Zinc Phthalocyanine Derivatives Research Articles

Substituents role in zinc phthalocyanine derivatives used as dye-sensitized solar cells. A theoretical study using Density Functional Theory

A series of zinc phthalocyanine dyes with different electron-donating and electron-withdrawing substituents and using the COOH as the anchor group that interacts with the semiconductor (TiO2) surface, were studied employing DFT and TDDFT methodologies. Their HOMO and LUMO orbital energies and, the redox mediator position would facilitate the injection process toward the conduction band of TiO2. We tested the effect of some electron-donating or electron-withdrawing substituents over zinc phthalocyanine dyes in terms of the Hammett parameters (Σσ). We obtained a linear correlation between the substituents properties versus the free energy change of the electron-injection (ΔGinject) process.

A new route for visible/near-infrared-light-driven H2 production over titania: Co-sensitization of surface charge transfer complex and zinc phthalocyanine

This work introduces a new strategy for visible/near-infrared (NIR) light responsive H2 production over TiO2 nanoparticles co-sensitized with zinc phthalocyanine derivative (Zn-tri-PcNc) and surface ligand-to-metal charge transfer (LMCT) complex, which is in situ formed on the TiO2 nanoparticles' surfaces by using ascorbic acid (AA). The in situ formed surface LMCT complex (AA-TiO2) exhibits obvious visible-light-responsive photoactivity (126.2 μmol/h) for H2 production with a high apparent quantum yield (AQY) of 16.1% at 420 nm monochromatic light irradiation. Moreover, the co-sensitized TiO2 nanoparticles (Zn-tri-PcNc-TiO2-AA) shows a much higher photoactivity (162.2 μmol/h) for H2 production than the surface LMCT complex, and broader spectral responsive region (400–800 nm) with a relatively high AQY value (0.97%) at 700 nm monochromatic light irradiation. The present result reveals a possible substitute for the conventional Ru(II)-bipyridyl complexes or organic dyes as sensitizer of semiconductors in the field of solar fuel conversion.

Tetra- and octa-[4-(2-hydroxyethyl)phenoxy bearing novel metal-free and zinc(II) phthalocyanines: Synthesis, characterization and investigation of photophysicochemical properties

In this study, four novel phthalonitriles (1–4) and their corresponding metal-free (5–8) and zinc(II) phthalocyanine derivatives (9–12) bearing 4-(hydroxyethyl)phenoxy groups were synthesized. These novel compounds were characterized by IR, elemental analyses, 1H-NMR, UV–vis, and MALDI-TOF spectral data. Furthermore, photophysical (fluorescence quantum yields and lifetimes) and photochemical properties (singlet oxygen generation and photodegradation quantum yields) of these phthalocyanines were investigated in dimethylsulfoxide. The studied zinc(II) phthalocyanines generated highly singlet oxygen which is very important for the photodynamic therapy (PDT) of cancer. The fluorescence quenching behaviour of the newly synthesized phthalocyanine compounds were also investigated using 1,4-benzoquinone.

Photodynamic Therapy Using Novel Zinc Phthalocyanine Derivatives and a Diode Laser for Superficial Tumors in Experimental Animals

Photodynamictherapy (PDT) using a photo sensitizing agent and several light sources has been shown to have nonspecific and noninvasive effects on superficial cancers. Phthalocyanine (Pc) derivatives as novel photosensitizers, trifluoroethoxy-coatedzinc Pcconjugated with β-cyclodextrin (βCD-4TFEO-Pc) was synthesized and its photodynamic effect in vitro and in vivo was evaluated. βCD-4TFEO-Pc alone was completely non-cytotoxic even at high concentrations, and showed excellentphotodynamic effects in B16-F10 and HT-1080 celllines. The in vivo antitumor effect of βCD-4TFEO-Pc against B16-F10 cells transplanted on to the chorioallantoic membranes of chickembryos was 52.7%, but that of laserirradiation alone and photosensitizer alone was <7% at thedose of 50 μg pereggand 100 J/cm2 (50 mW). These data suggest that βCD-4TFEO-Pc is a useful photosensitizer for the treatment of superficial cancers. If a high-power LED with optimal wavelength is developed, excellent treatment of superficial cancers could be achieved by applying βCD-4TFEO-Pc for PDT.

