- The electrochemistry of platinum phthalocyanine microcrystals - III. Electrochemical behaviour in aqueous electrolytes
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Platinum phthalocyanine (PtPc) films applied to gold and glassy carbon (GC) surfaces have been shown to exhibit complex electrochemistry in aqueous media. Upon potentiodynamic cycling three anodic (0.81, 1.10 and 1.27 V) and two cathodic peaks (1.12 and 0.59 V vs SCE) develop. These processes are ascribed to phthalocyanine ring oxidation and reduction processes. This phthalocyanine ring electrochemistry is thought to be controlled by anion doping within the film, the large separation between corresponding anodic and cathodic processes being manifestations of barrier potential to anion movement within the film. A large reduction peak at -0.6 V is attributed to the mass expulsion of anions from the film.
- Brown, Richard J.C,Kucernak, Anthony R
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- Electrochemistry of platinum phthalocyanine microcrystals: II. A microelectrode observation of nucleation-growth controlled solid-solid phase transformations in non-aqueous solvent
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The solid-solid phase transformations and switching reactions occurring in platinum phthalocyanine (PtPc) microcrystals were investigated by chronoamperometry on a microelectrode in acetonitrile containing 0.1 mol dm-3 of the tetrabutylammonium salt of either BF4-, ClO4- or PF6-. Three different states of the PtPc film (reduced, conductive and over-doped) can be demarcated, depending on its degree of oxidation. The transient response seen is dependent upon the initial and final state of the film. For the reduced film, a nucleation-growth process occurs in the film upon the application of an oxidative potential step to above 0.50 V. If the end-point of the potential step is increased past 0.75 V, a second nucleation-growth process occurs leading to the conductive film. Both of these processes are controlled by a solid-solid phase transformation. At potentials above approximately 1.1 V there is evidence of a further diffusion-controlled reaction, leading to the production of the over-doped film. Oxidation or reduction of the conductive film occurs quickly and appears to be diffusion controlled with no indications of a peak or shoulder in the current-time transients. Reduction of the over-doped film, appears to be controlled by one and possibly two nucleation-growth processes as evidenced by peaks in the chronoamperometric transient. The kinetics of solid-solid phase transformation and the switching reaction is only affected slightly by the nature of the anions present.
- Jiang, Junhua,Kucernak, Anthony
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- Electrochemistry of platinum phthalocyanine microcrystals: I. Electrochemical behaviour in acetonitrile electrolytes
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Platinum phthalocyanine (PtPc) microcrystals deposited upon platinum, glassy carbon and gold by a process of dry abrasion have been characterized by electrochemical techniques. This mechanical abrasion can produce good electronic contact and adhesion between the microcrystals and the electrode. The redox process of PtPc microcrystals is accompanied by two reversible electrochemical phase transformations, evidenced by a sharp peak and unusually large peak potential differences. Similar to conductive polymers, an obvious first-scan discrepancy and large capacitance are observed during electrochemical oxidation. Some of the intercalated anions remain in the re-reduced microcrystals and lead to a conductivity enhancement of the microcrystals, supported by AC impedance and X-ray photoelectron spectroscopy (XPS) results. Coulometry shows that the size of the anion determines the rate and degree of oxidation, and influences the reversible phase transformations. Chronoamperometry shows diffusion-controlled nucleation and growth kinetics, controlled by the diffusion of anions into the solid films. The conformational relaxation model was used to describe this process.
- Jiang, Junhua,Kucernak, Anthony
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- The Microwave-assisted syntheses and a conductivity study of a platinum phthalocyanine and its derivatives
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The parent platinum phthalocyanine (PtPc) and its derivatives with tetranitro (PtTNPc) and tetramine (PtTAPc) on the peripheral benzene were synthesized in the pure state for the first time by microwave irradiation. These complexes were characterized usin
- Lokesh,Uma,Achar
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- Comparative studies of photophysical and photochemical properties of solketal substituted platinum(II) and zinc(II) phthalocyanine sets
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A complete set of platinum(II) solketal substituted phthalocyanines has been synthesized and characterized. To evaluate their potential as Type II photosensitizers for photodynamic therapy, comparative studies of their photophysical and photochemical properties with analogous zinc(II) series have been achieved: electronic absorption, fluorescence quantum yields, lifetimes, and fluorescence quenching by benzoquinone, as well as singlet oxygen generation and photodegradation. It appears that platinum(II) phthalocyanines are worth being used as Type II photosensitizers, as they exhibit good singlet oxygen generation and appropriate photodegradation.
- Zorlu, Yunus,Dumoulin, Fabienne,Durmu?, Mahmut,Ahsen, Vefa
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- Spectroscopic and electrochemical studies on platinum and palladium phthalocyanines
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The synthesis, spectroscopy and electrochemical characterisation of palladium and platinum phthalocyanines is reported. Electrochemical techniques were used in conjunction with electronic absorption spectroscopy to analyse the reduced and oxidised phthalo
- Brown, Richard J. C.,Kucernak, Anthony M.,Long, Nicholas J.,Mongay-Batalla, Carlos
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- Synthesis of phthalocyanine derivatives of the Ru, Rh, Pt and Pd metals under solvent free conditions using microwave irradiation
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The phthalocyanine complexes of Ru, RhCl, Pt and Pd are easily prepared from phthalic anhydride and the corresponding metal salts by exposing to microwave radiation under solvent free conditions, which reduces reaction time considerably. The yield of metallophthalocyanines is increased by 12-15 % relative to that obtained by conventional methods.
- Shaabani,Bahadoran,Safari
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p. 195 - 197
(2007/10/03)
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