Aryl Ketone Photochemistry on Monolayer Protected Clusters: Study of the Norrish Type II Reaction as a Probe of Conformational Mobility and for Selective Surface Modification
Bibliographic record
Abstract
A series of aryl ketones, namely, 11-mercapto-1-phenyl-undecanone ( 1 ), 1-(4-hexyl-phenyl)-11-mercaptoundecanone ( 2 ), 1-(4-dodecyl-phenyl)-11-mercaptoundecanone ( 3 ), 1-[4-(11-mercaptoundecyl)phenyl]hexanone ( 4 ), and 1-[4-(11-mercaptoundecyl)phenyl]undecanone ( 5 ), anchored as mixed monolayers with one of hexanethiolate, dodecanethiolate, and octadecanethiolate on gold nanoclusters (so-called monolayer-protected clusters, MPCs) were prepared and characterized. The Norrish−Yang type II photoreactivity of these MPCs was investigated in benzene solution to serve as probes of conformational mobility within the monolayer environment. The aryl ketones react efficiently by a Norrish type II reaction (>75% completion) through their triplet excited state to yield a 1,4-biradical that fragments to give the corresponding alkene and substituted acetophenone-modified MPCs for 1 − 3 and 4 and 5, respectively. The extent of reaction and the efficiency do not appear to depend on the length of the alkanethiolate coadsorbed onto the MPC or on whether the aryl ketone is further embedded into the monolayer. Notably, there was no evidence for the generation of cyclobutanol products that would be generated from cyclization of the 1,4-biradical or other competing photochemical reactions. The findings of this investigation suggest that the MPC environment is quite dynamic; yet, the exclusive fragmentation products indicate that there are some factors affecting the conformational mobility of the triplet biradical. We further suggest that the reactivity in MPCs may be greatest at the edge/vertexes with larger constraints on the terraces. Regardless, the Norrish type II reactivity yields efficient fragmentation of either acetophenone or alkene moiety, suggesting such MPCs could find use for the controlled release of substrates in solution.
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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 | 0.000 | 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 | 0.000 | 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".