Free Phthalocyanine Research Articles

Phthalocyanine Based Anti-Corrosive Materials

Nanofibers possess exclusive physical, chemical, and electronic properties. Although different methods are known [1-2], electrospinning has been used with an increasing impact because of the ease of proceeding and the use of a wide range of polymeric materials [3–4] in the production of nanofibers. This electrostatic technique consists by the propulsion of a polymer solution trough an electrostatic field created by a high voltage applied syringe and an oppositely charged collector where the fibrins are formed. The applied electrical field, the collector distance, and the assets of the polymer solution had an immense effect on physical and morphological properties of the fiber such as the diameter, the surface area per unit mass and the pore size [5]. Because of the thermal, chemical and optical stability and the formation of an aligned crystalline film phthalocyanine derivatives have found applications as photovoltaic cells, solar cells, sensor electrodes, drug release systems, gas detectors and electroactive devices [6-9]. In this work, Metal free phthalocyanine grafted polypyrrole and cobalt metallated phthalocyanine grafted polypyrrole nanofibers were successfully collected onto Staineless Steel SAE 1020 (UNS G10200) by means of electrospinning technique. The anti-corrosion performance of the final system has been evaluated in 3 wt.% NaCl solution by means of Electrochemical Impedance Spectroscopy (EIS) and Tafel measurements. Different methods were used to characterize the obtained fibers. Fourier-transform infrared spectroscopy, Scanning electron microscope and polarized optical microscope were used for their morphological characterization, while electrical behaviors of the nanofibers were characterized by direct current and electrochemical impedance spectroscopy measurements. [1] Feng L., Li S., Li H., Zhai J., Song Y., Jiang L. Angew Chem Int Ed 2002; 41; 1221–1223. [2] Ma P.X., Zhang R. J Biomed Mat Res 1999; 46; 60–72. [3] Menon V. P., Lei, J., Martin, C. R. Chem Mater 1996; 8; 2382-86. [4] Joo J., Park K.T., Kim B.H., Kim M.S., Lee S. Y., Jeong C. K., Lee J. K., Park D. H., Yi W. K., Lee S. H., Ryu, K. S. Synth Met 2003; 135; 7-13. [5] Chronakis I.S., Grapenson S., Jakob A. Polymer 2006; 47; 1597–1603. [6] Li Y., Lu P., Yan X., Jin L., Peng Z. RSC Adv 2013; 3; 545-558. [7] Lu H.-L., Syu W.-J., Nishiyama N., Kataoka K., Lai P.-S. Journal of Controlled Release 2011;155;458–464. [8] Jeong S.I., Jun I.D., Choi M.J., Nho Y.C., Lee Y.M., Shin H. Macromol Biosc 2008;8;627–637. [9] Mugadza T., Nyokong T. Synthetic Metals 2010;160; 2089–2098.

Electrochemical and Spectroelectrochemical Analysis of 4‐(4‐(5‐Phenyl‐1,3,4‐oxadiazole‐2‐yl)phenoxy)‐Substituted Cobalt(II), Lead(II) and Metal‐Free Phthalocyanines

AbstractElectrochemical and spectroelectrochemical analyses of 4‐(4‐(5‐phenyl‐1,3,4‐oxadiazole‐2‐yl)phenoxy)‐substituted metal‐free phthalocyanine (H2Pc (1)) and metallated phthalocyanines (PbPc (2) and CoPc (3)) were performed in solution. Voltammetric characterizations of the phthalocyanine complexes were investigated by using cyclic voltammetry and square wave voltammetry techniques. CoPc (3) gave common metal and ring based electron transfer reactions; however they split due to the aggregation. Although PbPc (2) illustrated reversible reduction processes during the voltammetric measurements, it was de‐metallized and thus turned to the metal free phthalocyanine during repetitive voltammetric cycles and in situ spectroelectrochemical measurements.

Hybrid structures of polycationic aluminum phthalocyanines and quantum dots.

Semiconductor nanocrystals (CdSe/ZnS quantum dots, QDs) were used as inorganic focusing antenna, allowing for the enhancement of fluorescence and photosensitizing activity of polycationic aluminum phthalocyanines (PCs). It was found that QDs form stable complexes with PCs in aqueous solutions due to electrostatic interactions. In such hybrid complexes, we observed highly efficient nonradiative energy transfer from QD to PC, leading to a sharp increase in the effective absorption cross section of PC in the absorption bands of the CdSe/ZnS quantum dots. When hybrid complexes are excited within these bands, the intensity of PC fluorescence and the rate of photosensitized singlet oxygen generation increases significantly (up to 500 and 350%, correspondingly) compared to free PC at the same concentration. The observed effect is of interest for modeling primary stages of photosynthesis and increasing photosensitizing activity of dyes used in photodynamic therapy.

