021/jp406336q
It is accepted that the monolayer ligand shell in monolayer-protected gold nanoclusters (MPCs) plays an important role in stabilizing the metal core structure. Previous reports have shown that the core and shell do not interact chemically, and very few studies investigating the intramolecular charge transfer (ICT) between the core and ligand shell in clusters have been reported. The underlying excited state relaxation mechanisms about the influence of solvents, the optically excited vibration, and the roles of the core and shell in charge transfer remain unknown to a large extent. Here we report a femtosecond transient absorption study of a Au20(SR)16 (R = CH2CH2Ph) cluster in toluene and tetrahydrofuran. The ICT from the outside shell to the inside core upon excitation in Au20(SR)16 is identified. The observed solvation-dependent oscillations in different solvents further confirm the photoinduced ICT formation in Au20(SR)16. The results provide a fundamental understanding of the structure–property relationships about the solvation-dependent core–shell interaction in Au MPCs.
Co-reporter:Dr. Zhikun Wu;Dr. Rongchao Jin
Chemistry - A European Journal 2013 Volume 19( Issue 37) pp:12259-12263
Publication Date(Web):
DOI:10.1002/chem.201300592
Co-reporter:Eric Gottlieb;Dr. Huifeng Qian;Dr. Rongchao Jin
Chemistry - A European Journal 2013 Volume 19( Issue 13) pp:4238-4243
Publication Date(Web):
DOI:10.1002/chem.201203158
Abstract
Atomically precise alloying and de-alloying processes for the formation of Ag–Au and Cu–Au nanoparticles of 25-metal-atom composition (referred to as AgxAu25−x(SR)18 and CuxAu25−x(SR)18, in which R=CH2CH2Ph) are reported. The identities of the particles were determined by matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS). Their structures were probed by fragmentation analysis in MALDI-MS and comparison with the icosahedral structure of the homogold Au25(SR)18 nanoparticles (an icosahedral Au13 core protected by a shell of Au12(SR)18). The Cu and Ag atoms were found to preferentially occupy the 13-atom icosahedral sites, instead of the exterior shell. The number of Ag atoms in AgxAu25−x(SR)18 (x=0–8) was dependent on the molar ratio of AgI/AuIII precursors in the synthesis, whereas the number of Cu atoms in CuxAu25−x(SR)18 (x=0–4) was independent of the molar ratio of CuII/AuIII precursors applied. Interestingly, the CuxAu25−x(SR)18 nanoparticles show a spontaneous de-alloying process over time, and the initially formed CuxAu25−x(SR)18 nanoparticles were converted to pure Au25(SR)18. This de-alloying process was not observed in the case of alloyed AgxAu25−x(SR)18 nanoparticles. This contrast can be attributed to the stability difference between CuxAu25−x(SR)18 and AgxAu25−x(SR)18 nanoparticles. These alloyed nanoparticles are promising candidates for applications such as catalysis.
Co-reporter:Chenjie Zeng, Chunyan Liu, Yong Pei, and Rongchao Jin
ACS Nano 2013 Volume 7(Issue 7) pp:6138
Publication Date(Web):June 12, 2013
DOI:10.1021/nn401971g
We report a disproportionation mechanism identified in the transformation of rod-like biicosahedral Au38(SCH2CH2Ph)24 to tetrahedral Au36(TBBT)24 nanoclusters. Time-dependent mass spectrometry and optical spectroscopy analyses unambiguously map out the detailed size-conversion pathway. The ligand exchange of Au38(SCH2CH2Ph)24 with bulkier 4-tert-butylbenzenethiol (TBBT) until a certain extent starts to trigger structural distortion of the initial biicosahedral Au38(SCH2CH2Ph)24 structure, leading to the release of two Au atoms and eventually the Au36(TBBT)24 nanocluster with a tetrahedral structure, in which process the number of ligands is interestingly preserved. The other product of the disproportionation process, i.e., Au40(TBBT)m+2(SCH2CH2Ph)24–m, was concurrently observed as an intermediate, which was the result of addition of two Au atoms and two TBBT ligands to Au38(TBBT)m(SCH2CH2Ph)24–m. The reaction kinetics on the Au38(SCH2CH2Ph)24 to Au36(TBBT)24 conversion process was also performed, and the activation energies of the structural distortion and disproportionation steps were estimated to be 76 and 94 kJ/mol, respectively. The optical absorption features of Au36(TBBT)24 are interpreted on the basis of density functional theory simulations.Keywords: density functional theory; disproportionation mechanism; gold nanoclusters; ligand-induced transformation
Co-reporter:Huifeng Qian, Manzhou Zhu, Zhikun Wu, and Rongchao Jin
Accounts of Chemical Research 2012 Volume 45(Issue 9) pp:1470
Publication Date(Web):June 21, 2012
DOI:10.1021/ar200331z
Gold nanoparticles typically have a metallic core, and the electronic conduction band consists of quasicontinuous energy levels (i.e. spacing δ ≪ kBT, where kBT is the thermal energy at temperature T (typically room temperature) and kB is the Boltzmann constant). Electrons in the conduction band roam throughout the metal core, and light can collectively excite these electrons to give rise to plasmonic responses. This plasmon resonance accounts for the beautiful ruby-red color of colloidal gold first observed by Faraday back in 1857.On the other hand, when gold nanoparticles become extremely small (<2 nm in diameter), significant quantization occurs to the conduction band. These quantum-sized nanoparticles constitute a new class of nanomaterial and have received much attention in recent years. To differentiate quantum-sized nanoparticles from conventional plasmonic gold nanoparticles, researchers often refer to the ultrasmall nanoparticles as nanoclusters.In this Account, we chose several typical sizes of gold nanoclusters, including Au25(SR)18, Au38(SR)24, Au102(SR)44, and Au144(SR)60, to illustrate the novel properties of metal nanoclusters imparted by quantum size effects. In the nanocluster size regime, many of the physical and chemical properties of gold nanoparticles are fundamentally altered. Gold nanoclusters have discrete electronic energy levels as opposed to the continuous band in plasmonic nanoparticles. Quantum-sized nanoparticles also show multiple optical absorption peaks in the optical spectrum versus a single surface plasmon resonance (SPR) peak at 520 nm for spherical gold nanocrystals. Although larger nanocrystals show an fcc structure, nanoclusters often have non-fcc atomic packing structures. Nanoclusters also have unique fluorescent, chiral, and magnetic properties.Due to the strong quantum confinement effect, adding or removing one gold atom significantly changes the structure and the electronic and optical properties of the nanocluster. Therefore, precise atomic control of nanoclusters is critically important: the nanometer precision typical of conventional nanoparticles is not sufficient. Atomically precise nanoclusters are represented by molecular formulas (e.g. Aun(SR)m for thiolate-protected ones, where n and m denote the respective number of gold atoms and ligands).Recently, major advances in the synthesis and structural characterization of molecular purity gold nanoclusters have made in-depth investigations of the size evolution of metal nanoclusters possible. Metal nanoclusters lie in the intermediate regime between localized atomic states and delocalized band structure in terms of electronic properties. We anticipate that future research on quantum-sized nanoclusters will stimulate broad scientific and technological interests in this special type of metal nanomaterial.
Co-reporter:Anindita Das ; Tao Li ; Katsuyuki Nobusada ; Qiong Zeng ; Nathaniel L. Rosi
Journal of the American Chemical Society 2012 Volume 134(Issue 50) pp:20286-20289
Publication Date(Web):December 10, 2012
DOI:10.1021/ja3101566
We report the synthesis and total structure determination of a Au24 nanocluster protected by mixed ligands of phosphine and thiolate. Single crystal X-ray crystallography and electrospray ionization mass spectrometry (ESI-MS) unequivocally determined the cluster formula to be [Au24(PPh3)10(SC2H4Ph)5X2]+, where X = Cl and/or Br. The structure consists of two incomplete (i.e., one vertex missing) icosahedral Au12 units joined by five thiolate linkages. This structure shows interesting differences from the previously reported vertex-sharing biicosahedral [Au25(PPh3)10(SC2H4Ph)5X2]2+ nanocluster protected by the same type and number of phosphine and thiolate ligands. The optical absorption spectrum of Au24 nanocluster was theoretically reproduced and interpreted.
Co-reporter:Huifeng Qian ; De-en Jiang ; Gao Li ; Chakicherla Gayathri ; Anindita Das ; Roberto R. Gil
Journal of the American Chemical Society 2012 Volume 134(Issue 39) pp:16159-16162
Publication Date(Web):September 19, 2012
DOI:10.1021/ja307657a
We report single-atom doping of gold nanoclusters (NCs), and its drastic effects on the optical, electronic, and catalytic properties, using the 25-atom system as a model. In our synthetic approach, a mixture of Pt1Au24(SC2H4Ph)18 and Au25(SC2H4Ph)18 was produced via a size-focusing process, and then Pt1Au24(SC2H4Ph)18 NCs were obtained by selective decomposition of Au25(SC2H4Ph)18 in the mixture with concentrated H2O2 followed by purification via size-exclusion chromatography. Experimental and theoretical analyses confirmed that Pt1Au24(SC2H4Ph)18 possesses a Pt-centered icosahedral core capped by six Au2(SC2H4Ph)3 staples. The Pt1Au24(SC2H4Ph)18 cluster exhibits greatly enhanced stability and catalytic activity relative to Au25(SC2H4Ph)18 but a smaller energy gap (Eg ≈ 0.8 eV vs 1.3 eV for the homogold cluster).
