Masatoshi Fujimoto

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

Abstract 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 1 H- and 13 C-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.

Electrostatic Effects on the Inclusion Process of Sodium p-(3-t-Butyl-4-Hydroxyphenylazo)Benzene Sulfonate with Modified Cyclodextrin and Its Metal Complex

Abstract The electrostatic interaction between charged β-cyclodextrin having ethylenediamine group and the title azo compound was investigated by 1H-NMR spectroscopy.

Visible absorption spectral measurements of the formation of the cobalt porphyrin dioxygen complex using a high-pressure cell ag

Abstract The 1:1 complex formation between dioxygen and the meso -tetraphenylporphinatocobalt(II)pyridine complex in toluene was followed spectrophotometrically using a high-pressure cell. The values of the equilibrium constant K p obtained are 0.0278, 0.0513, 0.0840, 0.157 and 0.278 atm −1 at −30, −36, −42, −48 and −54dgC, respectively. The thermodynamic data are Δ H θ = −10.1±0.6 kcal mol −1 and gD S θ = −49±3 eu at a standard pressure of 1 atm.

Factors affecting the formation of alcohol and alkoxo complexes in the reactions of oxomolybdenum(V) tetraphenylporphyrin with various alcohols in dichloromethane

The addition of alcohols to dichloromethane solution of Mo(V)O(tpp)Br (tpp = meso-tetraphenylporphinato) causes three-step reactions. The products in the first, second and third stages of the reactions are solvated, alcohol and alkoxo complexes, respectively. t-Butyl alcohol does not afford the corresponding alcohol complex. The most important factor controlling the formation of alcohol complexes is the bulkiness of the alcohol molecules.

Thermodynamic parameters for the molecular inclusion reactions of some azo compounds with ?-cyclodextrin

Molecular inclusion reactions of some azo compounds with α-cyclodextrin were studied in aqueous solution by means of a stopped-flow method. The forward rate constants for the inclusion reactions were found to be in the order of 10–104mol-1 dm3 s-1. The thermodynamic activation parameters were also determined firstly in α-cyclodextrin system.

Dynamic Aspects of Molecular Inclusion Reactions by Cyclodextrins

Multi-step molecular inclusion reaction of organic ligands as guest molecule with α-cyclodextrin (α-CDx) in aqueous solution are described. The succesive two-step inclusion was observed in the case of x-alkyl-substituted p-hydroxy-phenylazo derivatives of sulfanilic acid (x-R-HAB). The occurrence of the succesive fast and slow inclusion are specifically related with the types of alkyl substituents in the ortho position to the phenolic hydroxyl group. The cause of the stepwise inclusion is ascribed to the size, the shape, and the hydrophobicity, and the flexibility of the alkyl substituent (x). The fast process is found to be a bimolecular binding of the guest molecule with α-CDx, the subsequent slow process to be the intramolecular rearrangement of the intermediate inclusion complex.

Molecular Inclusion Reaction of Charged Cyclodextrins

Molecular inclusion reaction of positively charged β-cyclodextrin, mono[6-(1-pyridin o)-6-deoxy]-β-cyclodextrin (β-CDxPy+) and mono[6-(l-ethylenediamino)-6-deoxy]-β-cyclodextrin (β-CDxen), with sodium p-(3-t-butyl-4-hydroxyphenylazo)benzene sulfonate (3-tBuHAB) was investigated by u.v.-visible, 1H-n.m.r., and CD spectroscopy. The presence of the electrostatic interaction in the host guest was demonstrated only in the acidic pH region for the β-CDx-enH2 2+ system. On the other hand, in the β-CDxPy+ system, the electrostatic interaction would exist in pH region ranging from 3 to 12.

Molecular inclusion reactions between metal complexes of azo complexons and ?-cyclodextrin in aqueous solution

Kinetics of the molecular inclusion reactions of the azo complexons and their metal complexes with α- and β-cyclodextrins (α- and β-CDx) were studied in aqueous solution by means of a spectrophotometric and a stopped-flow method. The acid dissociation of the azo complexons was regulated by the inclusion with CDx. Two-step process was observed for the interaction of α-cyclodextrin with LH*3- species of the azo complexons and with the metal complexes.