One-Dimensional Molecular Crystal of Phthalocyanine Confined into Single-Walled Carbon Nanotubes

New one-dimensional (1D) hybrid nanosystems are elaborated with metalated or metal free phthalocyanine molecules encapsulated into the hollow core of single-walled carbon nanotubes. The X-ray diffraction experiments coupled to simulation allow evidencing the 1D structural organization of the molecules inside the nanotubes. The angle between the molecule ring and the nanotube axis is close to 32° as determined from our density functional theory calculations. Confined molecules display Raman spectra hardly altered with respect to the bulk phase, suggesting a rather weak interaction with the tubes. For comparison, noncovalent functionalization at the outer surface of the tube is also investigated. The vibrational properties of the molecules functionalized at the outer surface of tubes display important modifications. A significant curvature of the phthalocyanine is induced by the interaction with the tube walls, leading to change of the central atom position within the molecular ring, in good agreement with our first-principles calculations.

Comparative study of aluminum phthalocyanine incorporating into two types of block copolymer: photo-physical property, size, and in vitro photodynamic therapy efficacy

Nanoparticles of amphiphilic triblock copolymer poly(l-lysine)-b-poly(ethylene glycol)-b-poly(l-lysine) and diblock copolymer methoxy-poly(ethylene glycol)-b-poly(l-lysine) were developed to encapsulate tetra(4-sulfoazophenyl-4′-aminosulfonyl) chloride aluminum phthalocyanine, a new photosensitizer used in photodynamic therapy. The mean nanoparticle sizes varied from 10 to 70 nm, and the encapsulation efficacy ranged from 56 to 73 % due to electrostatic self-assembly induced by two types of polymer. The characteristic photophysical parameters including the absorption spectrum profile, fluorescence quantum yield, and fluorescence decay curves for free and encapsulated phthalocyanine were analyzed. The cellular uptake amount and photoactivity of S-AlPc were improved by encapsulation. The aluminum phthalocyanine loaded with poly(l-lysine)-b-poly(ethylene glycol)-b-poly(l-lysine) presented suitable physical stability, improved photophysical properties, and enhanced phototoxicity in vitro, suggesting it may be considered as a promising formulation for PDT.

Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry

This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine–silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484μs for the conjugates and from 341 to 366μs for the free phthalocyanine complexes.

Synthesis, characterization, conduction, and dielectric properties of tetra tert-butylsulfanyl substituted phthalocyanines

The tert-butylsulfanylphthalonitrile has been prepared with optimized synthetic procedure. Metal free (H2Pc) and metallo phthalocyanines (Pcs) (ZnPc, CoPc, CuPc, PbPc) have been synthesized by cyclotetramerization of tert-butylsulfanylphthalonitrile in the presence of DBU and metal salts. Thus, tert-butylsulfanyl groups enhance the solubility, shift the Q band absorption to the red visible region, and inhibit efficient cofacial interaction of the Pcs (2–6) as evaluated by UV–vis spectra. The electrical conduction and dielectric properties of the synthesized Pc thin films sandwiched between indium tin oxide and aluminum electrodes (ITO–Pc–Al) were investigated from 300 to 500 K. At low bias voltage the conduction is ohmic while at high bias voltage the conduction becomes space charge limited with an exponential distribution of traps. The measured ac conductivity data are discussed in terms of classical models based on pair approximation. It was found that the ac conductivity obeys the power law given by σac = σ0ωs, in which the frequency exponent s decreases with temperature. The real and imaginary parts of the impedance are found to be dependent on both frequency and temperature.

In situ metalation of free base phthalocyanine covalently bonded to silicon surfaces

Free 4-undecenoxyphthalocyanine molecules were covalently bonded to Si(100) and porous silicon through thermic hydrosilylation of the terminal double bonds of the undecenyl chains. The success of the anchoring strategy on both surfaces was demonstrated by the combination of X-ray photoelectron spectroscopy with control experiments performed adopting the commercially available 2,3,9,10,16,17,23,24-octakis(octyloxy)-29H,31H-phthalocyanine, which is not suited for silicon anchoring. Moreover, the study of the shape of the XPS N 1s band gave relevant information on the interactions occurring between the anchored molecules and the substrates. The spectra suggest that the phthalocyanine ring interacts significantly with the flat Si surface, whilst ring–surface interactions are less relevant on porous Si. The surface-bonded molecules were then metalated in situ with Co by using wet chemistry. The efficiency of the metalation process was evaluated by XPS measurements and, in particular, on porous silicon, the complexation of cobalt was confirmed by the disappearance in the FTIR spectra of the band at 3290 cm−1 due to –NH stretches. Finally, XPS results revealed that the different surface–phthalocyanine interactions observed for flat and porous substrates affect the efficiency of the in situ metalation process.