Visible/Near-Infrared-Light-Induced H2 Production over g-C3N4 Co-sensitized by Organic Dye and Zinc Phthalocyanine Derivative

A new route is carried out to achieve broad spectral responsive photocatalytic H2 production over g-C3N4 co-sensitized by an indole-based D-π-A organic dye (LI-4) and an asymmetric zinc phthalocyanine derivative (Zn-tri-PcNc) with complementary absorption spectra. Experimental results indicate that both LI-4 and Zn-tri-PcNc are efficient photosensitizers of g-C3N4 for H2 production, and their co-sensitized g-C3N4 (LI-4/g-C3N4/Zn-tri-PcNc) exhibits an extremely high H2 production activity (371.4 μmol h–1) under visible/near-infrared (NIR) light (λ ≥ 420 nm) irradiation, which approximates the summation of the H2 production activity of LI-4/g-C3N4 (233.8 μmol h–1) and Zn-tri-PcNc/g-C3N4 (132.3 μmol h–1), although LI-4 and Zn-tri-PcNc can just absorb the light in the range of 400–600 and 600–750 nm, respectively. Moreover, the co-sensitized catalyst shows a broad visible/NIR light responsive range (400–800 nm) with impressively high apparent quantum yields (AQY) of 16.3, 7.7, and 1.75% at 420, 500, and 700 nm monochromatic light irradiation, respectively. The present work gives a new advance toward panchromatic light responsive photocatalytic application by combining the photosensitization of two different dyes with complementary absorption spectra on one kind of semiconductor.

An organic–inorganic rectifying contact based on a ZnPc derivative

An organic–inorganic rectifying contact was fabricated by forming a thin film of a Zinc Phthalocyanine (ZnPc) derivative, Zinc 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine (oc-ZnPc), on a p-Si wafer and evaporating Al on the structure. The current–voltage (I–V) and capacitance–voltage (C–V) measurements of Al/oc-ZnPc/p-Si structure were taken in dark at room temperature. The I–V measurements proved that the structure showed excellent rectification. Some basic diode parameters like ideality factor and barrier height were calculated from lnI–V plot. Ideality factor and barrier height values were found as 1.44 and 0.78eV, respectively. The series resistance value of the structure was determined as 5.46kΩ by means of Norde functions. The C–V measurements were taken for various frequencies and it was seen that the capacitance value decreased with increasing frequency.In addition I–V measurements of the Al/oc-ZnPc/p-Si/Al were repeated under light which had illumination intensity of 40–100mW/cm2. It was observed that reverse bias current of the diode increased with the light intensity. Therefore, the structure showed photodiode characteristics and it can be used for electrical and optoelectronic applications.

The synthesis and structural characterization of new metallo phthalocyanines with 1,2,4-triazole fragments

Novel Zn(II), Ni(II), Co(II) and Cu(II) phthaloyanine complexes that have [1,2,4]-triazole and Schiff's base moieties on peripheral positions have been synthesized. Key material, substituted phthalonitrile, was obtained in four-step reaction. Firstly hydrazone derivative has been obtained, then [1,2,4]-triazole moiety has been created, Schiff base fragment has been constituted and then phthalonitrile fragment has been added to the structure. The novel phthalocyanines are soluble in many organic solvents. The photophysical, photochemical and fluorescence quenching properties of zinc phthalocyanine derivative (10) have been studied in dimethylsulfoxide (DMSO) solution. These properties of the other metallophthalocyanine complexes (11, 12 and 13) have not been appreciated because zinc phthalocyanine is the best compound for photocatalytic applications due to the d10 configuration of the Zn2+ ion in the phthalocyanine cavity.

