Complex formation of some nonionic surfactants with hydroxypropyl-β-cyclodextrin and with heptakis (2,6-di-O-methyl)-β-cyclodextrin

The interaction of six nonionic surfactants -[4-(1,1,3,3-tetra-methylbutyl)phenyl]--hydroxypoly(oxy-1,2-ethanediyl) with hydroxypropyl--cyclodextrin (HPCD) and dimethyl--cyclodextrin (DIMEB) was studied by reversed-phase thin-layer chromatography in the presence and absence of sodium chloride. Each surfactant formed complexes with both cyclodextrin derivatives; however, the strength of interaction varied considerably. DIMEB formed more stable inclusion complexes with the surfactants than did HPCD. A longer ethyleneoxide chain decreased the strength of interaction, whereas sodium chloride exerted a negligible impact. Principal component analysis indicated that both the hydrophobicity and the specific hydrophobic surface are of the surfactant influenced the complex formation indicating the hydrophobic character of the interaction.Dedicated to Professor József Szejtli.     

The Heptakis-(2,6-di-O-methyl)-β-cyclodextrin Inclusion Complex with Acetic Acid

A novel monomer-type structure of heptakis-(2,6-di-O-methyl)--cyclodextrin in a typical monoclinic herringbone scheme has been determined by single crystal X-ray diffraction. Crystal data: space group P21, Z = 2, a = 15.165(6), b = 10.613(3), c = 23.188(8) Å, = 102.02(4)°, V = 3650(3) Å3 and R = 0.094 for 2933 observed MoK reflections with I > 3(I). A unique water molecule located in the intermolecular spaces, reinforces the cohesion between the herringbone chains. The analysis of the electron density distribution suggests that an acetic acid molecule is trapped within the macrocycle cavity, alternately with a water molecule.     

Interaction of Fluorocarbon Containing Hydrophobically Mdified Polyelectrolyte with Nonionic Surfactants

The interaction of fluorocarbon containing hydrophobically modified polyelectrolyte(FMPAANa) with two kinds of nonionic surfactants(hydrogenated and fluorinated)in a semidilute (0.5wt%) aqueous solution had been studied by rheological measurements,Association behavior was found in both systems.The hydrophobic interaction of FMPAANa with fluorinated surfactant(FC171) is much stronger than that with hydrogenated surfactant(NP7.5) at low surfactoant concentrations.The interaction is strengthened by surfactants being added for the density of active junctions increased.Whereas distinct phenomena for FC171 and NP7.5 start to be found as the surfactants added over their respective certain concentration.The interaction of polyelectrolyte with fluorinated surfactant increases dramatical ly while that with hydrogenated surfactant decreases.     

Interaction of Fluorocarbon Containing Hydrophobically Modified Polyelectrolyte with Nonionic Surfactants

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Thermal behavior of ground mixtures of heptakis (2,6-di-O-methyl)-β-cyclodextrin and benzoic acid

Characterization of an inclusion complex prepared from amorphous ground mixtures of heptakis (2,6-di-O-methyl)--cyclodextrin (DMCD) and benzoic acid was carried out by a sealed heating method. The formation of the crystalline inclusion complex and the variation in physicochemical properties of the ground mixture were investigated as a function of heating temperature. On the basis of X-ray diffractometry and Fourier transform infrared spectroscopy, the crystallization of the ground mixture was confirmed to take place at about 135°C. The crystallization temperature was shifted to lower temperatures and the bound molar ratio of benzoic acid to DMCD increased as the mixing molar ratio of benzoic acid to DMCD was raised.Tsumura & Co., 3586 Yoshiwara, Amimachi, Inashikigun, Ibaraki 300-11, Japan.     

