Push–Pull Porphyrin-Containing Polymers: Materials Exhibiting Ultrafast Near-IR Photophysics
Bibliographic record
Abstract
Four push–pull polymers of structure (C≡C– [Zn] –C≡C– A ) n ( A = isoindigo ( P1 ), bis(α-methylamino-1,4-benzene)quinone ( P2 ), 2-( N -methylamino-1,4-benzene)- N -1,4-benzene-maleimide ( P3 ), and 2,2′-anthraquinone ( P4 ); [Zn] = [bis( meso -aryl)porphyrin]zinc(II) = donor) and models M1 and M2 ( A ′–C≡C– [Zn] –C≡C– A ′; A ′ = respectively naphtoquinone and 2-anthraquinone) were prepared and characterized ( 1 H and 13 C NMR, elemental analysis, GPC, TGA, cyclic voltammetry, steady state and ultrafast time-resolved UV–vis and emission spectroscopy) and studied by density functional theory (DFT) and time-dependent DFT (TDDFT) in order to address the nature of the low-lying singlet and triplet excited states. P1 (fully conjugated polymer), P2 (formally nonconjugated but exhibit strong electronic communication accross the chain) and P4 (formally nonconjugated but local conjugation between the donor and acceptor) are near-IR emitters (λ max > 750 nm). M1 and M2 are mono-C≡C– [Zn] –C≡C species, and P3 exhibits a very modest CT contribution (as maleimide is a weak acceptor) and are not near-IR emitters. The nature of the S 1 and T 1 excited states are CT processes donor* → acceptor. In P1 – P4, a dual fluorescence (7.7 < τ F < 770 ps; except one value at 2.5 ns; P3 ) is depicted, which are assigned to fluorescences arising from the terminal and central units of the polymers identified from the comparison with M1 and M2 . The high and low energy fluorescences are respectively short (77 < τ F < 166 ps) and long-lived (688 < τ F < 765 ps) suggesting S 1 energy transfers with rates, k ET, of 7.1 ( P1 ), 12 ( P2 ) and 4.5 (ns) −1 ( P4 ). The fs transient absorption spectra exhibit particularly very short triplet lifetimes (2.3 < τ T1 < 87 ns) explaining the absence of phosphorescence. Also ultrafast lifetimes (85 < τ < 1290 fs) for species excited in the 0–0 peak of the Q-band (650 nm; i.e., ππ* porphyrin level) indicating its rather efficient nonradiative deactivation (S n ∼ > S 1 and S n ∼ > T m ). When cooling takes place or the solution concentration is increased, new red-shifted fluorescence bands appear, evidencing aggregate formation. Both fluorescence and transient absorption lifetimes of P1 – P4 become shorter and their band intensity lower. Finally, the position of the optically silent phosphorescence has been predicted to be in the 1300 ( P1, P2 ) and 1000 nm ( P3, P4 ) zones (DFT).
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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 | 0.001 | 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 | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".