Co-reporter:Rongchao Jin, Sang-Kee Eah and Yong Pei
Nanoscale 2012 vol. 4(Issue 14) pp:4026-4026
Publication Date(Web):15 Jun 2012
DOI:10.1039/C2NR90052A
A graphical abstract is available for this content
Co-reporter:Santosh Kumar and Rongchao Jin
Nanoscale 2012 vol. 4(Issue 14) pp:4222-4227
Publication Date(Web):15 Jun 2012
DOI:10.1039/C2NR30833A
This work was motivated by the unsatisfactory stability of Au25(SG)18 in solution under thermal conditions (e.g. 70–90 °C for DNA melting). Thus, we searched for a better, water-soluble thiol ligand. Herein, we report a one-pot synthesis and investigation of the stability and optical properties of captopril (abbreviated Capt)-protected Au25(Capt)18 nanoclusters. The Au25(Capt)18 (anionic, counterion: Na+) nanoclusters were formed via size focusing under ambient conditions. Significantly, Au25(Capt)18 nanoclusters exhibit largely improved thermal stability compared to the glutathione (HSG) capped Au25(SG)18. Both Au25(Capt)18 and Au25(SG)18 nanoclusters show fluorescence centered at ∼700 nm. The chiral ligands (Capt, SG, as well as chirally modified phenylethanethiol (PET*)) give rise to distinct chiroptical features. The high thermal stability and distinct optical properties of Au25(Capt)18 nanoclusters render this material quite promising for biological applications.
Co-reporter:Gao Li, Huifeng Qian and Rongchao Jin
Nanoscale 2012 vol. 4(Issue 21) pp:6714-6717
Publication Date(Web):28 Sep 2012
DOI:10.1039/C2NR32171H
Thiolate-protected gold nanoclusters are explored for catalytic application in the selective oxidation of sulfide to sulfoxide by PhIO. The TiO2-supported Au25(SR)18 nanocluster catalysts give rise to high catalytic activity (e.g. ∼97% conv. of Ph–S–CH3 and ∼92% selectivity for Ph–S(O)–CH3 sulfoxide) and show excellent recyclability in the sulfoxidation process.
Co-reporter:Gao Li, Chao Liu, Yu Lei and Rongchao Jin
Chemical Communications 2012 vol. 48(Issue 98) pp:12005-12007
Publication Date(Web):05 Nov 2012
DOI:10.1039/C2CC34765B
The Au25(SR)18/CeO2 nanocluster catalyst showed high activity in the homocoupling of aryl iodides (e.g. up to 99.8% yield with iodobenzene) and excellent recyclability.
Co-reporter:Xiaotao Nie, Huifeng Qian, Qingjie Ge, Hengyong Xu, and Rongchao Jin
ACS Nano 2012 Volume 6(Issue 7) pp:6014
Publication Date(Web):June 12, 2012
DOI:10.1021/nn301019f
In this work, we explore the catalytic application of atomically monodisperse, thiolate-protected Au25(SR)18 (where R = CH2CH2Ph) nanoclusters supported on oxides for CO oxidation. The solution phase nanoclusters were directly deposited onto various oxide supports (including TiO2, CeO2, and Fe2O3), and the as-prepared catalysts were evaluated for the CO oxidation reaction in a fixed bed reactor. The supports exhibited a strong effect, and the Au25(SR)18/CeO2 catalyst was found to be much more active than the others. Interestingly, O2 pretreatment of the catalyst at 150 °C for 1.5 h significantly enhanced the catalytic activity. Since this pretreatment temperature is well below the thiolate desorption temperature (∼200 °C), the thiolate ligands should remain on the Au25 cluster surface, indicating that the CO oxidation reaction is catalyzed by intact Au25(SR)18/CeO2. We further found that increasing the O2 pretreatment temperature to 250 °C (above the thiolate desorption temperature) did not lead to any further increase in activity at all reaction temperatures from room temperature to 100 °C. These results are in striking contrast with the common thought that surface thiolates must be removed—as is often done in the literature work—before the catalyst can exert high catalytic activity. The 150 °C O2-pretreated Au25(SR)18/CeO2 catalyst offers ∼94% CO conversion at 80 °C and ∼100% conversion at 100 °C. The effect of water vapor on the catalytic performance is also investigated. Our results imply that the perimeter sites of the interface of Au25(SR)18/CeO2 should be the active centers. The intact structure of the Au25(SR)18 catalyst in the CO oxidation process allows one to gain mechanistic insight into the catalytic reaction.Keywords: Au25(SR)18 nanocluster; CO oxidation; pretreatment temperature; supported catalyst; water vapor
Co-reporter:HuiFeng Qian;Chao Liu
Science China Chemistry 2012 Volume 55( Issue 11) pp:2359-2365
Publication Date(Web):2012 November
DOI:10.1007/s11426-012-4669-8
We report the controlled growth of Au25(SR)18 and Au38(SR)24 (where R = CH2CH2Ph) nanoclusters of molecular purity via size-focusing from the same crude product that contains a distribution of nanoclusters. In this method, gold salt was first mixed with tetraoctylammonium bromide (TOAB), and then reacted with excess thiol to form Au(I)-SR polymers in THF (as opposed to toluene in previous work), followed by NaBH4 reduction. The resultant crude product contains polydisperse nanoclusters and was then used as the common starting material for controlled growth of Au25(SR)18 and Au38(SR)24, respectively. In Route I, Au25(SR)18 nanoclusters of molecular purify were produced from the crude product after 6 h aging at room temperature. In Route II, the crude product was isolated and further subjected to thermal thiol etching in a toluene solution containing excess thiol, and one obtained pure Au38(SR)24 nanoclusters, instead of Au25(SR)18. This work not only provides a robust and simple method to prepare both Au25(SR)18 and Au38(SR)24 nanoclusters, but also reveals that these two nanoclusters require different environments for the size-focusing growth process.
Co-reporter:Huifeng Qian;Yan Zhu
PNAS 2012 Volume 109 (Issue 3 ) pp:
Publication Date(Web):2012-01-17
DOI:10.1073/pnas.1115307109
Since Faraday’s pioneering work on gold colloids, tremendous scientific research on plasmonic gold nanoparticles has been
carried out, but no atomically precise Au nanocrystals have been achieved. This work reports the first example of gold nanocrystal
molecules. Mass spectrometry analysis has determined its formula to be Au333(SR)79 (R = CH2CH2Ph). This magic sized nanocrystal molecule exhibits fcc-crystallinity and surface plasmon resonance at approximately 520 nm,
hence, a metallic nanomolecule. Simulations have revealed that atomic shell closing largely contributes to the particular
robustness of Au333(SR)79, albeit the number of free electrons (i.e., 333 - 79 = 254) is also consistent with electron shell closing based on calculations
using a confined free electron model. Guided by the atomic shell closing growth mode, we have also found the next larger size
of extraordinarily stability to be Au∼530(SR)∼100 after a size-focusing selection—which selects the robust size available in the starting polydisperse nanoparticles. This
work clearly demonstrates that atomically precise nanocrystal molecules are achievable and that the factor of atomic shell
closing contributes to their extraordinary stability compared to other sizes. Overall, this work opens up new opportunities
for investigating many fundamental issues of nanocrystals, such as the formation of metallic state, and will have potential
impact on condensed matter physics, nanochemistry, and catalysis as well.
Co-reporter:Chenjie Zeng;Dr. Huifeng Qian;Tao Li;Dr. Gao Li; Nathaniel L. Rosi;Dr. Bokwon Yoon;Dr. Robert N. Barnett; Robert L. Whetten; Uzi Lman; Rongchao Jin
Angewandte Chemie International Edition 2012 Volume 51( Issue 52) pp:13114-13118
Publication Date(Web):
DOI:10.1002/anie.201207098
Co-reporter:Chenjie Zeng;Dr. Huifeng Qian;Tao Li;Dr. Gao Li; Nathaniel L. Rosi;Dr. Bokwon Yoon;Dr. Robert N. Barnett; Robert L. Whetten; Uzi Lman; Rongchao Jin
Angewandte Chemie 2012 Volume 124( Issue 52) pp:13291-13295
Publication Date(Web):
DOI:10.1002/ange.201207098
Co-reporter:Manzhou Zhu, Huifeng Qian, Xiangming Meng, Shenshen Jin, Zhikun Wu, and Rongchao Jin
Nano Letters 2011 Volume 11(Issue 9) pp:3963-3969
Publication Date(Web):August 11, 2011
DOI:10.1021/nl202288j
Chirality in nanoparticles is an intriguing phenomenon. Herein, we have devised a well-defined gold nanoparticle system for investigating the origin of chirality in nanoparticles. We have designed chiral thiols (R- and S-isomers) and synthesized chiral gold nanoparticles composed of 25 gold atoms and 18 ligands, referred to as Au25(pet*)18, where pet* represents chirally modified phenylethylthiolate −SCH2C*H(CH3)Ph at the 2-position. These optically active nanoparticles are close analogues of the optically nonactive phenylethylthioalte-capped Au25(pet)18 nanoparticles, and the latter’s crystal structure is known. On the basis of the atomic and electronic structures of these well-defined Au25 nanoparticles, we have explicitly revealed that the ligands and surface gold atoms of Au25(pet*)18 play a critical role in effecting the circular dichroism responses from the nanoparticles. Similar effects are also observed in chiral Au25 rods. The mixing of electronic states of ligands with those of surface gold atoms constitutes the fundamental origin of chirality in such nanoparticles.
