Mechanism of Photoluminescence in Ag Nanoclusters: Metal-Centered Emission versus Synergistic Effect in Ligand-Centered Emission

It remains unclear whether the emission center of ligand-encapsulated metal nanoclusters (MNCs) is the surface ligands or the metal core. In this paper, we simultaneously observed metal-centered and ligand-centered emissions in Ag nanoclusters. The contributions of the surface ligands and the metal core were individually investigated to understand the nature of AgNC photoemission. A new ligand synergistic emission effect was observed. The amino correlated nπ* state provides a pivot to bridge the carboxyl correlated ππ* and nπ* states to enhance the charge transfer efficiency between different surface electronic states. Consequently, the photoluminescence quantum yields were significantly improved (∼1 to ∼10%). Transient absorption studies revealed that decreasing the pH could expand the potential energy curve and generate a conical intersection. This would facilitate the charge transfer and relaxation of excited electrons via a radiative pathway, thereby enhancing the emission intensity. These new insight...

[1]  Jun Yang,et al.  Precise control of alloying sites of bimetallic nanoclusters via surface motif exchange reaction , 2017, Nature Communications.

[2]  Jianhua Xu,et al.  Interfacial Clustering-Triggered Fluorescence-Phosphorescence Dual Solvoluminescence of Metal Nanoclusters. , 2017, The journal of physical chemistry letters.

[3]  R. Jin,et al.  Tailoring the Structure of 58-Electron Gold Nanoclusters: Au103S2(S-Nap)41 and Its Implications. , 2017, Journal of the American Chemical Society.

[4]  R. Jin,et al.  Electron localization in rod-shaped triicosahedral gold nanocluster , 2017, Proceedings of the National Academy of Sciences.

[5]  Xuemei Wang,et al.  Recent advances in biomedical applications of fluorescent gold nanoclusters. , 2017, Advances in colloid and interface science.

[6]  R. Jin,et al.  Emergence of hierarchical structural complexities in nanoparticles and their assembly , 2016, Science.

[7]  W. Yuan,et al.  Clustering-Triggered Emission of Nonconjugated Polyacrylonitrile. , 2016, Small.

[8]  Jinbin Liu,et al.  Luminescent Gold Nanoparticles with Size-Independent Emission. , 2016, Angewandte Chemie.

[9]  Jianhua Xu,et al.  Photoemission mechanism of water-soluble silver nanoclusters: ligand-to-metal-metal charge transfer vs strong coupling between surface plasmon and emitters. , 2014, Journal of the American Chemical Society.

[10]  E. Wang,et al.  Cu nanoclusters with aggregation induced emission enhancement. , 2013, Small.

[11]  C. M. Li,et al.  Carbon-based dots co-doped with nitrogen and sulfur for high quantum yield and excitation-independent emission. , 2013, Angewandte Chemie.

[12]  M. I. Setyawati,et al.  Highly luminescent silver nanoclusters with tunable emissions: cyclic reduction–decomposition synthesis and antimicrobial properties , 2013 .

[13]  Jianping Xie,et al.  From aggregation-induced emission of Au(I)-thiolate complexes to ultrabright Au(0)@Au(I)-thiolate core-shell nanoclusters. , 2012, Journal of the American Chemical Society.

[14]  Jie Zheng,et al.  Near-infrared emitting radioactive gold nanoparticles with molecular pharmacokinetics. , 2012, Angewandte Chemie.

[15]  Chen Zhou,et al.  Different sized luminescent gold nanoparticles. , 2012, Nanoscale.

[16]  Chen Zhou,et al.  Luminescent gold nanoparticles with pH-dependent membrane adsorption. , 2011, Journal of the American Chemical Society.

[17]  J. Perry,et al.  Optically enhanced, near-IR, silver cluster emission altered by single base changes in the DNA template. , 2011, The journal of physical chemistry. B.

[18]  Robin H. A. Ras,et al.  Fluorescent silver nanoclusters. , 2011, Nanoscale.

[19]  Hao Yan,et al.  Site-specific synthesis and in situ immobilization of fluorescent silver nanoclusters on DNA nanoscaffolds by use of the Tollens reaction. , 2011, Angewandte Chemie.

[20]  T. Pradeep,et al.  Luminescent Ag7 and Ag8 clusters by interfacial synthesis. , 2010, Angewandte Chemie.

[21]  Moon J. Kim,et al.  Luminescent Gold Nanoparticles with Mixed Valence States Generated from Dissociation of Polymeric Au (I) Thiolates. , 2010, The journal of physical chemistry. C, Nanomaterials and interfaces.

[22]  J. Perry,et al.  Electron transfer-induced blinking in Ag nanodot fluorescence. , 2009, The journal of physical chemistry. C, Nanomaterials and interfaces.

[23]  R. Improta,et al.  Photoinduced dynamics of guanosine monophosphate in water from broad-band transient absorption spectroscopy and quantum-chemical calculations. , 2009, Journal of the American Chemical Society.

[24]  E. Gwinn,et al.  Sequence‐Dependent Fluorescence of DNA‐Hosted Silver Nanoclusters , 2008 .

[25]  Tom Vosch,et al.  Strongly emissive individual DNA-encapsulated Ag nanoclusters as single-molecule fluorophores , 2007, Proceedings of the National Academy of Sciences.

[26]  Robert M Dickson,et al.  Highly fluorescent noble-metal quantum dots. , 2007, Annual review of physical chemistry.

[27]  R. Coleman,et al.  Protonation of excited state pyrene-1-carboxylate by phosphate and organic acids in aqueous solution studied by fluorescence spectroscopy. , 2006, Biophysical journal.

[28]  Katsuyuki Nobusada,et al.  Glutathione-protected gold clusters revisited: bridging the gap between gold(I)-thiolate complexes and thiolate-protected gold nanocrystals. , 2005, Journal of the American Chemical Society.

[29]  J. Spanget-Larsen,et al.  TD-DFT Computational Insight into the Origin of Wavelength-Dependent E/Z Photoisomerization of Urocanic Acid , 2004 .

[30]  G. Porter,et al.  Acidity constants of anthracene derivatives in singlet and triplet excited states , 1968 .