Pre‐oxidation of Gold Nanoclusters Results in a 66 % Anodic Electrochemiluminescence Yield and Drives Mechanistic Insights

Abstract

Gold nanoclusters (AuNCs) are attractive electrochemiluminescence (ECL) emitters because of their excellent stability, near IR emission, and biocompatibility. However, their ECL quantum yield is relatively low, and our limited fundamental understanding has hindered rational improvement of this parameter. Herein, we report drastic enhancement of the ECL of ligand‐stabilized AuNCs by on‐electrode pre‐oxidation with triethylamine (TEA) as a co‐reactant. The l‐methionine‐stabilized AuNCs resulted in a record high ECL yield of 66 %. This strategy was successfully extended to other AuNCs, and it is more effective for ligand shells that allow more effective electron transfer. In addition, excitation of the pre‐oxidized ECL required a lower potential than conventional methods, and no additional instrument was required. This work opens avenues for solving a challenging problem of AuNC‐based ECL probes and enriches fundamental understanding, greatly broadening their potential applications.

Electrochemiluminescence of Glutathione‐Stabilized Au Nanoclusters Fractionated by Gel Electrophoresis in Water

“…We synthesized Au NCs, of which ECL quantum yield (Φ ECL ) was reported as 0.42 % (a relative Φ ECL vs. Φ°E CL of Ru(bpy) 3 2 + taken as 5.0 %), [10] using a thiolate ligand (i. e., GSH) as reported previously (see Experimental Section for details). [8][9] Despite a narrow size distribution (1.2 � 0.2 nm) of the as-synthesized Au NCs (Supporting Information, Figure S1), [8] the native PAGE analysis allowed five discrete but closely spaced bands, which we refer to as 1-5 in the order of the mobility from the highest to the lowest; the bands were luminescent under UV light as shown in Figure 1a (inset).…”

Electroactive Metal–Organic Frameworks as Emitters for Self‐Enhanced Electrochemiluminescence in Aqueous Medium

“…These results further identified that the self- enhanced ECL was due to the accumulation of E-MOFC + during SP process. [18] On the other hand, in the presence of pre-reduction at À0.8 V, the ECL intensity demonstrated 17-fold enhancement with high stability (Figure 4 B; Supporting Information, Figure S11), which was attributed to the accumulation of E-MOFC + at this potential. When the pre-reduction potential shifted to À1.6 V, the ECL intensity diminished due to that the produced E-MOFC + was already exhausted via the reaction with the E-MOFC À generated at the more negative potential (Supporting Information, Figure S12).…”

6-Aza-2-Thio-Thymine Stabilized Gold Nanoclusters as Photoluminescent Probe for Protein Detection

“…Owing to their unique physical and chemical properties caused by quantum confinement effect, gold nanoclusters (AuNCs) have emerged as an intensely pursued material for nanoscience research and biological applications in the past decade [5][6][7][8][9]. The molecule-like properties of AuNCs, such as discrete electronic states and size-dependent photoluminescence, makes them a distinguished material from larger nanoparticles and bulk metals [10][11][12][13][14][15][16][17][18].…”