Co-reporter:Zhikun Wu ; Mark A. MacDonald ; Jenny Chen ; Peng Zhang
Journal of the American Chemical Society 2011 Volume 133(Issue 25) pp:9670-9673
Publication Date(Web):June 2, 2011
DOI:10.1021/ja2028102
This work presents a combined approach of kinetic control and thermodynamic selection for the synthesis of monodisperse 19 gold atom nanoclusters protected by thiolate groups. The step of kinetic control allows the formation of a proper size distribution of initial size-mixed Aun(SR)m nanoclusters following the reduction of a gold precursor. Unlike the synthesis of Au25(SR)18 nanoclusters, which involves rapid reduction of the gold precursor by NaBH4 followed by size focusing, the synthesis of 19-atom nanoclusters requires slow reduction effected by a weaker reducing agent, borane–tert-butylamine complex. The initially formed mixture of nanoclusters then undergoes size convergence into a monodisperse product by means of a prolonged aging process. The nanocluster formula was determined to be Au19(SC2H4Ph)13. This work demonstrates the importance of both kinetic control of the initial size distribution of nanoclusters prior to size focusing and subsequent thermodynamic selection of stable nanoclusters as the final product.
Co-reporter:Zhikun Wu;Jenny Chen
Advanced Functional Materials 2011 Volume 21( Issue 1) pp:177-183
Publication Date(Web):
DOI:10.1002/adfm.201001120
Abstract
A one-pot synthesis of glutathione (denoted as -SG) capped gold nanoparticles, including Au25(SG)18 (ca. 1 nm in diameter) 2- and 4-nm particles is reported. These nanoparticles are isolated by methanol-induced precipitation with a controlled amount of added methanol. Except for their particle size, these nanoparticles have an identical chemical composition (i.e., gold and -SG content), synthetic history, and surface conditions, which allows for precise comparison of their size-dependent properties, in particular the magnetic property as this could be attributed to contamination by trace iron impurities. Specifically, the structure, optical, and magnetic properties of these gold nanoparticles are compared. A trend from non-fcc (fcc = face centered cubic) Au25(SG)18 nanoclusters (ca. 1 nm) to 2- and 4-nm fcc-crystalline Au nanocrystals is revealed. The Au25(SG)18 nanoparticles resemble molecules and exhibit multiple optical absorption peaks ascribed to one-electron transitions, whereas the 4-nm nanoparticles exhibit surface plasmon resonance at around 520 nm related to the collective excitation of conduction electrons upon optical excitation. The transition from the non-fcc cluster state to the fcc crystalline state occurs at around 2 nm. Interestingly, both 2- and 4-nm particles exhibit paramagnetism, whereas the Au25(SG)18 (anionic) clusters are diamagnetic. The information attained on the evolution of the properties of nanoparticles from nanoclusters to fcc-structured nanocrystals is of major importance and provides insight into structure—property relationships.
Co-reporter:Huifeng Qian and Rongchao Jin
Chemistry of Materials 2011 Volume 23(Issue 8) pp:2209
Publication Date(Web):March 23, 2011
DOI:10.1021/cm200143s
We report a facile, one-pot method for synthesizing atomically monodisperse Au144(SR)60 nanoclusters under ambient conditions. In this method, gold salt precursor is first mixed with excess thiol and tetraoctylammonium bromide (TOABr) in methanol to form Au(I)-SR polymers. Then, Au(I)-SR is reduced by excess NaBH4 (aqueous solution) to form nanoclusters. Interestingly, the initially formed, polydisperse Au nanoparticles are size-focused into two monodisperse gold nanoclusters: Au144(SR)60 (major product) and Au25(SR)18 (side product) over a ∼5 h period. The side product (Au25(SR)18) can be easily removed by washing the product with acetone, giving rise to pure Au144(SR)60. This method is applicable to a number of thiol ligands, including PhC2H4SH and various CnH2n+1SH (where n = 4−8). Some critical parameters to obtain pure Au144(SR)60 have been identified, including the methanol solvent (as opposed to toluene traditionally used), large thiol-to-Au ratios (≥4), the presence of O2 and tetraoctylammonium halide (TOAX, where X = Br, Cl). The facile synthetic method and the product made by this method should largely contribute to the practical application of this new type of nanomaterial.Keywords: atomic precision; Au144(SR)60; gold; nanoclusters;
Co-reporter:Yan Zhu, Huifeng Qian and Rongchao Jin
Journal of Materials Chemistry A 2011 vol. 21(Issue 19) pp:6793-6799
Publication Date(Web):24 Mar 2011
DOI:10.1039/C1JM10082C
Nanogold has been found to be an effective catalyst for many chemical reactions. However, mechanistic studies have thus far only met with limited success, largely due to the unavailability of well-defined catalysts. We are motivated to create atomically precise gold (Au) nanoclusters in the hope of unraveling some fundamental aspects of nanogold catalysis. In this feature article, we summarize recent works on the catalytic promise of a new class of materials: ultrasmall (<2 nm), semiconducting Au nanoclusters protected by thiolates, referred to as Aun(SR)m, where n and m represent the number of gold atoms and thiolate ligands, respectively. The recent research is focused on the synthesis and structural determination of atomically precise Aun(SR)m nanoclusters as well as exploring their catalytic properties. The correlation of the X-ray crystal structures of the Aun(SR)m nanoclusters with their catalytic properties will ultimately permit a deep understanding of the origin of nanogold catalysis and will also benefit the future design of new catalysts with high selectivity and activity.
Co-reporter:Huifeng Qian and Rongchao Jin
Chemical Communications 2011 vol. 47(Issue 41) pp:11462-11464
Publication Date(Web):26 Sep 2011
DOI:10.1039/C1CC15099E
Since the pioneering work of Schmid et al. on phosphine-capped Au55 clusters, the search for thiolated Au55 has long been of major interest. This work reports the synthesis and electrospray ionization mass spectrometry (ESI-MS) evidence of Au55(SCH2CH2Ph)31 clusters.
Co-reporter:Huifeng Qian ; William T. Eckenhoff ; Mark E. Bier ; Tomislav Pintauer
Inorganic Chemistry 2011 Volume 50(Issue 21) pp:10735-10739
Publication Date(Web):October 11, 2011
DOI:10.1021/ic2012292
We previously reported a size-focusing conversion of polydisperse gold nanoparticles capped by phosphine into monodisperse [Au25(PPh3)10(SC2H4Ph)5Cl2]2+ nanoclusters in the presence of phenylethylthiol. Herein, we have determined the crystal structure of [Au25(PPh3)10(SC2H4Ph)5Cl2]2+ nanoclusters and also identified an important side-product—a Au(I) complex formed in the size focusing process. The [Au25(PPh3)10(SC2H4Ph)5Cl2]2+ cluster features a vertex-sharing bi-icosahedral core, resembling a rod. The formula of the Au(I) complex is determined to be [Au2(PPh3)2(SC2H4Ph)]+ by electrospray ionization (ESI) mass spectrometry, and its crystal structure (with SbF6– counterion) reveals Au–Au bridged by −SC2H4Ph and with terminal bonds to two PPh3 ligands. Unlike previously reported [Au2(PR3)2(SC2H4Ph)]+ complexes in the solid state, which exist as tetranuclear complexes (i.e., dimers of [Au2(PR3)2(SC2H4Ph)]+ units) through a Au···Au aurophilic interaction, in our case we found that the [Au2(PPh3)2(SC2H4Ph)]+ complex exists as a single entity, rather than being dimerized to form a tetranuclear complex. The observation of this Au(I) complex allows us to gain insight into the intriguing conversion process from polydisperse Au nanoparticles to monodisperse Au25 nanoclusters.
