Photovoltaic and electrocatalytic properties of novel ball-type phthalocyanines bridged with four dicumarol (original) (raw)
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Dalton Transactions, 2012
The phthalodinitrile derivative (3) was prepared by the reaction of 4,4′-(octahydro-4,7-methano-5H-inden-5-ylidene)bisphenol (1) and 4-nitrophthalonitrile (2) with dry DMF as the solvent in the presence of the base K 2 CO 3 by the method of nucleophilic substitution of an activated nitro group in an aromatic ring. The template reaction of 3 with the corresponding metal salts gave the novel bi-nuclear ball-type metallophthalocyanines, MPcs {M = Co (4), Cu (5), Zn (6)}. Newly synthesized compounds were characterized by elemental analysis, UV-vis, FT-IR (ATR), MALDI-TOF mass and 1 H-NMR spectroscopy techniques. The electronic spectra exhibit an intense π → π* transition of characteristic Q and B bands of the Pc core. The dielectric properties and interface between the spin coated films of 4-6 and a p-type silicon substrate have been studied by fabricating metal-insulator-semiconductor capacitors. The results indicated that the frequency dependence of the dielectric permittivity, ε′(ω), exhibits non-Debye type relaxation for all the temperatures investigated. The ac conductivity results indicated that the conduction mechanism can be explained by a hopping model at low temperatures (<430 K) and a free band conduction mechanism at high temperatures (≥430 K). The density of interface state calculations on these novel compounds showed that the combination of Au/4/p-Si is a promising structure with a high dielectric constant and a low interface trap density suitable for metal-oxide-semiconductor devices. The electrochemical properties of the Pc complexes were examined by cyclic voltammetry, differential voltammetry and controlled potential coulometry on platinum in non-aqueous media. The complexes showed ring-based and/or metal-based mixed-valence behaviours as a result of the remarkable interaction between the two Pc rings and/or metal centres. The mixed-valence splitting values for the complexes suggested that the mixed valence species are considerably stable. The Vulcan XC-72(VC)/Nafion(Nf)/4 modified glassy carbon electrode showed much a higher catalytic performance towards oxygen reduction than those of VC/Nf/5 and VC/Nf/6 modified ones. † Electronic supplementary information (ESI) available. See
Sensors and Actuators B-chemical, 2010
The new mono-nuclear Fe(II) phthalocyanine 2 and ball-type homo-dinuclear Fe(II)-Fe(II) phthalocyanine 3 were synthesized from the corresponding 4,4 -[1,1 -methylenebis-(naphthalene-2,1diyl)]bis(oxy)diphthalonitrile 1, and then ball-type hetero-dinuclear Fe(II)-Co(II) phthalocyanine 4 was synthesized from 2. The novel compounds have been characterized by elemental analysis, UV/vis, IR and MALDI-TOF mass spectroscopies. Electrocatalytic activity of the high-surface area carbon, Vulcan XC-72R (VC) and Nafion ® (Nf) supported complexes towards oxygen reduction was investigated and compared by surface cyclic voltammetry and rotating ring-disk electrode experiments in acidic medium. The VC/Nf/2 and especially VC/Nf/3 modified glassy carbon electrodes showed high catalytic performance, producing water as the main product through the direct four-electron path. A.c. and d.c. measurements were performed on spin coated 2-4 films as a function of temperature (290-436 K). The d.c. results showed an activated conductivity dependence on temperature. The a.c. results gave a temperature dependent frequency exponent s. Gas sensing properties of the films for the volatile organic compounds (VOCs) (toluene, chloroform, ethanol and carbontetrachloride) were also investigated in the temperature range from 290 to 436 K. It was observed that the operating temperature had a considerable effect on sensing characteristics of 3 but not 4. .tr (Ö. Bekaroglu).
Electrochimica Acta, 2007
A new water-soluble cobalt phthalocyanine, 2(3), 9(10), 16(17), 23(24)-tetrakis(4-(1-naphthoxy-4-sulfonic acid sodium salt)) phthalocyaninato cobalt(II) NhtCoPc, where Nht indicates naphthoxy-4-sulfonic acid sodium salt, was synthesized and its electro-spectroelectrochemical and electrocatalytic behavior towards oxygen reduction reaction were investigated in details. The complexation reaction was monitored with the UV-vis spectral changes of NhtH 2 Pc in methanol solution. The reaction was completed when the main Q-band was observed in maximum intensity. The electrochemical studies showed that the cobalt complex exhibited two reversible one-electron reductions with the corresponding anodic wave and an irreversible oxidation reaction in DMSO solution. These reduction processes were assigned to Co(2+)Pc(2−)/Co(+)Pc(2−) and Co(+)Pc(2−)/Co(+)Pc(3−) couples, respectively. The well-defined UV-vis spectra of the mono-anionic species [NhtCo(+)Pc(2−)] − , di-anionic species [NhtCo(+)Pc(3−)] 2− , and mono-cationic species [NhtCo(3+)Pc(2−)] + , were obtained by the applied potentials (E app = −0.60, −1.40, and 0.70 V, respectively) in a thin-layer cell. NhtCoPc was incorporated into the conductive polyaniline (PAni) films as a dopant-anion during electropolimerization in acid medium, and thus formed the Pt/PAni-NhtCoPc electrode. This modified electrode was characterized by scanning electron microscopy (SEM), as well. The addition of NhtCoPc to the polymerization solution changes markedly the morphology of the films obtained and increases the redox-activity towards oxygen reduction of the PAni film formed compared to those of Pt/PAni and bare platinum electrodes in the same experimental conditions. .tr (I. Yilmaz). solvents and they tend to aggregate. These limitations can be addressed by introducing bulky substituents, which will render them soluble by causing substantial disruption of the strong interactions of the parent phthalocyanine rings. Also, the presence of these substituents is known to offer a useful way of regulating the wavelength of the Q-band. Among these compounds, water-soluble phthalocyanines are the most promising materials on effective catalysts , photosensors [11] as well as photosensitizers in PDT (photodynamic therapy) . Especially, the cobalt phthalocyanine (CoPc) and its derivatives are shown to catalyze reactions like the reduction of oxygen, carbondioxide, formic acid, formaldehyde, trichloro acetic acid, and cysteine . The catalytic behavior of CoPc complexes is associated with the redox activity of the central metal which undergoes oxidation and reduction related with Co(3+)/Co(2+) 0013-4686/$ -see front matter
