Synthesis,electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric characterization of new phthalocyanines peripherally fused to four flexible crown ether moieties

Novel Ni(II), Zn(II), Co(II) and Cu(II) phthalocyanines with four peripheral 4-[methyleneoxy(18-crown-6)] groups have been synthesized via the cyclic tetramerization of 4-[{(18-crown-6)-yl}methyleneoxy]phthalonitrile and the corresponding metal salts (NiCl₂, Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The thermal stabilities of the metal-free and metallophthalocyanine compounds were determined by thermogravimetric analysis. The structures of the target compounds were confirmed using elemental analysis, IR, ¹H-NMR, ¹³C-NMR, UV–Vis and MS spectral data. Voltammetric and in situ spectroelectrochemical measurements show that while the cobalt phthalocyanine complex gives both metal-based and ring-based redox processes, the metal-free, nickel, zinc and copper phthalocyanines show only ring-based reduction and oxidation processes. An in situ electrocolorimetric method has been applied to investigate the color of the electro-generated anionic and cationic forms of the complexes.     

Synthesis and electrochemical characterization of biphenyl-malonic ester substituted cobalt,copper, and palladium phthalocyanines

Phthalocyanines with four biphenyl-malonic ester groups on the periphery were synthesized by cyclotetramerization of 4-(1,1-dicarbethoxy-2-(4-biphenyl)-ethyl)-phthalonitrile. The new compounds were characterized by elemental analyses, FT-IR, ¹H NMR, ¹³C NMR, UV–Vis, and MASS spectral data. Electrochemical behaviors of novel Co(II), Cu(II), and Pd(II) phthalocyanines were investigated by cyclic voltammetry, potential differential pulse voltammetry, and applied potential chronocoulometry techniques. While Cu(II) and Pd(II) phthalocyanines give up to four common phthalocyanine ring reductions, Co(II) phthalocyanine gave two ligand-centered and two metal-centered redox processes. HOMO–LUMO gap of the complexes are comparable with the reported MPc papers.     

Voltammetric determination of copper at chemically modified electrodes based on crown ethers

The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically and gave better voltammetric responses than the unmodified ones. The crown ethers studied and compared were 15-crown-5, benzo-15-crown-5 and dibenzo-18-crown-6. With a 3% benzo-15-crown-5 CME, Cu(II) could be quantified at sub-ppm levels by differential pulse voltammetry with a detection limit of 0.05 ppm. By differential pulse anodic stripping voltammetry Cu(II) could be quantified over the range I to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Fe(II), etc. have also been studied. The method was successfully applied to artificial as well as commercial samples of alcoholic beverages.     

Synthesis and characterization of novel flavonoid-substituted phthalocyanines using (±)naringenin

In this study, novel unsymmetrical mono- and di-substituted metal free and metallo phthalocyanines containing peripheral naringeninoxy moieties have been prepared. The naringenin-substituted phthalonitrile was synthesized from 4-nitrophthalonitrile and (±)naringenin in dimethylsulfoxide. Preparation of unsymmetrical mono- and di-substituted phthalocyanines, 2-naringenin-7-O-phthalocyaninatozinc, 2,9-bis-naringenin-7-O-phthalocyaninatozinc, 2,9-bis-naringenin-7-O-phthalocyaninatocobalt and 2,9-bis-naringenin-7-O-phthalocyanine was performed at 120-140 °C using the corresponding phthalonitrile in the presence of N,N-dimethylethanolamine (DMAE), ZnCl₂, CoCl₂ and LiCl, respectively. Synthesized new phthalocyanine compounds have been characterized by elemental analysis and ¹H NMR, ¹³C NMR, FT-IR, MS and UV-vis spectroscopy. These are the first known examples of flavonoid-substituted phthalocyanines.     

