Dimers, trimers and oligomers of phthalocyanines and related compounds

Rational design of a zinc phthalocyanine binding protein

Phthalocyanines have long been used as primary donor molecules in synthetic light-powered devices due to their superior properties when compared to natural light activated molecules such as chlorophylls. Their use in biological contexts, however, has been severely restricted due to their high degree of self-association, and its attendant photoquenching, in aqueous environments. To this end we report the rational redesign of a de novo four helix bundle di-heme binding protein into a heme and Zinc(II) phthalocyanine (ZnPc) dyad in which the ZnPc is electronically and photonically isolated. The redesign required transformation of the homodimeric protein into a single chain four helix bundle and the addition of a negatively charge sulfonate ion to the ZnPc macrocycle. To explore the role of topology on ZnPc binding two constructs were made and the resulting differences in affinity can be explained by steric interference of the newly added connecting loop. Singular binding of ZnPc was verified by absorption, fluorescence, and magnetic circular dichroism spectroscopy. The engineering guidelines determined here, which enable the simple insertion of a monomeric ZnPc binding site into an artificial helical bundle, are a robust starting point for the creation of functional photoactive nanodevices.

A highly stable double-coordinated 2-hydroxy-tri(tert-butyl)-substituted zinc phthalocyanine dimer: synthesis, spectral study, thermal stability and electrochemical properties

Photophysical properties of the thermally and chemically stable J-type phthalocyanine dimer were studied for the first time.

Effects of benzo-annelation of asymmetric phthalocyanine on the photovoltaic performance of dye-sensitized solar cells

Novel highly asymmetric zinc tetraazaporphyrin (TAP) derivatives (Zn-tri-TAPNc and Zn-tri-PcNc) with one carboxyl and three tert-butyl peripheral substituent groups for dye-sensitized solar cells were synthesized.

Germanium(IV) phthalocyanine-porphyrin based hetero trimers: synthesis, spectroscopy and photochemistry

The known oxophilicity of Germanium(IV) ion of Germanium(IV) phthalocyanine and porphyrins have been exploited to synthesize functionally active, "axial-bonding" -type hetero oligomers. These hetero trimers have been fully characterized by elemental analysis, FAB-MS, UV-visible, proton nuclear magnetic resonance (1D and 1 H -1 H COSY) and fluorescence spectroscopies, as well as differential pulse voltammetric method. Comparison of their spectroscopic and electrochemical data with those of the corresponding individual constituents reveals that there is no apparent π–π interactions in these "vertically" linked hetero oligomers. The fluorescence quantum yields were found to be lower of these hetero oligomers in comparison with those of the monomeric chromophores. Electronic energy transfer and photoinduced electron transfer from axial porphyrins to central metalloid phthalocyanine and photoinduced electron transfer from singlet state of axial porphyrins to central metalloid phthalocyanine is detected in these hetero oligomers.

Synthesis, interface (Au/M2Pc2/p-Si), electrochemical and electrocatalytic properties of novel ball-type phthalocyanines

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.

Synthesis, characterization and ESR spectroscopy of novel s-triazine bearing three oxygen-linked lutetium bisphthalocyanine sandwich complexes

The conversion of compound 1 [2,4,6-tris(2-oxaphthalonitrile)-s-triazine] into its isoindoline derivative of 2,4,6-tris[2-oxa(1,3-hexaimino isoindoline)]-s-triazine 2 was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives namely, compound 2 and 4,5-bis(hexylthio)-1,2-diimino-isoindoline 3 with lutetium(III) acetate, [ Lu ( OAc )3] in refluxed DMF by the method of statistically mixed condensation gave trimeric trilutetium phthalocyanine [( LuOAc )3( Pc )3]4. [ Lu 3( Pc )6]5 has been synthesized in situ by the reaction of phthalocyanine 4 and three equivalents of dilithium octakis-hexylsulfanyl phthalocyanine in amyl alcohol.

