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1.
以G5.0-OH PAMAM树形分子为模板,用紫外光辐照法制备银纳米簇.用透射电子显微镜、紫外-可见吸收光谱和共振散射光谱等对所制备的银纳米簇进行了表征.结果表明:用紫外光辐照法可以制备尺寸分布均匀、稳定的银纳米簇;且辐照时间、PAMAM树形分子的浓度及Ag+/PAMAM树形分子的摩尔比都会对所制备的银纳米簇产生较大的影响.由于所制备的银纳米簇的粒径小于树形分子的流体力学半径,表明树形分子起到了“内模板”作用.同时研究了银纳米簇的尺寸对其光致发光性能的影响,发现通过调节银纳米簇的尺寸可实现其光致发光的可调性. 相似文献
2.
Dr. Mahdi Hesari Prof. Dr. Zhifeng Ding 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(60):14821-14825
Bright, near-infrared electrochemiluminescence (NIR–ECL) of Au18 nanoclusters is reported herein. Spooling ECL and photoluminescence spectroscopy were used to track and link NIR emissions at 832 and 848 nm to three emissive species, Au180*, Au181+* and Au182+*, with a considerably high ECL efficiency of 5.5 relative to that of the gold standard Ru(bpy)32+/TPrA (with 5–6 % reported ECL efficiency). The unprecedentedly high efficiency is due to the overlapped oxidation potentials of Au180 and tri-n-propylamine as co-reactant, the exposed facets of Au180 gold core, and electrocatalytic loops. These discoveries will add a new member to the efficient NIR-ECL gold nanoclusters family and bring more potential applications. 相似文献
3.
Beata Sweryda-Krawiec Jeffery L. Coffer Shubhra Gancopadhahay 《Journal of Cluster Science》2002,13(4):637-645
Visible light emission emanating from nanostructured porous silicon is sensitive to adsorption of a number of small molecules, suggesting its utility as a chemical sensor. In this work we investigate the mechanistic origin of the diminution of the luminescence by n-propyl amine adsorption and restoration by trifluoroacetic acid, most sensitively by an examination of the changes in observed lifetime of the porous Si luminescence. This is quantified in terms of a stretched exponential model that is consistent with a distribution of luminescent centers in this nanophase material. 相似文献
4.
Synthetic routes for the preparation of Si or Ge nanoclusters as gaseous species, colloids, supported composites, or as unsupported powders are reviewed along with selected characterization data. The optical properties of these and related materials, such as porous Si, are summarized with particular emphasis on photo- or electroluminescence phenomena. Research opportunities related to Si and Ge cluster chemistry are suggested. 相似文献
5.
The Origin of the Photoluminescence Enhancement of Gold‐Doped Silver Nanoclusters: The Importance of Relativistic Effects and Heteronuclear Gold–Silver Bonds
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Dr. Xiao‐Ying Xie Dr. Pin Xiao Dr. Xiaoyan Cao Prof. Dr. Wei‐Hai Fang Prof. Dr. Ganglong Cui Prof. Dr. Michael Dolg 《Angewandte Chemie (International ed. in English)》2018,57(31):9965-9969
The weak photoluminescence of silver nanoclusters prevents their broad application as luminescent nanomaterials. Recent experiments, however, have shown that gold doping can significantly enhance the photoluminescence intensity of Ag29 nanoclusters but the molecular and physical origins of this effect remain unknown. Therefore, we have computationally explored the geometric and electronic structures of Ag29 and gold‐doped Ag29?xAux (x=1–5) nanoclusters in the S0 and S1 states. We found that 1) relativistic effects that are mainly due to the Au atoms play an important role in enhancing the fluorescence intensity, especially for highly doped Ag26Au3, Ag25Au4, and Ag24Au5, and that 2) heteronuclear Au?Ag bonds can increase the stability and regulate the fluorescence intensity of isomers of these gold‐doped nanoclusters. These novel findings could help design doped silver nanoclusters with excellent luminescence properties. 相似文献
6.
A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped AgxAu25−x Nanoclusters: The 13 th Silver Atom Matters
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Shuxin Wang Xiangming Meng Anindita Das Tao Li Yongbo Song Tiantian Cao Xiuyi Zhu Prof. Manzhou Zhu Prof. Rongchao Jin 《Angewandte Chemie (International ed. in English)》2014,53(9):2376-2380
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. 相似文献
7.