Anthracene Substituted Co (II) and Cu (II) phthalocyanines; Preparations,Investigation of Catalytical and Electrochemical Behaviors

An approach to investigation of catalytical behaviors of Co (II) and Cu (II) phthalocyanines is reported that is based on changing any parameter to effect these behaviors. Towards this end, new anthracene substituted Co (II) and Cu (II) phthalocyanines were prepared and characterized spectroscopic methods. New cobalt (II) and copper (II) phthalocyanines were used as catalyst for oxidation of different phenolic compounds (such as 2,3‐dichlorophenol, 4‐methoxyphenol, 4‐nitrophenol, 2,3,6‐trimethylphenol) with different oxidants. Then, electrochemical characterization of cobalt (II) and copper (II) phthallocyanines were determined by using cyclic voltammetry (CV) and square wave voltammetry (SWV) techniques. Although copper (II) phthalocyanine showed similar Pc based electron transfer processes, cobalt (II) phthalocyanine showed metal and ligand based reduction reactions as expected.     

Voltammetric determination of copper at chemically modified electrodes based on crown ethers

The feasibility of fabricating copper-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and in 40% (v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The electrodes so formed were able to bind Cu(II) ions chemically and gave better voltammetric responses than the unmodified ones. The crown ethers studied and compared were 15-crown-5, benzo-15-crown-5 and dibenzo-18-crown-6. With a 3% benzo-15-crown-5 CME, Cu(II) could be quantified at sub-ppm levels by differential pulse voltammetry with a detection limit of 0.05 ppm. By differential pulse anodic stripping voltammetry Cu(II) could be quantified over the range 1 to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Fe(II), etc. have also been studied. The method was successfully applied to artificial as well as commercial samples of alcoholic beverages. Received: 12 January 2000 / Revised: 14 March 2000 / Accepted: 16 March 2000     

Synthesis,characterization and electrochemistry of a new organosoluble metal-free and metallophthalocyanines

4-[2-(Phenylthio)ethoxy]phthalonitrile 3 was synthesized by nucleophilic displacement of nitro group in 4-nitrophthalonitrile with 2-(phenylthio)ethanol 1. The metal-free phthalocyanine 4 was prepared by the reaction of a dinitrile monomer with 2-(dimethylamino)ethanol. Ni(II), Co(II), Cu(I) phthalocyanines 5, 7, 8 were prepared by reaction of the dinitrile compound with the chlorides of Ni(II), Co(II), Cu(I) in DMAE. Zn(II) phthalocyanine 6, was prepared by reaction of the dinitrile compound with the acetates of Zn(II) in DMAE. Electrochemical behaviours of novel metal-free, Co(II) and Zn(II) phthalocyanines were investigated by cyclic voltammetry, potential differential pulse voltammetry techniques. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–Vis, elemental analysis and MS spectral data.     

Synthesis and electrochemistry of new octa-substituted metal-free and metallophthalocyanines

The synthesis and characterization of metal-free (H₂-Pc) and metal-containing (Zn, Co, and Cu) derivatives of a symmetrically octa-substituted phthalocyanine derived from 4,5-bis[2-(phenylthio)ethoxy]phthalonitrile were carried out by microwave irradiation. The electrochemical properties of the metal-free phthalocyanine 4 and metallophthalocyanine complexes 5 and 6 were investigated by cyclic voltammetry and differential pulse voltammetry. We have previously investigated the electrochemical properties of the tetra substituted 2-(phenylthio)ethoxy phthalocyanines. The reduction potential of the octa-substituted metal-free phthalocyanine shifted to more negative potential as a result of the electron donating of the 2-(phenylthio)ethoxy groups on the periphery compared to those of tetra substituted. The H₂Pc and ZnPc demonstrated ligand-based electron transfer processes, while CoPc complex has a metal-based reduction process. Similar aggregation behavior was observed for octa-substituted phthalocyanines. The compounds were characterized using IR, ¹H NMR, ¹³C NMR, elemental analysis, and MS spectral data.     

Synthesis and characterization of new polymeric phthalocyanines substituted with diaza-18-crown-6 macrocycles through ethyleneoxy bridges

A tetranitrile monomer was synthesized by nucleophilic aromatic substitution of N,N′-bis(2-hydroxyethyl)-4,13-diaza-18-crown-6 onto 4-nitrophthalonitrile. A series of polymeric metal-free and metallophthalocyanine (M = 2H, Zn, Cu, Co and Ni) polymers was prepared by polymeric tetramerization reaction of the tetranitrile monomer with proper materials. The electrical conductivities of the polymeric phthalocyanines measured as gold sandwiches were found to be ∼10⁻⁹–10⁻⁴ S cm⁻¹ in a vacuum and in argon. The extraction ability of the metal-free polymeric phthalocyanine was evaluated in tetrahydrofuran using several alkali metal picrates such as Li⁺, Na⁺, K⁺ and Cs⁺. The extraction affinity of the metal-free polymeric phthalocyanine for K⁺ was found to be highest in the heterogeneous solid–liquid phase extraction experiments. The disaggregation property of the metal-free polymeric phthalocyanine was investigated with sodium, potassium and ammonium ions and methanol. All the novel compounds were characterized by using elemental analysis, UV–Vis, FT-IR, NMR and MS spectral data and DTA/TG.     

