The terfenadine/β-cyclodextrin inclusion complex

Terfenatine (TFN) is a very hydrophobic antiallergic drug. It exists in three polymorphic and two solvated forms and is practically insoluble in water. These properties make a pharmaceutical formulation with acceptable biopharmaceutical characteristics difficult to prepare. Inclusion complexation with -cyclodextrin (CD) may eliminate such problems. The properties of the TFN/CD system have been studied in liquid, gaseous and solid phases by¹H and¹³C NMR spectroscopy, powder X-ray diffractometry, differential scanning calorimetry and fast atom bombardment mass spectrometry. The solubility phase diagram was also recorded. In solution and in the gaseous phase the 11 complex prevails, whereas a 12 TFN/CD complex has been isolated by precipitation from homogeneous solution.     

Selective hydrogenation of phenol in supercritical carbon dioxide

Liquid phase hydrogenation of phenol over Pt/C catalysts was investigated under conventional conditions and supercritical carbon dioxide (scCO2). The equivalent ration of hydrogen to phenol shows a significant effect on the product selectivity. Hydrogenation of phenol in different solvents was also studied, the experimental results show that polarity of solvents influences the yield of cyclohexanone remarkably, scCO2 has the highest one. Catalytic hydrogenation of phenol in scCO2 or sub-sc…     

Solubility of monocrotaline in supercritical carbon dioxide and carbon dioxide—ethanol mixtures

The solubility of monocrotaline, a chemotherapeutic drug precursor, in supercritical carbon dioxide and carbon dioxide—ethanol mixtures has been measured from 308.15 to 328.15 K and from 8.86 to 27.41 MPa. The solubility ranges from 6.0 × 10⁻⁶ to 2.21 × 10⁻⁴ mol fraction increasing up to 25-fold with the addition of ethanol. A new method for the estimation of the sublimation pressure of monocrotaline was developed based on the measured solubilities of monocrotaline in water. The sublimation pressure was then used in the compressed gas model to correlate the behavior of carbon dioxide—monocrotaline and carbon dioxide—ethanol—monocrotaline systems with reasonable success.     

Complex formation of cinnamaldehyde-methyl-β-cyclodextrin and muscone-methyl-β-cyclodextrin by supercritical carbon dioxide processing and sealed heating method

Firstly, the interaction between cinnamaldehyde (CIN) and methyl-β- cyclodextrin (MBCD) was studied in aqueous solution. 1:1 inclusion complex was formed and the association constant was 187 ± 9 M^?1. Then the complex of CIN–MBCD and muscone–MBCD was prepared both by sealed heating method and by supercritical carbon dioxide (sc CO₂) approach. Complete complex was obtained by both methods for CIN–MBCD. Some CIN molecules was weakly associated with MBCD molecules in products by sealed heating method, all CIN molecules was strongly associated with MBCD molecules in products by sc CO₂ processing. Complete complex between muscone and MBCD was not obtained. The choice for the size of guest molecule still existed for MBCD cavity in sealed heating method and sc CO₂ processing.     

Effects of several inter-molecular interactions on the inclusion between methyl substituted β-cyclodextrin and some linear macromolecule in supercritical carbon dioxide medium

In this work, the inclusion between methyl substitute β-cyclodextrin and some linear macromolecule in supercritical carbon dioxide medium was investigated. The contributions from several factors were studied; such as the hydrogen bonding interaction between the host and guest, the hydrogen bonding interaction between the neighborhood cyclodextrin rims threaded on the polymer chain, and the matching between the host cavity and the size of the polymer axis.     

Preparation and characterization of theβ-cyclodextrin inclusion complex with sulfafurazole

The 1 : 1 inclusion complex involving sulfafurazole (SF) and-cyclodextrin (-CD) is prepared by the freeze-drying method and characterized on the basis of its chemical analysis, thermal behavior, infrared spectrum, X-ray powder pattern and¹³C NMR spectrum in DMSO-d₆ solution. The stability constant of the inclusion complex was determined by the solubility method. The effect of cyclodextrin on the UV absorption spectrum of sulfafurazole was also observed.     

Solubility measurement of α-asarone in supercritical carbon dioxide

The solubility of α-asarone in supercritical CO₂ (sc-CO₂) has been measured using the dynamic method. The measurement was conducted in the pressure range from 9.0 to 18.0 MPa at temperature 35–49 °C. The experimental data were correlated using the Chrastil model. The results show that the solubility increases as the pressure rises and decreases as the temperature rises, which is well correlated with the Chrastil model.     

