Keiichi Sakamoto

Syntheses and Functional Properties of Phthalocyanines

Metal phthalocyanine tetrasulfonic acids, metal phthalocyanine octacarboxylic acids, metal octakis(hexyloxymethyl)phthalocyanines, and metal anthraquinocyanines have been synthesized. Then, zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazines, the cyclotetramerization products of a 1:1 mixture of 3,6-didecylphthalonitrile and 3,4-dicyanopyridine, were synthesized. Futher, subphthalocyanine and its derivatives, with substituents such as thiobutyl and thiophenyl moieties were synthesized. Electrochemical measurements were performed on the abovementioned phthalocyanine derivatives and analogues in order to examine their electron transfer abilities and electrochemical reaction mechanisms in an organic solvent. Moreover, 1,4,8,11,15,18,22,25-octakis(thio-phenylmethyl)phthalocyanes were synthesized. The Q-bands of the latter compounds appeared in the near-infrared region. Furthermore, non-colored transparent films in the visible region can be produced.

Synthesis and electron transfer property of phthalocyanine derivatives

Metal phthalocyanine derivatives exhibit high redox abilities. In this paper, soluble metal phthalocyanine derivatives, cobalt phthalocyanine tetrasulfonic acid and cobalt phthalocyanine octacarboxylic acid have been synthesized. Cyclic voltammograms and other electrochemical measurements were carried out for their cobalt phthalocyanine derivatives in order to estimate their electron transfer abilities and electrochemical mechanism in an organic solvent. Electrode processes were diffusion controlled at almost one electron transfer involving some weak adsorption and having the following chemical reaction.

Photosensitizer efficacy of non-peripheral substituted alkylbenzopyridoporphyrazines for photodynamic therapy of cancer

The triplet state of zinc non-peripheral substituted alkylbenzopyridoporphyrazines and position isomers were measured, using laser-flash photolysis in poly(methyl methacrylate) film. The triplet lifetime increased with an increasing pyridine number in the molecule. The lowest symmetric isomer having two pyridine rings in the molecule showed the longest triplet state lifetime. The compound was suitable for the use the photosensitizer as a photodynamic therapy of cancer.

Electrochemical characterization of soluble cobalt phthalocyanine derivatives

Cyclic voltammograms and chronocoulometry were measured for soluble cobalt phthalocyanine derivatives and cobalt anthraquinocyanine which had been previously synthesized, in order to examine their electron transfer abilities and electrochemical mechanism in an organic solvent. Electron transfer properties were shown to be similar except for the cobalt phthalocyanine octacarboxylic acid. Electrode processes were diffusion controlled at almost one electron transfer involving some weak adsorption and having the following chemical reaction, except for the cobalt phthalocyanine octacarboxylic acid.

Synthesis of cobalt phthalocyanine derivatives and their cyclic voltammograms

Abstract Metal phthalocyanine derivatives exhibit high electron transfer abilities. Metal phthalocyanine derivatives are insoluble in most common organic solvents, a factor which has inhibited their use in functional materials using their electron transfer properties. We report here the synthesis of three kinds of cobalt phthalocyanine derivatives: cobalt phthalocyanine tetrasulfonic acids, cobalt phthalocyanine octacarboxylic acids and cobalt octakis(hexyloxymethyl)phthalocyanines, and a new type of phthalocyanine derivative, cobalt anthraquinocyanine. The electron transfer behavior of this cobalt phthalocyanine derivatives was examined with cyclic voltammetry. Cobalt phthalocyanine tetrasulfonic acid and cobalt phthalocyanine octacarboxylic acid exhibited irreversible redox behavior and the cyclic voltammograms of cobalt anthraquinocyanine exhibited properties similar to that of cobalt phthalocyanine octacarboxylic acids.

Synthesis of near-infrared absorbed metal phthalocyanine with S-aryl groups at non-peripheral positions

Phthalocyanines are used as various applications, including as organic charge carriers in photocopiers, laser light absorbers in data storage systems, photoconductors in photovoltaic cells and electrochromic displays, and non-colored transparent film in visible region. The absorption maxima of phthalocyanines are best if moved near the infrared region for these applications. The Q band of phthalocyanines can be moved to bathochromic effects through extension of a π conjugation system such as naphthalocyanines and anthracyanines. Yields of naphthalocyanines and anthracyanines are, however, low. To solve the problem, novel metal phthalocyanines having non-peripheral S-aryl substituent were synthesized. The novel phthalocyanines show a high strain structure and no liquid crystal property. The target compounds were synthesized: 15 phthalocyanines from 2,3-dicyanohydroquinone in 3 steps via 1,2-dicyanobenzene-3,6-bis(trifluorate) and 1,2-dicyanobenzene-3,6-thiophenols. The Q bands of obtained compounds appeare...

