Kunihisa Sogabe

Spectral and electrochemical properties of vanadyl hexadecafluorophthalocyanine

A vanadyl complex with perfluorinate phthalocyanine, VOPcF16, was prepared. The monomer-dimer solvent dependence was confirmed based on the solvent effect for the Q-band position-that is, VOPcF16 exists as a monomer in a nonpolar solvent such as benzene, but dimerizes in a polar solvent such as acetone. Electron spin resonance data also supported the solvent dependence found. In addition, the substituent effect of fluorine atoms on the redox properties was investigated by measuring the cyclic voltammograms in dichloromethane. On the reduction side, three redox couples were observed, the first two of which were assigned as being due to the reduction of the phthalocyanine ring (to LUMO), whose potentials are 0.4–0.5 V higher than those of the tetra-t-butyl and octabutoxy derivatives, VOPc(t-Bu)4 and VOPc(O-n-Bu)8.

Oxygen-oxygenation of cyclohexene catalyzed by manganese(III), iron(III) and cobalt(II) complexes of tetra-tert-butylphthalocyanine in the presence of iso-butyraldehyde

Abstract The title reaction was catalyzed by the manganese(III), iron(III), and cobalt(II) complexes of tetra-tert-butylphthalocyanine, but not by the ligand itself and its zinc(II) complex. When the cobalt(II) complex was used as the catalyst, an induction period was observed.

Conductivity of reduced metallo-tetra-N-methyl-2,3-pyridinoporphyrazine complexes

Abstract Tetra- N -methyl-2,3-pyridinoporphyrazine complexes of cobalt(II), nickel(II), copper(II) and zinc(II) were reduced by sodium dithionite in an aqueous solution. The central metal ions were reduced in the cobalt(II), nickel(II) and copper(II) complexes, whereas the ligand was reduced in the zinc(II) complex. Conductivities of the complexes significantly increased in reduction.

Preparation and spectral and electrochemical properties of the nickel(II), palladium(II) and platinum(II) complexes of 2,3,9,10,16,17,23,24-octapropyltetrapyrazinoporphyrazine

Abstract The Ni(II), Pd(II) and Pt(II) complexes with 2,3,9,10,16,17,23,24-octapropyltetrapyrazinoporphyrazinate were prepared. Their absorption spectra and cyclic voltammograms (CV) in CH 2 Cl 2 were measured. The two absorption bands corresponding to the Q and B bands of metallophthalocyanines are observed in the 500–660 and 270–400 nm ranges, respectively. The two redox couples indicating reversible one-electron transfer processes appear in the reduction side of the CV. Irreversible oxidation with decomposition of the complex molecule was confirmed by a controlled-potential electrolysis experiment. The spectral and electrochemical properties of these complexes reflect the energy gap between the highest occupied and lowest unoccupied molecular orbitals of the ligand.

Fluorescence spectra and coloration of a europium(III) hexaaza macrocyclic complex in various solvents

Abstract The fluorescence intensity of a Eu(III)HAM (HAM = hexaaza macrocylic ligand) complex was strong in methanol but very weak in water solutions. The intensity was increased by the addition of salts such as sodium acetate and potassium oxalate. Upon heating the complex in solutions such as pyridine, DMSO and benzene a deep reddish purple colour developed under an argon atmosphere, but the colour immediately faded upon exposure to air. The coloration did not occur in water, alcohol or acetonitrile.

Silver ion-solvent complexing in acetylacetone and ionic Gibbs energies of transfer

Abstract For the purpose of elucidating ion-solvent interactions in acetylacetone (2,4-pentanedione, Hacac), the complex formation constants (β n ) of the silver ion in Hacac with some donor solvents have been determined at 298 K by potentiometry. The standard molar Gibbs energies of transfer (Δ G tr °) of silver, halide and tetraphenylborate ions from Hacac to 14 other solvents were also determined potentiometrically and correlated with some solvent parameters. The correlation between the β n and (Δ G tr °) values of the silver ion can be interpreted quantitatively on the basis of the coordination model of ionic solvation. Hacac was used as the reference solvent for silver ion complexing and ionic solvent transfer because it is a less basic and less acidic amphiprotic solvent.