Self-assembly behavior of inclusion complex formed by β-cyclodextrin with α-aminopyridine

An inclusion complex (1) has been prepared by β-cyclodextrin with α-aminopyridine. The result of X-ray crystallographic analyses showed that the α-aminopyridine molecules in the β-cyclodextrin cavities possess two opposite orientations, i.e. the amine group of α-aminopyridine pointing to the primary side (1a, occupancy: 41.2%) or the secondary side (1b, occupancy: 58.8%) of β-cyclodextrin, forming two scalelike supramolecular aggregations. The studies of 2D NMR and circular dichroism spectra indicated that the α-aminopyridine molecule is deeply embedded in the β-cyclodextrin cavity to form host-guest inclusion complex, showing a circular dichroism spectrum induced by the chiral cavity of cyclodextrin. The results obtained are helpful for understanding the molecular recognition and aggregation mechanism between the host and guest.     

Self-assembly behavior of inclusion complex formed by β-cyclodextrin withα-aminopyridine

~~Self-assembly behavior of inclusion complex formed by β-cyclodextrin withα-aminopyridine~~     

Co-solvent modulation of the inclusion selectivity ofβ-cyclodextrin

The solubility of-CD, which is increased to 87 gL^–1 in 75% water - 25% isopropanol mixtures, does not behave in a linear fashion as a function of the water/isopropanol ratio. Application of this increased solubility to the formation of inclusion complexes between-cyclodextrin and cineole : eugenol, cineole : pinene and eugenol : pinene shows strong solvent modulation of the inclusion selectivity. The proportion of guests complexed is in inverse ratio to the compatibility of the guests in the solvent mixture.     

Thermodynamic study on inclusion complex formation of riboflavin with hydroxypropyl-β-cyclodextrin in water

The inclusion complex formation of riboflavin (RF) with hydroxypropyl-β-cyclodextrin (HP-β-CD) in water was investigated by ¹H NMR, UV-vis spectroscopy, and solubility methods. A 1:1 stoichiometry and thermodynamic parameters of complex formation (K, Δ_c G ⁰, Δ_c H ⁰, and Δ_c S ⁰) were determined. Complexation was characterized by negative enthalpy and entropy changes due to prevalence of van der Waals interactions and hydrogen bonding between polar groups of the solutes. A partial insertion of RF into macrocyclic cavity was revealed on the basis of ¹H NMR data and molecular mechanics calculation. Location of benzene ring of RF molecule inside the hydrophobic cavity of HP-β-CD results in an increase of aqueous solubility of the former.     

Synthesis and characterization of praseodymium-2-hydroxypropyl-β-cyclodextrin inclusion complex

Journal of Radioanalytical and Nuclear Chemistry - The inclusion complex of PrCl3-XH2O-2-hidroxypropyl-β-cyclodextrin (Pr-2HPβCD) was prepared to increase the solubility and stability of...     

Enhancement inhibition efficiency of PBTCA depending on the inclusion complex with hydroxypropyl-β-cyclodextrin

For the first time, hydroxypropyl-β-cyclodextrin (HP-β-CD) has been brought in to include 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) in order to enhance inhibition efficiency of PBTCA, which leads a new approach to study oil–gas field corrosion inhibition in the process of acid treatment. Based on the host–guest inclusion reaction, the inclusion complex of PBTCA with HP-β-CD has been prepared in the laboratory. UV–Vis absorption spectrum was applied to study the inclusion behavior of PBTCA with HP-β-CD. The results revealed that PBTCA with HP-β-CD can form a 1:1 stoichiometry inclusion complex. The 1:1 inclusion complex synthesized by using lyophilization was further characterized by Fourier transform infrared spectroscopy. Besides, inhibition effect of the inclusion complex on the corrosion inhibition of Q235 carbon steel has been investigated in 0.1 M sulfuric acid (H₂SO₄) solution using potentiodynamic polarization, electrochemical impedance spectroscopy techniques and scanning electron microscopy (SEM). It was found that the presence of the inclusion complex better achieved the anti-corrosion property in aggressive medium than was the case with alone PBTCA and the highest inhibition efficiency of the inclusion complex over 90 % was obtained, which are suggestive of the active effect of the inclusion complex for improving inhibition efficiency of PBTCA. Meanwhile, the results obtained from SEM further showed that the inclusion complex acts as a more efficient corrosion inhibitor for Q235 carbon steel in H₂SO₄ medium.     

The effect of inclusion inβ-cyclodextrin on the chemistry of peroxides: Reactions of radicals withβ-cyclodextrin

Studies by electron paramagnetic resonance (EPR), differential scanning calorimetry, thermogravimetric analysis, HPLC and NMR showed that radicals produced by thermolysis and photolysis of benzoyl peroxide,t-butyl peroxide and cumene hydroperoxide included in-cyclodextrin (-CD), undergo significant reaction with the-CD. The formation of-CD radicals was observed by EPR. Products formed by addition of radicals to-CD were also observed. Such host:guest radical reactions explain the reported stabilization of peroxides, found with-CD inclusion, as being primarily due to the interruption of chain reactions by trapping of the chain carriers. A small increase in activation barrier for cleavage of the included peroxide in-CD was also observed.