Phthalocyanines formed from several precursors: synthesis,characterization, and comparative fluorescence and quinone quenching

Abstract

We have synthesized a new phthalonitrile with different substituents in 4- and 5-positions (1). Cyclotetramerization of 1 yielded phthalocyanines with cobalt(II) (2), zinc(II) (3), gallium(III)chloride (4), and indium(III)chloride (5) containing diethylamino-phenoxy and hexylsulfanyl substituents on each benzene unit. Elemental analyses, Fourier transform infrared spectra, ¹H-nuclear magnetic resonance spectra, mass spectra, and ultraviolet-visible spectra were used for characterization of the phthalocyanines. The aggregation behavior of the zinc phthalocyanine derivative was studied in different concentrations. Also four chloro and four diethyllaminophenoxy substituted zinc phthalocyanine (6) and octa-diethylaminophenoxy substituted zinc phthalocyanine (7) were synthesized. These phthalocyanines (3, 6, and 7) were compared for electronic absorption spectra, fluorescence quantum yields, fluorescent lifetimes, and fluorescence quenching in the presence of benzoquinone. The fluorescence quantum yield gives the efficiency of the fluorescence process. The fluorescence lifetime is an important parameter for practical applications of fluorescence such as fluorescence resonance energy transfer and fluorescence-lifetime imaging microscopy.     

Synthesis, characterization and comparative studies on the photophysical and photochemical properties of metal-free and zinc(II) phthalocyanines with phenyloxyacetic acid functionalities

The synthesis and characterization of new peripherally and non-peripherally tetra-substituted metal-free and zinc(II) phthalocyanines with 2-, 3- and 4-phenyloxyacetic acid functionalities are described for the first time in this study. The new compounds have been characterized by elemental analysis, FT-IR, UV-Vis, MALDI-TOF and ¹H-NMR spectra. Photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds are studied in dimethylformamide (DMF). The influence of the substituent position on the phthalocyanine framework (non-peripherally or peripherally), central metal ion (metal-free or zinc) and the position of the COOH group (2-, 3- or 4-position on the phenyloxyacetic acid) on the spectroscopic, photophysical and photochemical properties have been investigated. Non-peripherally zinc(II) phthalocyanines (1b and 2b) and peripherally zinc(II) phthalocyanine (4b) gave good singlet oxygen quantum yields (Φ_Δ) (0.37, 0.39 and 0.38, respectively) which indicate the potential of the complexes as photosensitizers in applications of PDT.     

Synthesis, photophysical and thermal studies of symmetrical and unsymmetrical zinc phthalocyanines

The novel zinc phthalocyanine (3) with malonylester and chloro groups on each benzo unit was synthesized from 4-diethoxymalonyl-5-chloro-phthalonitrile (1). The unsymmetrically substituted zinc phthalocyanine (5), carrying hexylthio, malonylester and chloro groups at the periphery, was obtained from 4-diethoxymalonyl-5-chloro-phthalonitrile (1) and 4,5-bis-hexylsulfanyl-phthalonitrile (2) by a statistical condensation method as an A₃B type unsymmetrical phthalocyanine compound. Transesterification of the malonyl esters of the new symmetrical and unsymmetrical phthalocyanines occurred during the cyclotetramerization of dinitriles with Zn(CH₃COO)₂ in 1-pentanol in the presence of DBU. Octa-hexylthio-substituted zinc phthalocyanine (4) was prepared according to the literature. The photophysical and thermal properties of all the phthalocyanine complexes are described for the first time. These novel symmetrical and unsymmetrical phthalocyanine macrocycles have been characterized by a series of spectroscopic methods including ¹H NMR, electronic absorption, IR and mass spectroscopy, in addition to elemental analysis. Their narrow long wavelength absorption band shows that the bulky substituents on the periphery prevent aggregation. The unsymmetrically substituted phthalocyanine (5) gave a greater fluorescence quantum yield in chloroform than the symmetrical analogues (3 and 4).     

Zinc(II) phthalocyanine containing Schiff base containing sulfonamide: synthesis,characterization, photophysical,and photochemical properties

Abstract

Synthesis and characterization of (E)-4-((5-bromo-2-(λ¹-oxidanyl)benzylidene)amino)-N-(5-methyl-1,3,4-thiadiazol-2-yl)benzenesulfonamide (1), its substituted phthalonitrile derivative (2), and its tetra substituted zinc(II) phthalocyanine complex (3) were performed. Compounds 1, 2, and 3 were characterized by methods such as elemental analyses, FT-IR, ¹H-NMR, ¹³C-NMR (except for 3), and MALDI-TOF mass spectra. The photophysical and photochemical properties of this substituted zinc(II) phthalocyanine complex aimed to be used as a photosensitizer were investigated in DMSO solution for determination of their photosensitizing abilities in photocatalytic applications such as photodynamic therapy (PDT). The influence of the substituent as a bioactive compound on the phthalocyanine skeleton on spectroscopic, photophysical, and photochemical properties were also determined and compared with unsubstituted zinc(II) phthalocyanine and some zinc(II) phthalocyanines containing different substituents previously studied. According to photophysical and photochemical investigations, 3 has potential as a photosensitizer for PDT.     