提出一种用于SO_2监测的多孔硅光学传感方案,其原理是以光催化氢化硅烷化处理的多孔硅作为敏感材料,根据多孔硅光致发光峰猝灭程度与SO_2浓度间定量关系,实现SO_2传感。实验采用电化学方法将n型单晶硅腐蚀形成多孔硅并进行氢化硅烷化处理,获得敏感膜层;研究多孔硅发光特性、传感特性、选择性和稳定性。结果表明该多孔硅具有良好光致发光性能,在大气环境和碱性介质中稳定性较高;当SO_2体积分数为5×10-5~2.5×10-4时,多孔硅传感SO2的过程服从SternVolmer方程,其SternVolmer常数k为5×104;同时,体积分数为0.05的CO_2或NO以及体积分数为0.01的CO或NO_2对多孔硅光致发光峰强度无影响。用本法测定样品中SO_2含量,结果满意。 相似文献
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A series of water soluble gold nanoclusters of variable core size were prepared and characterized. The clusters were synthesized using a ligand substitution reaction between CH3(OCH2CH2)3SH and hexanethiol encapsulated gold nanoclusters, and characterized using NMR, FTIR, and UV/Vis spectroscopy, as well as TGA, DSC, and TEM. Conductivity values were obtained for the clusters and increased as expected along with the gold core size. The substitution reaction used in the synthesis was followed by 1H NMR and found to produce only partial ligand substitution after 24 h, consistent with solubility observations and necessitating use of a two-step preparation scheme. 相似文献
9.
Jing Zou Philip Sanelle Katherine A. Pettigrew Susan M. Kauzlarich 《Journal of Cluster Science》2006,17(4):565-578
Synthesis of silicon nanoparticles of various sizes from 3 to 9 nm in diameter was accomplished via a low temperature solution route. These nanoparticles are prepared via reduction of SiCl4 with Na naphthalide in dimethoxyethane and capped with octasiloxane. The resulting nanoparticles were characterized by transmission electron microscopy (TEM), high resolution (HR) TEM, selected area electron diffraction (SAED), energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction, UV–vis, photoluminescence, and their quantum yields were determined. TEM micrographs show that the nanoparticles are well dispersed and SAED and lattice fringes are consistent with diamond structured silicon. X-ray powder diffraction provides no diffraction peaks. UV–vis and photoluminescence show characteristic shifts corresponding to size, consistent with quantum confinement. The smallest sized nanoparticles show the largest quantum yield, consistent with an indirect bandgap nanoparticles. 相似文献
10.
Ziyi Liu Fei Li Yi Luo Ming Li Guanghui Hu Xianjuan Pu Tao Tang Jianfeng Wen Xinyu Li Weitao Li 《Molecules (Basel, Switzerland)》2021,26(13)
High-photoluminescence (PL) graphene quantum dots (GQDs) were synthesized by a simple one-pot hydrothermal process, then separated by dialysis bags of different molecular weights. Four separated GQDs of varying sizes were obtained and displayed different PL intensities. With the decreasing size of separated GQDs, the intensity of the emission peak becomes much stronger. Finally, the GQDs of the smallest size revealed the most energetic PL intensity in four separated GQDs. The PL energy of all the separated GQDs shifted slightly, supported by density functional theory calculations. 相似文献
11.
Dr. Robert Ludmerczki Prof. Luca Malfatti Dr. Luigi Stagi Dr. Manuela Meloni Prof. Carlo Maria Carbonaro Prof. Maria Francesca Casula Dr. Dóra Bogdán Dr. Stefania Mura Prof. István M. Mándity Prof. Plinio Innocenzi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(7):2543-2550
Carbonized polymer dots (CPDs), a peculiar type of carbon dots, show extremely high quantum yields, making them very attractive nanostructures for application in optics and biophotonics. The origin of the strong photoluminescence of CPDs resides in a complicated interplay of several radiative mechanisms. To understand the correlation between CPD processing and properties, the early stage formation of carbonized polymer dots has been studied. In the synthesis, citric acid monohydrate and 2-amino-2-(hydroxymethyl)propane-1,3-diol have been thermally degraded at 180 °C. The use of an oil bath instead of a more traditional hydrothermal reactor has allowed the CPD properties to be monitored at different reactions times. Transmission electron microscopy, time-resolved photoluminescence, nuclear magnetic resonance, infrared, and Raman spectroscopy have revealed the formation of polymeric species with amide and ester bonds. Quantum chemistry calculations have been employed to investigate the origin of CPD electronic transitions. At short reaction times, amorphous C-dots with 80 % quantum yield, have been obtained. 相似文献
12.
