Energetics of the encapsulation of o-, m-, and p-hydroxybenzoic acids by β-cyclodextrin and its methylated and hydroxypropylated derivatives in aqueous solution

1999 ◽  
Vol 77 (3) ◽  
pp. 348-355 ◽  
Author(s):  
Elena Junquera ◽  
Valentin G Baonza ◽  
Emilio Aicart
Keyword(s):  
Aqueous Solution ◽  
Inclusion Complex ◽  
Aqueous Solutions ◽  
Inclusion Complexes ◽  
Binding Constant ◽  
Substituent Effect ◽  
Binding Constants ◽  
Hydroxybenzoic Acid ◽  
Guest Molecules ◽  
Hydroxybenzoic Acids

A fully computerized potentiometric technique has been used to analyze the energetics of the encapsulation of o-, m-, and p-hydroxybenzoic acids by β-cyclodextrin (β-CD) and (or) two of its most used derivatives: 2,6-di-O-methyl-β-cyclodextrin (DIMEB) and hydroxypropyl-β-cyclodextrin (HPBCD). The study has been carried out by measuring the pH of aqueous solutions of the three hydroxyacids in the absence of cyclodextrin at 25°C, and in the presence of cyclodextrin at several temperatures ranging from 15 to 40°C, keeping constant the concentration of the guest. The dissociation constant of the acids and the binding constants of the inclusion complexes formed have been simultaneously determined at all the temperatures by using a model previously derived by us. The carboxylic forms have been found to bind the CD with higher affinities than the carboxylate partners do, irrespective of the temperature, the cyclodextrin used, and the position of the substituents on the guest molecules. The formation of the inclusion complexes studied in this work has been found to be enthalpy driven, with a favorable enthalpic term dominant over an unfavorable entropic one. The effect of the substituents of both guest and host molecules on the thermodynamics of the inclusion processes has been analyzed. Key words: binding constant, β-cyclodextrin, hydroxybenzoic acid, inclusion complex, substituent effect.

Evaluation of the phase solubility of inclusion complexes of diisopropylphenol (INN) with hydroxypropyl-β-cyclodextrin

2021 ◽  
pp. 27-32
Author(s):  
Olga Mikhailovna Balakhonova ◽  
Viktoriya Sergeevna Tyukova ◽  
Stanislav Anatolievich Kedik
Keyword(s):  
Aqueous Solution ◽  
Inclusion Complex ◽  
Inclusion Complexes ◽  
Tween 80 ◽  
Phase Solubility ◽  
Cyclodextrin Inclusion ◽  
Solubility Method ◽  
Cyclodextrin Inclusion Complex ◽  
The Stability ◽  
Solubility Profiles

The paper presents the results of a study of the stability of aqueous solutions of inclusion complexes of hydroxypropyl-β-cyclodextrin with diisopropylphenol in various systems by the Higuchi-Connors phase solubility method. The phase solubility profiles for each system corresponding to the AN type are determined graphically, and the stability constants of the resulting inclusion complexes are calculated. An aqueous solution containing 0.2 % Tween 80 and 0.2 % mannitol was selected as the optimal condition for obtaining the hydroxypropyl-β-cyclodextrin inclusion complex with diisopropylphenol.

Inclusion complexation involving sugar-containing species: β-cyclodextrin and sugar surfactants

2004 ◽  
Vol 82 (1) ◽  
pp. 45-49 ◽  
Author(s):  
Vincent C Reinsborough ◽  
Vanessa C Stephenson
Keyword(s):  
Surface Tension ◽  
Critical Micelle Concentration ◽  
Inclusion Complex ◽  
Computer Modeling ◽  
Inclusion Complexation ◽  
Binding Constants ◽  
Guest Molecules ◽  
Sugar Moiety ◽  
G 12 ◽  
Concentration Surface

Surface tension, proton NMR, and computer modeling studies were undertaken in nonionic alkylpolyglycoside (APG) solutions containing β-cyclodextrin (β-CD) with a view to characterize the inclusion complexes formed and to determine if the sugar entities of the host and guest molecules played a significant role in the process. The APGs investigated were four glucopyranosides (octyl G8, decyl G10, dodecyl G12, tetradecyl G14) and two maltosides (decyl M10, dodecyl M12). Critical micelle concentrations (CMC) were obtained in the surfactant–β-CD systems, which in all cases increased with increasing β-CD concentration. The 1:1 APG–β-CD inclusion complex was principally formed with binding constants of 425 (mol L–1)–1 for the G12 complex, 340 (mol L–1)–1 for the G10 complex, and 125 (mol L–1)–1 for the M12 complex. The preferred configuration of the G-12–β-CD complex has the surfactant tail coiled in the CD cavity with the surfactant sugar moiety sealing off the narrower opening of the CD torus.Key words: alkylpolyglycoside, β-cyclodextrin, NMR, critical micelle concentration, surface tension.

