Hideo Akisada

The behavior of organic counterions in the micelle of alkylammonium decylsulfonates

Abstract The behavior of organic counterions in the micellar state was studied for alkylammonium decylsulfonate systems by 13 C NMR and conductivity measurements. The chemical shifts of C 2 ′C 5 ′ carbon atoms in n -butylammonium and n -pentylammonium ions showed a downfield shift of 0.2–0.6 ppm in comparison with those of the corresponding chlorides. Moreover, the spin—lattice relaxation time T 1 of the decylsulfonate ions had irregularities caused by collision between the decyl chains and the terminal methyl group of the counterions when the counterions were n -butylammonium and n -pentylammonium ions. The conductivity measurements indicated that the degree of dissociation of the counterions decreases with increasing counterion chain length. These facts can be explained by the long-chain counterions forming a mixed micelle with decylsulfonate ions while the short ones do not.

Hemispherical synthesis of dendritic poly(L-lysine) combining sixteen free-base porphyrins and sixteen zinc porphyrins

Dendritic poly(L-lysine) combining sixteen free-base porphyrins and sixteen zinc porphyrins hemispherically at the fifth generation was successfully synthesised and showed intramolecular fluorescence energy transfer in DMF.

Thermodynamics of ionic surfactant micelle

Abstract A Gibbs-Duhem equation for an ionic surfactant micelle system was derived. The derived Gibbs-Duhem equation took the effect of micelle dispersion and the electrical intermicellar interaction into consideration and assumed the sphericity and monodispersity of micelles. The theoretical consideration is based on the analogy of interfacial thermodynamics and thermodynamics of small systems, leading to an expression of contribution of all components to micelle formation. The analysis of the equation gives the physicochemical meaning of coefficient of added salt effect, the relation between surfactant ion and counterion activities, the relation between CMC (critical micelle concentration) and temperature or pressure, and the composition of mixed-micelle.

Substrate specificities of artificial flavo-enzymes

Previously, we have synthesized a 53-peptide containing Cys(Fla) residues at the hydrophobic side of the four α -helix bundle structure (Figure 1). The 53-peptide exhibi ted the catalyt ic act ivi ty toward the oxidat ion of 1-benzyl-1,4-dihydronicotinamide (Bzl-NAH) in the presence of sodium dodecylsulfate (SDS) [1]. Instead of the addition of a surfactant, we modified the substrate with various alkyl chains to evaluate the specificity. In addition, in order to compare the positioning of Cys(Fla) on the amphiphilic α-helix, we synthesized the related 53-peptides with different sequences for Cys (Figure 1A).

Determination by activity data of micellar aggregation number around CMC

Abstract The Gibbs-Duhem equation, which takes intermicellar interaction into consideration, shows the relation between the activity of free ions and the weight average aggregation number of the micelles. This relation, leading to the respective aggregation numbers of counterions and surfactant ions per micelle on the basis of activity data, is applied to a sodium decanoate system. By this application, a remarkable change in the micellar average aggregation number with the total surfactant concentration around the CMC and a broad, micellar size distribution were found.