Synthesis and Optical and Electronic Properties of Thiophene Derivatives
Bibliographic record
Abstract
Abstract Using the Hinsberg synthesis of thiophenes, a versatile method to prepare fully derivatized, π‐extended thiophenes is reported. Functionalized thiophenes were divergently synthesized to create three classes of compounds – electron‐deficient, extended conjugation and electron‐rich – to assess substituent effects on optical and electrochemical properties. Properties were assessed by solution absorption spectroscopy, solution‐ and solid‐state fluorescence spectroscopy, cyclic voltammetry and density functional theory calculations. Tetracyano derivatives, prepared through Knoevenagel condensations of malononitrile with thiophene‐2,5‐dicarbaldehydes, were used as electron‐poor analogs. These derivatives showed quasireversible reduction reactions and very low‐lying calculated LUMO energies (–0.55 V reduction potentials vs. Fc/Fc+). The effect of extending π conjugation on the optical and electrochemical properties was investigated by the installation of bis(2‐thienylacryonitrile) groups onto three thiophene cores. The extended conjugation led to compounds that demonstrated both solution‐ and solid‐state fluorescence and moderate, irreversible reduction potentials (–1.2 V versus Fc/Fc+). The Lewis‐acid‐catalyzed coupling of four indoles to thiophene‐2,5‐dicarbaldehydes was studied to assess the effects of both electron‐donating substituents and a quinoidal thiophene. The tetraindolic thiophenes possessed low HOMO–LUMO energy gaps of 1.91 eV, high‐lying HOMO energy levels and tunable LUMO energy levels, attributed to the thiophene quinoidal ground‐state structure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
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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".