Phthalocyanine Composites Research Articles

Graphene Oxide/Cholesterol-Substituted Zinc Phthalocyanine Composites with Enhanced Photodynamic Therapy Properties.

In the present work, cholesterol (Chol)-substituted zinc phthalocyanine (Chol-ZnPc) and its composite with graphene oxide (GO) were prepared for photodynamic therapy (PDT) applications. Briefly, Chol-substituted phthalonitrile (Chol-phthalonitrile) was synthesized first through the substitution of Chol to the phthalonitrile group over the oxygen bridge. Then, Chol-ZnPc was synthesized by a tetramerization reaction of Chol-phthalonitrile with ZnCl2 in a basic medium. Following this, GO was introduced to Chol-ZnPc, and the successful preparation of the samples was verified through FT-IR, UV-Vis, 1H-NMR, MALDI-TOF MS, SEM, and elemental analysis. Regarding PDT properties, we report that Chol-ZnPc exhibited a singlet oxygen quantum yield (Φ∆) of 0.54, which is slightly lower than unsubstituted ZnPc. Upon introduction of GO, the GO/Chol-ZnPc composite exhibited a higher Φ∆, about 0.78, than that of unsubstituted ZnPc. Moreover, this enhancement was realized with a simultaneous improvement in fluorescence quantum yield (ΦF) to 0.36. In addition, DPPH results suggest low antioxidant activity in the composite despite the presence of GO. Overall, GO/Chol-ZnPc might provide combined benefits for PDT, particularly in terms of image guidance and singlet oxygen generation.

Electrochemical sensing of cysteine using a novel carbon black and cobalt phthalocyanine composite

In this work, a novel composite material using carbon black and cobalt phthalocyanine (CoPc/CB) was produced. Characterizations by spectroscopic techniques (Raman and infrared), scanning electron microscopy, and X-ray diffraction confirmed the formation of the composite material. The proposed material was cast on the glassy carbon electrode surface, and its electrochemical sensing properties were checked using cysteine (CYS), an important amino acid widely used in medicine, food additives, and cosmetics, as a model molecule. Studies by cyclic voltammetry revealed that the modified electrode caused considerable electrocatalytic effects (detection at a potential close to 0.1 V) and enhanced in peak current compared to the unmodified electrode. A wide linear range (1—150 µmol/L) and adequate detectability (LOD = 0.75 µmol/L) were achieved by Batch Injection Analysis (BIA) with amperometric detection. Repeatability tests (n = 20) at two concentration levels (20 and 40 µmol/L) confirmed the precision of the method (RSD < 11 %). Interestingly, even under high flow conditions, good stability of the electrode modification was noticed. The proposed method was applied to determine CYS concentration in pharmaceutical samples, where adequate recovery values (89 and 110 %) and results statistically similar to those achieved by capillary electrophoresis indicated the accuracy and reliability of the electrochemical analyses.

Dry ball-milling preparation and characterization of graphite–phthalocyanine composites

The hybrids of phthalocyanines with carbon nanotubes, graphene and graphene oxide were demonstrated previously to be promising for different catalytical, electrocatalytical and other applications. Nevertheless, the above carbon nanomaterials are toxic and relatively expensive. We attempted to substitute them by low-cost and harmless graphite, using dry ball-milling of graphite–phthalocyanine mixtures under mild conditions. According to scanning electron microscopy imaging and powder X-ray diffraction, the composites obtained exhibit the absence of crystalline phthalocyanine phase, which implies high efficiency of phthalocyanine milling. According to Raman spectroscopy data, the mechanochemical treatment does not provoke the formation of large amounts of defects in graphite, but instead helps its exfoliation. The composites were characterized by UV-visible spectroscopy and thermal gravimetric analysis, which showed that all of them exhibit a reduced thermal stability compared to unprocessed graphite by roughly 100–250 °C. The strength of interaction of phthalocyanines with a graphene sheet (as a graphite surface model), geometries and selected electronic parameters (frontier orbital and spin density distribution, HOMO-LUMO gap energies) of the resulting noncovalent complexes were analyzed at the PBE-D2/DNP theoretical level. The interactions of phthalocyanines with the graphene sheet are strong, with the calculated formation energies (absolute values) for the noncovalent complexes of 62.1–70.1 kcal/mol.