Synthesis, structure, and properties of new phthalocyanines

Many low symmetry and/or deformed phthalocyanines (Pcs) have been synthesized, separated, and their spectroscopic and electrochemical properties elucidated in the last decade, mainly because of improvement in separation techniques of reaction mixtures and development of instruments and computers. In this overview, some advances in the chemistry of Pcs are surveyed. In recent years, many types of alkynyl Pcs, various isomers of low symmetry Pcs, severely sterically deformed Pcs, and chiral Pcs have been prepared and some of their properties are reproduced by quantum mechanical calculations, which have not been achieved previously. Also, in the field of Pc sandwich complexes, properties of hetero double- and triple-decker complexes can be compared, since many types of compounds are now available. Some hetrodinuclear planar dimers have also been reported in the last decade.

Light harvesting phthalocyanine/subphthalocyanine system: intermolecular electron-transfer and energy-transfer reactions via the triplet subphthalocyanine

Photoinduced electron transfer from the electron-donating zinc tetra-tert-butylphthalocyanine, ZnTBPc , to the electron-accepting dodecafluorosubphthalocyanine, SubPcF12 , in the polar benzonitrile has been investigated with nanosecond laser photolysis method. The examined ZnTBPc/SubPcF12 mixture absorbs the light in a wide section of the UV/vis/NIR spectra. Owing to the particular electronic properties of both entities, such combination seems to be perfectly suited for the study of intermolecular electron-transfer process in the polar solvents via the triplet-excited state of SubPcF12 . Upon excitation of SubPcF12 with 570 nm laser light in polar benzonitrile (εs = 25.2), the electron transfer from ZnTBPc to the triplet-excited state of SubPcF12 was confirmed by observing the transient absorption bands of ZnTBPc radical cation and SubPcF12 radical anion in the visible and near-IR region. On addition of an appropriate electron acceptor with excellent electron-accepting properties, namely dicyanoperylene-3,4,9,10-bis(dicarboximide) ( PDICN2 ), the anion radical of SubPcF12 transfers to the PDICN2 yielding the PDICN2 radical anion. These observations confirm the photosensitized electron-transfer/electron-mediating cycle of ZnTBPc/SubPcF12/PDICN2 system. In non-polar toluene (εs = 2.2), the energy-transfer process from the triplet-excited state of SubPcF12 to the low-lying triplet state of ZnTBPc was confirmed by the consecutive appearance of the triplet ZnTBPc .

Synthesis and characterization of highly soluble hexadecachloro- and hexadecafluorophthalocyanine ruthenium(II) complexes

A new synthesis is reported for hexadecafluorophthalocyanineruthenium(II), F16Pc (2-) RuIIand hexadecachlorophthalocyanineruthenium(II), Cl16Pc (2-) RuII, is reported for the first time. These paramagnetic species, which contain no axial ligand, are quite reasonably soluble in a range of common organic solvents. We report and discuss electronic and vibrational (infrared and resonance Raman) spectroscopic, MALDI-TOF and magnetic data. In addition we report electrochemical data and use spectroelectrochemical methods to obtain the electronic spectra of these species in the phthalocyanine(1-), (3-) and (4-) oxidation states.

Synthesis, characterization, and electrochemical and electrical properties of a novel ball-type hexanuclear metallophthalo-cyanine, bridged by calix[4]arenes substituted with four hexyl-thiometallophthalocyanines through nitro coupling

In this study, the synthesis of a supramolecular hexaphthalocyaninato hexazinc(II) with hexylthio substituents is reported. Starting from 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-dimethoxycalix[4]arene, mononitro derivative of calix[4]arene 1 was obtained. Compound 1 was converted to phthalodinitrile derivative 2 by the reaction with 4-nitrophthalonitrile in dry dimethylsulfoxide by the method of nucleophilic substitution of an activated nitro group in an aromatic ring. The tetramerization of compound 2 with Zn ( OAc )2·2 H 2 O in 1-pentanol gave the novel ball-type binuclear zinc (II) phthalocyanine 3 which was reacted with unsymmetric zinc(II) phthalocyanine 4 to furnish a supramolecular assembly of a zinc(II) phthalocyanine of a ball type with four zinc(II) phthalocyanines through azo bridges, 5. Newly synthesized compounds were characterized by elemental analysis, UV-vis, IR, MALDI-TOF MS and 1 H NMR spectra. The electrochemical and spectroelectrochemical properties of 5 were also examined in nonaqueous media. The measurements showed the formation of various mixed-valence oxidation and reduction species, due to the strong intramolecular interactions between the Pc rings. Both DC and AC conductivity data were analyzed by the existing theory.

