Molecular-Level Study of Photoorientation in Hydrogen-Bonded Azopolymer Complexes
Bibliographic record
Abstract
To optimize azobenzene-containing materials for applications such as rewritable waveguides and holographic data storage, it is imperative to understand the effect of the azobenzene structure on the photoresponse of the material. Supramolecular materials, in which a complexed photoactive azobenzene controls the motion or other properties of a passive polymer, are uniquely convenient for studying the impact of specific chemical modifications. Here, we use polarization modulation infrared structural absorbance spectroscopy (PM-IRSAS) to study hydrogen-bonded supramolecular azobenzene complexes using poly(4-vinylpyridine) (P4VP) as a model polymer. We show that changing the tail group from hydrogen (A H ) to cyano (A CN ) induces greater angular redistribution of the chromophores and, remarkably, provokes P4VP pyridine ring orientation. Increasing the degree of complexation decreases the saturated orientation of both A H and A CN, whereas for P4VP/A CN it increases the pyridine orientation as well as the orientation stability of both components. These results explain the contrasting photoinduced birefringence behavior previously observed for these complexes and identify azo–azo intermolecular interactions as the main reason. To our knowledge, this is the first molecular-level spectroscopic analysis of the contrasting contributions of azobenzenes to the photoorientation of supramolecular azopolymer complexes and the first report of the large impact of small molecular changes on the capacity of azo dyes to transfer light-induced orientation to a photopassive polymer.
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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 | 0.001 |
| 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".