Novel Graphene Oxide/Zinc Phthalocyanine Composites Bearing 3‐Chloro‐4‐Fluorophenoxy: Potential Usage for Sono/Photochemical Applications

AbstractThe aim of this paper is to explore the therapeutic contribution of graphene oxide (GO) to new sono/photosensitizers through sono/photochemical studies for the first time. For this purpose, new zinc (II) phthalocyanine bearing 3‐chloro‐4‐fluorophenoxy 2 was synthesized and then its GO‐based composites were prepared by non‐covalently coating ZnPc 2 on the graphene oxide surface. The photoactivity of these materials was compared and discussed in terms of their potential ability to be used in photosensitizer in photodynamic therapy (PDT) and sono‐photodynamic therapy (SPDT). In these application areas, GO can serve as photosensitizer carrier, while ZnPc 2 can be acting as PDT/SPDT agent. Therefore, phthalocyanine composites containing different percentages of graphene oxide by weight (wt.% GO) were prepared. SEM (scanning electron microscopy) results supported the interaction between GO and ZnPc 2. In the sono‐photochemical study, both ZnPc 2 and its composites gave very higher ΦΔ values than the photochemical study. The sono‐photochemical ΦΔ values were found to be 0.928 for 0 wt.% GO, 0.869 for 0.25 wt.% GO, 0.891 for 0.50 wt.% GO, 0.868 for 1 wt.% GO, 0.908 for 3 wt.% GO, 0.845 for 5 wt.% GO and 0.851 for 10 wt.% GO, respectively. According to obtained results, these materials could be promise as good photosensitizers for both the photochemical study and the sono‐photochemical study due to their very high singlet oxygen generation.

A novel MWCNT-encapsulated (2-aminoethyl)piperazine-decorated zinc(II) phthalocyanine composite: development of an electrochemical sensor for detecting the antipsychotic drug promazine in environmental samples.

A nanocomposite of (2-aminoethyl)piperazine ligand substituted with zinc(II) tetra carboxylic acid phthalocyanine (ZnTEPZCAPC) and MWCNTs was constructed and employed to develop an electrochemical sensor with outstanding sensitivity and a low detection limit. The macrocyclic complex ZnTEPZCAPC was first synthesized and then employed for the electrochemical determination of the antipsychotic drug promazine (PMZ). The as-prepared ZnTEPZCAPC and MWCNT nanocomposite was characterized using different techniques, such as Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). Further, the prepared ZnTEPZCAPC@MWCNT nanocomposites were modified on a glassy carbon electrode (GCE) surface, and the electrochemical activity was investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry (CA) tests in pH 7.0 phosphate buffer solution (PBS) in the potential window of 0.0-1 V. The ZnTEPZCAPC@MWCNTs displayed a superior electrochemical performance because of their high electrochemical active surface area (0.453 cm2), good conductivity, and a synergetic effect. The developed electrochemical sensor exhibited a broad linear range of 0.05-635 μM and the lowest detection limit of 0.0125 nM, as well as excellent sensitivity, repeatability, and reproducibility. Finally, the fabricated sensor was successively used for the real-time detection of PMZ in environmental and biological samples and displayed feasible recoveries.