Co-reporter: Rongchao Jin;Yan Zhu ;Huifeng Qian
Chemistry - A European Journal 2011 Volume 17( Issue 24) pp:6584-6593
Publication Date(Web):
DOI:10.1002/chem.201002390
Abstract
This Concept article provides an elementary discussion of a special class of large-sized gold compounds, so-called Au nanoclusters, which lies in between traditional organogold compounds (e.g., few-atom complexes, <1 nm) and face-centered cubic (fcc) crystalline Au nanoparticles (typically >2 nm). The discussion is focused on the relationship between them, including the evolution from the Au⋅⋅⋅Au aurophilic interaction in AuI complexes to the direct AuAu bond in clusters, and the structural transformation from the fcc structure in nanocrystals to non-fcc structures in nanoclusters. Thiolate-protected Aun(SR)m nanoclusters are used as a paradigm system. Research on such nanoclusters has achieved considerable advances in recent years and is expected to flourish in the near future, which will bring about exciting progress in both fundamental scientific research and technological applications of nanoclusters of gold and other metals.
Co-reporter:Huifeng Qian, Manzhou Zhu, Chakicherla Gayathri, Roberto R. Gil, and Rongchao Jin
ACS Nano 2011 Volume 5(Issue 11) pp:8935
Publication Date(Web):October 7, 2011
DOI:10.1021/nn203113j
We report the analysis of chirality in atomically precise gold nanoclusters by nuclear magnetic resonance (NMR) spectroscopic probing of the surface ligands. The Au38(SR)24 and Au25(SR)18 (where, R = CH2CH2Ph) are used as representative models for chiral and nonchiral nanoclusters, respectively. Interestingly, different 1H signals for the two germinal protons in each CH2 of the ligands on the chiral Au38(SR)24 nanocluster were observed, so-called diastereotopicity. For α-CH2 (closest to the chiral metal core), a chemical shift difference of up to ∼0.8 ppm was observed. As for the nonchiral Au25(SCH2CH2Ph)18–TOA+ nanocluster, no diastereotopicity was detected (i.e., no chemical shift difference for the two protons in the CH2), confirming the Au25 core being nonchiral. These two typical examples demonstrate that NMR spectroscopy can be a useful tool for investigating chirality in Au nanoclusters. Since the diastereotopicity induced on the methylene protons by chiral nanoclusters is independent of the enantiomeric composition of the chiral particles, NMR can probe the chirality of the nanoclusters even in the case of a racemic mixture, while circular dichroism spectroscopy is not useful for racemic mixtures.Keywords: chirality; diastereotopicity; gold nanoclusters; NMR
Co-reporter:Yan Zhu;Huifeng Qian;Manzhou Zhu
Advanced Materials 2010 Volume 22( Issue 17) pp:1915-1920
Publication Date(Web):
DOI:10.1002/adma.200903934
Co-reporter:Zhikun Wu and Rongchao Jin
Nano Letters 2010 Volume 10(Issue 7) pp:2568-2573
Publication Date(Web):June 15, 2010
DOI:10.1021/nl101225f
The fluorescence of metal nanoparticles (such as gold and silver) has long been an intriguing topic and has drawn considerable research interest. However, the origin of fluorescence still remains unclear. In this work, on the basis of atomically monodisperse, 25-atom gold nanoclusters we present some interesting results on the fluorescence from [Au25(SR)18]q (where q is the charge state of the particle), which has shed some light on this issue. Our work explicitly shows that the surface ligands (-SR) play a major role in enhancing the fluorescence of gold nanoparticles. Specifically, the surface ligands can influence the fluorescence in two different ways: (i) charge transfer from the ligands to the metal nanoparticle core (i.e., LMNCT) through the Au−S bonds, and (ii) direct donation of delocalized electrons of electron-rich atoms or groups of the ligands to the metal core. Following these two mechanisms, we have demonstrated strategies to enhance the fluorescence of thiolate ligand-protected gold nanoparticles. This work is hoped to stimulate more experimental and theoretical research on the atomic level design of luminescent metal nanoparticles for promising optoelectronic and other applications.
Co-reporter:Huifeng Qian ; William T. Eckenhoff ; Yan Zhu ; Tomislav Pintauer
Journal of the American Chemical Society 2010 Volume 132(Issue 24) pp:8280-8281
Publication Date(Web):June 1, 2010
DOI:10.1021/ja103592z
We report the total structure of Au38(SC2H4Ph)24 nanoparticles determined by single crystal X-ray crystallography. This nanoparticle is based upon a face-fused Au23 biicosahedral core, which is further capped by three monomeric Au(SR)2 staples at the waist of the Au23 rod and six dimeric staples with three on the top icosahedron and other three on the bottom icosahedron. The six Au2(SR)3 staples are arranged in a staggered configuration, and the Au38S24 framework has a C3 rotation axis.
Co-reporter:Huifeng Qian ; Yan Zhu
Journal of the American Chemical Society 2010 Volume 132(Issue 13) pp:4583-4585
Publication Date(Web):March 11, 2010
DOI:10.1021/ja1006383
We report chromatographic isolation of a new thiolate-protected gold cluster species from the ∼8 kDa Aun(SR)m clusters. This new cluster is separated by size-exclusion chromatography from Au38(SC2H4Ph)24 (a previously reported main component in the ∼8 kDa gold−thiolate species). Based on detailed MALDI and ESI mass spectrometry analyses, the new cluster possesses a core mass of ∼8.6 kDa and its formula is determined to be Au40(SC2H4Ph)24. The Au40(SR)24 species is also found to exist in other thiolate systems, including —SR═SC6H13 and SC5H11, indicating that Au40(SR)24 is a ubiquitous cluster as is Au38(SR)24.
Co-reporter:Rongchao Jin
Nanoscale 2010 vol. 2(Issue 3) pp:343-362
Publication Date(Web):08 Dec 2009
DOI:10.1039/B9NR00160C
The scientific study of gold nanoparticles (typically 1–100 nm) has spanned more than 150 years since Faraday's time and will apparently last longer. This review will focus on a special type of ultrasmall (<2 nm) yet robust gold nanoparticles that are protected by thiolates, so-called gold thiolate nanoclusters, denoted as Aun(SR)m (where, n and m represent the number of gold atoms and thiolate ligands, respectively). Despite the past fifteen years' intense work on Aun(SR)m nanoclusters, there is still a tremendous amount of science that is not yet understood, which is mainly hampered by the unavailability of atomically precise Aun(SR)m clusters and by their unknown structures. Nonetheless, recent research advances have opened an avenue to achieving the precise control of Aun(SR)m nanoclusters at the ultimate atomic level. The successful structural determination of Au102(SPhCOOH)44 and [Au25(SCH2CH2Ph)18]q (q = −1, 0) by X-ray crystallography has shed some light on the unique atomic packing structure adopted in these gold thiolate nanoclusters, and has also permitted a precise correlation of their structure with properties, including electronic, optical and magnetic properties. Some exciting research is anticipated to take place in the next few years and may stimulate a long-lasting and wider scientific and technological interest in this special type of Au nanoparticles.
Co-reporter:Rongchao Jin Dr.
Angewandte Chemie International Edition 2010 Volume 49( Issue 16) pp:2826-2829
Publication Date(Web):
DOI:10.1002/anie.200906462
Co-reporter:Ashok Mohanty Dr.;Niti Garg Dr.
Angewandte Chemie International Edition 2010 Volume 49( Issue 29) pp:4962-4966
Publication Date(Web):
DOI:10.1002/anie.201000902
Co-reporter:Manzhou Zhu, Huifeng Qian and Rongchao Jin
The Journal of Physical Chemistry Letters 2010 Volume 1(Issue 6) pp:1003-1007
Publication Date(Web):March 2, 2010
DOI:10.1021/jz100133n
We report a new gold thiolate cluster with molecular purity. Electrospray ionization (ESI) mass spectrometry in conjunction with thermogravimetric analysis (TGA), elemental analysis (EA), and 1H NMR, unambiguously determined the composition of the as-prepared Au nanocluster to be Au24(SC2H4Ph)20. The optical absorption spectrum of this cluster shows a highest occupied molecular orbital to lowest unoccupied molecular orbital (HOMO−LUMO) transition at 765 nm, indicating quantum confinement of electrons in the particle. The HOMO−LUMO gap (∼1.5 eV) of Au24(SR)20 is much smaller than that of Au20(SR)16 (∼2.1 eV) but slightly larger than that of Au25(SR)18 (∼1.3 eV). The number of valence electrons in Au24(SC2H4Ph)20 is 4e, which is not predicted by the superatom model.Keywords (keywords): Au24(SR)20; gold; nanocluster; size control; thiolate;
Co-reporter:Niti Garg, Clark Scholl, Ashok Mohanty and Rongchao Jin
Langmuir 2010 Volume 26(Issue 12) pp:10271-10276
Publication Date(Web):April 15, 2010
DOI:10.1021/la100446q
We report our findings on the important role of bromide ions in the seeding growth process of Au nanorods. The seed-mediated process constitutes a well-developed method for synthesizing gold nanorods in high yield, which is facilitated by a micelle-forming surfactant, cetyltrimethylammonium bromide (CTA-Br). Despite the tremendous work in recent years, the growth mechanism of Au nanorods has not been fully understood. Contrary to the widely accepted mechanism of CTA+ micelle-templated growth of Au nanorods, we have identified the critical role of bromide ions in the seeding growth of Au nanorods. We found that even when the micelle-forming agent (CTA+) concentration is below its critical micelle concentration (cmc), bromide ions added in the form of NaBr can successfully effect the growth of Au nanorods in good yield. By controlling the concentration of externally added bromide ions, the rod shape and dimensions of the resulting Au nanoparticles can be readily controlled in the presence of only a minimum amount of CTABr (as a steric stabilizer for nanorods). High-resolution TEM studies show that the as-formed nanorods are perfectly single crystalline, instead of penta-twinned ones, and are bound by {111} and {100} facets with a [110] direction as the elongation direction. A mechanism is proposed to account for the seeding growth of single crystalline Au nanorods. Overall, this work explicitly demonstrates that Br− indeed serves as an important shape-directing agent for gold nanorod formation in the seed-mediated process.
