A Grand Avenue to Au Nanocluster Electrochemiluminescence
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Bibliographic record
Abstract
Conspectus In most cases of semiconductor quantum dot nanocrystals, the inherent optical and electrochemical properties of these interesting nanomaterials do not translate into expected efficient electrochemiluminescence or electrogenerated chemiluminescence (ECL) because of the surface-state induction effect. Thus, their low ECL efficiencies, while very interesting to explore, limit their applications. As their electrochemistry is not well-defined, insight into their ECL mechanistic details is also limited. Alternatively, gold nanoclusters possess monodispersed sizes with atomic precision, low and well defined HOMO–LUMO energy gaps, and stable optical and electrochemical properties that make them suitable for potential ECL applications. In this Account, we demonstrate strong and sustainable ECL of gold nanoclusters Au 25 z (i.e., Au 25 (SR) 18 z, z = 1–, 0, 1+), Au 38 (SR) 24, and Au 144 (SR) 60, where the ligand SR is 2-phenylethanethiol. By correlation of the optical and electrochemical features of Au 25 nanoclusters, a Latimer-type diagram can be constructed to reveal thermodynamic relationships of five oxidation states (Au 25 2+, Au 25 +, Au 25 0, Au 25 –, and Au 25 2– ) and three excited states (Au 25 – *, Au 25 0 *, and Au 25 + *). We describe ECL mechanisms and reaction kinetics by means of conventional ECL–voltage curves and novel spooling ECL spectroscopy. Notably, their ECL in the presence of tri- n -propylamine (TPrA), as a coreactant, is attributed to emissions from Au 25 – * (950 nm, strong), Au 25 0 * (890 nm, very strong), and Au 25 + * (890 nm, very strong), as confirmed by the photoluminescence (PL) spectra of the three Au 25 clusters electrogenerated in situ. The ECL emissions are controllable by adjustment of the concentrations of TPrA· and Au 25 –, Au 25 0, and Au 25 + species in the vicinity of the working electrode and ultimately the applied potential. It was determined that the Au 25 – /TPrA coreactant system should have an ECL efficiency of >50% relative to the Ru(bpy) 3 2+ /TPrA, while those of Au 25 0 /TPrA and Au 25 + /TPrA reach 103% and 116%, respectively. Au 25 – * is the main light emission source for Au 25 z in the presence of benzoyl peroxide (BPO) as a coreactant, with a relative efficiency of up to 30%. For Au 38, BPO leads to the Au 38 – * excited state, which emits light at 930 nm. In the Au 38 /TPrA coreactant system, we find that highly efficient light emission at 930 nm is mainly from Au 38 + * (and also Au 38 3+ *), with an efficiency 3.5 times that of the Ru(bpy) 3 2+ /TPrA reference. We show that the ECL and PL of the various Au 38 charge states, namely, Au 38 2–, Au 38 –, Au 38 0, Au 38 +, Au 38 2+, and Au 38 4+, have the same peak wavelength of 930 nm. Finally, we demonstrate ECL with a peak wavelength of 930 nm from the Au 144 /TPrA coreactant system, which is released from the electrogenerated excited states Au 144 + * and Au 144 3+ *. In our opinion, these gold nanoclusters represent a new class of effective near-IR ECL emitters, from which applications such as bioimaging, biological testing, and medical diagnosis are anticipated once they are made water-dispersible with hydrophilic capping ligands.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it