Double‐decker lutetium and europium phthalocyanine composites with reduced graphene oxide as supercapacitor electrode materials

Double‐decker phthalocyanines were synthesized by a classical method with phthalonitrile and lanthanide metal salts, europium and lutetium acetate. Non-covalent double-decker phthalocyanine-reduced graphene oxide (MPc2/rGO) composites were then prepared by simple sonication method. All the phthalocyanines were peripheral tetrasubstituted 5-(3-pyridyl)-1,3,4-oxadiazole. Following spectroscopic and morphological characterisation, fabricated composites were subjected to detailed electrochemical analysis. EuPc2/rGO and LuPc2/rGO composite electrodes showed specific capacitance values of 115 F/g and 86 F/g, respectively. Coulombic efficiency values for those materials were determined as 85% and 74%, respectively, at a significant current density of 5 A/g. Following 5000 cycles, EuPc2/rGO and LuPc2/rGO electrodes retained 93% and 99% of their initial capacitance, respectively. These results demonstrated the significant electrochemical performance of double-decker phthalocyanines and can be certainly extended to other metal salts or other composite formers with double-decker phthalocyanines.

Metallophthalocyanines as optical active dopants in borate glass

B2O3 – phthalocyanine composites (B2O3@MPc) were synthesized at 410 °C by sintering boron trioxide doped with base metal-free phthalocyanine (H2Pc) and/or its complexes of Mg, Zn, Gd (Pc = C32H16N8, phthalocyanine ligand, M = metal ion). The glassy products were characterized by scanning electron microscopy (SEM, EDS) and diffuse reflectance spectroscopy (DRS) which confirmed the incorporation of the respective phthalocyanines into the amorphous borate matrix. FTIR results suggested a possible impact of the phthalocyanine dopants on the final solid structure of the glassy matrix. The UV-excited composites emitted a pronounced blue phosphorescence featured by a two-step quenching process and lifetimes of 28 and 670 ms. Optical stimulated luminescence (OSL) tests proved excellent luminescence properties revealed by the samples including H2Pc and GdPc2 dopants. Reversible photoconductivity of the composites was confirmed by impedance spectroscopy measurements at current frequencies of 103 and 102 Hz and UV irradiation. The best results exhibited B2O3@GdPc2 featuring an impedance modulus decrease of about 2 orders of magnitude at 102 Hz compared to the other composites.

Influence of Cyano Substituents on the Electron Density and Catalytic Activity Towards the Oxygen Reduction Reaction for Iron Phthalocyanine

Iron(II) 2,3,9,10,16,17,23,24-octa(cyano)phthalocyanine (OCNFePc), was tested as a catalyst for the oxygen reduction reaction (ORR) adsorbed on carbon nanotubes. The composite was analyzed spectroscopically and electrochemically characterized at pH 13 and pH 1. The composite showed close to 4 electron processes at pH 13. Computational analysis indicates that the O2 molecule binds end-on to the metal center and that the dioxygen molecule is dissociated on both the Fe metal center and the corral ring. An Analysis of the molecular electrostatic potential confirms the behavior of cyano residues as electron-withdrawing moieties in OCNFePc. As a result of its catalytic behavior and theoretical analysis of its O2 binding energy, OCNFePc was placed in a high position on a volcano correlation of similar phthalocyanine composites.

Synthesis of graphene oxide and copper phthalocyanine, AC electrical characterization and tuning the bandgap of RGO-CuPc composite

Graphene oxide (GO) was synthesized in our laboratory by the improved Hummer’s method. Reduced graphene oxide/Copper Phthalocyanine (RGO-CuPc) composite was prepared through the chemical reduction of GO by Hydrazine hydrate. This composite was analyzed by FT-IR, UV–vis spectroscopy, FESEM microscopy, and the results showed that CuPc molecules were successfully attached on RGO sheets by π-π intermolecular interaction. Also, UV–vis spectroscopy results showed that the tuning of the bandgap is applicable for RGO-CuPc composite. Sandwich devices of RGO-CuPc thin film with aluminum electrodes (Al/RGO-CuPc/Al) were fabricated to investigate the AC electrical properties of RGO-CuPc composite over the frequency range of 102–105 Hz and temperature range of 298–393 K. The band theory is applicable to explain the thin film conduction mechanism. Also, this composite acts as a semiconductor with high electron mobility.