Effects of annealing on device parameters of organic field effect transistors using liquid-crystalline tetrasubstituted zinc phthalocyanine

The device performance of organic thin-film transistors (OTFTs) employing the solution processed films of room temperature liquid-crystalline tetrasubstituted zinc phthalocyanine derivative was found to depend upon the film morphology. Atomic force microscopic and X-Ray diffraction studies show that the annealing at produced a preferentially unidirectional void-free film with improved surface smoothness. The OTFTs with the annealed films exhibited enhanced conductivity, threefold reduction in threshold voltage, a nearly one order of magnitude increase in the on/off ratio and more than one-third reduction of hysteresis in the transfer characteristics.

A versatile synthetic strategy for nanoporous gold–organic hybrid materials for electrochemistry and photocatalysis

Nanoporous gold (npAu) was employed as high surface area substrate for immobilization of redox- and photooxidative-active organic molecules. A two-step synthetic routine is demonstrated as a versatile and robust method for immobilization of various molecules. First, self-assembled monolayers (SAMs) of thiols containing an azide moiety were prepared on npAu substrates. Then, alkyne-modified ferrocene, tetrathiafulvalene, and zinc(II)phthalocyanine derivatives were covalently bound via the click reaction to this linker. Following the provided synthetic procedures high performance composite materials are generated for electrochemistry and photochemistry. The robust bonding between the organic functional group and the gold support provides stability even under strongly oxidizing conditions (applied potential or singlet oxygen).

Femtosecond Transient Absorption Study of Supramolecularly Assembled Metal Tetrapyrrole–TiO2 Thin Films

Photoexcited electron injection and back electron transfer dynamics of metal tetrapyrrole bound to TiO2 nanoparticle surfaces via the metal–ligand axial coordination approach have been investigated using femtosecond pump–probe transient spectroscopic technique. The employed metal tetrapyrroles include zinc and magnesium metalated meso-tetraarylporphyrins having halogen substituents on the peripheral aryl groups, perfluorinated zinc phthalocyanine derivatives, and zinc naphthalocyanine. The employed metal tetrapyrroles covered absorption at different portions of the visible and near-IR region of the spectrum with excited-state reduction potentials ranging between −0.61 eV and −1.34 V, that is, having energy higher than the TiO2 conduction band edge (−0.57 V vs NHE). Two linkers, pyridine and phenylimidazole, have been employed to visualize electronic coupling between the dye and metal oxide surface for optimal electron injection and back electron transfer dynamics. In agreement with the previously reported photocurrent generation of dye-sensitized solar cells constructed using this self-assembly approach (J. Am. Chem. Soc. 2009, 131, 14646), spectral evidence for electron injection from the excited metal tetrapyrrole to the TiO2 nanoparticle in the form of a tetrapyrrole radical cation has been obtained. The time profile of the π-cation radical of tetrapyrroles revealed the occurrence of ultrafast electron injection (time constant = 470–700 fs), while the back electron transfer processes were found to be complicated due to the intricate environment of the metallotetrapyrrole–TiO2 interface.

Ionic Interactions between Charged Phthalocyanine and Fullerene Derivatives

The syntheses of positively and negatively charged zinc(II) phthalocyanine and fullerene derivatives are described. UVvis absorption and fluorescence spectra show that ground and excited state interactions between oppositely charged phthalocyanine and fullerene derivatives occur. In contrast to the more complex synthesis of covalently connected dyads of phthalocyanines and fullerenes, the ionic interaction is more easily realized by simple mixing of oppositely charged components. This ionic interaction leads to a significant increase of the photocatalytic activity of phthalocyanines in the photooxidation of 2-mercaptoethanol by molecular oxygen.

