Impact of the Selenolate Ligand on the Bonding Behavior of Au<sub>25</sub> Nanoclusters
Bibliographic record
Abstract
We report the intriguing bonding behavior of selenolate-protected Au 25 nanoclusters (Au 25 (SeR) 18 ), revealed by temperature-dependent X-ray absorption spectroscopy (XAS) from both the metal (Au L 3 -edge) and ligand (Se K-edge) perspectives. The structure of Au 25 (SeR) 18 was first analyzed in great detail using a site-specific, multishell (i.e., Au–Au core/surface/staple, Au–Se/Se-Au and Se–C shells) approach. It was found that the Au 13 core of Au 25 (SeR) 18 remains relatively unchanged at low temperature while aurophilic interactions on the surface are significantly longer in distance compared with their thiolate-protected counterpart, Au 25 (SR) 18 . Remarkably, temperature-dependent studies showed a significant thermal contraction of the Au–Au framework in Au 25 (SeR) 18, which is absent in the Au 25 (SR) 18 system. This unusual bonding behavior of Au 25 (SeR) 18 is proposed to be induced by the dimeric staple-like motif (−Au–Se–Au–Se–Au−) surface structures, where aurophilic bond distances and Au–Se–Au bond angles are sensitive toward temperature change. Density functional theory and molecular dynamics (DFT-MD) simulations were conducted to confirm this mechanism and provide further insight into the bonding behavior of the Au 25 (SeR) 18 nanocluster. Finally, we use near-edge XAS results to demonstrate that the thermal contraction effect induces a change to the electronic properties of both the Au and Se and consistently accounted for using ab initio simulations of the near-edge and valence band structure.
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How this classification was reachedexpand
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 | 0.000 |
| 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 | 0.001 | 0.000 |
| 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".