Journal of Porphyrins and Phthalocyanines

In this work, voltammetric, spectroelectrochemical, and electrocatalytic properties of the metallophthalocyanines bearing four chloro and four biphenyl-malonic ester bulky groups were investigated. Voltammetric and spectroelectrochemical measurements of the metallophthalocyanines show that while cobalt phthalocyanine presents both metal-based and ring-based redox processes, all other complexes give only ring-based reduction and oxidation processes. The redox processes have generally diffusion-controlled, reversible and one-electron transferred mechanisms. Cobalt phthalocyanine electrocoated easily on the glassy carbon working electrode during the repeating cycles, a very useful feature for application in fabrication of thin films. Electrocatalytic activity of cobalt phthalocyanine to hydrogen evolution reaction was studied in solution titrated with perchloric acid and on glassy carbon electrode modified with cobalt phthalocyanine in aqueous solution. Electrocatalytic measurements show that cobalt phthalocyanine has significant catalytic activities towards hydrogen evolution reaction. Moreover, the catalytic activity of the complex enhanced significantly when the complex was incorporated into the cation exchange Nafion polymeric matrix.

The new peripherally 2-mercaptopyridine tetrasubstituted zinc phthalocyanine (2) and its quaternized derivative (3) have been synthesized and characterized by elemental analysis, IR, ¹H NMR spectroscopy, electronic spectroscopy and mass spectra. The quaternized compound (3) shows excellent solubility in water, which makes it a potential photosensitizer for use in photodynamic therapy (PDT) of cancer. Fluorescence and singlet oxygen quantum yield measurements were conducted on 2-mercaptopyridine appended zinc phthalocyanines in dimethylsulphoxide (DMSO) for both the non-ionic (2) and quaternized (3) derivatives, and in aqueous media for the water-soluble complex 3. General trends are described for fluorescence and singlet oxygen quantum yields of these compounds. In this study, the cells were incubated with a novel water-soluble zinc phthalocyanine derivative (3) and thereafter the cells were illuminated using broad-band incoherent light source of various energy levels. Cytotoxicity of PDT on two pleural malign mesothelioma cell lines was determined by colorimetric proliferation assay. In addition, after PDT treatment, determination of activity matrix metalloproteinases (MMPs) were evaluated using gelatine zymography.

The synthesis of metal-free and metallophthalocyanines (M = Zn, Co) obtained from 7,8-dihexyloxy-3-[p-(3',4'-dicyanophenoxy)phenyl]coumarin are described. The newly prepared compounds have been characterized by elemental analysis, IR, NMR, mass and UV-vis spectral data. Their electronic absorption and fluorescence spectral properties are reported. Cyclic voltammetry of the compounds have also been studied. In situ spectroelectrochemistry of the Co(II) complex in THF and DCM is included to identify the difference in its redox behavior, as compared with other complexes.

The synthesis and spectroscopic characterization of tetraimidazophthalocyanines are presented. This kind of molecules have not been intensively studied due to difficulty in (i) obtaining an easily obtainable synthon: a benzimidazole ring with a variety of substituent, and (ii) achieving the Rosenmund-Von Braun reaction with good yields. The synthesis of novel 2-substituted-5,6-dicyanobenzimidazoles (4a–e) achieved from 4,5-dibromo-N,N'-diacetylated-1,2-phenylene diamine (2a–e) or 2-substituted-5,6-dibromobenzimidazole (3a–e) were optimized. Depending on the starting compound, the reaction could be done according to a two-step pathway (cyclization followed by nitrilation) or a one-pot procedure using microwave irradiation. The target compounds, tetraimidazophthalocyanines (ImiPc(M)) (5a–e;6a–d), were prepared. The effect of the four imidazoles introduced in the phthalocyanines core were compared and discussed.

