Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Miskolczy, Zsombor; Biczók, László

doi:10.1021/jp500603g

Cited by 54 publications

(75 citation statements)

References 42 publications

(129 reference statements)

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“…The binding constant for the latter host, K(B + @CB7) = 2.97×10 7 M 1 at 294 K, was taken from our previous study. 44 The best fit of the experimental data gave K 1 = (1.0 ± 0.2) ×10 7 M 1 in good agreement with the directly measured value (vide supra).…”

Section: Absorption and Fluorescence Characteristics Of Cb8 Complexessupporting

confidence: 77%

“…The slow escape of B + from 2B + @CB8 (k 2 = 0.6 s 1 ) is attributed to the large endothermicity of the process, whose activation enthalpy exceeds H 2 = 69 kJ mol 1 , the enthalpy of B + dissociation from the 2:1 complex (Table 2). Although H 2 matches the activation enthalpy of B + release 44 from B + @CB7, the egression from B + @CB7 is almost 4 times slower than from 2B + @CB8. The difference in the exit rate constants indicates that the removal of B + has a larger activation entropy (ΔS ‡ ) from 2B + @CB8 than from B + @CB7.…”

mentioning

confidence: 82%

“…Further 6 experimental details have been reported in a former paper. 44 Fluorescence decays were measured with time-correlated single-photon counting technique using the previously described instrument. 49 The results of spectrophotometric and fluorescence titrations were analyzed with homemade programs written in MATLAB 7.9.…”

Section: Methodsmentioning

confidence: 99%

“…About twice smaller equilibrium constant was found for the binding in CB8 than in the smaller CB7 macrocycle 44 (Table 2). Des ite the slight (≈ 2 kJ mol 1 ) difference in the driving forces at 298 K, the confinement is much less exothermic in CB8 than in CB7.…”

mentioning

confidence: 94%

“…[47][48] We have demonstrated that berberine (B + ), a pharmaceutically important isoquinoline alkaloid, is an excellent guest for the investigation of the complex formation dynamics with CB7. 44 Activation enthalpy of 32 and 69 kJ mol −1 were found for the association and dissociation implying that the tight carbonyl-laced portal of the host constituted a steric barrier.…”

Section: Introductionmentioning

confidence: 99%

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Sequential inclusion of two berberine cations in cucurbit[8]uril cavity: kinetic and thermodynamic studies

Miskolczy

Biczók

2014

Phys. Chem. Chem. Phys.

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A combination of absorption and fluorescence spectroscopic studies with isothermal calorimetric titrations and stopped-flow measurements is a powerful way to reveal the thermodynamics and kinetics of inclusion complex formation with cucurbit[8]uril (CB8). The unique photophysical characteristics of berberine (B + ), a pharmaceutically important natural alkaloid, was exploited to distinguish the consecutive encapsulation processes, and to examine the confinement in CB8 cavity. The highly environment sensitive fluorescence lifetime of B + permitted of the selective detection of various cucurbituril complexes, and indicated to what extent the embedded guest is available for interaction with water. Highly stable 1:1 and 2:1 B + CB8 complexes were produced due to the release of the high energy water molecules from the CB8 interior, and the second binding step proved to be almost 3 times more exothermic. The favorable entropy change appreciably contributed to the driving force of 1:1 encapsulation. Contrarily, the embedment of the second B + in CB8 led to substantial entropy diminution. The kinetics of encapsulation was followed in real time by recording the fluorescence intensity change after rapid mixing of B + and CB8. No evidence was found for intermediates. The rate constants of (64 ± 9)×10 6 , and (5.0 ± 0.5)×10 6 M 1 s 1 were found for 1:1 and 2:1 associations, whereas 3.8 ± 0.6, and 0.6 ± 0.1 s 1were obtained for the rate constants of the reverse processes at 283 K, respectively.3

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Section: Absorption and Fluorescence Characteristics Of Cb8 Complexessupporting

confidence: 77%

mentioning

confidence: 82%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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Sequential inclusion of two berberine cations in cucurbit[8]uril cavity: kinetic and thermodynamic studies

Miskolczy

Biczók

2014

Phys. Chem. Chem. Phys.

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Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

Xiao

Sun

et al. 2022

Angewandte Chemie

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We introduce a versatile recognition tunneling technique using doubly cucurbit[7]uril‐functionalized electrodes to form supramolecular junctions that capture analytes dynamically by host–guest complexation. This results in characteristic changes in their single‐molecule conductance. For structurally related drug molecules (camptothecin, sanguinarine, chelerythrine, and berberine) and mixtures thereof, we observed distinct current switching signals related to their intrinsic conductance properties as well as pH‐dependent effects which can be traced back to their different states (protonated versus neutral). The conductance variation of a single molecule with pH shows a sigmoidal distribution, allowing us to extract a pKa value for reversible protonation, which is consistent with the reported macroscopic results. The new electronic method allows the characterization of unmodified drug molecules and showcases the transfer of dynamic supramolecular chemistry principles to single molecules.

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Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

Xiao

Sun

et al. 2022

Angew Chem Int Ed

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We introduce a versatile recognition tunneling technique using doubly cucurbit [7]uril-functionalized electrodes to form supramolecular junctions that capture analytes dynamically by host-guest complexation. This results in characteristic changes in their single-molecule conductance. For structurally related drug molecules (camptothecin, sanguinarine, chelerythrine, and berberine) and mixtures thereof, we observed distinct current switching signals related to their intrinsic conductance properties as well as pH-dependent effects which can be traced back to their different states (protonated versus neutral). The conductance variation of a single molecule with pH shows a sigmoidal distribution, allowing us to extract a pK a value for reversible protonation, which is consistent with the reported macroscopic results. The new electronic method allows the characterization of unmodified drug molecules and showcases the transfer of dynamic supramolecular chemistry principles to single molecules.

show abstract

Kinetics and Thermodynamics of Berberine Inclusion in Cucurbit[7]uril

Abstract: The kinetics and thermodynamics of berberine inclusion in cucurbit [7]uril was studied by

Cited by 54 publications

References 42 publications

Sequential inclusion of two berberine cations in cucurbit[8]uril cavity: kinetic and thermodynamic studies

Sequential inclusion of two berberine cations in cucurbit[8]uril cavity: kinetic and thermodynamic studies

Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

Dynamic Interconversions of Single Molecules Probed by Recognition Tunneling at Cucurbit[7]uril‐Functionalized Supramolecular Junctions

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