Co-reporter:Yan Zhu Dr.;Huifeng Qian;BethanyA. Drake
Angewandte Chemie International Edition 2010 Volume 49( Issue 7) pp:1295-1298
Publication Date(Web):
DOI:10.1002/anie.200906249
Co-reporter:Rongchao Jin Dr.
Angewandte Chemie 2010 Volume 122( Issue 16) pp:2888-2892
Publication Date(Web):
DOI:10.1002/ange.200906462
Co-reporter:Yan Zhu Dr.;Huifeng Qian;BethanyA. Drake
Angewandte Chemie 2010 Volume 122( Issue 7) pp:1317-1320
Publication Date(Web):
DOI:10.1002/ange.200906249
Co-reporter:Dr. Yan Zhu;Huifeng Qian ; Rongchao Jin
Chemistry - A European Journal 2010 Volume 16( Issue 37) pp:11455-11462
Publication Date(Web):
DOI:10.1002/chem.201001086
Abstract
An atomic-level strategy is devised to gain insight into the origin of nanogold catalysis by using atomically monodisperse Aun(SR)m nanoclusters as well-defined catalysts for styrene oxidation. The Aun(SR)m nanoclusters are emerging as a new class of gold nanocatalyst to overcome the polydispersity of conventional nanoparticle catalysts. The unique atom-packing structure and electronic properties of Aun(SR)m nanoclusters (<2 nm) are rationalized to be responsible for their extraordinary catalytic activity observed in styrene oxidation. An interesting finding is that quantum size effects of Aun(SR)m nanoclusters, rather than the higher specific surface area, play a major role in gold-catalyzed selective oxidation of styrene. For example, Au25(SR)18 nanoclusters (≈1 nm) are found to be particularly efficient in activating O2, which is a key step in styrene oxidation, and hence, the ultrasmall Au25 catalyst exhibits higher activity than do larger sizes. This atomic-level strategy has allowed us to obtain an important insight into some fundamental aspects of nanogold catalysis in styrene oxidation. The ultrasmall yet robust Aun(SR)m nanoclusters are particularly promising for studying the mechanistic aspects of nanogold catalysis and for future design of better catalysts with high activity and selectivity for certain chemical processes.
Co-reporter:Huifeng Qian ; Matthew Y. Sfeir
The Journal of Physical Chemistry C 2010 Volume 114(Issue 47) pp:19935-19940
Publication Date(Web):November 4, 2010
DOI:10.1021/jp107915x
The ultrafast electron relaxation dynamics of anionic and neutral Au25(SR)18 nanoclusters are investigated using broad-band time-resolved optical spectroscopy. From an analysis of the wavelength-dependent transient absorption kinetics, we have obtained valuable information on the spectral features that originate from excitation of “core” and “core−shell” states. In both clusters, photoexcitation occurs into two nondegenerate states near the HOMO−LUMO gap that are derived from the core orbitals. A large difference in the lifetime of the core excitations is observed, with [Au25(SR)18]− exhibiting a decay rate more than 1000 times slower than the neutral cluster. Both clusters show strong coupling to two different coherent phonon modes, which are observed at 2.4 and 1.2 THz. The electron−phonon coupling is analyzed in terms of the spectral distribution and damping of the coherent modes.
Co-reporter:Zhikun Wu, De-en Jiang, Eric Lanni, Mark E. Bier and Rongchao Jin
The Journal of Physical Chemistry Letters 2010 Volume 1(Issue 9) pp:1423-1427
Publication Date(Web):April 15, 2010
DOI:10.1021/jz100317w
Recently we reported synthesis and characterization of a monodisperse thiolate-protected Ag7 cluster. Here we show in detail that a unique series of silver sulfide cluster anions (AgnS4−) were observed sequentially from n = 7 to 1 when subjecting the thiolate-protected Ag7 cluster to an MS/MS experiment. Random silver cluster anion distributions were not observed in a wide range of collision energies. This indicates the special structure and stability of these gas phase AgnS4− clusters. Global minimum search based on density functional theory-enabled basin hopping has yielded the most stable structures for AgnS4− (1 ≤ n ≤ 7). The global minima show a transition from three-dimensional to two-dimensional and then to one-dimensional geometry with decreasing n for AgnS4− clusters. This joint experimental and computational effort provides a pathway to discover and elucidate metal-sulfide clusters of unique stoichiometry, which are not accessible through conventional methods such as laser ablation of mixed metal and sulfur powders.Keywords (keywords): density functional theory; MS/MS; S4; silver sulfide cluster anion; structure;
Co-reporter:Rongchao Jin, Huifeng Qian, Zhikun Wu, Yan Zhu, Manzhou Zhu, Ashok Mohanty, and Niti Garg
The Journal of Physical Chemistry Letters 2010 Volume 1(Issue 19) pp:2903-2910
Publication Date(Web):September 16, 2010
DOI:10.1021/jz100944k
Controlling nanoparticles with atomic precision, somewhat like the way organic chemists control small molecules by organic chemistry principles, is highly desirable for nanoparticle chemists. Recent advances in the synthesis of gold nanoparticles have opened the possibility to precisely control the number of gold atoms in a particle. In this Perspective, we will discuss a size-focusing methodology that has been developed in the synthesis of a number of atomically monodisperse ultrasmall gold nanoparticles (also called nanoclusters). We focus our discussion on thiolate-stabilized Au nanoclusters (referred to as Aun(SR)m, where n and m are the respective number of metal atoms and ligands). The underlying principle of this size-focusing process is primarily related to the peculiar stability of certain sized Aun(SR)m nanoparticle, that is, “survival of the robustest”, much like the natural law “survival of the fittest”. We expect that this universal size-focusing method will ultimately allow for preparing a full series of size-discrete, atomically monodisperse nanoparticles that span the size regimes of both nonplasmonic nanoclusters and plasmonic nanocrystals. These well-defined nanoparticles will be of major importance for both fundamental science research and technological applications.
Co-reporter:Huifeng Qian and Rongchao Jin
Nano Letters 2009 Volume 9(Issue 12) pp:4083-4087
Publication Date(Web):2017-2-22
DOI:10.1021/nl902300y
We report a facile, two-step synthetic method for preparing truly monodiserse Au144(SCH2CH2Ph)60 nanoparticles with their formula determined by electrospray mass spectrometry in conjunction with other characterization. A remarkable advantage of our synthetic approach lies in that it solely produces Au144(SCH2CH2Ph)60 nanoparticles, hence, eliminating nontrivial, postsynthetic steps of size separation, which has proven to be very difficult. This advantage makes the approach and the type of nanoparticles generated by it of broad utility for practical applications. Unlike their larger counterparts, Au nanocrystals (typically >2 nm) that are crystalline and show a prominent surface plasmon resonance band at ∼520 nm (for spherical particles), the Au144(SCH2CH2Ph)60 nanoparticles instead exhibit a stepwise, multiple-band absorption spectrum, indicating quantum confinement of electrons in the particle. In addition, these ultrasmall nanoparticles do not adopt face-centered cubic structure as in Au nanocrystals or bulk gold.
Co-reporter:Zhikun Wu ; Eric Lanni ; Wenqian Chen ; Mark E. Bier ; Danith Ly
Journal of the American Chemical Society 2009 Volume 131(Issue 46) pp:16672-16674
Publication Date(Web):November 3, 2009
DOI:10.1021/ja907627f
We report a high yielding synthesis of truly monodisperse, thiolate-protected silver clusters via a rationally designed approach. The cluster composition was determined by electrospray ionization (ESI) mass spectrometry to be Ag7(DMSA)4, where DMSA represents meso-2,3-dimercaptosuccinic acid. The Ag7 thiolate clusters exhibit distinct optical properties. The approach developed in this work provides some insight into the cluster growth kinetics and may be extendable to the synthesis of other sized silver nanoclusters.