Electrochimica Acta, 2017
A new series of functional compounds, (((perfluoropropane-2,2-diyl) bis (4, 1-phenylene)) bis (oxy))-bridged ball-type metal-free and zinc(II), cobalt (II) and iron (II) metallophthalocyanines, behaving as the air catalyst in zinc-air batteries have been developed, and characterized with common spectroscopic methods. The catalyst composites were characterized by scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDS), and energy dispersive elemental mapping (EDS mapping). The catalytic activites of the dimeric type complexes on oxygen reduction reaction (ORR) have been evaluated by static and dynamic voltammetric techniques. In particular, iron (II) complex displayed spectacular catalytic activity with slightly more positive half-wave potential than that of the commercial Pt/C for ORR in alkaline media, mainly due to its distinctive cofacial molecular structure with dual redox-active metal centers. The electrocatalytic performance tests, carried out in a homemade Zn-air battery prototype, suggested that this complex can be used as an efficient ORR catalyst in this type of batteries.
Polyhedron, 2011
Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1 0-binaphthyl-8,8 0-diol and ball-type dinuclear Co 2 Pc 2 substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1 0-binaphtholbridges were prepared from the corresponding phthalonitriles 4-7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(Co I Pc À2) 2 ] 2À /[(Co I Pc À3) 2 ] 4À (I), (Co II Pc À2) 2 /[(Co I Pc À2) 2 ] 2À (II) and one oxidation process assigned to [(Co III Pc À2) 2 ] 2+ /Co II Pc À2) 2 (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.
Electrochimica Acta, 2008
Alloy Pt-M (M = Co, Ni) nanocatalysts, supported on carbon Vulcan XC-72, were synthesized using the carbonyl chemical route. A high dispersion on such substrate was revealed by transmission electron microscopy (TEM). Alloy formation on the nanometre scale length was shown by high-resolution transmission microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX) on a nanoparticle. The metal M in Pt-M nanoalloys segregates preferentially on the nanoparticles' surface, as determined by the hydrogen adsorption electrochemical reaction. An increased tolerance towards methanol of such nanoalloy materials was observed for the oxygen reduction reaction (ORR) in acid media. To better understand the structure and segregation phenomena of these nanoalloys, molecular dynamics (MD) with a self-optimized reactive force field was applied.
Polyhedron, 2011
The syntheses of new ball-type Co(II) phthalocyanines containing 4,4 0-(9H-fluorene-9,9-diyl)diphenol substituents at non-peripheral (complex 6) and peripheral (complex 7) positions are presented. These complexes were characterized by UV-Vis, FT-IR, mass spectroscopy and electrochemical methods. Both complexes exhibit metal and ring based redox processes, typical of cobalt phthalocyanine complexes. For 6, the metal based reduction was observed at À0.46 V followed by a ring based reduction at À1.40 V. The metal oxidation for 6 was observed at +0.16 V and the ring based oxidation at +1.05 V. For 7, reductions are easier but the oxidations are more difficult. The metal based reduction for 7 was observed at À0.38 V followed by a ring based reduction at À1.03 V. The metal oxidation for 7 was observed at +0.20 V and the ring based oxidation at +1.35 V.
Computational Materials Science, 2017
The high cost of platinum-based catalysts has hampered the commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Hence, the electronic structure and oxygen reduction ability of [Ti(IV)Pc] 2+ , Ti(II)Pc titanyl-phthalocyanines, and their tailored peripheral and axial ligand complexes were theoretically investigated to determine non-precious cathode catalysts. Our results revealed that the peripherally substituted and unsubstituted Ti(II)Pc triplet complexes can spontaneously reduce peroxide. The singlet [Ti(IV)Pc] 2+ parent complex has a 6.45 eV barrier. However, fluorine substitution at peripheral positions reduced the energy barrier up to 0.45 eV. In addition, chlorine substitution has shown spontaneous peroxide reduction as in the case of triplets. The high catalytic activity of Ti(II)Pc complexes and singlet chlorine substituted complex is attributed to the optimal charge transfer between dioxygen molecule and the novel catalyst complexes. As a result, Ti(II)Pcs and chlorine substituted singlet complexes are considered as potential substitutions for the noble Pt-based catalyst for the PEMFCs.
Oxygen electroreduction catalysts based on phthalocyanine complexes of 3d-metals
The electroreduction of oxygen on activated carbon of AG-3 electrodes promoted with pyrolyzed phthalocyanine complexes of the 3d-metals Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ has been investigated. The conditions of synthesis of catalytic constructions influencing the efficiency of oxygen electroreduction have been determined. It is shown that the catalyst activity series depends on the central atom and substituents in phthalocyanine ring.