Electrochemical characterization of Co(II) and Pd(II) phthalocyanines carrying diethoxymalonyl and carboxymethyl substituents

In this study, electrochemical behaviors of Co(II) and Pd(II) phthalocyanines carrying tetrakisdiethoxymalonyl and Pd(II) phthalocyanine carrying tetrakiscarboxymethyl substituents at the peripheral positions are investigated by cyclic voltammetry and applied potential chronocoulometry techniques. Cyclic voltammetric studies show that, while Pd(II) phthalocyanines carrying diethoxymalonyl and carboxymethyl substituents give up to three common phthalocyanine ring reductions, Co(II) phthalocyanine carrying diethoxymalonyl substituents gives a metal-centered oxidation and a metal-centered reduction and three ligand-centered reduction and a ligand-centered oxidation processes. First reduction processes of both the PdPc complexes have shoulders. This different voltammetric behaviors of Pd(II) phthalocyanines carrying carboxymethyl and diethoxymalonyl substituents results from interaction of this distinctive substituents with the phthalocyanine ring π electron system and interaction with the different solvent systems. Observation of the splitting of the first reduction process of Pd(II) phthalocyanines carrying diethoxymalonyl and carboxymethyl substituents suggests the aggregation of the complex. Very small diffusion coefficient of the complexes with respect to Co(II) phthalocyanine also confirms the existence of the aggregation of the complex during the electrochemical studies. Effects of the substituents and the solvent media are clearly observed from the differences of the voltammograms of Pd(II) phthalocyanines carrying diethoxymalonyl and carboxymethyl substituents in DMSO and THF solvent media, respectively. Published in Russian in Elektrokhimiya, 2006, Vol. 42, No. 1, pp. 36–43. The text was submitted by the authors in English.     

Synthesis of non-peripherally substituted tetra(dihexylmalonate) alcohol soluble phthalocyanines

Dimethyl-(2,3-dicyanophenyl)malonate was prepared by the reaction of dimethylmalonate and 3-nitrophthalonitrile. A cyclotetramerization reaction of dimethyl-(2,3-dicyanophenyl)malonate with the corresponding divalent metal salt was achieved in hexanol in the presence of DBU, affording the non-peripherally substituted tetra(dihexylmalonate) Cu(II), Pd(II), and Co(II) phthalocyanines. Transesterification occurred under these reaction conditions, so that methyls in the phthalonitrile derivative were converted into hexyl groups during phthalocyanine formation in hexanol. The new compounds were characterized by elemental analyses, FT-IR, ¹H-NMR, ¹³C-NMR, UV-Vis, and mass spectral data.     

Phthalocyanines prepared from 4-chloro-/4-hexylthio-5-(4-phenyloxyacetic acid)phthalonitriles and functionalization of the related phthalocyanines with hydroxymethylferrocene

The phthalonitrile derivative chosen for the synthesis of substituted phthalocyanines [M: 2H, Zn(II), Co(II)] with four chloro and four phenyloxyacetic acid substituents on the periphery is 4-chloro-5-(4-phenyloxyacetic acid)phthalonitrile. The sodium salt of carboxyl substituted zinc phthalocyanine is good soluble in water. Further reactions of zinc and cobalt phthalocyanines bearing phenyloxyacetic acid with thionylchloride gave the corresponding acylchlorides. This functional group reacted with hydroxymethylferrocene in dry DMF to obtain ferrocenyl substituted phthalocyanines. Also chloro substituent in new phthalonitrile was substituted with hexylsulfanyl substituent and its cyclotetramerization in the presence of Zn(AcO)₂·2H₂O and 2-(dimethylamino)ethanol resulted with zinc phthalocyanine. The compounds have been characterized by elemental analysis, MALDI-TOF mass, FT-IR, ¹H NMR, UV-Vis and fluorescence data. Aggregations properties of phthalocyanines were investigated at different concentrations in tetrahydrofuran, dimethylformamide, dimethylsulfoxide, water, and water/ethanol mixture. Also fluorescence spectral properties are reported.     