Co-reporter:Manzhou Zhu ; Huifeng Qian
Journal of the American Chemical Society 2009 Volume 131(Issue 21) pp:7220-7221
Publication Date(Web):May 11, 2009
DOI:10.1021/ja902208h
We report a kinetically controlled approach to synthesizing thiolate-capped 20-atom gold clusters. ESI mass spectrometry analysis in combination with other methods, including elemental analysis, XPS, NMR, and thermogravimetric analysis, determines the cluster composition to be Au20(SCH2CH2Ph)16. The Au20(SCH2CH2Ph)16 clusters exhibit a stepwise, multiple-band optical absorption spectrum, reminiscent of quantum confinement behavior. The optical energy gap is determined to be Eg ≈ 2.15 eV; this HOMO−LUMO gap is remarkably larger than that of Au25(SR)18 (1.3 eV). The Au20(SCH2CH2Ph)16 clusters were also found to be particularly robust again excess thiol etching, in contrast to the previous report on the thiol etching stability of a series of glutathione-capped Aun(SG)m (n < 25) clusters. This stability difference might indicate some structural differences between Au20(SCH2CH2Ph)16 and Aun(SG)m (n < 25). The crystal structure of the Au20(SCH2CH2Ph)16 cluster remains to be unraveled in future work.
Co-reporter:Zhikun Wu ; Chakicherla Gayathri ; Roberto R. Gil
Journal of the American Chemical Society 2009 Volume 131(Issue 18) pp:6535-6542
Publication Date(Web):April 20, 2009
DOI:10.1021/ja900386s
Despite the recent crystallographic determination of the crystal structure of Au25(SCH2CH2Ph)18 clusters, the question−whether all thiolate-capped, 25-atom gold clusters adopt the same structure, regardless of the types of thiols (e.g., long-chain alkylthiols, aromatic thiols, or other functionalized ones)−still remains unanswered. To crystallize long-chain or bulky ligand (e.g., glutathione)-capped Au25(SR)18 clusters has proven to be difficult due to the major amorphousness caused by such ligands; therefore, one needs to seek other strategies to probe the structural information of such gold clusters. Herein, we report a strategy to probe the Au25 core structure and surface thiolate ligand distribution by means of NMR in combination with mass spectrometry. We use glutathione-capped Au25(SG)18 clusters as an example to demonstrate the utility of this strategy. One-dimensional (1D) and two-dimensional (2D) correlation NMR spectroscopic investigation of Au25(SG)18 reveals fine spectral features that explicitly indicate two types of surface binding modes of thiolates, which is consistent with the ligand distribution in the Au25(SCH2CH2Ph)18 cluster. Laser desorption ionization (LDI) mass spectrometry analysis shows that Au25(SG)18 exhibits an identical ionization and core fragmentation pattern with phenylethylthiolate-capped Au25 clusters. The charge state of the native Au25(SG)18 clusters was determined to be −1 by comparing their optical spectrum with those of [Au25(SCH2CH2Ph)18]q of different charge states (q = −1, 0). Taken together, our results led to the conclusion that glutathione-capped Au25(SG)18 clusters indeed adopt the same structure as that of Au25(SCH2CH2Ph)18. This conclusion is also valid for other types of thiolate-capped Au25 clusters, including hexyl- and dodecylthiolates. Interestingly, the chiral optical responses (e.g., circular dichroism (CD) signals in the visible wavelength region) from the Au25(SG)18 clusters seem to be imparted by the chiral glutathione ligands because no similar CD signals were observed in Au25(SCH2CH2Ph)18.
Co-reporter:Zhikun Wu, Joseph Suhan and Rongchao Jin
Journal of Materials Chemistry A 2009 vol. 19(Issue 5) pp:622-626
Publication Date(Web):12 Dec 2008
DOI:10.1039/B815983A
We report a one-pot method for synthesizing atomically monodisperse Au25 nanoclusters stabilized with various functionalized thiols. This approach permits facile incorporation of specific functionality [such as –OH, –COOH, and atom transfer radical polymerization initiator –OC(O)C(CH3)2Br] into the protecting thiol ligand shell and provides convenient access to new types of Au25 nanoclusters inaccessible by the previous two-phase approach. Importantly, a distinct “size-focusing” process was identified in the growth process of Au25 nanoclusters in the one-pot reaction. This facile, one-pot synthesis of thiol-functionalized Au25 nanoclusters allows for the development of specific surface chemistry for practical applications of such nanoclusters, such as bioconjugation, sensing, and surface polymerization, and thus makes the approach and the Au25 nanoclusters of broad utility.
Co-reporter:Huifeng Qian, Manzhou Zhu, Eric Lanni, Yan Zhu, Mark E. Bier and Rongchao Jin
The Journal of Physical Chemistry C 2009 Volume 113(Issue 41) pp:17599-17603
Publication Date(Web):September 16, 2009
DOI:10.1021/jp9073152
We report a facile conversion of polydisperse Au nanoparticles (1−3.5 nm) into well-defined monodisperse 25-atom (Au25) nanorods and nanospheres via one-phase and two-phase thiol etching, respectively. Our method involves two main steps: first, small Au nanoparticles (polydisperse, predominantly 1−3.5 nm) were prepared by NaBH4 reduction of Au(III) salt in the presence of triphenylphosphine; subsequently, these polydisperse Au nanoparticles were used as a common precursor for shape-controlled synthesis of Au25 nanorods and nanospheres following one-phase and two-phase thiol etching, respectively. Our results demonstrate that the Au25 particle shape can be conveniently controlled by using different types of thiol ligands in the second step of thiol etching. These ultrasmall Au25 nanoparticles do not support surface plasmons as do their larger counterparts (i.e., Au nanocrystals); instead, they exhibit molecular-like optical absorption behavior. This conversion process is striking in two features, size focusing and shape control, and may be extendable to the synthesis of other robust well-defined Au nanoclusters.
Co-reporter:Huifeng Qian, Yan Zhu and Rongchao Jin
ACS Nano 2009 Volume 3(Issue 11) pp:3795
Publication Date(Web):October 27, 2009
DOI:10.1021/nn901137h
We report a facile, high yielding synthetic method for preparing truly monodisperse Au38(SC2H4Ph)24 nanoclusters. The synthetic approach involves two main steps: first, glutathionate (−SG) protected polydisperse Aun clusters (n ranging from 38 to ∼102) are synthesized by reducing Au(I)−SG in acetone; subsequently, the size-mixed Aun clusters react with excess phenylethylthiol (PhC2H4SH) for ∼40 h at 80 °C, which leads to Au38(SC2H4Ph)24 clusters of molecular purity. Detailed studies by mass spectrometry and UV−vis spectroscopy explicitly show a gradual size-focusing process occurred in the thermal etching-induced growth process. The formula and molecular purity of Au38(SC2H4Ph)24 clusters are confirmed by electrospray ionization (ESI) and matrix-assisted laser desorption ionization (MALDI) mass spectrometry, and size-exclusion chromatography. The optical and electrochemical properties of Au38(SC2H4Ph)24 clusters show molecule-like behavior and the HOMO−LUMO gap of the cluster was determined to be ∼0.9 eV. The size focusing growth process is particularly interesting and may be exploited to synthesize other robust gold thiolate clusters.Keywords: Au38; gold clusters; monodispersity; stability; thiolate
Co-reporter:Zhikun Wu and Rongchao Jin
ACS Nano 2009 Volume 3(Issue 7) pp:2036
Publication Date(Web):June 23, 2009
DOI:10.1021/nn9004999
This report presents a detailed investigation on the structural stability of the Au25(SG)18 nanoclusters (where, −SG represents glutathionate) with a focus on the oxidation resistance and thermal stability of the Au−S bonds in the cluster. Two types of Au−S binding modes were previously indentified in the crystal structure of phenylethylthiolate-capped Au25 clusters, and the Au25(SG)18 nanoclusters have been confirmed to adopt the same structure as Au25(SCH2CH2Ph)18 in our previous works. Herein, NMR in combination with optical spectroscopy revealed some distinct differences in both antioxidation and thermal stability of the two Au−S binding modes in the Au25(SG)18 nanocluster, that is, the mode I thiolate ligands (total 12 ligands) exhibit a much higher stability than the mode II ligands (total 6 ligands). Upon the basis of this major observation as well as an abundant [Au25S12]− species detected in laser desorption ionization (LDI) mass spectrometry analysis of Au25(SG)18 clusters, a metastable species similar to Au25(SG)12 (i.e., a loss of six type II ligands of −SG) may exist in the processes of oxidation and thermal treatment. Overall, this work provides a deep insight into the intriguing structure of thiolate-capped Au25 clusters, which will benefit future studies pertaining to the potential applications of such nanoclusters.Keywords: Au−S binding; gold cluster; NMR; stability
Co-reporter:Huifeng Qian, Manzhou Zhu, Ulla N. Andersen and Rongchao Jin
The Journal of Physical Chemistry A 2009 Volume 113(Issue 16) pp:4281-4284
Publication Date(Web):February 12, 2009
DOI:10.1021/jp810893w
It has long been a major challenge to achieve synthetic control over size and monodispersity of gold thiolate nanoclusters. Among the reported Aun thiolate clusters, Au38 has been shown to be particularly stable but was only obtained as a minor product in previous syntheses. In this work, we report a bulk solution synthetic method that permits large-scale, facile synthesis of truly monodisperse Au38 nanoclusters. This new method explores a two-phase ligand exchange process utilizing glutathione-capped Aun clusters as the starting material. The ligand exchange process with neat dodecanethiols causes gold core etching and secondary growth of clusters, and eventually leads to monodisperse Au38 clusters in high purity, which eliminates nontrivial postsynthetic separation steps. This method can be readily scaled up to synthesize Au38(SC12H25)24 in large quantities and thus makes the approach and Au38 nanoclusters of broad utility.