Chromenone 12-crown-4 substituted zinc phthalocyanine complexes: investigation of spectral, photophysical and photochemical properties

The synthesis of novel 6,7-[(12-crown-4)-3-[p-(3,4-dicyanophenoxy)phenyl]coumarin (1), 6,7-[(12-crown-4)-3-[p-(2,3-dicyanophenoxy)phenyl]coumarin (2), and their corresponding tetra-(chromenone 12-crown-4)-substituted zinc (II) phthalocyanine complexes (3 and 4) have been prepared. These new compounds have been characterized by elementel analysis, (1)H NMR (1 and 2), MALDI-TOF, IR and UV-Vis spectral data. The fluorescence intensity changes for 1 and 2 by addition of Na(+) or K(+) ions have been determined at 25°C in THF. Intensity of the binding Na(+)- and K(+)-complexes (1 and 2) have decreased. The effects of the chromenone crown ether on the phthalocyanine molecule concerning photophysical and photochemical properties are also investigated. Photodegredation, singlet oxygen, fluorescence quantum yields, and fluorescence lifetimes of zinc phthalocyanine complexes (3 and 4) are also examined in DMSO.

Synthesis, characterization, and electrochemical and electrical properties of novel mono and ball-type metallophthalocyanines with four 9,9-bis(4-hydroxyphenyl)fluorene

The new mono-nuclear 4-5 and ball-type homo-dinuclear 6 phthalocyanines have been synthesized from the corresponding phthalodinitrile derivative 3. The synthesized compounds have been characterized by elemental analysis, UV-vis, IR,(1)H-NMR and MALDI-TOF-mass spectroscopies. The redox behaviours of the complexes were identified by cyclic voltammetry and square wave voltammetry. The temperature dependence of the electronic properties of compounds and adsorption of SO(2) on thin film of 6 were investigated by conductivity measurements using an interdigital transducer structure on glass substrate. Dc conductivity, measured between 300-475 K, is thermally activated with the activation energy ranging between 0.67 and 0.90 eV. The ac conductivity is found to vary with frequency, ω, as ω(s) in which the frequency exponent s decreases with temperature suggesting a hopping conduction mechanism for all compounds. The SO(2) sensing result showed that the spin coated film of 6 exhibits very good SO(2) sensing properties, fast response and recovery rate, high sensitivity and good repeatability.

A discrete quadruple-decker phthalocyanine

The reaction of a double-decker phthalocyanine (Pc) complex, bis(phthalocyaninato)lutetium ([LuPc(2)](-)), with cadmium acetate at 400 degrees C for 30 min under argon provided the first example of a discrete quadruple-decker Pc complex, 1. The structure of 1 was unambiguously determined through the use of high-resolution mass spectrometry, elemental analysis, and NMR techniques such as (1)H-(1)H COSY, (13)C-(1)H COSY, and NOE experiments. The absorption and magnetic circular dichroism spectra of 1 resembled those of [LuPc(2)](-) and [Lu(2)Pc(3)] rather than those of the neutral double-decker species [LuPc(2)](0), since the formal charge on each Pc moiety is 2-. Electrochemical measurements exhibited a stacking effect based on the delocalization of the holes or electrons introduced by oxidation or reduction, respectively, over the entire complex.

Efficient removal of dyes in water using chitosan microsphere supported cobalt (II) tetrasulfophthalocyanine with H2O2

A new efficient catalyst, CoTSPc@chitosan, was developed by immobilizing water soluble cobalt (II) tetrasulfophthalocyanine onto adsorbent chitosan microspheres covalently for the heterogeneous catalytic oxidation of C. I. Acid Red 73 with H(2)O(2). The result indicated that the COD removal and discoloration of C. I. Acid Red 73 made 55 and 95% respectively in the presence of CoTSPc@chitosan with H(2)O(2) in 4h. In addition, CoTSPc@chitosan-H(2)O(2) system could proceed efficiently in a relatively wide pH range and remain high catalytic activity after 6 reuse cycles. Furthermore, the adsorption study of CoTSPc@chitosan confirmed that chitosan was an outstanding support which contributed a lot to the removal reaction. In conclusion, the combination of adsorption process and catalytic oxidation made the CoTSPc@chitosan-H(2)O(2) system achieve a simple, efficiently and environmentally friendly water treatment.