Preparation of Light and Moisture Stable Flexible and Rigid Asymmetrical Polystannanes
Bibliographic record
Abstract
<p>Theoretical calculations of polystannanes in an all trans-configuration possess a relatively small band gap (~2.8 eV). This is due to the extensive σ-σ overlap of the diffuse 5sp3 orbitals of Sn atoms in the conjugated Sn-Sn polymer backbone, which leads to a visible σ-σ* transition by UV-vis spectroscopy. The electronic properties of polystannanes suggests that these materials are candidates for semi-conducting intrinsic polymers. However, due to the weak bonding between Sn-Sn atoms and the Lewis acidic nature of Sn centers, polystannanes readily degrade with exposure to daylight and moist atmospheres. This project demonstrates clear synthetic pathways and designs to stabilize the Sn-Sn backbone. This was accomplished by incorporating functional ligands with Lewis basic heteroatoms such as oxygen or nitrogen moieties which can form a hypercoordinate interaction with the Sn center. Two major types of asymmetrical polystannane systems were investigated: 1) a flexible system where Sn centers are attached to a propyl chain containing either a bulky or small functional donor ligand and 2) a rigid system where the Sn center contain either a hypercoordinate benzyl methoxy ether (C,O) or benzyl dimethyl amine (C,N) ligand prepared using a direct approach. This thesis is broken into three different chapters. Chapter 1 and 3 include all synthetic pathways, characterization and stability testing of both flexible and rigid polystannanes. Chapter 2 describes a high molecular weight (Mw = 60 kDa) film forming, semi-crystalline (Tg = 49.3 °C and Tm = 110.1 °C) flexible asymmetrical polystannane containing a propylhydroxy ligand that displays exceptional stability to light and moisture (> 9 months). In addition, a tosyl containing polystannane that could function as a macromolecular intermediate was prepared. Substitution of model tosyl stannanes was demonstrated, and substitutions of the tosyl polystannane are ongoing.</p> <p><br></p>
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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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".