Co-reporter:Rongchao Jin Dr.
Angewandte Chemie International Edition 2008 Volume 47( Issue 36) pp:6750-6753
Publication Date(Web):
DOI:10.1002/anie.200801301
Co-reporter:Manzhou Zhu ; William T. Eckenhoff ; Tomislav Pintauer
The Journal of Physical Chemistry C 2008 Volume 112(Issue 37) pp:14221-14224
Publication Date(Web):August 21, 2008
DOI:10.1021/jp805786p
We report a solution-phase conversion process of the [Au25(SCH2CH2Ph)18]− anionic cluster into a charge neutral cluster [Au25(SCH2CH2Ph)18]0 via air oxidation. The one-electron loss of the Au25− cluster and conversion to Au250 is a surprise in light of the chemical inertness of gold nanoparticles. In contrast with the crystal structure of the anion cluster Au25−, which exhibits apparent structural distortions in the Au25S18 framework, such distortions are not observed in the neutral cluster. The cluster charge effect is also manifested in the optical absorption spectra of the clusters. Given the only recently reported structure of the parent Au25− cluster, it is of substantial interest whether its one-electron oxidized product is similar to that of Au25−. This work unambiguously determined the structure of the one-electron oxidized product and correlates the structure with the optical properties.
Co-reporter:Rongchao Jin Dr.
Angewandte Chemie 2008 Volume 120( Issue 36) pp:6852-6855
Publication Date(Web):
DOI:10.1002/ange.200801301
Co-reporter:Gao Li, De-en Jiang, Chao Liu, Changlin Yu, Rongchao Jin
Journal of Catalysis (October 2013) Volume 306() pp:177-183
Publication Date(Web):1 October 2013
DOI:10.1016/j.jcat.2013.06.017
•Explored 25-gold-atom nanoclusters (1.3 nm) for catalyzing Sonogashira cross-coupling.•Obtained high conversion of p-iodoanisole (96.1%) and excellent selectivity (88.1%).•Provided an important clue as to the catalytically active site.We report that thiolate-protected Au25(SR)18 (R = CH2CH2Ph) nanoclusters supported on oxides (such as CeO2, TiO2, MgO, and SiO2) can catalyze Sonogashira cross-coupling reaction between phenylacetylene andp-iodoanisole with high conversion of p-iodoanisole (up to 96.1%) and excellent selectivity (up to 88.1%). The well-defined structure of Au25(SR)18 provides an important clue as to the catalytically active sites: the sterically unhindered facets on the cluster surface allow easy reactant access; each facet comprises three surface gold atoms from three separate “staple”-like –S(R)–Au–S(R)–Au–S(R)– surface-protecting motifs. Density functional theory modeling of the reactant adsorption shows that both reactants prefer to adsorb on the open facet with the phenyl ring facing a surface gold atom. Each reactant has an adsorption energy of −0.40 to −0.48 eV. When they co-adsorb on the catalyst, the total adsorption energy reaches −0.90 eV (a relatively strong adsorption state); more interestingly, at this state the two reactants are well positioned to couple with their Ph–CCH and Ph–I groups pointing toward the third gold atom of the open facet. The combined experimental and DFT results suggest a great potential to correlate the atomic configuration of the active sites to the catalytic performance of an atomically precise nanocluster.Graphical abstractDownload high-res image (193KB)Download full-size image
Co-reporter:Changlin Yu, Wanqin Zhou, Lihua Zhu, Gao Li, Kai Yang, Rongchao Jin
Applied Catalysis B: Environmental (5 May 2016) Volume 184() pp:
Publication Date(Web):5 May 2016
DOI:10.1016/j.apcatb.2015.11.026
•Dendritic α-Bi2O3/Bi2O2CO3 biphasic heterostructures.•Plasmonic Au NPs and Au NRs with different length and diameter.•Synergetic effect of α-Bi2O3/Bi2O2CO3 interface and SPR of Au NSs or Au NRs.•Au NSs brought ∼4 times increase in activity and Au NRs 5–11 times.To explore the relationship between semiconductor structure and plasmonic noble metal nanoparticles (NPs) property is crucial for developing highly efficient visible light driven photocatalyst. Here, dendritic α-Bi2O3/Bi2O2CO3 biphasic heterostructures were first synthesized by a facile and low-cost phase transformation method. Then, plasmonic Au NPs (including Au nanospheres (NSs, ∼30 nm)) and Au nanorods (NRs, ∼20, ∼30, and ∼35 nm) were loaded onto the α-Bi2O3/Bi2O2CO3 heterostructure. The results revealed that these α-Bi2O3/Bi2O2CO3 heterostructures exhibited much higher visible-light photocatalytic activities than α-Bi2O3 for dye degradation. More importantly, compared to plain α-Bi2O3/Bi2O2CO3 heterostructures, loading of Au NSs brought ∼4 times increase in activity and Au NRs 5–11 times depending on nanorods size. The significant boosting of activity is attributed to the large enhancement of charge separation by the formation of α-Bi2O3/Bi2O2CO3 interface and more production of OH radicals by Au NSs or Au NRs. The surface plasmon resonance (SPR) absorption of these gold NPs on the α-Bi2O3/Bi2O2CO3 heterostructures could also have significant contribution to the activities due to their strong plasmonic near-fields. This work demonstrates that tailoring the semiconductor substrate structure and the plasmonic noble metal NPs properties should constitute a promising strategy for the design efficient solar energy driven photocatalytic materials.
Co-reporter:Yan Zhu, Zhikun Wu, Chakicherla Gayathri, Huifeng Qian, Roberto R. Gil, Rongchao Jin
Journal of Catalysis (4 May 2010) Volume 271(Issue 2) pp:155-160
Publication Date(Web):4 May 2010
DOI:10.1016/j.jcat.2010.02.027
Atomically monodisperse Au25(SR)18 (where RCH2CH2Ph) nanoparticles are explored as a stereoselective catalyst for hydrogenation of cyclic ketone to one specific isomer of cyclic alcohol product. A complete (∼100%) stereoselectivity is obtained. The catalytic performance is correlated with the crystal structure and core-shell electronic nature of Au25(SR)18 superatoms, in which the electron-rich Au13 core activates the CO bond, whereas the electron-deficient Au12 shell provides active sites for H2 adsorption and dissociation. This work demonstrates promising catalytic performance of ultrasmall gold nanoparticles. The atomically precise Au25(SR)18 superatom catalyst may be explored as hydrogenation catalysts for some important chemical processes.Atomically monodisperse Au25(SR)18 (RCH2CH2Ph) nanoparticles are explored as a new type of stereoselective catalyst for hydrogenation of cyclic ketone to a specific isomer of the cyclic alcohol product. A complete (100%) stereoselectivity is obtained and the catalytic performance is further correlated with the crystal structure of the Au25(SR)18 nanoparticle.Download high-res image (79KB)Download full-size image
Co-reporter:Chenjie Zeng; Yuxiang Chen; Kenji Iida; Katsuyuki Nobusada; Kristin Kirschbaum; Kelly J. Lambright
Journal of the American Chemical Society () pp:
Publication Date(Web):March 2, 2016
DOI:10.1021/jacs.5b12747
Revealing the size-dependent periodicities (including formula, growth pattern, and property evolution) is an important task in metal nanocluster research. However, investigation on this major issue has been complicated, as the size change is often accompanied by a structural change. Herein, with the successful determination of the Au44(TBBT)28 structure, where TBBT = 4-tert-butylbenzenethiolate, the missing size in the family of Au28(TBBT)20, Au36(TBBT)24, and Au52(TBBT)32 nanoclusters is filled, and a neat “magic series” with a unified formula of Au8n+4(TBBT)4n+8 (n = 3–6) is identified. Such a periodicity in magic numbers is a reflection of the uniform anisotropic growth patterns in this magic series, and the n value is correlated with the number of (001) layers in the face-centered cubic lattice. The size-dependent quantum confinement nature of this magic series is further understood by empirical scaling law, classical “particle in a box” model, and the density functional theory calculations.