Spectrophotometric study of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) complexes with some crown ethers in dimethylsulphoxide solution using murexide as a metallochromic indicator

The complexation reactions between Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions and benzo-15-crown-5, dicyclohexyl-18-crown-6, dibenzo-18-crown-6 and 1,10-diaza-18-crown-6 have been studied in dimethylsulphoxide solution at 25 degrees by means of a competitive spectrophotometric method using murexide as a metallochromic indicator. With the exception of Pb(II)(benzo-15-croqn-5)(2) the stoichiometry of the resulting complexes was found to be 1:1. The formation constants of the complexes were determined, and found to follow the Irving-Williams rule for the cations of the first transition series. It was found that the metal ion-18-crown interactions are strongly dependent on the nature of the substituents on the ring.     

Synthesis,characterization, and determination of photophysicochemical properties of peripheral and nonperipheral tetra‐7‐oxy‐3,4‐dimethylcoumarin substituted zinc,indium phthalocyanines

The photochemical and photophysical properties of peripheral and nonperipheral zinc and indium phthalocyanines containing 7‐oxy‐3,4‐dimethylcoumarin synthesized were investigated in this study. 7‐Hydroxy‐3,4‐dimethylcoumarin ( 1 ) was synthesized via Pechmann condensation reaction and then the phthalonitrile derivatives [4‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 2 ) and 3‐(7‐oxy‐3,4‐dimethylcoumarino)phthalonitrile ( 3 )] were synthesized by nucleophilic aromatic substitution. Phthalocyanine compounds containing coumarin units on peripheral ( 4 and 5 ) and nonperipheral ( 6 and 7 ) positions were prepared via cyclotetramerization of phthalonitrile compounds. All compounds' characterizations were performed by spectroscopic methods and elemental analysis. The phthalocyanine derivatives' ( 4–7 ) photochemical and photophysical properties were studied in DMF. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines ( 4 – 7 ) were studied in DMF. They produced good singlet oxygen (e.g., Φ_Δ = 0.93 for 7 ) and showed appropriate photodegradation (in the order of 10^?5), which is very important for photodynamic therapy applications.     

Selective metal sensor phthalocyanines bearing non-peripheral functionalities: Synthesis,spectroscopy, electrochemistry and spectroelectrochemistry

A novel alcohol-soluble ionophore ligand and its non-peripherally tetrasubstituted functional 1,8,15,22-tetrakis(6-hydroxyhexylsulfanyl) metallophthalocyanines M[Pc(α-SC₆H₁₂OH)₄] (M = Cu(II), Zn(II), Co(II); Pc = phthalocyanine) are reported. The aggregation and cation binding behaviors of the phthalocyanine compounds in the presence of soft Ag^I and Pd^II metal ions were investigated by using UV–Vis spectroscopy. The new compounds have been characterized by elemental analysis, IR, ¹H, ¹³C NMR, UV/Vis spectroscopy, ESI and MALDI–TOF–MS mass spectra. Voltammetric and in-situ spectroelectrochemical studies show that while copper and zinc phthalocyanine complexes give well-defined ring-based reduction and oxidation processes, the cobalt phthalocyanine gives both metal-based and ring-based redox processes which have reversible and diffusion controlled character.     

Polytopic cation receptor functional phthalocyanines: Synthesis,characterization, electrochemistry and metal ion binding

