N<sup>2</sup>-Functionalized Blue Luminescent Guanosines by 2,2′-Dipyridylamino and 2-(2′-Pyridyl)benzimidazolyl Chelate Groups and Their Interactions with Zn(II) Ions
Bibliographic record
Abstract
The syntheses of new blue luminescent N(2)-modified guanosine derivatives with chromophores p-4,4'-biphenyl-NPh2 (1a), p-4,4'-biphenyl-N(2-py)2 (1b), and p-4,4'-biphenyl-2-(2'-pyridyl)benzimidazolyl (1c), respectively, have been achieved. These new N(2)-guanosines are moderate blue emitters with lambda(max) = 395 nm (1a), 370 nm (1b), and 403 nm (1c) and Phi = 0.13, 0.07, and 0.10 in tetrahydrofuran, respectively. Spectroscopic studies and density-functional theory calculations established that the guanine moiety and the new chromophore in all three molecules are involved in the luminescent process. We have also established that guanosines 1a-1c can interact with metal ions such as Zn(II). The interactions of Zn(II) ions with the three guanosines were examined via absorption, fluorescence, circular dichroism (CD), and NMR spectroscopic analyses. We have found that these guanosines display a distinct fluorescent response toward Zn(II) ions which can be attributed to the presence of the chelate chromophore N(2-py)2 in 1b and 2-py-benzimidazolyl in 1c. For 1a and 1b, the addition of Zn(II) ions causes straight fluorescent quenching while for 1c the addition of Zn(II) ions causes quenching initially, which is followed by a distinct spectral red shift and the intensity enhancement of the new emission peak. NMR and CD studies demonstrated that the Zn(II) ions bind preferentially to the guanine moiety in 1a and 1b but to the 2-(2'-py)benzimidazolyl chelate site in 1c. Moreover, the anion-dependent CD response of 1a-1c toward Zn(II) salts points to the possible involvement of intramolecular hydrogen bonding between the acetate bound to the Zn(II) ion and the hydroxyl groups of the guanosine.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".