Syntheses of asymmetric zinc phthalocyanines as sensitizer of Pt-loaded graphitic carbon nitride for efficient visible/near-IR-light-driven H2 production

Zinc phthalocyanine (ZnPc) derivatives with asymmetric (Zn-tri-PcNc-2) or symmetric (Zn-tetrad-Nc) structure, which possess wide spectral response in the visible/near-IR light region, are synthesized and utilized as a sensitizer of graphitic carbon nitride (g-C3N4) with 0.5 wt% Pt-loading for photocatalytic H2 production. The experimental results indicate that Zn-tri-PcNc-2 exhibits much better photosensitization on g-C3N4 than Zn-tetrad-Nc under visible/near-IR light although Zn-tetrad-Nc possesses wider and stronger optical absorption property than Zn-tri-PcNc-2. Zn-tri-PcNc-2-Pt/g-C3N4 exhibits an average H2 production rate of 132 μmol h(-1), which is much better than that (26.1 μmol h(-1)) of Zn-tetrad-Nc-Pt/g-C3N4 under visible-light (λ ≥ 500 nm) irradiation. Moreover, Zn-tri-PcNc-2-Pt/g-C3N4 also shows much higher apparent quantum yield (AQY) than Zn-tetrad-Nc-Pt/g-C3N4 under red/near-IR light irradiation. Especially, Zn-tri-PcNc-2-Pt/g-C3N4 exhibits impressively higher AQY (1.07%) than that (0.22%) of the Zn-tetrad-Nc-Pt/g-C3N4 under 700 nm monochromatic light irradiation. The much better photoactivity of Zn-tri-PcNc-2-Pt/g-C3N4 than Zn-tetrad-Nc-Pt/g-C3N4 is caused by the asymmetric structure of Zn-tri-PcNc-2, which can result in the electronic orbital directionality of its excited state, much faster photogenerated electron transfer to g-C3N4, and higher red/near-IR light utilization efficiency as compared to Zn-tetrad-Nc-Pt/g-C3N4. The present results provide an important insight into the effects of molecular structure and optical absorption property of phthalocyanine derivatives on the photoactivity of the dye-sensitized semiconductor, and also guide us to further improve the solar energy conversion efficiency by optimizing the molecular structure and effectively utilizing the visible/near-IR light of sunlight.

Diphenylethoxy-substituted metal-free and metallophthalocyanines as potential photosensitizer for photodynamic therapy: synthesis and photophysical and photochemical properties

The synthesis of a 4-(2,2-diphenylethoxy)phthalonitrile (1) and its organosoluble free base (2), zinc(II) (3), nickel(II) (4), and cobalt(II) (5) phthalocyanine derivatives is presented in this work. The novel complexes were characterized by elemental analyses and spectral data such as infrared, nuclear magnetic resonance, ultraviolet visible, and mass data. General tendencies were described for photophysics (fluorescence) and photochemistry (photodegradation and singlet oxygen quantum yields) of the free base and zinc(II) phthalocyanine derivatives in dimethylformamide. The quantum yield values of fluorescence (\Phi_F), singlet oxygen formation (\Phi_{\Delta}), and photodegradation (\Phi_d) for the zinc phthalocyanine were found to be 0.37, 0.48, and 9.12 \times 10^{-4}, respectively. The photophysicochemical properties of the phthalocyanines (2 and 3) clearly reveal that these phthalocyanines could be used in singlet oxygen applications such as photodynamic therapy.

Highly Asymmetric Phthalocyanine as a Sensitizer of Graphitic Carbon Nitride for Extremely Efficient Photocatalytic H2 Production under Near-Infrared Light

