Optoelectronic property tailoring of conjugated heterocyclic azomethines – the effect of pyrrole, thiophene and furans
Bibliographic record
Abstract
A series of de novo symmetric heterocyclic azomethine dyads and triads consisting uniquely of furans, thiophenes, pyrroles and methyl‐pyrroles were prepared. These were prepared to investigate the effect of various heterocycles and the degree of conjugation on the spectroscopic and electrochemical properties. The crystallographic structures of the symmetric azomethines were also compared with their unsymmetric and heterocyclic and homoaryl counterparts. It was found that for a similar series, bathochromic absorbance and fluorescence shifts occurred when progressing in the order of furan < thiophene < pyrrole ≈ methyl‐pyrrole. The spectroscopic properties of the heterocyclic azomethines were also bathochromically shifted relative to their homoaryl analogues as a result of increased degree of conjugation and electronic effects. The former was in part confirmed by crystallographic studies showing the heterocycles adopted co‐planar and antiparallel arrangements. Although all the compounds studied showed weak fluorescence at room temperature, their fluorescence could be restored at low temperatures, implying deactivation of the singlet excited manifold by bond rotation. Meanwhile, irreversible oxidation was observed for all the azomethines studied and their oxidation potentials were contingent on the heterocycle and number of azomethines, ranging between 0.8 and 1.4 V versus Ag+. The irreversible oxidation was due to radical cation cross‐coupling resulting in products with higher degrees of conjugation. Copyright © 2011 John Wiley & Sons, Ltd.
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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) | 0.001 | 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".