Complex formation of hexakis(2,6-di-O-methyl)-α-cyclodextrin with substituted benzenes in aqueous solution

The host-guest interaction of hexakis(2,6-di-O-methyl)--cyclodextrin (DM--CDx) with substituted benzenes in aqueous solution has been investigated by circular dichroism spectra. From the resemblance of the spectra, it is concluded that the guest molecules are included in the DM--CDx ring in a manner similar to that of corresponding -cyclodextrin complexes. Thermodynamic parameters of the complex formation were determined on the basis of the temperature dependent intensity change of the spectra. In spite of the considerable variation in H and AS values, the free energy does not change much among complexes because of the strong compensation effect. The compensation temperature was 309 ± 11K. Negative values of H and S, suggesting that the complex formation is not governed by the hydrophobic interaction, can be interpreted in terms of the tight binding of the guest molecule within the host cavity.     

The Use of Principal Component Analysis for the Study of the Interaction of Anionic Surfactants with Hydroxypropyl-β- Cyclodextrin

The interaction of 11 sulfosuccinic acid ester anionic surfactants with hydroxypropyl--cyclodextrin (HPCD) were determined with reversed-phase thin-layer chromatography and the relative strength of interaction was calculated. The relationship between the strength of interaction and the physicochemical parameters of anionic surfactants was elucidated with principal component analysis (PCA). HPCD interacted with the anionic surfactants decreasing their hydrophobicity. The distribution of the points of the strength of interaction and physicochemical parameters on the two dimensional nonlinear map of PC loadings suggested that the strength of interaction between the anionic surfactants and HPCD is of mixed steric character, with hydrophobic and electronic forces being involved in the interaction.     

Ab initio Study on the Interaction of La (Ⅲ) with Adrenaline

IntroductionInrecentyears,thebiologlcaIeffectsofrareearthshavcbeendsdsedestensiveyinChina.IthasbecnfoundthatrareearthsshowintcreedngneuralandendocrineeffeCtlll.Thermdyontheintcractionofrareearth8withhormoncisveryhoportanttoclariopgthencuralandendocrinceffecofrareearth8anditsmeckanism.Adrenalineisavitalkindofhormone.ThermdiesoncomplexesofmstaiionswithadrenalinhavebecnrePOrted12'4l.Bowever,whichgroupofadrenalinescrvesasdonorhasbeenund6rcoatmersyforalongtimc.Thus,theinteractionofLa(III)witba…     

Inclusion interaction of chloramphenicol and heptakis (2,6-di-O-methyl)-β-cyclodextrin: phase solubility and spectroscopic methods

The inclusion interaction between chloramphenicol and heptakis (2,6-di-O-methyl)-β-cyclodextrin (DMBCD) had been investigated by phase solubility and spectroscopic methods such as UV-vis spectroscopy, circular dichroism, Fourier transform infrared (FT-IR) spectroscopy, proton nuclear magnetic resonance spectroscopy ((1)H NMR) as well as 2D-ROESY spectra. Phase solubility analysis showed A(L)-type diagram with DMBCD, which suggested the formation of 1:1 inclusion complex of DMBCD with chloramphenicol. The estimated stability constant (K(s)) of the inclusion complex of chloramphenicol with DMBCD is 493 M(-1) at 293 K. The solubility enhancement of chloramphenicol in the presence of DMBCD is stronger than that in the presence of β-CD, HP-β-CD and M-β-CD. The results obtained by spectroscopic methods showed that the nitrophenyl moiety of chloramphenicol is deeply inserted into inner cavity of DMBCD from the narrow rim of DMBCD, which the inclusion model of chloramphenicol with DMBCD differs from that with β-CD.     

Interaction of some antibiotics with hydroxypropyl-β-cyclodextrin

The interaction between 19 antibiotics and hydroxypropyl--cyclodextrin (HPCD) was studied by reversed-phase thin-layer chromatography. HPCD formed inclusion complexes with 16 compounds, the complex always being more hydrophilic than the uncomplexed drug. The intensity of interaction significantly increased with increasing specific hydrophobic surface area of the guest molecule proving the preponderant role of hydrophobic interactions in inclusion complex formation. The intensity of the HPCD-drug interaction significantly decreased with increasing concentration of methanol in the environment indicating that methanol can also enter the cyclodextrin cavity and inhibits competitively the inclusion complex formation or the free energy of transfer from water to the HPCD cavity should be less negative at higher concentration of methanol in the aqueous medium.Dedicated to Professor József Szejtli.     

