Substituted Benzoxadiazoles as Fluorogenic Probes: A Computational Study of Absorption and Fluorescence
Bibliographic record
Abstract
General chemical strategies which provide controlled changes in the emission or absorption properties of biologically compatible fluorophores remain elusive. One strategy employed is the conversion of a fluorophore-attached alkyne (or azide) to a triazole through a copper-catalyzed azide-alkyne coupling (CuAAC) reaction. In this study, we have computationally examined a series of structurally related 2,1,3-benzoxadiazole (benzofurazan) fluorophores and evaluated changes in their photophysical properties upon conversion from alkyne (or azide) to triazole forms. We have also determined the photophysical properties for a known set of benzoxadiazole compounds. The absorption and emission energies have been determined computationally using time-dependent density functional theory (TD-DFT) with the Perdew, Burke, and Ernzerhof exchange-correlation density functional (PBE0) and the 6-31+G(d) basis set. The TD-DFT results consistently agreed with the experimentally determined absorption and emission wavelengths except for certain compounds where charge-transfer excited states occurred. In addition to determining the absorption and emission wavelengths, simple methods for predicting relative quantum yields previously derived from semiempirical calculations were reevaluated on the basis of the new TD-DFT results and shown to be deficient. These results provide a necessary framework for the design of new substituted benzoxadiazole fluorophores.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".