Synthesis of subphthalocyanine derivatives and their characterization

Subphthalocyanine and its derivatives which possessed substituents such as thiobutyl and thiophenyl were synthesized. These compounds were measured using spectroscopic measurements and cyclic voltammetry. Sensitization properties of synthetic subphthalocyanine (SubPC) in 2,4,6-Tris(trichloromethyl)-1,3,5-triazine as radical generation reaction in a poly(methyl methacrylate) film have been investigated by laser flash photolysis.

Synthesis of octasubstituted cobalt phthalocyanines and their redox properties

Octakis(alkoxymethyl) cobalt phthalocyanines with relatively short side chains were synthesized which exhibited no thermotropic liquid crystalline behaviour. The final products as well as the intermediates have been characterized by proton magnetic resonance, infrared and electron spectra and elemental analysis. Cyclic voltammograms were measured for octakis(alkoxymethyl) cobalt phthalocyanines in order to examine their electron transfer properties. The electron transfer properties of octakis (alkoxymethyl) cobalt phthalocyanines depend on the kind and number of substituents and are due to the interaction between the phthalocyanine ring, the central metal which is influenced by the conjugated π electron current of the porphyrazine ring.

Syntheses of near infrared absorbed phthalocyanines to utilize photosensitizers

Phthalocyanines have become of major interest as functional colorants for various applications. In order to use various applications especially photosensitizers, the absorption maxima called Q-band of phthalocyanines are required to be shifted to the near infrared region. Substituted phthalocyanine analog alkylbenzopiridoporphyrazins, especially zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazine, and toroidal-shaped phthalocyanines having aminoamine dendric side chains such as toroidal zinc poly(aminoamine)phthalocyanine dendrons were synthesized. Phthalocyanines of two types reportedly use photosensitizers for photodynamic therapy of cancer. The respective efficacies of photodynamic therapy of cancer for zinc bis(1,4-didecylbenzo)-bis(3,4-pyrido)porphyrazine and its regioisomers were estimated using laser-flash photolysis. The capability of using photodynamic therapy for toroidal zinc poly(aminoamine)phthalocyanine dendrons was assessed using a cancer cell culture. Both phthalocyanines were suitable for the use as a photosensitizer as photodynamic therapy of cancer. Then, non-peripheral thioaryl substituted phthalocyanines, 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines, such as 1,4,8,11,15,18,22,25-octakis(thiophenylmethyl)phthalocyanines, 1,4,8,11,15,18,22,25-octakis(thiophenylmethoxy)phthalocyanines, and 1,4,8,11,15,18,22,25-octakis(thiophenyl tert-butyl)phthalocyanines were also synthesized in order to develop next- generation photovoltaic cells and/or dye-sensitized solar cells. Non-peripheral substituted 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines exhibited a Q-band in the near infrared region. Electrochemical measurements were performed on the above-mentioned 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines described above to examine their electron transfer abilities and electrochemical mechanisms. The compounds 1,4,8,11,15,18,22,25-octakis(thioaryl)phthalocyanines are anticipated to be appropriate materials for use in the next generation of photovoltaic cells.

Laser-flash photolysis of dialkylbenzodipyridoporphyrazines

In the course of a fundamental study of photosensitizers for photodynamic therapy of cancer, a non-peripheral substituted phthalocyanine analogue, zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine and its position isomers were examined to measure their photoexcited triplet state lifetimes in poly(methyl methacrylate) film using laser-flash photolysis. The isomer mixture of zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine showed the most intense absorption in the 660-710 nm region, and the longer triplet state lifetime. The lowest symmetry isomer of zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine was found to have the longest triplet state lifetime when all isomers were separated. The compound is proposed to be suitable for use as a photosensitizer for photodynamic therapy of cancer.