Inclusion Reaction Research Articles

High-Pressure Stopped-Flow Study of Inclusion Reactions with α-Cyclodextrin: Dynamic Aspects in Host-Guest Interactions

The full volume and entropy profiles of the inclusion reaction between α-cyclodextrin and the guest molecules, ethylorange (1) and mordant yellow 7 (2), have been constructed from variable-pressure and -temperature stopped-flow kinetic experiments.

Calorimetric detection of organic vapours using inclusion reactions with organic coating materials

The application of calorimetric heat-power sensors for the determination of organic vapours using inclusion reactions has been investigated. Crystalline host compounds that are able to form clathrates with organic vapour molecules are used as coating materials. Due to the short response time of the monolithic integrated thermopile sensor that is used and because of the high reaction rate of inclusion, sensitivities of practical relevance can be achieved. Furthermore, the use of miniaturized calorimetric devices opens up new possibilities for studying the mechanism of the inclusion process on the surface of the sensor.

The first volume profile for a host–guest interaction: a variable pressure kinetic study of an inclusion reaction with α-cyclodextrin

The full volume and entropy profiles of the inclusion reaction between α-cyclodextrin and the guest molecule, mordant yellow 7, are constructed from variable pressure and temperature kinetic experiments, showing a two-step mechanism where both steps involve contracted transition states.

Anorganische und organische “Modell”‐Oberflächen für chemische Sensoren

AbstractA brief introduction is given on charge transfer reactions and inclusion reactions for oxide‐based and supramolecular compound‐based chemical sensors, respectively. TiO2 serves as inorganic “model” d0 oxide in the present study. By employing different surface spectroscopies and scanning tunneling microscopy, the formation and the role of intrinsic defects and Pt dopants at the thermodynamic most stable (110) surface is characterized with implications for the design of Schottky diode sensors and heterogeneous catalysts.Organic supramolecular compounds like calix[4]arene and resorcin[4]arendialkylsulfide form molecular recognition structures at surfaces which act as specific interaction sites for small organic molecules. Adsorption/desorption properties have been studied using quartz microbalance oscillators, thermal desorption spectroscopy and theoretical force field calculations.

Study on the kinetic process of the complex reaction between bilirubin and cyclodextrins

The complex behavior of bilirubin (BR) with γ-CD (cyclodextrin) and π-CD in aqueous and dimethylformamide (DMF) solution was investigated by absorption spectroscopy and cyclic voltammetry respectively. The data shows that the complexation mechanisms in these two solvents are different. In aqueous solution, the complexes of BR-β-CD and BR-γ-CD were formed by internal inclusion reactions, while in DMF, they were formed by external, non-inclusion ways. The dissociation constants obtained for these complexes are K d1 = 9.5 × 10 −4 M, K d2 = 5.1 × 10 −4 M in aqueous solution and K d3 = 12.5 × 10 −2 M, K d4 = 1.73 × 10 −2 M in DMF, respectively.

ChemInform Abstract: Dynamic Aspects in Host‐Guest Interactions. Part 2. Directional Inclusion Reactions of Some Azo Guest Molecules with α‐ Cyclodextrin.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Dynamic aspects in host–guest interactions. Part 2. Directional inclusion reactions of some azo guest molecules with α-cyclodextrin

The inclusion reactions of the azo guest molecules, 3′,5′-(Me)2–4′-(OH)Ph–NN–Ph–Y 1–4 and 3′-Pr–4′-(OH)Ph–NN–Ph–Y 5–8(Y = CO2–, SO2NH2, SO3– and AsO3H–). with α-cyclodextrin were investigated. The formation constants of the inclusion complexes ranged from 5.0 × 103 to 1.75 × 104 mol–1 dm3. The rate constants for the inclusion reactions in aqueous solution at 25 °C were determined by the stopped-flow method. The rate constants and reaction mechanism were quite sensitive to the substituent group Y on C-4 of one phenyl ring. The reactions of 1 and 5(Y = CO2–) were found to be very fast (millisecond or less) and to proceed as one step processes. On the other hand, the reactions of 4 and 8(Y = AsO3H–) were quite slow (several tens of minutes). In the case of the reaction of [graphic omitted] 2, 6(Y = SO2NH2) and 3, 7(Y = SO3–), the inclusion clearly proceeds as a two-step process. A specific orientation and/or direction of reactant within the inclusion complex is also discussed.