Complex Formation between Heptakis(2,3,6-tri-O-butyl)-β-cyclodextrin with p-Nitrophenol in Heptane

CyCIodeXtrin(CD)hasacavityinthemoIecuIarcenter,itcanaccommodatevariousguestmoIecuIesinitscavityinaqueoussoIUtion,forminginCIusioncompounds13.However.sofarthereareontyafewstudiesconcemingtheinteraCtionbetW6enCDderivativesandguestsinorganicsolventonthebasisofsP6CtroscoP/.Inthepresentwork,weaimedtoinvestigatetbecompIexfOrmationOfaperaIMatedboodeXtrinderivative,heptakis(2,3,&tri-ren-b~)-6-CyCIOdedrinrrB5-CD),whhpnttrophenolpeP)inhePtane-bymeansofabsorPtionandNMRspeCtroscoPy.Synthes…     

Binding of vitamin A byβ-cyclodextrin and heptakis(2,6-O-dimethyl)-β-cyclodextrin

Inclusion complexation of all-trans-retinol, retinal and retinoic acid with -cyclodextrin (-CD) and heptakis(2,6-O-dimethyl)--cyclodextrin (DM--CD) were investigated by means of UV-vis spectroscopy. The association constants (K _a) obtained for vitamin A with DM--CD is greater than with -CD. On the other hand, for the same host compoundK _a values of retinol, retinal and retinoic acid are very close to each other.     

Composition and properties of freeze-dried products of nicotinic acid withβ-cyclodextrin and heptakis (2,6-0-dimethyl)-β-cyclodextrin

The purpose of the study was to examine the formation of inclusion compounds in the freeze-dried products obtained from aqueous solutions of nicotinic acid and -cyclodextrin (-CD), or heptakis (2,6-0-dimethyl)--cyclodextrin (DIMEB). The molar ratios used were 1:1 and 2:1. In addition two freezing temperatures (–40 and –196°C) and different secondary drying temperatures (+50 and +80°C) were used. Freeze-dried products with -CD obtained after low temperature freezing are of the same crystallographic structure as seen in a pure inclusion compound prepared by coprecipitation. Amorphous products were formed after fast freezing. The molar ratios of included nicotinic acid in the freeze-dried products vary — dependent on the preparation conditions — between 0.75:1 and 1:1. A factorial design proves that the included drug amount can be increased by enhancement of the amount of nicotinic acid used, by faster freezing, and by the combination of these two factors. The proof of inclusion formation was given by a combination of X-ray diffractography, differential scanning calorimetry, thermogravimetry and thermofractography.The freeze-dried preparations obtained with DIMEB were amorphous mixtures of the two components. No proof for inclusion of the nicotinic acid in the cyclodextrin cavity could be given. Higher (–40°C) or lower (–196°C) freezing temperatures and the running of the secondary drying process could not influence these results. The very low stability constant of the complex and steric reasons are responsible for this behavior.     

Study on the inclusion compound of β-cyclodextrin with (η5-cyclopentadienyl)tricarbonylmanganese(0)

The supramolecular inclusion compound of β-cyclodextrin (β-CD, host) with (η5-cyclopentadienyl)tricarbonylmanganese [MnCp(CO)3, guest] was obtained in a crystalline state. The host-guest compound is thermally stable and do not liberate the guest on heating at 100$ in vacuum. It was characteried by elemental analysis,1H NMR, differential scanning thermal (DSC) analysis and TLC. Continueous variation plot by NMR method shows that β-CD formed 1:1 inclusion compound with MnCp(CO)3. On the basis of 1H NMR spectra and the model building with Corey Pauling Koltum (CPK) models, the most probable inclusion mode is proposed.     