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.     

Synthesis of novel unsymmetrical phthalocyanines substituted with crown ether and nitro groups

This work reports on the synthesis of new unsymmetrically substituted phthalocyanines (M = Zn, Cu, Co, Ni) bearing three benzo-15-crown-5 units through oxy bridges and a nitro group. Phthalocyanines were prepared by a statistical condensation of 4-nitro phthalonitrile and 1-{[(benzo-15-crown-5)-4′-yl]oxy}phthalonitrile in the presence of anhydrous metal salts. All the target unsymmetrical phthalocyanines were separated by column chromatography and characterized elemental analyses, ¹H NMR, IR, mass and UV–Vis spectral data. Electrochemical behaviors of Cu (II) phthalocyanine by cyclic voltammetry and differential pulse voltammetry techniques gave two common phthalocyanine ring reductions and one ring oxidation processes. Peak-to-peak separation of the processes II and III (388 mV) and the measure of gap (1.672 V) between the HOMO and LUMO for the complex, fits a phthalocyanine with electrochemically inactive metal center.     

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,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 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.     

Synthesis and solution properties of new metal-free and metallo-phthalocyanines containing four bis(indol-3-yl)methane groups

Metallo-phthalocyanines bearing four bis(indol-3-yl)methane groups were successfully prepared by reaction of the corresponding phthalonitriles with anhydrous metal salts [Zn(CH₃COO)₂, NiCl₂ and CoCl₂] in the presence of a catalytic amount of DBU in 2-(dimethylamino)ethanol. The metal-free phthalocyanine was obtained by treating a mixture of the phthalonitrile derivative in similar conditions but in the absence of a metal salt. All of these phthalocyanines are soluble in DMSO, DMF, and pyridine. The products were characterized by IR, NMR, and UV-vis spectroscopy, MALDI-TOF-MS, and thermogravimetric analysis. The aggregation properties of the phthalocyanines were investigated at different concentrations in DMSO. All the phthalocyanines showed monomeric behavior in solution.     

Unsymmetrical phthalocyanines with alkynyl substituents

The synthesis of unsymmetrically substituted metallophthalocyanines (M = Zn, Ni, Co) bearing two phenylethyl moieties and six alkythio substituents was achieved by co-cyclotetramerization of two different phthalonitrile derivatives, namely 4,5-di(hexylthio)phthalonitrile and 4,5-di(phenylethynyl)phthalonitrile in the presence of zinc, cobalt or nickel salts. In contrast to the totally alkyne substituted phthalocyanines, these partially alkyne-containing derivatives are more soluble and their Q band absorptions are red-shifted when compared with all alkylthio phthalocyanines. Electrochemical properties of the phthalocyanines were studied by cyclic voltammetry.     

Synthesis and electrochemistry of tetrakis(7-coumarinthio-4-methyl)-phthalocyanines,and preparation of their cinnamic acid and sodium cinnamate derivatives

Novel water soluble free-base, Zn(II) and Co(II) metallo phthalocyanines with four cinnamic acid moieties were prepared from the corresponding tetrakis(7-coumarinthio-4-methyl)-phthalocyanine by the lactone ring opening reaction. The new compounds were purified and characterized by elemental analysis, ¹H NMR, Maldi-TOF, FT-IR and UV–Vis spectral data. Cyclic and differential pulse voltammetry and in situ spectroelectrochemistry of the 2,9,16,23-tetrakis(7-coumarinthio-4-methyl) substituted free-base 1a, Zn(II) 1b and Co(II) 1c phthalocyanines, employed as the starting compounds have been studied. This allowed us not only to identify metal- and phthalocyanine ring-based redox processes of the complexes, but also the effect of aggregation on these processes.     

Synthesis, photophysical and photochemical properties of substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}oxy) and 4-({3,4,5-tris-[2-(2-ethoxyethoxy)ethyloxy]benzyl}thio) zinc(ii) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, (1)H and (13)C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, fluorescence and triplet excited state quantum yields, and triplet state and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). The fluorescence of the complexes was quenched by benzoquinone (BQ). The effects of the substitution on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (6, 7 and 8) are also reported. Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The substituted Zn(II) phthalocyanines showed high triplet and singlet oxygen quantum yields. High singlet oxygen quantum yields are very important for Type II mechanism. Thus, these complexes show potential as Type II photosensitizers.     

The Synthesis of New Phthalocyanines Substituted with 12-Membered Diazadioxa Macrocycles

 A macrocyclic diazadioxa dibromo compound was synthesized by ring closure of 1,2-bis-(2-iodoethoxy)-4,5-dibromo-benzene and 1,4-bis-(p-tolylsulfonyl)-ethylenediamine. Its phthalonitrile derivative was obtained by cyano substitution. This diazadioxa macrocyclic dibromo derivative was directly converted into the copper(II) phthalocyanine by reaction with CuCN in tetramethyl urea. Conversion of this phthalonitrile derivative into the metal-free phthalocyanine was accomplished by refluxing with DBU. The zinc(II) phthalocyanine was prepared by reaction of the dinitrile derivative with Zn(OAc)₂ in quinoline. The lutetium bis-(phthalocyaninate) complex was obtained by treating the dinitrile derivative with anhydrous lutetium acetate and DBU in 1-hexanol. The new compounds were characterized by elemental analyses and IR, ¹H NMR, mass, UV/Vis, and ESR spectra.     