Enhancement and Inhibition by Linear Alcohol of the Formation of Inclusion Complexes betweend-Limonene and Cyclodextrins at Low Water Content

The influence of linear alcohols on the formation of inclusion complexes between d-limonene and α-, β-, or γ-cyclodextrin has been examined at a low water content using a micro-aqueous method. In the presence of alcohols, particularly methanol and ethanol, the formation of inclusion complexes between d-limonene and β- or γ-cyclodextrin is enhanced. The alcohol included in the cyclodextrin at the low water content was replaced with d-limonene as the water content increased. This implies that these alcohols would behave like water and activate the inclusion reaction between d-limonene and β- or γ-cyclodextrin. On the contrary, the formation of d-limonene complexes with α-cyclodextrin is inhibited by the presence of alcohols except for methanol. By means of the apparent water content, the amount of d-limonene complex in β- and γ-cyclodextrin correlated well with a single sigmoid curve.

Spectrofluorometric Study on the Inclusion Reaction of Flavonols with β-Cyclodextrin

Kinetics and thermodynamics of the inclusion reaction of flavonols with β-cyclodextrin have been studied fluorometrically in 30% v/1v methanolic aqueous solution. The equilibrium constants of this reaction were determined for flavonol and its 12 different hydroxy and methoxy derivatives in acidic and alkaline media where each flavonol is present quantitatively as fully protonated or deprotonated species. A thermodynamic consideration on the substituent effects reflected in these constants leads to a model for the present inclusion complex. With the inclusion constants for a monoprotic flavonol and its conjugate base, the effect of β-cyclodextrin on the acid dissociation equilibrium of the flavonol is quantitatively described. Kinetic aspects of this inclusion reaction are also discussed

Solid-state formation and amorphization of the inclusion compound tri- O-methyl-β-cyclodextrin-benzoic acid

Differential scanning calorimetry (DSC), X-ray powder diffraction, and IR spectroscopy of a 1:1 inclusion compound of tri- O-methyl-β-cyclodextrin (TMCD) and benzoic acid (BA) were carried out. About 75% of the inclusion compound was formed by shaking an equimolar physical mixture of TMCD-BA for 180 min. The X-ray diffraction pattern of the inclusion compound formed was almost the same as that of the pure TMCD crystal. The inclusion reaction was completed by grinding for 3 min with a vibrating mill. Further grinding for 40 min transformed all the inclusion crystals into an amorphous state, whose X-ray diffraction pattern is similar to that of a liquid-quenched glass. A glass transition was observed in the temperature range of 58–64°C. The grinding-time dependence of the T g was almost the same as that of the pure TMCD, i.e. the T g increased with grinding and approached that of the liquid-quenched glass. The amorphous TMCD-BA inclusion compound crystallized at around 80°C into a metastable phase, which has an entropy smaller than that of the stable phase. The metastable phase then underwent an irreversible transition to the stable phase at around 100°C with an endothermic effect. The stable crystalline modification fused at 174°C.

Retention behavior of β-cyclodextrin complexes of anthracene and pyrene using reversed-phase liquid chromatography: The effects of tert.-butanol and cyclopentanol

The effects of tert.-butanol and cyclopentanol on the formation of β-cyclodextrin (β-CD)-anthracene and β-CD-pyrene complexes have been studied using reversed-phase liquid chromatography. The retention times of anthracene and pyrene were monitored when eluted in a C 18 column with mobile phase mixtures consisting of methanol, water, β-CD, and a small amount of tert.-butanol or cyclopentanol. Plots of capacity factor of anthracene versus concentration of β-CD in the mobile phase in methanol-water mixtures and in mixtures containing 1% (v/v) cyclopentanol or tert.-butanol as secondary modifiers showed very similar trends. This suggests that anthracene forms weak complexes with β-CD, and that the presence of these secondary mobile phase modifiers have little effect on the β-CD-anthracene inclusion reaction. In contrast, pyrene showed no discernable change in retention time with increases in β-CD concentration. However, in the presence of 1% (v/v) tert.-butanol or cyclopentanol, capacity factor of pyrene decreased drastically, more in 1% (v/v) cyclopentanol than in 1% (v/v) tert.-butanol. Formation of a ternary β-CD-pyrene-alcohol complex has been proposed to explain the effects.

Inclusion Reaction by Swellable Clay Minerals. IV.

Inclusion Reaction by Swellable Clay Minerals. IV.

Mass Transport of Leveling Agents in Plating: Steady‐State Model for Blocking Additives

A quantitative model for the leveling effects of plating additives is presented. The fundamental assumption of this model is that the coverage of adsorbed additive is controlled by mass transport. Adsorbed additive is consumed through inclusion and electrochemical reaction and hence is replaced through transport and adsorption from the bulk solution. The primary effect of the adsorbed additive is assumed to be the blocking of the deposition current at the adsorption site. This steady‐state model reproduces the unique characteristics of additive polarization curves, including hysteresis and peaks in overpotential. Three dimensionless groups which characterize additive modified kinetics are identified. The model predicts the extent of either positive leveling or growing roughness on both the micro and macro scales. Sample plating maps are presented which indicate recommended operating windows for producing smooth and level deposits for various mass transfer boundary layer thicknesses and additive compositions.

