Iwao Tabushi

A,B,D,F-tetrasubstituted β-cyclodextrin as artificial channel compound

Abstract As a channel forming compound, β-cyclodextrin having four hydrophobic tails and three metal binding sites, 1, [A,C,D,F,-tetra-6-(6-n-butyrylamino-n-hexylsulfenyl)-β-cyclodextrin] was synthesized as a “half channel”. Artificial liposome modified with 1 transported Co ++ efficiently with the rate, 4.5 × 10 −4 sec −1 for 55 μM 1, much faster tahn the rate for the unmodified liposome.

A STUDY OF THE KINETICS OF INCLUSION OF HALONAPHTHALENES WITH ß-CYCLODEXTRIN VIA TIME CORRELATED PHOSPHORESCENCE

Abstract— The phosphorescence of 1‐bromonaphthalene and 1‐chloronaphthalene is readily observable in nitrogen purged aqueous solutions containing ß‐cyclodextrin. Addition of acetonitrile increases both the phosphorescence intensity and lifetime. The quenching of halonaphthalene phosphorescence in aqueous solution by nitrite is substantially inhibited upon addition of ß‐cyclodextrin, as a result of a guest‐host complex. The rate constants for formation and dissociation of the l‐bromonaphthalene/ß‐cyclodextrin complex are evaluated from an analysis of the dependence of phosphorescence lifetimes on nitrite concentration.

Gable-porphyrin as a cytochrome-c3 model

Abstract Cytochromec3 has two quite different heme-heme interaction models, “gable”-type and “twist”-type. Bis m-(meso-triphenylporphinyl) benzene was newly prepared as a gable conformation model. This “gable” porphyrin exhibited moderate porphyrin-porphyrin and heme-heme interaction.

Synergetic combination of catalysis of the phase transfer-electron transfer type for the oxidation of alcohols or hydrocarbons

Abstract Successful synergetic combination of the electron-transfer catalyst, TPPMn, and the phase-transfer catalyst, TOMA, in the oxidation of alcohols or hydrocarbons were reported.

Supramolecular sensor based on SnO2 electrode modified withoctadecylsilyl monolayer having molecular binding sites

Abstract Octadecylsilyl (ODS) monolayer covalently bound onto SnO2 was found to aquire molecular binding sites via extracting out co-implanted inert guest(n-hexadecane). Intense electrochemical response of ODS/SnO 2 was found toward vit-K 1 , K 2 and E adsorbed to the molecular binding sites.

New liquid crystals having 4,4′-biphenanthryl core

Abstract 4,4′-Biphenanthryl carrying six or four long tails forms a stable thermotropic liquid crystalline mesophase, giving promises of preparing new mesogens having skewed-disc shaped core

Guest-induced conformational change of β-cyclodextrin capped with an environmentally sensitive chromophore

Abstract A capped cyclodextrin, 6-deoxy-6-( p -hydroxy- m -nitrophenacylthio)-β-cyclodextrin, was prepared in order to detect any conformational change of the host upon the guest binding. The association constant between the cyclodextrin and 1-adamantanecarboxylate, cyclohexanecarboxylate, p -methylbenzoate, 3,3-dimethylbutyrate, or 2,2-dimethylpropionate was enhanced 20, 5.3, 3.7, 2.3, or 2.0 times, respectively, by chromophore capping. The changes in the electronic, NMR, and circular dichroism spectra as well as p K a of this cyclodextrin upon binding of the guest strongly indicate a conformational change around the chromophoric moiety of the cyclodextrin.

The oxidation of adamantane with an iron salen complex modelling ω-hydroxylase

Abstract An interesting regioselectivity (high secondary selectivity) was observed in the oxidation of adamantane in the presence of (FeSalen) 2 O, 2-mercapto-ethanol, pyridine, and oxygen, giving 1-adamantanol (67 % based on the catalyst used), 2-adamantanol (162 %) and 2-adamantanone (51 %) for a typical example. The yield of each product was dependent on the reaction conditions especially on the mercaptan concentration. This high secondary selectivity (product ratio, 3.2 : 1) and the predominant formation of 2-adamantanol is unique and quite different from those (ca 1 : 1 mostly adamantanone/1-adamantanol) of autoxidation. This is the first successful ω-hydroxylase model.

Functionalized cyclodextrins as artificial receptors: guest binding to bisimidazolyl-β-cyclodextrin.zinc

Abstract A systematic investigation of the binding of cyclohexane derivatives to bisimidazolylcyclodextrine zinc was carried out. The basic host-guest interacti and the relative significance of polar and coordination interactions was estimated.

Catalytic hydroxylation on aromatic rings by use of an artificial P-450 system assisted by acid and acid anhydride

Abstract Aromatic compounds are effectively monohydroxylated by the artificial P-450 type catalytic system, consisting of TPP · Mn, N-methylimidazole, colloidal Pt, O2 and H2. Addition of benzoic anhydride and/or hydrogen chloride favored o- and p-hydroxylation.