Highly asymmetric zinc phthalocyanine derivative (Zn-tri-PcNc) with intense near-IR light (650–800 nm) absorption is utilized as a sensitizer to extend the spectral response region of graphitic carbon nitride (g-C3N4) from ∼450 nm to more than 800 nm. Ultraviolet–visible light (UV-vis) diffuse reflectance absorption spectra (DRS), photoluminescence (PL) spectra, time-resolved photoluminescence spectra (TRPS), and energy band structure analyses are adopted to investigate the photogenerated electron transfer process between Zn-tri-PcNc and g-C3N4 on both thermodynamics and dynamics aspects. After optimizing the photocatalytic condition and adding chenodeoxycholic acid (CDCA) as coadsorbent, Zn-tri-PcNc sensitized g-C3N4 photocatalyst shows a H2 production efficiency of 125.2 μmol h–1 under visible/near-IR-light (λ ≥ 500 nm) irradiation, corresponding to a turnover number (TON) of 5008 h–1 with an extremely high apparent quantum yield (AQY) of 1.85% at 700 nm monochromatic light irradiation. The present work...

Application of a CdS nanostructured layer in inverted solar cells

An inverted solar cell has been constructed by the growth of a CdS layer on an indium tin oxide (ITO)/glass substrate followed by spin-coating of organic poly(3-hexylthiophene) : [6,6]-phenyl C61-butyric acid methyl ester (P3HT : PCBM) or a zinc phthalocyanine derivative (ZnPc-4R): PCBM composite layer and using a free-standing PEDOT : PSS composite film as the top electrode. It has been found that CdS plays the role of an electron-selective (hole-blocking) layer to rectify the electron flow from the P3HT : PCBM or ZnPc-4R : PCBM bulk heterojunction to the ITO electrode. By changing the morphology of the CdS layer from a textured continuous film to a nanowire array we demonstrate an improved collection efficiency of charge carriers due to the increased organic–inorganic interface area. Thus, a bifunctional role of the CdS nanostructured layer as a bottom electrode with better electron affinity than ITO and as a means to increase the interface for better electron collection from the organic active layer has been demonstrated.

An effective zinc phthalocyanine derivative for photodynamic antimicrobial chemotherapy

Bacterial infection is a common clinical problem. The emergence of antibiotic resistant bacteria posts a severe challenge to medical practice worldwide. Photodynamic antimicrobial chemotherapy (PACT) uses laser light at specific wavelength to activate oxygen molecule in the human tissue into reactive oxygen species as antimicrobial agent. This activation of oxygen by laser light is mediated through a photosensitizer. Two key properties for potent photosensitizer are its absorbance of light in the infrared region (630–700nm), which promotes tissue penetration depth, and the selective accumulation on bacteria instead of human tissue. We herein report a zinc phthalocyanine derivative, pentalysine β-carbonylphthalocyanine zinc (ZnPc-(Lys)5) and its antimicrobial effects in vitro and in an animal infection model. This photosensitizer has strong capability to kill bacteria at 670nm. Chemically, it is a water-soluble and cationic photosensitizer carrying positive charge under physiological pH, and can specifically target to bacteria which usually bears negative charges on its surface. Compared with anionic ZnPc counterparts, ZnPc-(Lys)5 shows a higher phototoxicity toward bacteria. PACT studies of ZnPc-(Lys)5 in experimental infection animal model showed a significant bacteria inhibition compared to controls, and high selectivity of ZnPc-(Lys)5 toward bacteria. These findings suggest ZnPc-(Lys)5 is a promising antimicrobial photosensitizer for the treatment of infectious diseases.

Highly asymmetric phthalocyanine-sensitized solar cells: The effect of coadsorbent and adsorption temperature of phthalocyanine

Highly asymmetric zinc phthalocyanine derivative (Zn-tri-PcNc) containing tribenzonaphtho-condensed porphyrazine with one carboxyl and three tert-butyl (t-Bu) substituent groups is used as a sensitizer to fabricate dye-sensitized solar cells (DSSCs), and the effects of chenodeoxycholic acid (CDCA) as a coadsorbent and the dye adsorption temperature on the solar cell's performance are investigated. It is found that CDCA coadsorption can hinder the dye aggregation, which is beneficial for improving the electron injection efficiency and retarding the charge recombination, and thus resulting in the enhancement of the short-circuit current density and open-circuit photovoltage. Moreover, the dye adsorption temperature on electrode also shows a significant impact on the photovoltaic performance of the solar cell, and an optimal dye adsorption condition of the TiO2 electrode is found to be 5×10−5M Zn-tri-PcNc ethanol solution containing 7.5mM CDCA at 5°C, which can contribute to the maximum conversion efficiency of 2.89% with short-circuit current density of 9.42mAcm−2 and open-circuit photovoltage of 0.48V, improved by 47% as compared to the solar cell fabricated with TiO2 electrode sensitized by the zinc phthalcoyanine in absence of CDCA.