Iron Phthalocyanine/Graphene Composites as Promising Electrocatalysts for the Oxygen Reduction Reaction

Recently, the development of non-precious electrocatalysts for the oxygen reduction reaction (ORR) has become important in replacing currently employed platinum (Pt)-based catalysts. Although Pt-based catalysts exhibit satisfactory ORR performances, their high price, easy methanol/CO2 poisoning, and poor long-term stability significantly hamper the forward movement of fuel cell technology. Among the various candidates, graphene-supported iron phthalocyanine (FePc) composites have attracted great attention because of their unique advantages, including low cost, good dimensional stability, high durability, and tunable catalytic activity. In the composite catalyst, FePc molecules are immobilized on graphene via noncovalent or covalent interactions. In addition, two-dimensional graphene substrates can improve not only the electrical conductivity of the composite, but also the dispersion of FePc molecules, triggering a significant improvement in the catalytic properties of the composite catalyst. Herein, we summarize the recent advances in FePc/graphene composite catalysts used for the ORR. Moreover, we discuss the challenges and future perspectives of this promising field.

Influence of cyano substituents on the electron density and catalytic activity towards the oxygen reduction reaction for iron phthalocyanine. The case for Fe(II) 2,3,9,10,16,17,23,24-octa(cyano)phthalocyanine

Iron(II) 2,3,9,10,16,17,23,24-octa(cyano)phthalocyanine (OCNFePc), was tested as a catalyst for the oxygen reduction reaction (ORR) adsorbed on carbon nanotubes. The composite was analyzed spectroscopically and electrochemically characterized at pH 13 and pH 1. The composite showed close to 4 electron processes at pH 13. Computational analysis indicates that the O2 molecule binds end-on to the metal center and that the dioxygen molecule is dissociated on both the Fe metal center and the corral ring. An Analysis of the molecular electrostatic potential confirms the behavior of cyano residues as electron-withdrawing moieties in OCNFePc. As a result of its catalytic behavior and theoretical analysis of its O2 binding energy, OCNFePc was placed in a high position on a volcano correlation of similar phthalocyanine composites.

Synthesis and Characterization of Iron Phthalocyanine Supported on Graphene Oxide and Catalysis of Adrenaline

Iron tetranitro-phthalocyanine was synthesized by the reaction of 4-nitrophthalimide with FeCl₃, and was then modified by γ-(trimethoxysilyl)propane-1-thiol to prepare functionalized iron phthalocyanine. A graphene oxide/iron phthalocyanine composite was then prepared, comprising functionalized iron phthalocyanine supported on the surface of graphene oxide via covalent bonds. All these complexes were characterized by infrared spectra (IR), X-ray diffraction, ultraviolet/visible (UV/vis) and Raman spectroscopy, and scanning electron microscopy. The catalytic properties of the graphene oxide/iron phthalocyanine composite for catalyzing adrenaline oxidation were evaluated by measuring the absorbance intensity at the characteristic peak of the oxidation product. A fiberoptic adrenaline sensor based on a graphene oxide/iron phthalocyanine composite catalyst and fluorescence quenching was fabricated and studied. The relationship between the concentrations of dissolved oxygen and adrenaline was investigated by measuring the phase delay φ. The results showed that the graphene oxide/iron phthalocyanine composite can effectively catalyze adrenaline oxidization, and the optimal conditions are pH = 8.0, T = 30 °C, and mGO-FePc = 4.0 mg/mL; moreover, concentrations of adrenaline can be detected in the range from 1.8×10-6 to 9.2×10-5 mol/L with a sensor response time of 4 min.