Novel metal(III) and metal free soft phthalocyanine metal ion sensors bearing (1-hydroxyhexan-3-ylthio)-substituents: Synthesis, characterization, aggregation behavior

A new substituted phthalonitrile derivative, 4-(1-hydroxyhexan-3-ylthio) phthalonitrile, was prepared by the nucleophilic displacement reaction between 1-hydroxyhexan-3-ylthio and 4-nitrophthalonitrile. The highly soluble novel metallo phthalocyanines [M: 2H (2), Ga(III) (3), In(III) (4)] with four peripheral 1-hydroxyhexan-3-ylthio groups were synthesized by cyclotetramerization. Purification of these compounds was tedious because of their high solubility and they were purified by column chromatography. They were characterized by elemental analysis, FTIR, 1H and 13C NMR, MALDI-TOF and UV–Vis spectral data. The complexes were soluble in both polar solvents and non-polar solvents, such as MeOH, EtOH, CHCl3, CH2Cl2, benzene, toluene and even hexane. Absorption spectral changes of the functional MPcs during addition of Ag(l) and Pd(ll) soft-metal ions were evaluated by UV–Vis spectroscopy, with monomer-dimer formation.

Direct arylation of aromatic C[sbnd]H bond catalyzed by phthalocyanine

Free base phthalocyanine H2(obopc) in 3mol% loading catalyzed the direct CH arylation of benzene with aryl iodides.

Copper phthalocyanine and metal free phthalocyanine bulk heterojunction photodetector

In this study we present the dependence of electrical properties of copper phthalocyanine (CuPc) and metal free phthalocyanine (H2Pc) bulk heterojunction structure under different illumination levels. To fabricate the device on ITO coated glass substrate the bulk heterojunction thin film of CuPc and H2Pc with thickness varying from 100nm to 300nm are deposited by thermal evaporator. Aluminum thin film was deposited by thermal evaporation as a top contact. The optical properties of the fabricated device are investigated using UV–vis spectroscopy. The current-voltage characteristics in dark and under illumination show that the device is sensitive towards visible light. The absorption spectrum describes its photo sensitivity in the range of wavelength from 200nm to 850nm. Simulation of current-intensity of light curve is carried out and experimental results are found in good agreement with simulated ones.

Free base tetraazaporphine isolated in inert gas hosts: matrix influence on its spectroscopic and photochemical properties.

The absorption, fluorescence, and excitation spectra of free base tetraazaporphine (H2TAP) trapped in Ne, N2, and Ar matrices have been recorded at cryogenic temperatures. Normal Raman spectra of H2TAP were recorded in KBr discs and predicted with density functional theory (DFT) using large basis sets calculations. The vibrational frequencies observed in the Raman Spectrum exhibit reasonable agreement with those deduced from the emission spectra, as well as with frequencies predicted from large basis set DFT computations. The upper state vibrational frequencies, obtained from highly resolved, site selected excitation spectra, are consistently lower than the ground state frequencies. This contrasts with the situation in free base phthalocyanine, where the upper state shows little changes in vibrational frequencies and geometry when compared with the ground state. Investigations of the photochemical properties of H2TAP isolated in the three matrices have been performed using the method of persistent spectral hole-burning (PSHB). This technique has been used to reveal sites corresponding to distinct N-H tautomers which were not evident in the absorption spectra. An analysis of the holes and antiholes produced with PSHB in the Qx (0-0) absorption band made it possible to identify inter-conversion of distinct host sites.