Co-reporter:Chenjie Zeng ; Chong Liu ; Yuxiang Chen ; Nathaniel L. Rosi
Journal of the American Chemical Society () pp:
Publication Date(Web):August 15, 2014
DOI:10.1021/ja506802n
Understanding how gold nanoclusters nucleate from AuISR complexes necessitates the structural elucidation of nanoclusters with decreasing size. Toward this effort, we herein report the crystal structure of an ultrasmall nanocluster formulated as Au20(TBBT)16 (TBBT = SPh-t-Bu). The structure features a vertex-sharing bitetrahedral Au7 kernel and an unprecedented “ring” motif—Au8(SR)8. This large ring protects the Au7 kernel through strong Auring–Aukernel bonding but does not involve S–Aukernel bonding, in contrast to the common “staple” motifs in which the S–Aukernel bonding is dominant but the Austaple–Aukernel interaction is weak (i.e., aurophilic). As the smallest member in the TBBT “magic series”, Au20(TBBT)16, together with Au28(TBBT)20, Au36(TBBT)24, and Au44(TBBT)28, reveals remarkable size-growth patterns in both geometric structure and electronic nature. Moreover, Au20(TBBT)16, together with the Au24(SR)20 and Au18(SR)14 nanoclusters, forms a “4e” nanocluster family, which illustrates a trend of shrinkage of bitetrahedral kernels from Au84+ to Au73+ and possibly to Au62+ with decreasing size.
Co-reporter:Qi Li, Anindita Das, Shuxin Wang, Yuxiang Chen and Rongchao Jin
Chemical Communications 2016 - vol. 52(Issue 99) pp:NaN14301-14301
Publication Date(Web):2016/11/24
DOI:10.1039/C6CC07825G
The catalytic potential of atomically precise quantum-sized gold nanoclusters (Au38(SC2H4Ph)24) is explored for the three-component coupling of an aldehyde, an alkyne and an amine to synthesize propargylamines. A high catalytic efficiency with a very low loading (0.01 mol%) is achieved. Furthermore, the synergistic effect of the electron-deficient surface (i.e. Auδ+, 0 < δ+ < 1) and the electron-rich Au23 core of the ligand-protected nanoclusters is critical for this catalytic reaction.
Co-reporter:Qi Li, Shuxin Wang, Kristin Kirschbaum, Kelly J. Lambright, Anindita Das and Rongchao Jin
Chemical Communications 2016 - vol. 52(Issue 29) pp:NaN5197-5197
Publication Date(Web):2016/03/10
DOI:10.1039/C6CC01243D
We report a method for heavy doping of the Au25(SR)18 nanocluster (where R = C6H11) with silver through the Ag(I)–thiolate complex induced size/structure transformation of Au23(SR)16− into Au25–xAgx(SR)18−. X-ray crystallographic analysis revealed that Ag dopants are distributed not only in the icosahedral core but also in the surface staple motifs; the latter was not achieved in earlier studies of alloy Au25–xAgx nanoclusters.
Co-reporter:Man-Bo Li, Shi-Kai Tian, Zhikun Wu and Rongchao Jin
Chemical Communications 2015 - vol. 51(Issue 21) pp:NaN4436-4436
Publication Date(Web):2015/02/06
DOI:10.1039/C4CC08830A
A new nanocluster of atomic precision, Au44(SC2H4Ph)32, is obtained by an oxidation–decomposition–recombination (ODR) process from Au25(SC2H4Ph)18 under mild conditions with high yield (75%). Among the investigated gold nanoclusters, Au44(SC2H4Ph)32 exhibits the highest catalytic activity for the reduction of 4-nitrophenol, especially at low temperature, indicating that the catalytic properties of gold nanoclusters are not only size-dependent, but also structure-sensitive.
Co-reporter:Chenjie Zeng, Yuxiang Chen, Gao Li and Rongchao Jin
Chemical Communications 2014 - vol. 50(Issue 1) pp:NaN57-57
Publication Date(Web):2013/11/05
DOI:10.1039/C3CC47089J
We report the synthesis of a Au44(SR)28 nanocluster (SR = 4-tert-butylbenzenethiolate). Based on the structural rules learned from the known Au28(SR)20 and Au36(SR)24 structures, we propose a plausible structure for Au44(SR)28, which is predicted to comprise a six-interpenetrating cuboctahedral Au36 kernel protected by four dimeric staples and sixteen bridging thiolates, i.e. Au36[Au2(SR)3]4(SR)16.
Co-reporter:Gao Li, Chao Liu, Yu Lei and Rongchao Jin
Chemical Communications 2012 - vol. 48(Issue 98) pp:NaN12007-12007
Publication Date(Web):2012/11/05
DOI:10.1039/C2CC34765B
The Au25(SR)18/CeO2 nanocluster catalyst showed high activity in the homocoupling of aryl iodides (e.g. up to 99.8% yield with iodobenzene) and excellent recyclability.
Co-reporter:Huifeng Qian and Rongchao Jin
Chemical Communications 2011 - vol. 47(Issue 41) pp:NaN11464-11464
Publication Date(Web):2011/09/26
DOI:10.1039/C1CC15099E
Since the pioneering work of Schmid et al. on phosphine-capped Au55 clusters, the search for thiolated Au55 has long been of major interest. This work reports the synthesis and electrospray ionization mass spectrometry (ESI-MS) evidence of Au55(SCH2CH2Ph)31 clusters.
Co-reporter:Yan Zhu, Huifeng Qian and Rongchao Jin
Journal of Materials Chemistry A 2011 - vol. 21(Issue 19) pp:NaN6799-6799
Publication Date(Web):2011/03/24
DOI:10.1039/C1JM10082C
Nanogold has been found to be an effective catalyst for many chemical reactions. However, mechanistic studies have thus far only met with limited success, largely due to the unavailability of well-defined catalysts. We are motivated to create atomically precise gold (Au) nanoclusters in the hope of unraveling some fundamental aspects of nanogold catalysis. In this feature article, we summarize recent works on the catalytic promise of a new class of materials: ultrasmall (<2 nm), semiconducting Au nanoclusters protected by thiolates, referred to as Aun(SR)m, where n and m represent the number of gold atoms and thiolate ligands, respectively. The recent research is focused on the synthesis and structural determination of atomically precise Aun(SR)m nanoclusters as well as exploring their catalytic properties. The correlation of the X-ray crystal structures of the Aun(SR)m nanoclusters with their catalytic properties will ultimately permit a deep understanding of the origin of nanogold catalysis and will also benefit the future design of new catalysts with high selectivity and activity.
Co-reporter:Zhikun Wu, Joseph Suhan and Rongchao Jin
Journal of Materials Chemistry A 2009 - vol. 19(Issue 5) pp:NaN626-626
Publication Date(Web):2008/12/12
DOI:10.1039/B815983A
We report a one-pot method for synthesizing atomically monodisperse Au25 nanoclusters stabilized with various functionalized thiols. This approach permits facile incorporation of specific functionality [such as –OH, –COOH, and atom transfer radical polymerization initiator –OC(O)C(CH3)2Br] into the protecting thiol ligand shell and provides convenient access to new types of Au25 nanoclusters inaccessible by the previous two-phase approach. Importantly, a distinct “size-focusing” process was identified in the growth process of Au25 nanoclusters in the one-pot reaction. This facile, one-pot synthesis of thiol-functionalized Au25 nanoclusters allows for the development of specific surface chemistry for practical applications of such nanoclusters, such as bioconjugation, sensing, and surface polymerization, and thus makes the approach and the Au25 nanoclusters of broad utility.
Co-reporter:Xi Kang, Meng Zhou, Shuxin Wang,
, Shan Jin, Guodong Sun, Manzhou Zhu and Rongchao Jin
Chemical Science (2010-Present) 2017 - vol. 8(Issue 4) pp:NaN2587-2587
Publication Date(Web):2017/01/05
DOI:10.1039/C6SC05104A
The atomic-structure characterization of alloy nanoclusters (NCs) remains challenging but is crucial in order to understand the synergism and develop new applications based upon the distinct properties of alloy NCs. Herein, we report the synthesis and X-ray crystal structure of the Pt1Ag28(S-Adm)18(PPh3)4 nanocluster with a tetrahedral shape. Pt1Ag28 was synthesized by reacting Pt1Ag24(SPhMe2)18 simultaneously with Adm-SH (1-adamantanethiol) and PPh3 ligands. A tetrahedral structure is found in the metal framework of Pt1Ag28 NC and an overall surface shell (Ag16S18P4), as well as discrete Ag4S6P1 motifs. The Pt1Ag12 kernel adopts a face-centered cubic (FCC) arrangement, which is observed for the first time in alloy nanoclusters in contrast to the commonly observed icosahedral structure of homogold and homosilver NCs. The Pt1Ag28 nanocluster exhibits largely enhanced photoluminescence (quantum yield QY = 4.9%, emission centered at ∼672 nm), whereas the starting material (Pt1Ag24 NC) is only weakly luminescent (QY = 0.1%). Insights into the nearly 50-fold enhancement of luminescence were obtained via the analysis of electronic dynamics. This study demonstrates the atomic-level tailoring of the alloy nanocluster properties by controlling the structure.
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