Gold‐Doping Effect on Two‐Photon Absorption and Luminescence of Atomically Precise Silver Ligated Nanoclusters

Abstract

Noble metal nanoclusters allow for the atomically-precise control of their composition. However, to create nanoclusters with pre-defined optical properties, comprehensive description of their structure-property relation is required. Here, we report the gold atom doping impact on one-photon and two-photon absorption (TPA) and luminescence properties of ligated silver nanoclusters via combined experimental studies and time-dependent density functional theory simulations (TD-DFT). We synthesized a series of Ag 25À x Au x -(DMBT) 18 nanoclusters where x = 0, 1 and 5-10. For Ag 24 Au 1 (DMBT) 18 we demonstrate that the presence of the central Au dopant strongly influences linear and non-linear optical properties, increasing photoluminescence quantum yield and two-photon brightness, with respect to undoped silver nanoclusters. With improved TPA and luminescence, atomically-precise AuAg alloys presented in our work can serve as robust luminescent probes e.g. for bioimaging in the second biological window.

Effects of Single Platinum Atom Doping on Stability and Nonlinear Optical Properties of Ag29 Nanoclusters

“…9 Other factors like relativistic effects (mainly due to the Au atoms), the exact position of metal dopants, and heteronuclear Au−Ag bonds 10 can affect the fluorescence intensity of gold-doped nanoclusters. 11 While most of doping of nanoclusters with heteroatoms was done with the highly stable single thiolated (SR) Au 25 SR 18 , 12−18 and Ag 25 SR 18 , 19,20 dithiolated (SSR) Ag 29 SSR 12 nanoclusters 21−26 are another interesting candidate for doping strategies. 11 The use of dithiolated molecules allows for exploring different staple motifs (as compared to those obtained with single thiolated molecules) and therefore adds some versatility to doping strategies.…”

“…For Ag 24 Au 1 DMBT 18 , it was demonstrated that the presence of the central Au dopant strongly influences linear and nonlinear optical properties, increasing PL upon both one-and twophoton excitations, with respect to undoped silver nanoclusters. 20 Indeed, the central silver atom replacement with Au atoms leads to the localization of electron charge in the icosahedral center, inducing changes in the electronic structure of Ag 24 Au 1 .…”

“…While most of doping of nanoclusters with heteroatoms was done with the highly stable single thiolated (SR) Au 25 SR 18 , − and Ag 25 SR 18 , , dithiolated (SSR) Ag 29 SSR 12 nanoclusters − are another interesting candidate for doping strategies . The use of dithiolated molecules allows for exploring different staple motifs (as compared to those obtained with single thiolated molecules) and therefore adds some versatility to doping strategies.…”

“…In particular, silver-doped gold–cysteine supramolecular assemblies, as well as silver-doped gold nanoclusters display efficient nonlinear optical signals (both two-photon excited fluorescence and second harmonic response). , Recently, a series of Ag 25– x Au x DMBT 18 nanoclusters where x = 0, 1, and 5–10 were synthesized. For Ag 24 Au 1 DMBT 18 , it was demonstrated that the presence of the central Au dopant strongly influences linear and nonlinear optical properties, increasing PL upon both one- and two-photon excitations, with respect to undoped silver nanoclusters . Indeed, the central silver atom replacement with Au atoms leads to the localization of electron charge in the icosahedral center, inducing changes in the electronic structure of Ag 24 Au 1 .…”

Alloying and dealloying of Au18Cu32nanoclusters at precise locationsviacontrolling the electronegativity of substituent groups on thiol ligands

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] Unlike large nanoparticles, metal nanoclusters exhibit strong quantum-size effects; that is, changing one atom in a nanocluster will introduce non-negligible disturbances in its electronic structure, drastically affecting its catalytic and optical performance. [14][15][16][17][18][19][20][21][22] These properties of metal nanoclusters provide a fascinating opportunity to study their structure-property relationship at the atomic level.…”