基于重铬酸根离子(Cr_2O_7~(2-))对胞苷保护的荧光铜纳米簇(Cu NCs)的猝灭作用,构建了一种可用于检测Cr_2O_7~(2-)的荧光传感器.实验结果表明,该传感体系检测Cr_2O_7~(2-)的线性范围为0.05~7.0μmol/L,检出限为24 nmol/L(S/N=3).该传感器对Cr_2O_7~(2-)的检测具有良好的选择性,可用于湖水样中Cr_2O_7~(2-)的检测. 相似文献
13.
Gold Doping of Silver Nanoclusters: A 26‐Fold Enhancement in the Luminescence Quantum Yield
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Giada Soldan Maha A. Aljuhani Dr. Megalamane S. Bootharaju Lina G. AbdulHalim Dr. Manas R. Parida Dr. Abdul‐Hamid Emwas Prof. Omar F. Mohammed Prof. Osman M. Bakr 《Angewandte Chemie (International ed. in English)》2016,55(19):5749-5753
A high quantum yield (QY) of photoluminescence (PL) in nanomaterials is necessary for a wide range of applications. Unfortunately, the weak PL and moderate stability of atomically precise silver nanoclusters (NCs) suppress their utility. Herein, we accomplished a ≥26‐fold PL QY enhancement of the Ag29(BDT)12(TPP)4 cluster (BDT: 1,3‐benzenedithiol; TPP: triphenylphosphine) by doping with a discrete number of Au atoms, producing Ag29?xAux(BDT)12(TPP)4, x=1–5. The Au‐doped clusters exhibit an enhanced stability and an intense red emission around 660 nm. Single‐crystal XRD, mass spectrometry, optical, and NMR spectroscopy shed light on the PL enhancement mechanism and the probable locations of the Au dopants within the cluster. 相似文献
14.
Dr. Franck Bertorelle Dr. K. David Wegner Martina Perić Bakulić Hussein Fakhouri Clothilde Comby-Zerbino Dr. Amin Sagar Dr. Pau Bernadó Dr. Ute Resch-Genger Prof. Vlasta Bonačić-Koutecký Dr. Xavier Le Guével Dr. Rodolphe Antoine 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(39):e202200570
Atomically precise gold nanoclusters are a fascinating class of nanomaterials that exhibit molecule-like properties and have outstanding photoluminescence (PL). Their ultrasmall size, molecular chemistry, and biocompatibility make them extremely appealing for selective biomolecule labeling in investigations of biological mechanisms at the cellular and anatomical levels. In this work, we report a simple route to incorporate a preformed Au25 nanocluster into a model bovine serum albumin (BSA) protein. A new approach combining small-angle X-ray scattering and molecular modeling provides a clear localization of a single Au25 within the protein to a cysteine residue on the gold nanocluster surface. Attaching Au25 to BSA strikingly modifies the PL properties with enhancement and a redshift in the second near-infrared (NIR-II) window. This study paves the way to conrol the design of selective sensitive probes in biomolecules through a ligand-based strategy to enable the optical detection of biomolecules in a cellular environment by live imaging. 相似文献
15.
本文以聚酰胺-胺(PAMAM)树形分子为模板,原位制备AgI纳米簇.系统地研究了AgI纳米簇制备过程中各种反应条件如树形分子端基、反应时间、Ag+与PAMAM摩尔比等对AgI纳米簇粒径的影响,分别用紫外-可见光谱、荧光光谱、透射电镜等对所制备的纳米簇进行表征.在相同的条件下,以G4.5-COOH3为模板较以G5.0-NH2为模板制备的AgI纳米簇粒径小、分布均匀,这主要取决于G4.5-COOCH3PAMAM树形分子所起的“内模板”作用.G4.5-COOH3树形分子浓度为1×10-5mol/L,Ag+与树形分子摩尔比为30:1时所制备的AgI纳米簇的粒径分布均匀、稳定性好,室温避光可稳定存在两个月以上. 相似文献
16.
