Formation of Highly Stable Heterodimers in Aqueous Solution Between .beta.-Cyclodextrin Derivatives Bearing Multiple Opposite Charges

Hamelin, B.; Jullien, Ludovic; Guillo, F.; Lehn, Jean‐Maríe; Jardy, Alain; Robertis, L. de; Driguez, Hugues

doi:10.1021/j100051a012

Cited by 35 publications

(42 citation statements)

References 5 publications

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“…[19] Potentiometric investigations with heptaamino-b-cyclodextrin have illustrated that the pK a of five amines range between 6.1 to 8.1, while two amines have pK a values of 8.8 and 9.3. [20] The aminocyclodextrin channel 1 will presumably follow a similar trend-below pH 6 the amines will be completely protonated, at neutral pH the pore will bear 3-5 positive charges, and above pH 9 the amines will be completely deprotonated.…”

Section: Understanding the Ph Effect On Ion Transportmentioning

confidence: 99%

Increasing pH Causes Faster Anion‐ and Cation‐Transport Rates through a Synthetic Ion Channel

Madhavan

Gin

2007

ChemBioChem

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Ion-channel mimics are able to transmit electrical signals across phospholipid membranes, and can be envisioned as nanoswitches for molecular electronics. Here, we reported the use of pH to alter ion-transport rates through a synthetic aminocyclodextrin ion channel. Both cation- and anion-transport rates were found to increase with an increase in pH due to the unique electrostatics of the multiple ammonium groups that line the channel pore. Such pH regulation of ion transport rates is unique and can be exploited for sensing applications.

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Section: Understanding the Ph Effect On Ion Transportmentioning

confidence: 99%

Increasing pH Causes Faster Anion‐ and Cation‐Transport Rates through a Synthetic Ion Channel

Madhavan

Gin

2007

ChemBioChem

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“…These factors could also be influenced by the pH value, considering that am-b-CD, going from pH¼8.0 to pH¼9.0, passes from its charged form to its neutral form. 11 Similarly, fluorophore guests were chosen for their different shapes and sizes, that can influence the size of the empty cavity, but also for their different polarities.…”

Section: Introductionmentioning

confidence: 99%

Stability and stoichiometry of some binary fluorophore–cyclodextrin complexes

et al. 2004

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Abstract-The stability and stoichiometric ratio of binary complexes among five fluorophores and b-cyclodextrin (b-CD) or heptakis-(6-amino-6-deoxy)-b-cyclodextrin (am-b-CD) were determined by means of fluorescence measurements in borate buffer at pH¼8.0 and 9.0. Structure of both host and guest affected the characteristics of the binary complexes. Pyrene and anthraquinone formed a 1:2 (fluorophore: cyclodextrin) complex with both cyclodextrins. Xanthone formed 1:1 complex with b-CD and 1:2 complex with am-b-CD. A more defined behaviour was observed for crysene. In fact, both stoichiometric different complexes were detected with both hosts. Only 1:1 complexes were observed for antracene. The complex stability was affected by the pH of the solution. MM2 calculations were performed in order to gain information about the forces working on the formation of complexes. q

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“…[10] Especially 6 A -amino-6 A -deoxy-b-CD (mono-NH 2 -b-CD) and heptakis(6-amino-6-deoxy)-b-CD (per-NH 2 -b-CD) in protonated forms are common cationic CDs whose reported pK a values are 8.5 and 6.9 ± 8.5, respectively. [11,12] At pH < 6, mono-NH 2 -b-CD and per-NH 2 -b-CD exist as the monovalent and polyvalent cations, respectively (mono-NH 3 -b-CD and per-NH 3 -b-CD). It has been reported that the binding constants (K) for the mono-NH 3 -b-CD complexes of aromatic carboxylic acids in the undissociated forms are considerably larger than those of the complexes of the corresponding carboxylate anions, [11] suggesting that Coulomb interaction between a monovalent CD cation and a monovalent guest anion is not effective for stabilizing an inclusion complex.…”

Section: Introductionmentioning

confidence: 99%

Complexation of Polyvalent Cyclodextrin Ions with Oppositely Charged Guests: Entropically Favorable Complexation Due to Dehydration

et al. 2000

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Thermodynamic parameters for complexation of polyvalent cyclodextrin (CD) cation and anion with oppositely charged guests have been determined in D2O containing 0.02 M NaCl by means of 1H-NMR spectroscopy. Protonated heptakis(6-amino-6-deoxy)-beta-CD (per-NH3+-beta-CD) forms stable inclusion complexes with monovalent guest anions. The enthalpy (deltaH) and entropy changes (deltaS) for complexation of per-NH3+-beta-CD with p-methylbenzoate anion (p-CH3-Ph-CO2-) are 3.8 +/- 0.7 kJ mol(-1) and 88.6 +/- 2.2 J mol(-1) K(-1), respectively. The deltaH and deltaS values for the native beta-CD-p-CH3-Ph-CO2- system are -8.6 +/- 0.1 kJ mol(-1) and 15.3 +/- 0.7 J mol(-1) K(-1), respectively. The thermodynamic parameters clearly indicate that dehydration from both the host and guest ions accounts for the entropic gain in inclusion process of p-CH3-Ph-CO2- into the per-NH3+-beta-CD cavity. The fact that the neutral guests such as 2,6-dihydroxynaphthalene and p-methylbenzyl alcohol hardly form the complexes with per-NH3+-beta-CD exhibits that van der Waals and/or hydrophobic interactions do not cause the complexation of the polyvalent CD cation with the monovalent anion. The acetate anion is not included into the per-NH3+-beta-CD cavity, while the butanoate and hexanoate anions form the inclusion complexes. The complexation of the alkanoate anions is entropically dominated. Judging from these results, it may be concluded that Coulomb interactions cooperated with inclusion are required for realizing the large entropic gain due to extended dehydration. Entropically favorable complexation was also observed for the anionic CD-cationic guest system. The present study might present a general mechanism for ion pairing in water.

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Formation of Highly Stable Heterodimers in Aqueous Solution Between .beta.-Cyclodextrin Derivatives Bearing Multiple Opposite Charges

Cited by 35 publications

References 5 publications

Increasing pH Causes Faster Anion‐ and Cation‐Transport Rates through a Synthetic Ion Channel

Increasing pH Causes Faster Anion‐ and Cation‐Transport Rates through a Synthetic Ion Channel

Stability and stoichiometry of some binary fluorophore–cyclodextrin complexes

Complexation of Polyvalent Cyclodextrin Ions with Oppositely Charged Guests: Entropically Favorable Complexation Due to Dehydration

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