Electrochemical and morphological analysis on novel phthalocyanine grafted conductive polymeric nanofibers

Metal free phthalocyanine grafted polypyrrole and cobalt metallated phthalocyanine grafted polypyrrole nanofibers were prepared by electrospinning method. The electrospun PPy and phthalocyanine grafted polypyrrole fibers were coated on indium tin oxide electrode surface for a proper investigation of the electrochemical activity of the fibers. Different methods were used to characterize the obtained fibers. Fourier-transform infrared spectroscopy, Scanning electron microscope and polarized optical microscope were used for their morphological characterization, while electrical behaviors of the nanofibers were characterized by direct current and electrochemical impedance spectroscopy measurements.The synthesis and characterization results showed that the incorporation of phthalocyanine metal chelate affected the electrical behavior of the fibers. The electrical conductivity of the Polyvinylpyrrolidone fiber was improved by grafting cobalt metallated phthalocyanine to the polypyrrole main chain, while the unmetallated phthalocyanine showed an unforeseen electrical property.

Metallo and metal free phthalocyanines bearing (4-(1(4-phenoxyphenyl)-1-phenylethyl)phenol substituents: Synthesis, characterization, aggregation behavior, electronic, antioxidant and antibacterial properties

As starting material the phthalonitrile derivative bearing (4-(1(4-phenoxyphenyl)-1-phenylethyl)phenol substituents at peripheral position was prepared by a nucleophilic displacement reaction. Cyclotetramerization of 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalonitrile derivative in the presence of corresponding metal salts gave the new metallophthalocyanines. Metal free phthalocyanine was obtained from the reaction of 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalonitrile units. The novel compounds have been characterized by using various spectroscopic data. The aggregation investigations carried out in different concentrations indicate that 4-(4-(1-(4-hydroxyyphenyl)-1-phenylethyl)phenoxy)phthalocyanine compounds do not have any aggregation behavior for the concentration range of 10−4–10−5M in tetrahydrofuran. The antioxidant activities of novel compounds were analyzed through radical scavenging ability of 1,1-diphenyl-2-picrylhydrazyl, chelating ability to ferrous ions and reducing power. In addition to these, the antibacterial activities of compounds were investigated. Moreover, the ground-state geometries of the complexes were optimized using B3LYP/6-31G(d,p) level of density functional theory in order to predict the three-dimensional geometries and electronic structure.

Synthesis, aggregation and spectroscopic studies of novel water soluble metal free, zinc, copper and magnesium phthalocyanines and investigation of their anti-bacterial properties

In this study, novel phthalonitrile derivative (3) was synthesized by the reaction between 4-nitrophthalonitrile (2) and a triazole derivative (1) containing pyridine moiety. Crystal structure of compound (3) was characterized by X-ray diffraction. New metal free and metallo-phthalocyanine complexes (Zn, Cu, and Mg) were synthesized using the phthalonitrile derivative (3). Cationic derivatives of these phthalocyanines (5, 7, 9, and 11) were prepared from the non-ionic phthalocyanines (4, 6, 8, and 10). All proposed structures were supported by instrumental methods. The aggregation behaviors of the phthalocyanines (4–11) were investigated in different solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), chloroform and water. Water soluble cationic Pcs (5, 7, 9, and 11) aggregated in water and sodium dodecyl sulfate was used to prevent the aggregation. The second derivatives of the UV–Vis spectra of aggregated Pcs were used for analyzing the Q and B bands of aggregated species. Thermal behaviors of the phthalocyanines were also studied. In addition, anti-bacterial properties of the phthalocyanines were investigated. We used four gram negative and two gram positive bacteria to determine antibacterial activity of these compounds. Compound 7 has the best activity against the all bacteria with 125μg/mL of MIC value. Compounds 4, 6, and 10 have the similar effect on the bacteria with 250μg/mL of MIC value.

Homobinuclear phthalocyaninato metal complexes. Synthesis, structure, spectroscopy, and electrochemistry

Reaction of metal free homobinuclear phthalocyanine H2Pc(OR)6-H2Pc(OR)6 with M(OAc)2 (M = Co, Ni) in refluxing dimethyl formamide led to the isolation of the binuclear phthalocyaninato metal complexes MPc(OR)6-MPc(OR)6 (M = Co, Ni) (1, 2). These binuclear phthalocyanine compounds were characterized by a series of spectroscopic methods including mass, 1H NMR, electronic absorption, and IR spectroscopy in addition to elemental analysis. In particular, their binuclear phthalocyanine nature has been directly revealed on the basis of single crystal X-ray diffraction analysis of the homo-dicobalt species CoPc(OR)6-CoPc(OR)6 (1) for the first time. In addition, their electrochemical data over these binuclear phthalocyanine compounds have also been provided by cyclic voltammetry measurements.

