Chloromethoxytrityls: Tuning the SOMO Level of Stable Luminescent Radicals
Bibliographic record
Abstract
Luminescent radicals are of significant recent interest because of the unique quantum properties of the doublet excited state. Control of the energy level of the singly-occupied molecular orbital (SOMO) is essential for the design and application of open-shell materials, but most triarylmethyl radicals are very electron-poor and exhibit similar SOMO values. In this work, we show how a combination of chlorine and methoxy substituents in triarylmethyl radicals allows tuning of their SOMO level over a wide range of -5.7 to -3.9 eV. We demonstrate that both methoxy and chlorine groups provide sufficient stabilization of the radical against peroxide formation, but one-electron oxidation in air limits the SOMO ≤ -4.5 eV to maintain bench stability. Two new stable radicals are characterized by X-ray crystallography, cyclic voltammetry, and luminescence measurements in solution and doped films. We show that the combination of chlorine and methoxy substituents improves the photostability of triarylmethyl radicals compared to tris(trichlorophenyl)methyl (TTM). The extraordinarily large range of SOMO levels in these radicals provides an opportunity to benchmark computational methods for predicting redox potentials. We find that most common density functional theory functionals and even coupled-cluster (CCSD) calculations overestimate the substituent effects in these open-shell species.
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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) | 0.001 | 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 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".