Solvent effects on chemical processes. 9. Energetic contributions to the complexation of 4-nitroaniline with α-cyclodextrin in water and in binary aqueous-organic solvents

Mulski, Michael J.; Connors, Kenneth A.

doi:10.1080/10610279508028936

Cited by 29 publications

(26 citation statements)

References 12 publications

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“…Other phenomenological models can be found in the literature to evaluate solvent effects on complexation processes (20,21). In particular, the model of Abraham et al (20), which assumes a linear relationship between the logarithm of the association constant K and the solvophobicity parameter S p , directly related to the percent volume of organic cosolvent, is another way of managing the effect of the hydrophobicity of the medium with similar conclusions.…”

Section: Resultsmentioning

confidence: 95%

Role of Hydrophobic Effect on the Noncovalent Interactions Between Salicylic Acid and a Series of β-Cyclodextrins

Junquera

Ruiz

Aicart

1999

Journal of Colloid and Interface Science

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Section: Resultsmentioning

confidence: 95%

Role of Hydrophobic Effect on the Noncovalent Interactions Between Salicylic Acid and a Series of β-Cyclodextrins

Junquera

Ruiz

Aicart

1999

Journal of Colloid and Interface Science

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Section: Theorymentioning

confidence: 99%

“…6,7 One of the processes to which the theory has been applied is complex formation. 8,9 In the fully aqueous solution, our present concern, the free energy change of complex formation is given by eq 1.In eq 1, ∆G* comp is given by eq 2, where K mf is the binding constant on the mole fraction scale, and the free energy change is on a per molecule basis; k and T have their usual meanings. ∆G intrasol C describes substrateligand interaction within the complex.…”

mentioning

confidence: 99%

Prediction of Binding Constants of α-Cyclodextrin Complexes

Connors¹

1996

Journal of Pharmaceutical Sciences

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Proceeding from a phenomenological theory of pairwise interactions (solvent-solvent, solvent-solute, and solute-solute), the binding constant K11 (in M-1) for 1:1 complex formation by alpha-cyclodextrin at a substrate binding site, at 25 degrees C in water, is given by log K11 = -1.74 - [Z] + 0.032(-delta A), where [Z] incorporates solvent-solute (solvation) and solute-solute interactions and delta A is the decrease in nonpolar surface area (in A2 molecule-1) on the substrate that is exposed to solvent when the binding site enters the cyclodextrin cavity. delta A is estimated from the structure of the binding site. Three levels of approximation are described for estimating [Z]. At the third (highest) level, the procedure when applied to 569 complex systems generated predicted values of log K11 that agreed within 0.30 unit of the experimental values in 58% of cases, and that agreed within 1.00 unit in 95% of cases.

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“…As examples, we choose two drugs: the anti-inflammatory ibuprofen and antiasmatic terbutalin; the stability constants at 37°C of their complexes with -CD, obtained by applying the competitive model to the plot Correlation between log K 2 and log P 0 . The investigated alcohols (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) show very different efficiency in destabilizing the nitroxide:CD complexes. This behavior can be understood on the basis of the different tendency of these alcohols to be included in the CD cavity.…”

Section: Discussionmentioning

confidence: 99%

The Binding Behavior of Cyclodextrins toward a Nitroxide Spin Probe in the Presence of Different Alcohols As Studied by EPR

2008

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Stability constants, rates of association and dissociation, and thermodynamic and activation parameters for the formation of inclusion complexes between the radical guest, N-benzyl- tert-butyl- d 9-nitroxide and beta- or 2,6- O-dimethyl-beta-cyclodextrin (CDs), have been determined by EPR spectroscopy in water in the presence of 14 different alcohols, differing in size and lipophilicity. In all cases, it was found that addition of alcohol, depending on its structure and concentration, causes a reduction of the stability of the paramagnetic complex. Global analysis of EPR data allowed us to explain the CDs binding behavior: we discarded the formation of a ternary complex, where alcohol and radical guest are coincluded into CD cavity, while data were found more consistent with the formation of a binary complex alcohol:CD competing with the monitored complex nitroxide:CD. Both kinetic and thermodynamic analysis of the experimental results have revealed that the presence of alcohols affects to a larger extent the dissociation rather then the association of radical probe and CD and that the former process is of greater importance in determining the stability of the complex, this confirming the reliability of the competition model proposed. This competition has been used for the indirect determination of the stability constants of complexes between CD and examined alcohols. By using a similar approach, we showed EPR spectroscopy can be considered a rapid and accurate technique to investigate the CDs binding behavior toward different nonradical guest.

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Solvent effects on chemical processes. 9. Energetic contributions to the complexation of 4-nitroaniline with α-cyclodextrin in water and in binary aqueous-organic solvents

Cited by 29 publications

References 12 publications

Role of Hydrophobic Effect on the Noncovalent Interactions Between Salicylic Acid and a Series of β-Cyclodextrins

Role of Hydrophobic Effect on the Noncovalent Interactions Between Salicylic Acid and a Series of β-Cyclodextrins

Prediction of Binding Constants of α-Cyclodextrin Complexes

The Binding Behavior of Cyclodextrins toward a Nitroxide Spin Probe in the Presence of Different Alcohols As Studied by EPR

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