A comparative photophysicochemical study of mono substituted phthalocyanines grafted onto silica nanoparticles

In this study, we report on the covalent linking of carboxylic acid functionalized silica nanoparticles with zinc phthalocyanine mono-substituted non-peripherally and peripherally with either a 4-amino phenoxy (1, peripheral and 2, non-peripheral) or an amino group (3 peripheral). The grafting is achieved via the formation of an amide bond between the carboxylic acid of the silica nanoparticles and the amino group of the phthalocyanine complexes. The hybrid nanoparticles retained the amorphous nature of silica nanoparticles after conjugation. A slight decrease in fluorescence and a general improvement in triplet quantum yields compared to free Pcs were observed. Triplet lifetimes for 2- SiNPs and 3- SiNPs also improved when compared to the free phthalocyanine. The changes in singlet oxygen quantum yields upon conjugation were minimal.

Photophysical behavior of Zn aminophenoxy substituted phthalocyanine conjugates with carboxylic acid-coated silica nanoparticles: Effect of point of substitution

This work reports on the grafting of silica nanoparticles with zinc phthalocyanine complexes tetra-substituted non-peripherally and peripherally with a 4-amino phenoxy group. The phthalocyanine dyes have free amino groups, facilitating covalent attachment of the dyes on the silica surface via amide bond formation. The surface area of the functionalized silica nanoparticles increased on conjugation but the pore volumes were reduced. The phthalocyanine functionalized silica nanoparticles showed lower fluorescence quantum yields as well as shorter triplet lifetimes compared to the free phthalocyanines in dimethyl formamide. For the non-peripherally substituted phthalocyanines increases in triplet yield quantum yields, lifetimes, and singlet oxygen quantum yields were observed.

Synthesis, photophysicochemical properties and TD-DFT calculations of tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanines

The synthesis of metal free, magnesium and zinc tetrakis(2-benzoyl-4-chlorophenoxy) phthalocyanine derivatives (2–4) is described along with their characterization by elemental analysis, IR, UV-visible absorption, and 1 H NMR spectroscopy and mass spectrometry. Trends observed in the fluorescence, triplet state, singlet oxygen and photodegradation quantum yields and the triplet state lifetimes are also analyzed. The compounds exhibit high solubility in a wide range of organic solvents and no evidence of aggregation was observed over a wide concentration range. The Zn ( II ) complex (4) was found to have a very high singlet oxygen quantum yield (ΦΔ = 0.78) in dimethylsulfoxide (DMSO) and a reasonably large triplet state quantum yield (ΦT = 0.82). The photophysical and photochemical properties clearly demonstrate that these compounds could prove useful in singlet oxygen applications such as photodynamic therapy (PDT). DFT and TD-DFT calculations were used to assess the impact of the positional isomerism of the 2-benzoyl-4-chlorophenoxy substituents on the electronic structures and optical spectroscopy.

Electrochemical Analysis of Phthalocyanine Grafted Polymer Nanofibers

Nanofibers possess exclusive physical, chemical, and electronic properties. Although different methods are known [1-2], electrospinning has been used with an increasing impact because of the ease of proceeding and the use of a wide range of polymeric materials [3–4] in the production of nanofibers. Metal free phthalocyanine grafted polypyrrole and cobalt metallated phthalocyanine grafted polypyrrole nanofibers were prepared by electrospinning method. The electrospun PPy and phthalocyanine grafted polypyrrole fibers were coated on indium tin oxide electrode surface for a proper investigation of the electrochemical activity of the fibers. Different methods were used to characterize the obtained fibers. Fourier-transform infrared spectroscopy, Scanning electron microscope and polarized optical microscope were used for their morphological characterization, while electrical behaviors of the nanofibers were characterized by direct current and electrochemical impedance spectroscopy measurements.[1] Feng L, Li S, Li H, Zhai J, Song Y, Jiang L. Super-Hydrophobic Surface of Aligned Polyacrylonitrile Nanofibers. Angew Chem Int Ed 2002;41:1221–1223.[2] Ma PX, Zhang R. Synthetic nano-scale fibrous extracellular matrix. J Biomed Mat Res 1999;46:60–72.[3] Menon VP, Lei J, Martin CR. Membrane-Based Synthesis of Nanomaterials. Chem Mater 1996; 8: 2382-86.[4] Joo J, Park KT, Kim BH, Kim MS, Lee SY, Jeong CK, Lee JK, Park DH, Yi WK, Lee SH, Ryu KS. Conducting Polymer Nanotube and Nanowire Synthesized by Using Nanoporous Template: Synthesis, Characteristics, and Applications. Synth Met 2003;135:7-13.