Silver Doping‐Induced Luminescence Enhancement and Red‐Shift of Gold Nanoclusters with Aggregation‐Induced Emission

Abstract

A deep understanding on the luminescence property of aggregation‐induced emission (AIE) featured metal nanoclusters (NCs) is highly desired. This paper reports a systematic study on enhancing the luminescence of AIE‐featured Au NCs, which is achieved by Ag doping to engineer the size/structure and aggregation states of the AuI‐thiolate motifs in the NC shell. Moreover, by prolonging the reaction time, the luminescence of the as‐synthesized AuAg NCs could be further tailored from orange to red, which is also due to the variation of the AuI‐thiolate motifs of NCs. This study can facilitate a better understanding of this AIE‐featured luminescent probe and the design of other synthetic routes for this rising family of functional materials.

The Synthesis of Chiral Ag4Pd2(SR)8 by Nonreplaced Galvanic Reaction

“…Fortunately, the unique configuration helps us determine the elemental types, that is, four corner atoms forming a square plane should be Ag and two remaining atoms occupying the vertex should be Pd (Figure 1a), given that Ag and Pd atoms are usually 2-coordinated and 4-coordinated, respectively. Thus, the formula of this doped NC is predetermined to be Ag 4 Pd 2 (SR) 8 . XPS data shows a Ag:Pd:S atom ratio of 2.07:1:3.94, which is in excellent agreement with the expected atom ratio of 2:1:4, further verifying the aforementioned formula.…”

“…XPS data shows a Ag:Pd:S atom ratio of 2.07:1:3.94, which is in excellent agreement with the expected atom ratio of 2:1:4, further verifying the aforementioned formula. In addition, the absorption onset of Ag 4 Pd 2 (SR) 8 occurs at about 530 nm in Galvanic reaction is a classic reaction and widely applied in nanoscience and nanotechnology. However, it is rarely employed in the synthesis of doped metal nanoclusters with size less than ≈2 nm and remains to be exploited in nanocluster (NC) community.…”

“…During the past decade, atomically precise doped nanoclusters (NCs, ultrasmall nanoparticles with size less than ≈2 nm) have gained considerable attention from nanoscientists because of the synergistic or even new properties (e.g., catalytic and optical properties) of doped NCs compared to their homometallic counterparts. [1][2][3][4][5][6][7][8][9][10] A general synthesis method is the synchrosynthesis (i.e., the mixed metal precursors are concurrently reduced by reducing agent like NaBH 4 ), such as the preparation of Au 24 Pd(SR) 18 , [11,12] Au 24 Pt(SR) 18 , [12][13][14] Au 25−x Ag x (SR) 18 , [15] Au 38−x Ag x (SR) 18 , [16] Au 36 Pd 2 (SR) 18 , [17] Au 36 Pt 2 (SR) 24 , [17] Ag 24 Pd(SR) 18 , [18][19][20] Ag 24 Pt(SR) 18 , [21] Ag 32 Au 12 (SR) 30 , [22,23] and [Au 12+n Cu 32 (SR) 30+n ] [24] NCs (SR: thiolate). Due to the limitation of synchro-synthesis in obtaining more atomically disperse alloy nanoclusters, a novel synthesis method dubbed antigalvanic reaction (AGR) [25] was introduced by Wu in 2012 and a few atomically disperse alloy nano clusters have been facilely obtained so far, such as Ag 2 Au 25 (SR) 18 , [26] HgAu 24 (SR)…”

“…The shortening of bond length implies enhanced interactions between metal atoms and SR ligands that can contribute to higher stability of the Ag 4 Pd 2 (SR) 8 NC ( Figure S2, Supporting Information), which can be further indicated by the larger electrochemical gap of 2.6 V determined by DPV (differential pulse voltammetry), see Figure S3 in the Supporting Information. Note that phenyl tails from the two SR ligands bounded to the same Ag are staggered rather than eclipsed in the total structure of Ag 4 Pd 2 (SR) 8 offering additional stability, as the staggered configuration is more stable compared to the eclipsed one due to steric hindrance. Furthermore, all metal atoms in the octahedral framework of Ag 4 Pd 2 (SR) 8 are unshielded, which may be beneficial to catalytic applications as active sites.…”

“…During the past decade, atomically precise doped nanoclusters (NCs, ultrasmall nanoparticles with size less than ≈2 nm) have gained considerable attention from nanoscientists because of the synergistic or even new properties (e.g., catalytic and optical properties) of doped NCs compared to their homometallic counterparts . A general synthesis method is the synchro‐synthesis (i.e., the mixed metal precursors are concurrently reduced by reducing agent like NaBH 4 ), such as the preparation of Au 24 Pd(SR) 18 , Au 24 Pt(SR) 18 , Au 25− x Ag x (SR) 18 , Au 38− x Ag x (SR) 18 , Au 36 Pd 2 (SR) 18 , Au 36 Pt 2 (SR) 24 , Ag 24 Pd(SR) 18 , Ag 24 Pt(SR) 18 , Ag 32 Au 12 (SR) 30 , and [Au 12+ n Cu 32 (SR) 30+ n ] NCs (SR: thiolate).…”