scholarly journals NMR spectroscopic study of inclusion complexes of cetirizine dihydrochloride and β-cyclodextrin in solution

2007 ◽  
Vol 21 (3) ◽  
pp. 177-182 ◽  
Author(s):  
Syed Mashhood Ali ◽  
Santosh Kumar Upadhyay ◽  
Arti Maheshwari
Keyword(s):  
Aqueous Solution ◽  
Chemical Shift ◽  
Spectroscopic Study ◽  
Inclusion Complexes ◽  
Binding Constant ◽  
Spectroscopic Studies ◽  
Chemical Shift Change ◽  
Nmr Chemical Shift ◽  
H Nmr ◽  
Shift Change

Cetirizine dihydrochloride (CTZ), an antihistamine, forms two 1:1 inclusion complexes with β-cyclodextrin (β-CD) in aqueous solution as confirmed by detailed1H NMR, COSY and ROESY spectroscopic studies. The stoichiometry and overall binding constant of the complexes were determined by the treatment of1H NMR chemical shift change (Δδ) data. Most of the CTZ protons exhibited splitting in the presence of β-CD.

scholarly journals Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

2017 ◽  
Vol 13 ◽  
pp. 1572-1582 ◽  
Author(s):  
Spyros D Chatziefthimiou ◽  
Mario Inclán ◽  
Petros Giastas ◽  
Athanasios Papakyriakou ◽  
Konstantina Yannakopoulou ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Molecular Recognition ◽  
Aqueous Solutions ◽  
Crystalline State ◽  
Dimeric Complex ◽  
Nmr Studies ◽  
Guest Molecules ◽  
Crystallographic Order

The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only β-CD–L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). In contrast, crystals of the complex β-CD–D-NAcTrp were never obtained, although numerous conditions were tried. In aqueous solution, the orientation of the guest in both complexes is different than in the β-CD–L-NAcTrp complex in the crystal. Overall, the study shows that subtle differences observed between the β-CD–L,D-NAcTrp complexes in aqueous solution are magnified at the onset of crystallization, as a consequence of accumulation of many soft host–guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with β-CD.

The Host–Guest Properties Observed Between the Viologens and Cyclopentanocucurbit[6]uril

2020 ◽  
Vol 73 (7) ◽  
pp. 601
Author(s):  
Si-Yuan Cheng ◽  
Yun-Xia Qu ◽  
Zhu Tao ◽  
Kai-Zhi Zhou ◽  
Lian-Tong Wei ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Nmr Spectroscopy ◽  
Inclusion Complexes ◽  
Electronic Absorption ◽  
1H Nmr Spectroscopy ◽  
Guest Molecule ◽  
Binding Mode ◽  
Titration Calorimetry ◽  
Aryl Group ◽  
Guest Molecules

The interactions between cyclopentanocucurbit[6]uril (abbreviated as CyP6Q[6]) and a series of dialkyl-4,4′-bipyridinium and diaryl-4,4′-bipyridinium dicationic guest molecules, where the alkyl group is CH3(CH2)n with n=0–6 (expressed as G1 to G7) and the aryl group is phenylene (G8) and xylene (G9), have been investigated in aqueous solution using 1H NMR spectroscopy, isothermal titration calorimetry (ITC), and electronic absorption spectroscopy. Our results show that G1 and G2 form 1:1 host–guest inclusion complexes with CyP6Q[6], in which the bipyridinium core is partially embedded in the cavity of CyP6Q[6]. G3–G9 form 2:1 dumbbell-type host–guest inclusion complexes, in which the substituents are encapsulated by CyP6Q[6]. At the same time, CyP6Q[6] was compared with several other cucurbit[n]urils (Q[n]s) and their derivatives, such as Q[6], Q[7], and TMeQ[6], which have been reported to interact with this type of guest molecule. In its binding mode, CyP6Q[6] shows many interesting and different properties, and this difference was mainly reflected with G1 and G2.

scholarly journals Identification of β -cyclodextrin inclusion complex by infrared spectroscopy

