Shun-ichi Nozakura

Cooperative inclusion of sodium 1-pyrenesulfonate by γ-cyclodextrin

SummaryThe interaction of γ-cyclodextrin(γ-CD) with sodium 1-pyrenesulfonate(PS) was studied spectrophotometrically. γ-CD was found to cause much larger decrease in the absorption maxima of PS than β-CD. The fluorescence spectra of PS in the presence of γ-CD showed excimer emission, while those of PS with β-CD showed only monomer emission, indicating that γ-CD forms 1∶2 (γ-CD∶PS) complexes in which two PS molecules are included in the γ-CD cavity in a face-to-face fashion. The binding isotherm showed a sigmoidal curve. The association constants were estimated by computer simulation of the binding curve. The 1∶2 (CD∶PS) complex was found to be much more stable (K=106 M−1) than the 1∶1 complex (K=1 M−1). At high concentration of γ-CD another γ-CD cooperates in binding two PS molecules, resulting in the formation of a 2∶2 complex.

Formation of organized structures in systems of polyelectrolyte-ionic surfactants

SummaryThe interaction of polyelectrolytes with ionic surfactants is studied by turbidimetry and electron micrography. The turbidity of the mixed solution of PVS (poly(vinyl sulfate)) and CTAB (cetyltrimethylammonium bromide) showed a sharp maximum at the mole ratio of 1∶1, indicating quantitative binding between PVS and CTAB. A multilayer structure was observed on the electron micrograph only at the mole ratio of PVS:CTAB=2∶1 with a spacing of about 25A. At the mole ratio of PVS:CTAB=1∶1, a single strand structure was observed. The system of ionene polymer (3,4)

AMPHIPHILIC COPOLYMERS AS MEDIA FOR LIGHT-INDUCED ELECTRON TRANSFER-II. ELECTROSTATIC EFFECT ON THE BACK ELECTRON TRANSFER

\left( {\begin{array}{*{20}c} + \\ {\text{N}} \\ \end{array} {\text{CH}}_{\text{2}} )_3 - \begin{array}{*{20}c} + \\ {\text{N}} \\ \end{array} {\text{CH}}_{\text{2}} )4} \right)

Cationic Copolymerization with Depropagation. The Copolymerization of α-Methylstyrene and Styrene

-SDS (sodium lauryl sulfate) forms a multilayer structure at the equivalent ratio of 1∶1 with a spacing of 20A.

Rectifying photocurrent flow across the junction of a polymer bilayer film

SummaryVarious polymers of aromatic vinyl compounds having haloalkyl groups at the both chain-ends were prepared by terminating the living anionic polymers with 1,2-dichloroethane or 1,4-dibromobutane. Using these polymers as initiators, 2-methyl-2-oxazoline was polymerized to result in the block copolymers.

Radical copolymerization of optically active acryloyl-d-phenylglycine methyl ester with methyl methacrylate or with methyl acrylate in optically active solvent

Abstract— Photosensitized reduction of zwitterionic viologen (SPV) and methyl viologen (MV2+) was investigated using an amphiliphilic copolymer having phenanthryl and sulfonate groups (APh) as photosensitizer in aqueous solutions. In the presence of triethanolamine the accumulation of SPV * (photoproduct) was found to be faster than that of MV+. This attributed to the electrostatic repulsion between SPV. and anionic segments of APh. Such difference between SPV and MV2+ was minimized in the case of the related monomer model. Retardation of the back reaction for the APh‐SPV system was also demonstrated by laser photolysis, kb= 8.7 × 107M‐1 s‐1 for the polymer system as compared to kb= 2.8 × 109M‐1 s‐1 for the monomer model system. Strong salt‐effects on the yield of the photoreduction and the rate of back reaction confirm the strong electrostatic interaction between the photoproducts and polyanions. This remarkable electrostatic effect of the polyanions was simulated by electrochemical redox reactions by using a graphite electrode coated with APh.

The effects of solvents on chain-transfer reaction in radical polymerizations of styrene, methyl methacrylate and vinyl acetate.

Abstract— Anionic polyelectrolytes functionalized with the 5‐deazaflavin group (dFl) were synthesized. The lifetime of the triplet excited dFl in the polyelectrolytes with a 2‐mol% dFl content (AdFl‐2) was about 10 times longer than that of a low molecular weight analog (AdFl‐M). 2‐Mercaptoethanol (RSH) reduced the triplet dFl with the rate constant of kred= 2.01 × 108M−1 s−1 for AdFl‐M and kred= 4.4 × 107M−1 s−1 for AdFl‐2. A zwitterionic viologen (SPV) oxidized the triplet dFl with the rate constant of kred= 3.69 × 109M−1 s−1 for AdFl‐M and kox= 7.4 × 108 M−1 s−1 for AdFl‐2. The smaller rate constants for the polymer system were discussed in terms of the hindering effect of the macromolecular microenvironment. The back electron transfer was shown to be drastically slowed in the AdFl‐2‐SPV system as a result of the intensive electrostatic effect of the polyelectrolytes. The buildup of the viologen radicals was studied under the steady‐state illumination of the three component systems including viologen and RSH. The dFl group was demonstrated to serve as a very efficient photosensitizer in the oxidative cycle in case back electron transfer was retarded. This is the case of the AdFl‐2‐SPV system which gave the quantum yield of about 0.4 for the SPV− buildup. By comparison, the AdFl‐2‐MV2+ system resulted in a much slower buildup of MV +radicals.

Vinylation Reaction of Sulfonamides with Acetylene

ABSTRACT To evaluate the existence of the depropagation reaction in the copolymerization of vinyl monomers, the cationic copolymerization of α-methylstyrene with styrene was studied. The copolymer composition exhibited an extensive dependency on the temperature of polymerization and the monomer concentration, this fact not being explained by the Mayo-Lewis equation. Treatment of the copolymerization in terms of the depropagation reaction led to an estimate of the monomer reactivity ratio and the equilibrium constant between the polymer and the monomer of α-methylstyrene. A comparison of the equilibrium constants thus obtained with those reported in the literature indicates that the magnitude of the equilibrium constants depends on the sequence length of α-methylstyrene units. By extrapolation to long sequence length, the equilibrium constants approach the values which are reported for high molecular weight poly(α-methylstyrene).