Jinglin Shen Zhi Wang Congxin Xia Prof. Di Sun Prof. Shiling Yuan Prof. Xia Xin 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(18):4713-4721
Research on the self-assembly of various amphiphilic molecules is a relatively new research area and of great significance. However, new kinds of metal-nanocluster (NC)-based amphiphilic molecule have rarely been explored. Herein, hydrophobic cation 1-hexadecyl-3-methylimidazolium (C16mim+) was chosen to modify hydrophilic (NH4)6[Ag6(mna)6] (Ag6-NCs, H2mna=2-mercaptonicotinic acid) and Ag6@C16mim-NCs were obtained. Ag6@C16mim-NCs displayed thermotropic liquid crystal and thermofluorescent properties. Moreover, the Ag6@C16mim-NCs exhibits benign amphiphilicity, and it can self-assemble into ordered nanosheets and nanorods through aggregation in water/dimethyl sulfoxide (DMSO) binary solvent mixtures, whereas single Ag6-NCs do not. Meanwhile, the Ag6@C16mim-NCs also displays aggregation-induced emission properties owing to the restriction of intramolecular vibrations of the capping ligands. Furthermore, the luminescent aggregates could detect arginine selectively with the detection limit at 28 μm . This study introduces a new kind of metal-NC-based amphiphilic molecule in a supramolecular self-assembly field, and they have potential to be used as optical materials in applied research. 相似文献
17.
Lingwen Liao Chengming Wang Shengli Zhuang Nan Yan Yan Zhao Ying Yang Jin Li Haiteng Deng Zhikun Wu 《Angewandte Chemie (International ed. in English)》2020,59(2):731-734
Kernel atoms of Au nanoclusters are packed layer‐by‐layer along the [001] direction with every full (001) monolayer composed of 8 Au atoms (Au8 unit) in nanoclusters with formula of Au8n+4(TBBT)4n+8 (n is the number of Au8 units; TBBTH=4‐tert‐butylbenzenelthiol). It is unclear whether the kernel atoms can be stacked in a defective‐layer way along the [001] direction during growth of the series of nanoclusters and how the kernel layer number affects properties. Now, a nanocluster is synthesized that is precisely characterized by mass spectrometry and single‐crystal X‐ray crystallography, revealing a layer stacking mode in which a half monolayer composed of 4 atoms (Au4 unit) is stacked on the full monolayer along the [001] direction. The size and the odevity of the kernel layer number influence the properties (polarity, photoluminescence) of gold nanoclusters. The obtained nanocluster extends the previous formula from Au8n+4(TBBT)4n+8 to Au4n+4(TBBT)2n+8 (n is the number of Au4 units). 相似文献
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Dr. Yu Wang Xiao-He Liu Dr. Sergey A. Kovalenko Prof. Qing-Yun Chen Prof. Nicola Pinna 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(18):4814-4820
The atomically precise bimetallic nanocluster (NC), Au24Ag20(PhCC)20(SPy)4Cl2 ( 1 ) (Py=pyridine), was employed for the first time as a stable photosensitizer for photoelectrochemical applications. The sensitization of TiO2 nanotube arrays (TNA) with 1 greatly enhances the light-harvesting ability of the composite because 1 shows a high molar extinction coefficient (ϵ) in the UV/Vis region. Compared to a more standard Au25(SG)18-TNA ( 2 -TNA; SG=glutathione) composite, 1 -TNA shows a much better stability under illumination in both neutral and basic conditions. The precise composition of the photosensitizers enables a direct comparison of the sensitization ability between 1 and 2 . With the same cluster loading, the photocurrent produced by 1 -TNA is 15 times larger than that of 2 -TNA. The superior performance of 1 -TNA over 2 -TNA is attributed not only to the higher light absorption ability of 1 but also to the higher charge-separation efficiency. Besides, a ligand effect on the stability of the photoelectrode and charge-transfer between the NCs and the semiconductor is revealed. This work paves the way to study the role of metal nanoclusters as photosensitizers at the atomic level, which is essential for the design of better material for light energy conversion. 相似文献