Excited State Dynamics of Odd [<i>n</i>]Cumulenes: Chain Length and Conformational Effects
Bibliographic record
Abstract
Over the past decades, carbon allotropes have been extensively studied and applied to various technological applications due to their unique electronic and optical properties. Contemporary research has focused on quasi-1D, 2D, and 3D materials. On the other hand, the synthesis and isolation of carbyne as the 1D sp-hybridized carbon nanostructure remains elusive. Significant effort has been directed toward synthesis and study of carbon atomic wires (CAWs) as finite analogues of carbyne. The properties of CAWs composed of alkyne building blocks (oligoynes and polyynes) have provided glimpses of the potential properties of carbyne, while the synthesis and study of the alternative structure of CAWs, [ n ]cumulenes, remains in its infancy. Herein, we present an in-depth photophysical investigation of three odd [ n ]cumulenes ( n = 3, 5, 7) assisted by quantum-chemical calculations. In contrast to the oligoynes, the photophysical properties of cumulenic carbon chains are dramatically impacted by both length and conformational effects of terminal end groups. We demonstrate how the subtle control over rotational motion with respect to the terminal CC bonds of cumulenes alters their electronic ground and excited states as well as dominating the photophysical deactivation cascade.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".