Aggregation‐Induced Emission (AIE) in Ag−Au Bimetallic Nanocluster

Abstract

Herein we report the synthesis and structure determination of a non-fluorescent Au Ag (dppm) (SAdm) (BPh ) (dppm=bis(diphenylphosphino)methane and HSAdm=1-adamantane mercaptan) nanocluster in methanol with extremely strong AIE when aggregating to the solid state (i.e., film or crystal). This phenomenon was rarely reported in structural determined noble metal nanoclusters. The extended X-ray absorption fine structure (EXAFS) measurement ruled out the hypothesis that the luminescence originated from the structure change in different states. Besides, the crystal structure (determined by X-ray diffraction) revealed that the tightly combined left- and right-handed enantiomers induced the strong restriction of intramolecular motions (RIM), which may have an impact on aggregation-induced emission.

Insight of the photoluminescence of atomically precise bimetallic nanoclusters with free electrons

“…Using the co‐reduction method, Au 4 Ag 5 (dppm) 2 (S‐Adm) 6 (BPh 4 ) (Au 4 Ag 5 for short, dppm: bis[diphenylphosphino]methane; HS‐Adm: Adamantanethiol) was prepared by Jin et al in 2018. [ 45 ] Au 4 Ag 5 was soluble in many kinds of organic solvents (i.e., CH 2 Cl 2 , CH 3 OH) but show poor solubility in water. When dissolved in CH 3 OH, no significant fluorescence was found in Au 4 Ag 5 nanocluster under irradiation of UV light (Figure 4a), while the luminescence intensity was boosted when the poor solvent (i.e., water) was added.…”

Aggregation-induced phosphorescence sensitization in two heptanuclear and decanuclear gold–silver sandwich clusters

“…5,7,14,19 One of the topical studies is the doping of silver atoms into gold clusters, whereby their same valence shell electrons and similar coordination modes could bring unique optoelectronic behaviours. 20–26 A representative example is gradually substituting gold atoms with silver in the 25-metal-atom NC Ag x Au 25− x and the 13th silver atom replacement results in a 200-fold boost in photoluminescence quantum yield ( Φ PL ) 20 which is attributed to a combination of stabilization of the lowest unoccupied molecular orbital (LUMO), rigidity enhancement, and symmetry preservation despite the great perturbation of the electronic structure. 21 In other words, the stoichiometric ratio of Au : Ag is a key factor in regulating the photophysics of these molecular clusters.…”

“…21 In other words, the stoichiometric ratio of Au : Ag is a key factor in regulating the photophysics of these molecular clusters. 22–26…”

Rapid Conversion of a Au9Ag12 into a AuxAg16‐x Nanocluster via Bisphosphine Ligand Engineering

“…Aggregation‐induced emission (AIE) is an intriguing strategy to enhance the luminescence of metal nanoclusters for further applications [17–20] . The Au x Ag 16‐x (SAdm) 8 (Dppe) 2 nanocluster emits weak red fluorescence at 676 nm in CH 2 Cl 2 solution under 365 nm excitation.…”