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Monosaccharides were oxidatively degraded by FeCl3with irradiation of a near-UV to visible light under aerobic atmosphere. d-Fructose and d-arabinose were degraded to d-erythrose in a yield of more than 80 mol%. d-Glucose and d-mannose were at first degraded to d-arabinose, which was subsequently degraded to d-erythrose. While, d-ribose was directly degraded to d-erythrose and d-glyceraldehyde. The degradation processes were selective, and these reactions were shown to proceed viaformation of an Fe(III)–monosaccharide complex. The kinetic data and other features of these reactions were also discussed.

The 1,3-dipolar cycloaddition reactions of nitrile oxides with substituted p-benzoquinones are discussed in terms of Frontier Molecular Orbital (FMO) theory. The calculation is carried out by ab initioSelf Consistent Field (SCF) method with STO-3G basis set. The site- and regio-selectivities in the reactions are correlated with two types of FMO interactions. Some predictions have been confirmed by experimental results.

The reaction of 6,6'-dibromo-2,2'-bipyridine with ammonia in an autoclave gave 6,6'-diamino-2,2'-bipyridine (DABP) in more than 80% yields. DABP behaved as a diacidic base in the pH range of 0 to 10 with the conformational changes. DABP formed complexes with Cu(II), Ni(II), Co(II), and Zn(II). The amino groups at 6 and 6' positions play a role as strong electron-donationg groups and not as coordination sites. pKa values and complex formation constants were estimated.

A series of 2-, 3-, or 4-substituted pyrido[1′,2′ : 1,2]imidazo[4,5-b]quinoxalines (PIQs) were synthesized in moderate-to-good yields by the reactions of 2-amino-3-chloroquinoxalines (ACQs) with substituted pyridines, and the structures were established. The reactions of ACQs with 3-phenoxycarbonyl and 3-benzoylpyridines gave the corresponding 2-substituted PIQs, while those with 3-methyl, 3-ethyl, 3-benzyl, 3-phenyl, 3-ethoxycarbonyl, and 3-acetylpyridines gave the corresponding 4-substituted PIQs. PIQ derivatives having substituents at the 2,4,8, and/or 9-positions were also studied. The spectroscopic and electrochemical properties of a series of PIQs derivatives were studied. PIQ showed a strong green fluorescence at 481.5 and 505 nm (Φ= 0.40) in ethanol. The introduction of substituents at the 3 position of PIQ altered the color of the fluorescence from blue to green without deteriorating the high quantum yield of PIQ. All of the derivatives showed strong (blue to orange) fluorescence in both solution and the solid state.

The synthetic method of the title compound was improved to 16.1% yield. The 1H NMR studies established that the oxygen-through-the-annulus rotation is not inhibited by the butyl group but inhibited by the bulkier octyl group.

A new type of N2O2tetradentate ligands, 6,6′-bis(acylamino)-2,2′-bipyridines, was synthesized and their complex formations with copper(II) were investigated. They form two types of 1:1 complexes; one is the non-deprotonated type having external counter anions and the other is the deprotonated type having no external counter anions. They serve as square planar N2O2tetradentate ligands in either case and the structures of the complexes are very similar to salen complexes. The structures and properties of these complexes were investigated and discussed.

The pKaof Phenol Blue shifted from 4.6 to 6.2 because of complexation of protonated Phenol Blue in the cavity of hexasulfonated calix[6]arene with dodecyl substituents (2C12). The finding stimulated us to examine whether the analogs (2C) suppress the dediazoniation of arenediazonium ions in an aqueous system as crown ethers do in organic solvents. We have found that 2C can suppress the dediazoniation in an aqueous system where neither 18-crown-6 nor anionic micelles are effective. The magnitude of the inhibition effect was 4–5 fold. The reaction rate of the diazo coupling with N,N-dimethylaniline was significantly suppressed in the presence of 2C, suggesting that arenediazonium ions are deactivated through complexation with 2C. The novel stabilization effects were explained by the strong anionic reaction field which neither 18-crown-6 nor anionic micelles have: that is, 2C has a peculiar architecture that six sulfonato groups are circularly arranged on the edge of the calixarene cavity.

The association constants (K) for aqueous complexes with water-soluble p-sulfonatocalix[n]arene (1n: n=4, 6, and 8) were determined by the NMR method. It was found that 14and 16form 1 : 1 complexes with guest molecules (trimethylanilinium chloride and 1-adamantyltrimethylammonium chloride), whereas 18forms 1 : 2 18/guest complexes. The finding supports the view that calixarenes 1n’s are capable of molecular recognition on the basis of the ring size. Examination of the thermodynamic parameters for the association process established that the complexation with 14is mainly due to the electrostatic force, whereas that with 16and 18is mainly due to the hydrophobic force. The coalescence temperatures (Tc’s) for calixarene ring inversion were subject to the template effect by these molecules. The activation parameters for the rate of ring inversion were estimated by a computer-assisted spectrum simulation: it was found that the Tcincrease, observed in the presence of these guest molecules acting as templates, is caused by the increase in ΔH\eweq. These findings provide new insights into the association characteristics of water-soluble calixarenes.

