Synthesis and Electronic Structure Investigations of α,ω-Bis(arylthio)oligothiophenes: Toward Understanding Wire-Linker Interactions in Molecular-Scale Electronic Materials
Bibliographic record
Abstract
Several oligothiophenes with 2-mesitylthio (MesS) substituents have been prepared and studied by UV−visible spectroscopy and cyclic voltammetry. These compounds can be considered as models for thiol-terminated conjugated oligomers, which have attracted intense interest as materials for molecular-scale electronics. Three types of oligomers were prepared: α,ω-bis(mesitylthio)oligothiophenes 4 − 7, α,ω-bis(mesitylthio)oligo(3,4-ethylelendioxythiophene)s 12 − 14, and α,ω-bis(mesitylthio)oligomers 15 − 19 containing both thiophene and 3,4-ethylenedioxythiophene rings. The mesitylthio groups were introduced via nucleophilic attack of lithiated thiophenes on mesitylenesulfenyl chloride. The oligomers were assembled by oxidative coupling or palladium-catalyzed Stille coupling of 2-stannylthiophenes with 2-bromothiophenes. The solution electronic spectra of all oligomers display a red-shift in the lowest-energy transition maximum (λ max ) relative to oligothiophenes lacking the MesS- group. The red-shift arises from conjugative overlap of a mesitylthio sulfur lone pair with the oligothiophene π system. Cyclic voltammetry studies indicate that the MesS group significantly lowers the first and second oxidation potentials of the oligomers and improves the stability of the incipient radical cations and dications relative to alkyl-capped oligothiophenes. Additionally, the difference between first and second oxidation potentials in the MesS-substituted oligomers is much lower than known alkyl-substituted oligomers. This effect is due to the terminal MesS groups which cause charge density in the radical cations to concentrate at the chain ends, thereby lowering the Coulombic barrier to introduction of a second charge. The electronic structure perturbations caused by the MesS- group are discussed in the context of single-molecule conduction in thiol-terminated conjugated oligomers bound to gold electrodes.
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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".