In this study, we report a novel both alcohol and haloganated solvent soluble selective ionophore functional ligand and its β-substituted 2(3),9(10),16(17),23(24)-tetrakis(1-hydroxyhexan-3-ylthio)-phthalocyanines, M{Pc[S-CH(CH₂CH₂CH₃)(CH₂CH₂OH)]₄}, (Pc: Phthalocyanine) (M = Zn, Cu, Co), where -OH indicates peripheral functionality. Pcs exhibiting both hydrophobic and hydrophilic character were characterized spectroscopically (FT-IR, ¹H and ¹³C NMR, MS (MALDI-TOF) and UV-vis), electrochemically and spectroelectrochemically. The complexes were soluble in both polar solvents, such as MeOH and EtOH, and non-polar solvents such as CHCl₃, CH₂Cl₂, benzene, toluene, and even hexane. Absorption spectral changes of the functional MPcs during addition of Ag^I and Pd^II soft-metal ions are evaluated by monomer-oligomer and even polymer formations technique and monitored for in situ monitoring technique in the UV-vis spectroscopy. The binding process results in considerable blue-shift in the absorption spectra of MPcs. According to continuous variation method, the ligand:metal ratio was found ca. 1:1 and 1.5:1 for total concentration of 1.0 × 10^-5M and 7.5 × 10^-5M, respectively. Their electrochemical and spectroelectrochemical studies show that the complexes exhibited stable monoanionic M{Pc[S-CH(CH₂CH₂CH₃)(CH₂CH₂OH)]₄}^1-, dianionic M{Pc[S-CH(CH₂CH₂CH₃)(CH₂CH₂OH)]₄}^2- and monocationic M{Pc[S-CH(CH₂CH₂CH₃)(CH₂CH₂OH)]₄}¹⁺ species during reduction and oxidation processes.

Ni(II) and Zn(II) phthalocyanines carrying four or eight branched oligo(ethyleneoxy)-thia groups on peripheral positions have been synthesized from new phthalonitrile derivatives. The new compounds have been characterized by elemental analysis, IR, NMR, mass spectra and electronic spectroscopy. The aggregation behaviors of the phthalocyanine complexes were studied in different solvents and concentrations. General trends are described for photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The effects of the substitution on the photophysical and photochemical parameters of the nickel(II) (3a and 4a) and zinc(II) phthalocyanines (4b) are also reported. The octasubstituted zinc(II) complex (3b) is not stable for these measurements. Preliminary investigation of the photophysical and photochemical properties of phthalocyanine complexes are very useful for further PDT applications. The mesogenic properties of these new materials were studied by differential scanning calorimetry (DSC), optical polarized microscopy and X-ray investigations.

A novel synthetic pathway for the preparation of a new phthalonitrile derivative, methyl (E)-3-[2-(3,4-dicyanophenoxy)-4-(hexyloxy)phenyl]acrylate (3), based on the opening of the lactone ring of 7-hexyloxycoumarin (2H-1-benzopyrane-2-one, 2H-chromen-2-one) and ether formation of the formed hydroxy group with 4-nitrophthalonitrile, is presented. Cyclotetramerization of this dinitrile in 2-N,N-dimethylaminoethanol gives the desired Zn(II), Co(II) and Cu(II) phthalocyanines (4, 5 and 6) with four methyl 4-hexyloxy-2-phenoxy acrylate moiety on periphery. The complexes are characterized by IR, elemental analysis, ¹H NMR, ¹³C NMR MALDI-TOF and UV-vis spectroscopy. The redox behavior of the complexes are also discussed.

The synthesis of the iron phthalocyanine bearing four fused tetraazamacrocycles starting from N,N',N″,N‴-tetrakis(p-tolylsulfonyl)triethylenetetraamine and 1,2-dibromo-4,5-bis(bromomethyl)benzene is reported. The exchange of protecting tosyl groups by acetyl groups was necessary to obtain iron phthalocyanine. The efficiency of iron phthalocyanine as oxidation catalyst was tested for the practically important oxidation of 2,3,6-trimethylphenol (TMP) at different reaction conditions.

Metal-free and metallophthalocyanines with four 9-anthroyl groups bound through ethylthio ester bridges on the periphery have been prepared. The new compounds were characterized by elemental analyses, ¹H NMR, IR, mass and UV-vis spectral data. The electronic spectra exhibit an intense π-π* transition of 9-anthroyl identity together with characteristic Q and B bands of the phthalocyanine core. Effect of metal ions on intensity of fluorescence spectra of phthalocyanine derivatives substituted with 9-anthroyl groups was investigated. The energy transfer to the phthalocyanine core and radiative decays of the 9-anthroyl emission and phthalocyanine core were examined.

A complete series of solketal octasubstituted phthalocyanines have been synthesized, with peripheral (β) or non-peripheral (α) substitution pattern. Their ¹³C NMR and UV-vis properties are compared relatively to this substitution pattern or the nature of the central metal (Ni, Zn or H₂).