Study on the Interaction of Colloidal Gold with Taq DNA Polymerase

The interaction of colloidal gold with Taq DNA polymerase （Taq） was investigated in this study. Taq-gold conjugate was formed by adding the enzyme to the colloidal gold solution, as evidenced by UV-Vis spectroscopy, X-ray photoelectron spectroscopy, and photon cross correlation spectroscopy measurements. The conjugate was further characterized by transmission electron microscopy. It was found that the Taq-gold conjugate particles were still spherical and well-dispersed. The influence of gold nanoparticles on the bioactivity of Taq was studied by analyzing the yield of the polymerase chain reaction amplification. Results indicated that the enzymatic activity of Taq decreased after interaction with the colloidal gold.     

Stereoselective reduction with sodium dithionite of conjugated enones in the presence ofβ-cyclodextrin and its heptakis(2,6-di-O-methyl) derivative as host compounds or phase transfer agents

The reduction with sodium dithionite in aqueous alkaline solution of the conjugated carbon-carbon double bond of carbonyl compounds1–5 as inclusion compounds in-cyclodextrin (CD) and its heptakis(2,6-di-O-methyl) derivative (DMCD) has been investigated. These results are compared with those obtained under phase transfer conditions (1 : 1 water-toluene) using methyltrioctylammonium chloride or DMCD as transfer agents. Remarkable kinetic effects as well as regio-and stereoselectivities were observed, depending on the nature of the host molecule and of the substrate.     

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.     

Synergistic Effect in Mixed Capillary Gas Chromatographic Stationap Phases Containing Heptakis(2,3,6-tri-o-pentyl)-β-cyclodextrin and Dibenzo-18-crown-6

Thecrownetherhashighselectivityfortheseparationofpolarpositionisomersandcyclodextrlnstationaryphasesfortheseparationofchlralcompoundsandpositionalisomers．RecentlyourresearchgrouphasshowntheexlstenceofsynerglstlceffectInsomemixedgaschromatographlcsta...     

Study on inclusion interaction of hydrophilic 2-chloromandelic acid with hydroxypropyl-β-cyclodextrin

The inclusion interaction between hydroxypropyl-β-cyclodextrin (HP-β-CD) and hydrophilic 2-chloromandelic acid (CMA) was studied by ultraviolet (UV) absorption spectrophotometer. A reliable determination of the complex stoichiometry was provided by the continuous variation technique. ¹H NMR spectrum and Thermo-gravimetric/differential thermal analyzer (TG/DTA) techniques were explored to further characterize the inclusion complex, and molecular modeling was used to investigate the mechanism of inclusion interaction. The results showed that HP-β-CD reacted with R,S-CMA to form inclusion complexes, with 1:1 stoichiometry and inclusion stability constants K_R and K_S were 24 and 39 L/mol determined from UV data by the method of Benesi-Hildebrand’s. Molecular modeling confirmed experimental observation and indicated that the hydrogen bonding interaction plays an important role in the interactive inclusion between HP-β-CD and CMA. Besides, compared with the HP-β-CD, molecular modeling showed R, S-CMA interact with β-CD through different binding modes, in which Vander Waals is the main intermolecular force between β-CD and R-CMA (or S-CMA) while without obvious hydrogen bonding interaction.     

The Effects of Nonionic Surfactants on the Tris (2,2'-bipyridyl)Ruthenium( Ⅱ ) Tripropylamine Flow Injection Electrochemiluminescence System

研究了非离子表面活性剂聚乙二醇辛基苯基醚(Triton X-100)对流动注射电化学发光的影响.结果发现,Triton X-100对检测低浓度三联吡啶钌(Ru(bpy)2+3)有增强作用,而且Triton X-100的引入可以改变流动注射电化学发光分析系统中 Ru(bpy)2+3-三正丙胺(TPA)反应电极电位.在检测电位1.35 V,进样量100μL,进样速度50 μL/s条件下,对Ru(bpy)2+3进行检测,检出限(S/N=3)达1.0×10-10 mol/L,较添加Triton X-100前灵敏度提高50倍.