Synthesis and in Vitro Photodynamic Activity of Oligomeric Ethylene Glycol–Quinoline Substituted Zinc(II) Phthalocyanine Derivatives

A new series of zinc(II) phthalocyanine derivatives have been synthesized and characterized. These macrocycles exhibited a sharp absorption band in the red visible region in DMF, which indicated that they were dissolved well and almost did not aggregate in this solvent. Compared with the unsubstituted zinc(II) phthalocyanine, all these phthalocyanines have a red-shifted Q-band (at 678-699 vs 670 nm) and exhibit a relatively weaker fluorescence emission and a higher efficiency at generating singlet oxygen. The monosubstituted photosensitizers also exhibit high photocytotoxicity toward HepG2 human hepatocarcinoma cells with IC50 values as low as 0.02-0.05 μM (λ = 670 nm, 80 mW·cm(-2), 1.5 J·cm(-2)). The high photodynamic activities of these compounds are in accordance with their low aggregation tendency and high cellular uptake. Their structure-activity relationship was assessed by determining the photophysical properties, cellular uptake, and in vitro photodynamic activities of this series of compounds. As shown by confocal microscopy, monosubstituted phthalocyanines can target the mitochondria and lysosomes of the cells, and tetrasubstituted phthalocyanines tend to target the lysosomes of the cells.

Synthesis and photophysical properties of a novel ethynyl zinc(II) phthalocyanine and its functionalized derivative with click chemistry

The synthesis of novel, symmetrical zinc(II) phthalocyanine (ZnPc) bearing four ethynylcyclohexyloxy terminal moieties was achieved by cyclotetramerization of novel 4-(2-ethynylcyclohexyloxy) phthalonitrile in pentanol in the presence of DBU and zinc acetate without any protective/deprotective chemistry. Subsequently, this new zinc(II) phthalocyanine derivative was reacted with 6-azido-hexanoic acid under "click-chemistry" conditions to give phthalocyanine-hexanoic acid conjugates linked by 1,2,3-triazole units. The new compounds have been characterized by using elemental analyses, UV-vis, FTIR, 1 H NMR and mass spectroscopic data. The aggregation properties of the compounds were investigated in different concentrations. General trends are also described for fluorescence quantum yields and lifetimes of novel zinc derivatives in tetrahydrofuran. The fluorescence of the tetrasubstituted zinc(II) phthalocyanine complexes is effectively quenched by 1,4-benzoquinone (BQ) in THF.

The synthesis of novel unmetallated and metallated phthalocyanines including (E)-4-(3-cinnamoylphenoxy) groups at the peripheral positions and photophysicochemical properties of their zinc phthalocyanine derivatives

This paper reports on the synthesis and characterization of new peripherally tetra-substituted metal-free (4), nickel(II) (5), zinc(II) (6), cobalt(II) (7), copper(II) (8), lead(II) (9) and octa-substituted zinc(II) (12) phthalocyanines containing (E)-4-(3-cinnamoylphenoxy) groups for the first time. Synthesized compounds have been characterized by electronic absorption, FT-IR, 1H NMR, 13C NMR, elemental analysis, mass spectra and thermogravimetric analysis. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties of zinc phthalocyanine derivatives (6 and 12) were investigated in dimethylsulfoxide. The fluorescence quenching behavior of zinc phthalocyanine derivatives (6 and 12) by 1,4-benzoquinone was also examined in same solution.