2018 ◽  
pp. 87-91
Author(s):  
I. O. Omelchenko ◽  
T. G. Yarnyh ◽  
I. B. Yanchuk ◽  
G. I. Borschevskiy
Keyword(s):  
Infrared Spectroscopy ◽  
Inclusion Complex ◽  
Inclusion Complexes ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Rapid Identification ◽  
Mechanical Mixture ◽  
Molar Ratio ◽  
Guest Molecules ◽  
Cyclodextrin Inclusion

Fast and reliable identification of obtaining product is very important in the industrial technology of synthesis of pharmaceutical substances. Objective - to study inclusion complexes of β-cyclodextrin with α-bromizovalerian acid and β-cyclodextrin with mint oil by applying near infrared spectroscopy absorption. Compare the spectra obtained with the spectra of equimolar mechanical mixture of the respective components. Β-cyclodextrin complexes with α-bromizovalerian acid and β-cyclodextrin with mint oil were prepared at a well-known technique. Mechanical mixture of β-cyclodextrin with α-bromizovalerian acid and β-cyclodextrin with mint oil were obtained by mixing the components in a molar ratio of 1:1. This paper shows the possibility using method of absorption near-infrared spectroscopy for rapid identification β-cyclodextrin inclusion complexes, as an example used complexes of β-cyclodextrin with α-bromizovalerian acid and β-cyclodextrin with peppermint oil. By comparing the spectra obtained inclusion complexes with the spectra of equimolar mechanical mixture of the corresponding components proved reliability the identification of the target product and the ability to distinguish between an inclusion complex and the mechanical mixture of the components. It is shown that the near infrared spectra obtained using an instrument Thermo Nicolet IS50, Thermo Scientific, inclusion complexes of β-cyclodextrin with a different guest molecules are different from each other.

NMR Studies of the Inclusion Complexes Between Ezetimibe and Cyclodextrins

2018 ◽  
Vol 69 (7) ◽  
pp. 1838-1841
Author(s):  
Hajnal Kelemen ◽  
Angella Csillag ◽  
Bela Noszal ◽  
Gabor Orgovan
Keyword(s):  
Inclusion Complex ◽  
Inclusion Complexes ◽  
Water Solubility ◽  
Solution Nmr ◽  
Spectroscopic Techniques ◽  
Nmr Studies ◽  
The Poor ◽  
Poor Water Solubility

Ezetimibe, the antihyperlipidemic drug of poor bioavailability was complexed with native and derivatized cyclodextrins.The complexes were characterized in terms stability, stoichiometry and structure using various 1D and 2D solution NMR spectroscopic techniques. The complexes were found to be of moderate stability (logK[3). The least stable inclusion complex is formed with b-cyclodextrin, while the ezetimibe-methylated-b--cyclodextrin has a 7-fold higher stability. The results can be useful to improve the poor water-solubility and the concomitant bioavailability of ezetimibe.

Effect of thermal history of aqueous solutions of KCl on the metastable zone width

1984 ◽  
Vol 49 (3) ◽  
pp. 559-569 ◽  
Author(s):  
Jaroslav Nývlt
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Thermal History ◽  
Equilibrium Solubility ◽  
Metastable Zone Width ◽  
Zone Width ◽  
Preceding Experiment ◽  
History Of ◽  
Metastable Zone ◽  
The Given

The metastable zone width of an aqueous solution of KCI was measured as a function of the time and temperature of overheating above the equilibrium solubility temperature. It has been found that when the experiments follow close upon one another, the parameters of the preceding experiment affect the results of the experiment to follow.The results are interpreted in terms of hypotheses advanced in the literature to account for the effect of thermal history of solution. The plausibility and applicability of these hypotheses are assessed for the given cause of aqueous solution of a well soluble electrolyte.

scholarly journals I. Thermo-electric behaviour of aqueous solutions with mercurial electrodes

1879 ◽  
Vol 29 (196-199) ◽  
pp. 472-482 ◽  
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Internal Diameter ◽  
Thermo Electric ◽  
Thin Glass ◽  
Mercury Surface

In order to investigate this subject, I devised and constructed the following apparatus :—A and B are two thin glass basins, 81 millims. internal diameter (= 5,153 sq. millims. of mercury surface), and 6·0 centims. deep; each containing a layer of mercury about 1·0 centim. deep, covered by a layer, about 3 centims. deep, of the aqueous solution to be examined.

Sign in / Sign up

Export Citation Format

Share Document