The microwave-assisted synthesis and characterization of novel, octakis(2-hydroxyethoxy)resorcinarene bridged polymeric metallophthalocyanines

The new metallophthalocyanine (Zn, Cu, Ni, Co) polymers containing 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene are described. Firstly, 4,6,10,12,16,18,22,24-octakis(2-hydroxyethoxy)-2,8,14,20-tetramethylresorcinarene compound (1) was synthesized by treating resorcinarene with 2-chloroethanol under microwave irradiation. Then, tetrakis(4,5-bis(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound (2) and octakis(4-(2-hydroxyethoxy))phthalonitrile substituted resorcinarene compound (3) were synthesized by treating compound (1) with 4,5-dichloro-1,2-dicyanobenzene and 4-nitro-1,2-dicyanobenzene, respectively, under microwave irradiation. The chlorides Cu (II), Ni (II), Co (II), were employed in order to synthesize the corresponding metallophthalocyanine polymers (2b–d and 3b–d) and Zn(CH₃COO)₂ was used for the preparation of zinc phthalocyanine polymers (2a and 3a). All products were synthesized by microwave-assisted synthesis method. The structures were characterized by elemental analyses, ¹H NMR, ¹³C NMR, UV–Vis and FTIR spectroscopy.     

Synthesis and properties of two new N-alkyl substituted phthalocyanines

The synthesis and properties of tetrakis(1,1-dimethyl-2-phthalimido)ethylphthalocyaninato zinc (II) (6) and tetrakis(1,1-dimethyl-2-amino)ethylphthalocyaninato zinc (II) (7) are described. N-Alkyl substituted phthalonitrile 5 was converted to phthalocyanine 6 . which was deprotected to afford the free amino phthalocyanine 7 .     

The Synthesis of New Phthalocyanines Substituted with 12-Membered Diazadioxa Macrocycles

Summary.  A macrocyclic diazadioxa dibromo compound was synthesized by ring closure of 1,2-bis-(2-iodoethoxy)-4,5-dibromo-benzene and 1,4-bis-(p-tolylsulfonyl)-ethylenediamine. Its phthalonitrile derivative was obtained by cyano substitution. This diazadioxa macrocyclic dibromo derivative was directly converted into the copper(II) phthalocyanine by reaction with CuCN in tetramethyl urea. Conversion of this phthalonitrile derivative into the metal-free phthalocyanine was accomplished by refluxing with DBU. The zinc(II) phthalocyanine was prepared by reaction of the dinitrile derivative with Zn(OAc)₂ in quinoline. The lutetium bis-(phthalocyaninate) complex was obtained by treating the dinitrile derivative with anhydrous lutetium acetate and DBU in 1-hexanol. The new compounds were characterized by elemental analyses and IR, ¹H NMR, mass, UV/Vis, and ESR spectra. Received May 8, 2001. Accepted (revised) June 25, 2001     

Oxidation of benzyl alcohol by novel peripherally and non-peripherally modular C2-symmetric diol substituted cobalt (II) phthalocyanines

In this study, a modular ligand structure was designed by altering the binding position of the phenyl group at backbone of hydrobenzoin. A series of regio isomeric substituted phthalonitriles derived from this modular C₂-symmetric ligand was synthesized and characterized. Then, eight cobalt (II) phthalocyanines (CoPc) were obtained from the reaction of phthalonitrile derivatives with cobalt (II) chloride. The catalytic activities of synthesized cobalt (II) phthalocyanines were tested for benzyl alcohol oxidation in acetonitrile using tert-butylhydroperoxide as the oxygen source and in the presence of N-bromosuccinimide as an additive at 80 °C for 5 hr of the reaction. In this sense, the effect of substrate to catalyst ratio and oxidant to catalyst ratio have been studied in detail for getting the highest benzaldehyde selectivity (up to 83%). The effect of structural design of substituents at peripheral or non-peripheral positions of phthalocyanine skeleton on the catalytic activity performance of cobalt (II) phthalocyanines in benzyl alcohol oxidation was also clarified. All newly synthesized compounds are characterized by FT-IR, ¹H NMR, IR, UV–Vis and MALDI-TOF MS spectral data.     

Synthesis of 3-nitrophthalonitrile and tetra-α-substituted phthalocyanines

An efficient synthesis of phthalocyanines prepared from ortho-substituted phthalonitriles is described. The precursor to these phthalocyanines, 3-nitrophthalonitrile, is a key reagent for syntheses of phthalonitriles substituted at the 3-position by means of nucleophilic aromatic substitutions. An example of this type of phthalocyanine, prepared from 3-(4-cumylphenoxy)phthalonitrile, is compared with the phthalocyanine derived from 4-(4-cumylphenoxy)phthalonitrile. Substitution of the phthalocyanine at this more sterically crowded site causes a 20 nm bathochromic shift of the Q-band (π-π* transition).