Enhanced Nucleation of LiCl during Lithium Battery Discharging with Carbon Nanotubes Supported Nitrogen-Rich Manganese Phthalocyanine Catalysts

Large-size LiCl particles deposited on the carbon cathode of lithium thionyl chloride battery during discharge are mainly limited by the sluggish kinetics, decreasing the voltage platform and service life. In this work, the carbon nanotubes supported nano-sized nitrogen-rich manganese phthalocyanine composites (MnTAP/CNTs) were prepared by in situ solid phase synthesis as catalysts. The effect of reaction kinetics of the battery with/without catalysts on nucleation process of LiCl particles is investigated. After discharge, the surface of the carbon cathode with MnTAP/CNTs displays LiCl particles approximately 200 nm, which is only a fifth of the size without catalysts. Moreover, a large number of nano LiCl particles appear inside compared to the catalyst free. The fast reaction kinetics of SOCl2 with MnTAP/CNTs is favorable for the nucleation of LiCl particles. Meanwhile, the electrolyte resistance, the surface film resistance and the charge transfer resistance of the battery are reduced to approximately 57%, and the discharge time and voltage platform are 15.6 min and 0.2 V higher than that without catalysts.

A highly sensitive fenobucarb electrochemical sensor based on graphene nanoribbons-ionic liquid-cobalt phthalocyanine composites modified on screen-printed carbon electrode coupled with a flow injection analysis

A sensitive and rapid method for the determination of fenobucarb by using screen-printed carbon electrode modified with graphene nanoribbons - ionic liquid - cobalt phthalocyanine (GNRs-IL-CoPc/SPCE) composites based on flow injection analysis (FIA) was developed and applied to vegetable samples. The prepared GNRs-IL-CoPc composite was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). Moreover, cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS) were used to characterize the electrochemical behavior of the modified SPCE. The amperometric current responses were obtained from the oxidation of 2-sec-butyl-phenol, which is the product of alkaline hydrolysis of fenobucarb. The optimization of chemical variables and instrumental analysis such as composite amounts, pH, applied potential, and flow rate were carried out to obtain the best measurement. Under the optimal conditions, the proposed sensor yielded sensitivity of 0.0884 M/A·cm2, a wide linear range for detection of fenobucarb from 0.025 to 110 μM with a low detection, and quantification limits of 0.0089 μM and 0.0252 μM, respectively. Additionally, the developed sensor showed good repeatability (RSD = 3.5%, n = 10 measurements) and good reproducibility (RSD = 3.9%, n = 5 sensors). The proposed method could be effectively applied for the determination of fenobucarb in vegetable samples.

Graphene wrapped organic nanotube: A promising material for Oxygen Reduction Reaction

In search of alternatives of Platinum-based electrocatalysts, graphene – Phthalocyanine composites are under recent research focus. We, therefore, in this study, have addressed and explored the electrochemical performances of graphene/copper phthalocyanine nanocomposites towards oxygen reduction reaction. It is found that, graphene functionalized copper phthalocyanine show better catalytic activity than bare phthalocyanine nanostructure, which may be attributed to the π-π interaction between the components and higher conductivity of graphene in the composite.

Synthesis of asymmetric zinc phthalocyanine supported on multi-walled carbon nanotubes and its improvement of catalytic activity on styrene oxidation

An asymmetric zinc phthalocyanine composites ([3α-(OPh-t-Bu)-α-NO2]ZnPc-MWCNTs) have been prepared. The as-prepared composites are characterized via UV–Vis spectroscopy, Fourier transform infrared spectra, X-ray diffraction, scanning electron microscope and transmission electron microscopy techniques. The catalytic performance of [3α-(OPh-t-Bu)-α-NO2]ZnPc-MWCNTs composites are evaluated by studying the catalytic oxidation of styrene. Effects of different solvents and oxidant, mass ratio of composite catalyst and styrene, temperature, time on catalytic activity were also investigated. It can be found that the [3α-(OPh-t-Bu)-α-NO2]ZnPc-MWCNTs composites have better catalytic activity with higher conversion and selectivity. When the mass ratio of [3α-(OPh-t-Bu)-α-NO2]ZnPc-MWCNTs/styrene is 1:15, the highest conversion rate and the optimal selectivity can reach 96.6% and 86.1%, respectively. Moreover, the possible catalytic mechanism of [3α-(OPh-t-Bu)-α-NO2] ZnPc-MWCNTs composites for the oxidation of styrene was discussed.