Our efforts toward the development of the synthesis of a novel type of receptor ligand and its tetrasubstituted phthalocyanines, 2,9,16,23-tetrakis(6-hydroxyhexylsulfanyl) phthalocyanine, M[Pc(S–C₆H₁₃OH)₄] (M = Zn(II), Cu(II), Co(II)), bearing sulfur and oxygen donor atoms on the periphery together with hexyl moieties, have been carried out together with spectroscopic and electrochemical characterization. The newly synthesized functional phthalocyanines were soluble in MeOH, EtOH, THF, DMF, CNP (α-chloronapthalene), DMSO and quinoline, and less soluble in i-PrOH and CH₃CN. Cation binding abilities of the functional phthalocyanines with Ag⁺, Pd²⁺, Hg²⁺ and Cd²⁺, resulting in the formation of polynuclear phthalocyanine complexes, were evaluated by UV–Vis spectroscopic techniques. The spectroscopic properties of the complexes were affected strongly by the electron-donating sulfanyl units on the periphery. The cyclic voltammetry of the complexes were examined on a platinum electrode in DMSO. The new synthesized compounds have been characterized by elemental analysis, FTIR, ¹H and ¹³C NMR, MS (ESI and MALDI-TOF) and UV–Vis spectral data.     

Synthesis and characterization of a new organo-soluble metal-free and metallophthalocyanines bearing flexible moieties

This paper describes a new symmetric metal-free phthalocyanine and its transition metal complexes which were prepared by a condensation of 1,2-dihydroacenaphthylen-1-ol 1 and 4-nitro phthalonitrile 2 with Co(II), Ni(II), Cu(II), and Zn(II) salts in 2-(dimethylamino)ethanol, respectively. The novel phthalocyanines bearing oxygen donor atoms on peripheral position have been characterized by IR, UV-Vis, ¹H NMR, ¹³C NMR, Mass spectra and elemental analysis. The thermal behaviours of 4-8 were investigated by TG/DTA.     

Novel peripherally tetra substituted metal-free,cobalt(II), copper(II) and manganese(III) phthalocyanines bearing polyethoxy chain attached by 2,6-diphenylphenol groups: synthesis,characterization and their electrochemical studies

Metal free (6), cobalt(II) (7), copper(II) (8) and manganese(III) (9) phthalocyanines, which are tetra substituted at the peripheral positions with 2-[2-(1,1′:3′,1′′-terphenyl-2′-yloxy)ethoxy]ethoxy groups, were synthesized and characterized by IR, ¹H-NMR,¹³C-NMR, UV–Vis and mass spectroscopy. Electrochemistry of the phthalocyanines were studied with voltammetric measurements by using cyclic voltammetry and square wave voltammetry techniques in DCM/TBAP electrolyte on a Pt working electrode. Electrochemical measurements exhibit that incorporation of redox active metal ions, Co^II and Mn^III, into the phthalocyanine core extends the redox capabilities of the Pc ring including the metal-based reduction couples of the metal. While Mn^IIIClPc showed only metal based reduction reactions, Co^IIPc showed metal based and ligand based reduction reactions as expected. Cyclic and square wave voltammetric studies showed that phthalocyanines have reversible/quasireversible/irreversible redox processes, which are the main requirement for the technological usage of these compounds.     

Synthesis and electrochemical behavior of novel peripherally and non-peripherally substituted ball-type cobalt phthalocyanine complexes

The syntheses of new ball-type Co(II) phthalocyanines containing 4,4′-(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 −0.46 V followed by a ring based reduction at −1.40 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 −0.38 V followed by a ring based reduction at −1.03 V. The metal oxidation for 7 was observed at +0.20 V and the ring based oxidation at +1.35 V.     

Synthesis,electrochemical, in situ spectroelectrochemical and in situ electrocolorimetric characterization of new metal-free and metallophthalocyanines substituted with 4-{2-[2-(1-naphthyloxy)ethoxy]ethoxy} groups

The synthesis of novel metal-free and metallophthalocyanines [Ni(II), Zn(II), Co(II), Cu(II)] were prepared by cyclotetramerization of a novel 4-{2-[2-(1-naphthyloxy)ethoxy]ethoxy}phthalonitrile and the corresponding metal salts (NiCl₂, Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The structures of the target compounds were confirmed using elemental analysis, IR, ¹H NMR, ¹³C NMR, UV–Vis and MS spectral data. Voltammetric and in situ spectroelectrochemical measurements show that while cobalt phthalocyanine complex gives both metal-based and ring-based redox processes, metal-free, and zinc phthalocyanines show only ring-based reduction and oxidation processes. All complexes decomposed and coated on the electrode as nonconductive film at positive potential window of the electrolyte. An in situ electrocolorimetric method has been applied to investigate color of the electro-generated anionic and cationic forms of the complexes.