Self‐Assembly of N<sup>2</sup>‐Modified Guanosine Derivatives: Formation of Discrete G‐Octamers
Bibliographic record
Abstract
In the presence of Na(+) ions, two N(2)-modified guanosine derivatives, N(2)-(4-n-butylphenyl)-2',3',5'-O-triacetylguanosine (G1) and N(2)-(4-pyrenylphenyl)-2',3',5'-O-triacetylguanosine (G2), are found to self-associate into discrete octamers that contain two G-quartets and a central ion. In each octamer, all eight guanosine molecules are in a syn conformation and the two G-quartets are stacked in a tail-to-tail fashion. On the basis of NMR spectroscopic evidence, we hypothesize that the pi-pi-stacking interaction between the N(2)-side arms (phenyl in G1 and pyrenyl in G2) can considerably stabilize the octamer structure. For G1, we have used NMR spectroscopic saturation-transfer experiments to monitor the kinetic ligand exchange process between monomers and octamers in CD(3)CN. The results show that the activation energy (E(a)) of the ligand exchange process is 31 +/-5 kJ mol(-1). An Eyring analysis of the saturation transfer data yields the enthalpy and entropy of activation for the transition state: DeltaH(not =)=29 +/-5 kJ mol(-1) and DeltaS(not =)=-151 +/-10 J mol(-1) K(-1). These results are consistent with an associative mechanism for ligand exchange.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".