The sonochemical functionalization of MoS2 by zinc phthalocyanine and its visible light-induced photocatalytic activity

Here, the synthesis of a molybdenum disulfide–zinc phthalocyanine (MoS2–ZnTTBPc) composite is reported where the scalable synthesis of MoS2 was done by a simple solvothermal route followed by the sonochemical attachment of ZnTTBPc.

Graphene wrapped phthalocyanine: Enhanced oxidative desulfurization for dibenzothiophene in fuel

Graphene wrapped metal phthalocyanine (MPc/RGO, M = Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) composites are synthesized by a facile ‘in situ hydrothermal’ method, using graphene oxide, M (CH3COO)2 and phthalic anhydride as the precursors. A biomimetic catalytic system of MPc/RGO and molecular O2 have high activity for ultra‐deep removal of dibenzothiophene (DBT) in model oil containing n‐octane. Compared with pure graphene oxide and MPc, MPc/RGO composites displayed highly enhanced catalytic activity for the oxidation of dibenzothiophene in n‐octane. The conversion ratio of DBT was up to 97.51% after 180 min treatment at 60 °C and atmospheric pressure. The photostability of RGO/MPc composites photocatalystic degradation of dibenzothiophene was investigated. Mechanistic studies revealed that the RGO/MPc − O2· species were the main active intermediate via the π‐π stacking interaction of MPc and RGO. The RGO wrapped phthalocyanine materials offer great potential as active photocatalysts for degradation of thiophene derivatives in fuel.

The effect of oxygen content of carbon nanotubes on the catalytic activity of carbon-based iron phthalocyanine for oxygen reduction reaction

The development of cost-effective non-precious metal catalysts has attracted much research attention because of their high oxygen reduction reaction (ORR) performance. Herein, based on three kinds of carbon nanotubes (CNTs) with different oxygen content, we prepare three CNTs-based iron phthalocyanine (FePc) composites via only a simple physical method. In surprise, the FePc-CNTs composites with the most oxygen content exhibit the highest ORR catalytic activity in comparison with commercial Pt/C in alkaline media, especially its half-wave potential (E1/2) and durability as well as methanol tolerance. A large amount of experimental measurements show that these superb catalytic activities can be mainly attributed to the possible formation of novel interactions between FePc and oxidized CNTs. It not only provides more active sites, but also is in favor of stabilizing active centers and removing intermediates in catalytic process. This work displays the effects of oxygen content and roughness of CNTs on the interactions between FePc and CNTs and their important role in ORR catalysis, providing a new insight into simple application of carbons materials.

Redox-Mediated Iron Phthalocyanine Hybrid Electrocatalyst for Lithium-Oxygen Battery Application

We report a redox-mediated hybrid electrocatalyst for lithium-air battery using a soluble iron phthalocyanine catalyst combined with hierarchically porous air cathode. A simple and cost-effective technique is utilized to prepare carbon-iron phthalocyanine composites. Furthermore, ball milling effect on catalytic activity of the composite is highlighted. The perovskite La0.6Sr0.4CoO3-δ, which is an effective oxygen evolution reaction catalyst, is also combined with the iron phthalocyanine to prepare a redox-mediated hybrid electrocatalyst. The prepared iron phthalocyanine-carbon and the perovskite La0.6Sr0.4CoO3-δ-iron phthalocyanine composites exhibit better catalytic activity in both oxygen reduction and oxygen evolution reaction than Pt/C, with low overpotential (0.7 V) and 100% reversibility in the tested lithium-air battery.