Thermodynamic Properties of Inclusion Complexes between β-Cyclodextrin and Naphthenic Acid Fraction Components
Bibliographic record
Abstract
The spectral displacement technique was used to determine the 1:1 equilibrium binding constants ( K 2 ) of the complexes formed between β-cyclodextrin and carboxylate anion guests, including either single components or mixtures in aqueous solution at variable temperatures (25–55 °C). A van’t Hoff analysis of the results afforded thermodyamic parameters (Δ H °, Δ S °, and Δ G °) of the single-component carboxylate anions and complex mixtures of carboxylic acid species, referred to as naphthenic acids (NAs). Three types of single-component examples of NAs with variable hydrogen deficiency ( z ) values were studied: n -octanoic ( z = 0; S1), trans -4-pentylcyclohexanecarboxylic acid ( z = −2; S2), and dicyclohexylacetic acid ( z = −4; S3). The carboxylate anion mixtures were obtained from commercial suppliers and an industrial source obtained from oil sands process water. The estimated K 2 values decrease with increasing temperature, and the standard Gibbs energy change (Δ G °) for complex formation is generally favorable (from −16 to −28 kJ/mol) and largely enthalpy-driven (from −12 to −30 kJ/mol). The change in entropy of complex formation (Δ S °) for S1, S2, and S3 varies (−23 and 44 J mol –1 K –1 ) depending on the guest size and relative lipophilicity. The positive correlation between complex stability, host–guest size-fit complementarity, and lipophilicity of the carboxylate anion reveals the importance of the hydrophobic effect, as evidenced by compensation phenomena for such host–guest complexes.
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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 | 0.001 |
| 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) | 0.001 | 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".