Inclusion reactions of some phthalein and sulphophthalein compounds with cyclomalto-hexaose and -heptaose

Rate and equilibrium constants for the inclusion reactions of cyclomaltohexaose and -heptaose (α- and β-cyclodextrin) with phenolphthalein, o-cresolphthalein, Phenol Red, and Cresol Red in aqueous solution have been obtained spectrophotometrically. The structures of the inclusion complexes in solution have been also investigated by 1H- and 13C-n.m.r. spectroscopy. The change in u.v.-visible absorption spectra accompanying the formation of the phenolphthalein-β-cyclodextrin inclusion complex demonstrates that the formation of a lactone ring is induced on inclusion.

1H-NMR Study of the Inclusion Reactions of Charged Derivatives of α-Cyclodextrin with Sodium p-(3-t-Butyl-4-hydroxyphenylazo)benzenesulfonate

Abstract Presence of an intermediate inclusion species is demonstrated by 270 MHz 1H-NMR spectroscopy in the system of the title azo compound and the charged derivatives of α-cyclodextrin. The 1H-NMR peaks due to the sulfanilate moiety of the guest molecule are distinctly split into two peaks upon binding to the positively charged cyclodextrin, suggesting the formation of an intermediate species.

Kinetic Studies on the Inclusion Reaction of Ethylenediamine Mono-substituted α-Cyclodextrin with Sodium p-(3-t-Butyl-4-hydroxyphenylazo)benzenesulfonate in Aqueous Solution

Abstract Kinetics of the inclusion reactions of the title azo compound having negative charge and an α-cyclodextrin derivative with positive charge is investigated by means of stopped-flow method. A two-step inclusion mechanism is proposed.

Design and testing of a microcalorimeter with semiconductor thermopiles as temperature sensor and study of the inclusion of Cu(II) with β-cyclodextri

In this investigation, a microcalorimeter has been designed and tested which is primarily intended for studying heats of reaction in dilute solution at room temperature to 40° C. This microcalorimeter uses semiconductor thermopiles as the temperature difference sensor. Electrical calibration experiments and property testings indicate that the precision of the microcalorimeter is 0.3% for heat changes of about 2 J. The sensitivity is 170 μV mW −1; the time constant is 260 sec. The enthalpy of neutralization of TRIS with standard HCl solution has been measured. At 25°C, Δ H = −47.48±0.16 kJ mol −1, at 30°C, Δ H = −47.08 ± 0.26 kJ mol −1: these results are in good agreement with values given in the literature. Using this microcalorimeter the enthalpy of the inclusion reaction of β-cyclodextrin with Cu(II) in dilute solution was measured and a value of Δ H = −184.2 ± 0.7 kJ mol −1 obtained at 30.0°C.

Compensation effect in host-guest interactions: the activation parameters for the inclusion reactions of .alpha.-cyclodextrin with hydroxyphenylazo derivatives of naphthalenesulfonic acids

Determination par la methode du flux stoppe. Les parametres d'activation sont tres influences par la structure du solvant autour du site d'inclusion de la molecule hote

A TWO-STEP MECHANISM FOR THE INCLUSION REACTIONS OF α-CYCLODEXTRIN WITH MONO ALKYL-SUBSTITUTED HYDROXYPHENYLAZO DERIVATIVES OF SULFANILIC ACID

Abstract Kinetic studies on the inclusion reactions of the title azo compounds with α-cyclodextrin (α-CDx) in aqueous solution by means of the stopped-flow method reveal a two-step inclusion mechanism involving a fast binding process of the guest compounds to α-CDx followed by the slow intramolecular transformation of the intermediate inclusion complex. Activation parameters for each step were determined.

RATE CONSTANTS AND THERMODYNAMIC PARAMETERS FOR THE INCLUSION REACTIONS OF SOME p-HYDROXYPHENYLAZO DERIVATIVES OF SULFANILIC ACID WITH α-CYCLODEXTRIN

Abstract Inclusion reactions of the title azo compounds with α-cyclodextrin were studied in aqueous solution by means of the stopped-flow method. The forward rate constants for the inclusion reactions were found to be in the order of magnitude 102–104 mol−1 dm3 s−1 Activation parameters were first determined for α-cyclodextrin system.