Yutaka Kagaya

Synthesis, spectral, and electrochemical characterization of the first arsenic(V)-phthalocyanines.

The first arsenic(V)-phthalocyanines, [As(tbpc)X(2)](+), where tbpc denotes tetra(tert-butyl)phthalocyaninate, C(48)H(48)N(8)(2-) and X = F, Cl, and Br) have been prepared through an appropriate oxidative addition process to a highly soluble arsenic(III) derivative, [As(tbpc)](+). Among them, [As(tbpc)F(2)](+) has been isolated as PF(6)(-) salt. Unlike conventional metal derivatives of phthalocyanines, they show a significantly red-shifted (by >1000 cm(-1)) Q-band and facile reduction of the macrocyclic ligand (redox potentials for [As(tbpc)F(2)](+) have been determined by cyclic voltammetry; 1.13 V vs ferricinium(+)/ferrocene (tbpc(-/2-)), -0.45 V (tbpc(2-/3-)), and -0.90 V (tbpc(3-/4-)), of which the values are anodically shifted by about 1 V) as compared to those of conventional phthalocyanines. Although the anomaly in their spectral and electrochemical properties is similar to that of the known antimony analogues, the arsenic-phthalocyanines have been found less stable.

The syntheses of amphiphilic antimony(V)-phthalocyanines and spectral investigation on their aggregation behaviors in aqueous and non-aqueous solutions.

Three amphiphilic antimony(V)-phthalocyanines have been synthesized by treating [Sb(R(4)Pc)(OH)(2)](+) salts in concentrated H(2)SO(4) and isolated as zwitter ions, [Sb(R(4)Pc)(SO(4)H)(SO(4))], where R(4)Pc denotes tetra-substituted phthalocyaninate; R(4)Pc=pc (R=H), tbpc (R=(t)Bu), and tObpc (R=O(n)Bu). Their solubility (R=tbpc>pc >>tObpc in H(2)O (much improved by the presence of surfactant or alcohol) while tbpc>tObpc >>pc in CH(2)Cl(2)) and aggregation behaviors are highly sensitive to the nature of the peripheral substituents. The pc and tbpc derivatives form well-behaved J-aggregates in aqueous media in the presence of surfactant or alcohol.

Synthesis and spectral properties of a dihydroxo(phthalocyaninato)antimony(V) complex

The title complex cation, [Sb(pc)(OH)2]+, (pc = phthalocyaninate, C32H16N82-) has been prepared by oxidizing [Sb(pc)]I3 with tert-butyl perbenzoate and isolated as hexafluorophosphate and triflate salts. These salts are relatively well-soluble in polar solvents (e.g.CH2Cl2, acetonitrile, acetone) without detectable aggregation. In particular, they dissolve relatively well in ethanol and methanol in which [Sb(pc)Br2]+ or [Sb(pc)Cl2]+ salts are poorly soluble whereas they have extremely low solubility in 1-chloronaphthalene and CHCl3, unlike the bromo or chloro analogs. The spectral properties of [Sb(pc)(OH)2]+ have been investigated by optical absorption and magnetic circular dichroism spectroscopy. Although its Q band tends to appear at a longer wavelength in a solvent with a larger refractive index, as is the case for its Br and Cl analogs, the Q band positions in donor solvents deviate considerably from linear correlation between Onsagers solvent polarity function. In the Soret band region, spectra of [Sb(pc)(OH)2]+ are different in CH2Cl2 and acetonitrile, particularly around the B1/B2 bands, unlike the bromo and chloro analogs. The solvent dependence of absorption spectra and the difference in solubility suggests that the presence of the axial hydroxyl groups endows the phthalocyanine macrocycle with considerable hydrophilicity. It also suggests that there are some specific chemical interactions between the axial hydroxyl groups and the surrounding donor solvent molecules.

Synthesis, spectral and electrochemical properties of a novel phosphorous(V)-phthalocyanine

A novel phosphorous(V)-phthalocyanine, [P(tppc)(OH)(O)], where tppc denotes tetrakis{(2′,6′-dimethyl)phenoxy}phthalocyaninate, has been synthesized and its spectral properties in non-aqueous and aqueous media have been investigated. This compound has been found free from aggregation in EtOH whereas forms J-aggregates in CH2Cl2 and acetonitrile, suggesting the presence of chemical interaction between the axial ligand and the surrounding solvent molecules. The most intense absorption band (Q-band) appears at 683 nm in EtOH, however, reaction with CF3COOH has given rise to a large red shift of the Q-band without lowering of its C4 symmetry (evidenced by magnetic circular dichroism spectroscopy), indicating protonation at the axial site. Its fluorescence quantum yield has been determined (0.49 in EtOH) and has been found much higher than those of the known SbV or AsV derivatives by more than one order of magnitude. The first reduction potential has been determined by cyclic voltammetry (-1.09 V vs. ferroceniu...

Rapid reactions of phthalocyanines with tellurium tetrachloride in non-aqueous solutions

Rapid reactions of tetra(tert-butyl)phthalocyanine, H2(tbpc), and its zinc complex, [Zn(tbpc)], with tellurium tetrachloride (TeCl4) in non-aqueous solutions have been investigated. Upon mixing respective solutions containing the reactants, drastic spectral changes occurred in chloroform and toluene even at room temperature. The electronic spectra of the products indicated that the reactions involved an acid-base equilibrium where the phthalocyanines and tellurium tetrachloride acted as a Lewis base and a Lewis acid respectively. By monitoring the spectral changes based on various initial molar ratios of the reactants, the compositions of the products for each system have been determined. [Zn(tbpc)] formed a 1:1 (tbpc:TeCl4) adduct in both chloroform and toluene, showing the same spectra close to those of the known monoprotonated phthalocyanines. On the other hand, H2(tbpc) formed a 1:1 adduct in chloroform but a 1:3 adduct in toluene even though both products showed essentially the same spectra close to ...