A Volumetric Study of Cyclodextrin-α,ω-Alkyl Dicarboxylate Anion Complexes in Aqueous Solutions
Bibliographic record
Abstract
The apparent molar volumes ( V φ,S ) of a homologous series of sodium α,ω-alkyl dicarboxylate [(CH 2 ) x (CO 2 Na) 2, x = 4, 6, 8, 10, 12] salts (S) have been determined in water (w) and in aqueous cyclodextrin (CD) solutions at 25 °C. The magnitude of V φ,S in ternary (w+S+CD) solutions containing β-CD and DM-β-CD (2,6-di-O-methyl β-cyclodextrin) are greater than in the binary (w+S) aqueous systems. However, in ternary solutions containing α-CD, the magnitude of V φ,S is lower than in the binary systems. The apparent molar volume (AMV) of the α,ω-alkyl dicarboxylate salts in ternary aqueous solutions can be related to the formation of inclusion complexes between the CD and the anions (C x 2- where x = 6, 8, 10, 12). The transfer volume of the C x 2- guests at infinite dilution from water to aqueous CD solutions are well described by a simple molecular additivity scheme which accounts for the number of methylene groups of the guest that are included and the number of water molecules displaced from the CD interior. The volumetric properties of the ternary systems have been quantitatively described in terms of a two- or three-site model that accounts for the AMV of bound and unbound species. In cases where CD-S inclusion complexes are formed, β-CD and DM-β-CD form 1:1, α-CD forms 1:1 ( x ≤ 8) and 2:1 complexes ( x ≥ 10). The binding mode involves threading of the methylene chain of the guest through the CD interior while the carboxylate groups remain hydrated in the bulk solvent or adjacent to the CD annuli. The calculated 1:1 binding constants ( K 1:1 ) vary between 10 1 −10 3 kg mol -1 and the 2:1 binding constants ( K 2:1 ) are ca. 10 2 kg 2 mol -2 . The relative binding affinity of the host systems with a common C x 2- guest are as follows: α-CD > β-CD > DM-β-CD, and these differences are mainly related to the diameter of the host cavity.
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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 | 0.001 |
| 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".