Complex formations of an N2O2tetradentate ligand, 6,6′-bis(benzoylamino)-2,2′-bipyridine (babpH2) with various divalent metal ions were investigated. BabpH2complexes of Ni(II), Co(II), and Zn(II) were obtained as dinitrate and/or diacetate, and their deprotonated complexes, [Ni(babp)], [Co(babp)], and [Zn(babp)], where babp represents the deprotonated form of amide protons of babpH2, were also isolated. The deprotonated complexes were shown to have high thermal stability up to 300 °C. The structures, stabilities, and spectral properties of these complexes were discussed in relation to the copper(II) complexes of babpH2and babp.

d-Fructose is susceptible to photochemically-induced oxidation by atmospheric oxygen in the presence of a catalytic amount of iron or manganese cations in a neutral to weakly basic pH range. Metal hydroxide does not precipitate from a solution in this pH range because of the high sequestering ability of d-fructose. Upon irradiation of Pyrex-filtered light, d-fructose degraded into d-erythrose and other fragments. This reaction is shown to proceed by coupling with an oxidation-reduction cycle involving a metal cation, i.e., the photooxidation of d-fructose by M(III) and the subsequent reoxidation of the resultant M(II) by atmospheric oxygen.

The properties of the reversed micelles of dodecylammonium propionate (DAP) and of solubilized water were examined for systems with hexane, chloroform and benzene as a nonpolar component. The aggregation number of DAP, the conductivity, the heat of solution of water, IR and NMR spectra, and near infrared spectra of solubilized water were measured. From the results the properties of the reversed micellar system were analyzed, the following conclusion being obtained. The aggregation state of DAP is scarcely affected by the addition of water. Water is first dispersed in the nonpolar organic phase, and then solubilized in the cores of the reversed micelles. The former is free or weakly bonded water, while the latter is bonded water like that in the bulk phase. The catalytic effect of DAP reversed micellar system is discussed.

The iodination reactions of ketones in the reversed micellar systems of dodecylammonium propionate (DAP) in hexane were studied at 25.0 °C in relation to the enzymatic function of aldolase or enolase. The reaction rate in the DAP reversed micellar system is 106–107times greater than that in the system without DAP, 100 times greater even in comparison with that in DAP aqueous system at pH 6.8. As in the ammonium ion catalyzed reaction in aqueous media, the reaction in the presence of DAP proceeds viaketimine formation between ammonium groups of DAP and acetone and subsequent enolization of ketimine to enamine, which reacts very rapidly with iodine. The catalytic effect of DAP reversed micellar system in each reaction step was discussed. Further, this reversed micellar system shows a marked selectivity for acetone as compared with higher analogs.

The nonenzymatic hydrolysis of adenosine 5'-triphosphate (ATP) in micellar and reversed micellar system was examined as an approach to elucidate the function of ATPase. In aqueous micellar systems an anionic surfactant does not affect the hydrolysis rate, but a cationic surfactant, cetyltrimethylammonium bromide(CTAB), retards the hydrolysis. This deceleration effect is interpreted to be owing to the pH change or accumulation of hydroxide ions at the cationic micellar-water interface which serves as reaction site. In the reversed micellar system where aqueous ATP phase is solubilized in n-hexane by dodecylammonium propionate(DAP), the hydrolysis rate of ATP is enhanced by several times as compared with that in an aqueous system. Addition of Mg2+or Ca2+enhances the hydrolysis rate markedly only in the DAP reversed micellar system. The catalytic effect of the DAP reversed micellar system is discussed with respect to the polarity of water phase solubilized in the core of reversed micelles.

The 1,3-dipolar cycloaddition reactions of nitrile oxides with methoxy p-benzoquinones are discussed in terms of FMO theory. The unusual reaction pattern of methoxy p-benzoquinones with nitrile oxides is interpreted by considering both antibonding secondary orbital interaction and SHOMO(quinone)–LUMO (nitrile oxide) interaction.

The lowest-energy p–p*band of 6,6'-diamino-2,2'-bipyridine (dabp) appeared at near-UV region, and was found to suffer a characteristic solvent effect. The results were discussed in terms of its electronic structure calculated by ab initio method using a STO-3G basis set.

ESR spectra of hexaaqua complex of Mn(II) in a hexadecyltrimethylammonium bromide (HTAB)/chloroform reversed micellar system are studied. The structure of the Mn(II) complex is distorted at low water concentrations because of the dehydration due to the lack of water molecules available for the complexes. The effect of dehydration of metal ions on their catalysis for ATP hydrolysis is discussed.

Complex formation between Fe(III) and d-fructose in an acidic solution was studied by electronic and CD spectroscopy, and the role of the complex in the photochemically-induced oxidation of d-fructose by Fe(III) was discussed.