Spectroscopic and Time-Dependent DFT Study of the Photophysical Properties of Substituted 1,4-Distyrylbenzenes
Bibliographic record
Abstract
In this contribution, we examine the photophysical properties of 15 totally trans–trans 1,4-distyrylbenzene derivatives (DSBs) functionalized with different electron-donating (ED) and electron-withdrawing (EW) groups by experimental and computational methodologies. We use UV–vis and fluorescence spectroscopies to determine the experimental optical properties such as the maximum absorption (λabsexp) and emission (λemexp) wavelengths, the highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gaps (ΔEabsexp), the molar extinction coefficients (ε), the fluorescence quantum yields (Φf), and the fluorescence lifetimes (τ). We also calculate the experimental spontaneous emission decay rate (krexp) and correlate all of these magnitudes to the corresponding calculated properties, maximum absorption (λabscal) and emission (λemcal) wavelengths, vertical transition energies (ΔEabscal), oscillator strength (Fosc), and spontaneous emission decay rate (krcal), obtained by the time-dependent density functional theory method. We analyze the effect of the electronic nature of the substituents on the properties of the DSBs, finding that the ED and EW groups lead to bathochromic shifts. This is consistent with the decrease of ΔE values as the strength of ED and EW substituents increases. We find excellent correlations between calculated and experimental values for λabs, λem, and ΔEabs (r ∼ 0.99–0.95). Additionally, the correlations between the relative ε with Fosc values and the kr values are in good agreement (r ∼ 0.88–0.72) with the experimental properties. Overall, we find that for substituted 1,4-DSBs, computational chemistry is an excellent tool to predict structure–property relationships, which can be useful to forecast the properties of their polymeric analogues, which are usually difficult to determine experimentally.
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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 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 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".