Formation Of Phthalocyanine Research Articles

Formation of zinc phthalocyanine on polymethyl methacrylate chain: Its nanographene‐based composite, thermal, electrical and optical behaviors

AbstractPoly[4‐((4‐vinylbenzyl)oxy) phthalonitrile‐co‐methyl methacrylate] [P(VBOPN10.7%‐co‐MMA)] was prepared by atom transfer radical polymerization (ATRP) method at 110°C. Green colored single chain polymer molecule via intramolecular formation of zinc phthalocyanine (SCP‐ZnPc) on polymer chain was synthesized using VBOPN as a precursor copolymer under conditions of dilute cyclohexanol and at 140–150°C. The successful formation of zinc phthalocyanine on a single chain molecule was confirmed using Fourier‐transform infrared spectroscopy (FT‐IR) and UV/Vis spectroscopy techniques. Nanogaphene‐based SCP‐ZnPc composite was prepared to employ 6 weight (wt)% of total weight and were investigated its thermal, electrical, dielectric and optical properties. The dielectric and DC electrical conductivity of SCP‐ZnPc/NG 6 wt% nanocomposite were found to increase depending upon temperature. And the conduction obeyed the Arrhenius relationship with the activation energy, Ea values for I. and II. regions were 0.345 eV and 0.275 eV, respectively. The optical constants (refractive index, real value of optical dielectric constant) and the optical band gap of SCP‐ZnPc/NG 6 wt% were estimated. The direct band gap and refractive index of SCP‐ZnPc/NG 6 wt% were estimated, and its direct band gap was estimated as 2.7 eV.

Facile, Mild-Temperature Synthesis of Metal-Free Phthalocyanines

AbstractIt is important for the synthesis and research of phthalocyanine compounds for these compounds to be easily obtained at low temperature. We observed that metal-free phthalocyanine was sometimes found in a simple system used to synthesize phthalocyanine precursors at room temperature, and further studies showed that the key to the effective formation of phthalocyanines at low temperature lay in the presence of equal volumes of alcohol and amine, in addition to substrate phthalonitriles and solvents, in the reaction system. A synthetic mechanism was proposed and facile syntheses have been realized, such as the synthesis of tetra-α(β)-nitrophthalocyanines and tetra-α(β)-(4-tert-butylphenoxy)phthalocyanines from the corresponding substituted phthalonitriles at mild temperature (37 °C). The results are significant for the design and synthesis of new phthalocyanine derivatives, and the method is convenient and easy to adopt for general use in standard laboratories.

Electronic structures and photovoltaic properties of a novel phthalocyanine and titanium dioxide phthalocyanine for dye sensitized-solar cells

In the present work, geometries, electronic structures, photovoltaic and optical properties have been carried out on a series of structures formation of phthalocyanine and Titanylphthalocyanine dyes, which are replaced by several subgroup. A density functional theory (DFT) approach together with hybrid function (B3LYP) at SDD basis set was used for the ground state properties in the gas phase. The time-dependent density functional theory (TD-DFT)/ B3LYP was used to investigate the excitation properties of new dyes and analyzed the trends in their optical and redox characteristics. Theoretical principles of HOMO and LUMO energy levels of dyes is requisite in analyzing organic solar cells, thus, HOMO, LUMO levels, open circuit voltage, energy gap, light harvestings efficiency, electron regeneration and electron injection have been calculated and discussed. The outcome of the efficiency, the considered dyes explain absorption energy and wavelength properties that correspond to the solar spectrum requirements. According to results, all the considered materials have a good property and possibility of electron injection procedure from the dyes to conduction band of TiO2, PC60BM or PC60BM. As a result, the molecular changes affect the electronic properties of dye molecules for solar cells. Also, a study of new dyes sensitizers showed that designed materials will be excellent sensitizers. Theoretical designing will prae a way for experimentalists to synthesize the efficient sensitizers for solar cells clearer.

Preparation, characterization and electrical behaviors of greenish single-chain polymeric molecule-via intramolecular ball type cobalt phthalocyanines/ graphite oxide composites

The greenish single-chain polymeric molecule-ball type CoPc (SCPM-ball type CoPc) was prepared via the intramolecular formation of cobalt phthalocyanine from polystyrene-co-poly[4,4′-((((4-vinylbenzyl)azanediyl)bis(ethane-2,1diyl))bis(oxy))diphthalonitrile] [P(PNDEAMSt12%-co-St)] (linear copolymer precursor) under diluted conditions at 150 °C. The structure of SCPM-ball type CoPc was confirmed by FT-IR, MALDI-TOF-MS, UV and SEM. The conversion dependence of the experimental activation energy was readily determined by an isoconversional method. So, the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) showed that the linear copolymer precursor's activation energies were as average 128.7 kJ/mol and 124.0 kJ/mol and those of SCPM-ball type CoPc were average 161.9 kJ/mol and 153.8 kJ/mol, respectively. Conductivity mechanism of composites was suggested as Correlated Barrier Hoping (CBH). The linear copolymer precursor/graphite oxide (GO) composite has a significant performance for dielectric constant of 696.4 at 130 °C, but it was with a comparatively greater dielectric loss. Those of SCPM-ball type CoPc/14wt% GO increased virtually the same relative ratio.

A theoretical insight into the curing mechanism of phthalonitrile resins promoted by aromatic amines.

High-temperature phthalonitrile resins have a wide range of applications, and understanding their curing mechanism is of great importance for academic research and engineering applications. However, the actual curing mechanism is still elusive. We presented a density functional theory study on the curing mechanism of phthalonitrile resins promoted by aromatic amines using phthalonitrile and aniline as the model compounds. We found that the rate-determining step is the initial nucleophilic addition of amines with nitrile groups on phthalonitrile to generate an amidine intermediate. The amines play a vital role in the H-transfer promoter throughout the curing reaction. The amidine and isoindoline are the critical intermediates, which can readily react with phthalonitrile through 6-membered transition states. The intramolecular cyclization of amidine intermediates is the vital step in forming isoindoline intermediates, which can be significantly promoted by amines. The proposed curing reaction pathways are kinetically more favorable than the previously reported ones, which can account for the formation of triazine, polyisoindoline, and phthalocyanine and provide a molecular-level understanding of the curing reaction.

Novel peripheral tetra-substituted phthalocyanines containing methoxylated chalcone group: Synthesis, spectral, electrochemical and spectroelectrochemical properties

This paper reports the synthesis, electrochemical and spectroelectrochemical properties of peripheral tetra substituted phthalocyanines that include (E)-1-(2,5-dimethoxyphenyl)-3-(4 hydroxyphenyl)prop-2-en-1-one. Precursor phthalonitrile compound (3) for the formation of phthalocyanines was synthesized at first, then related phthalocyanine compounds CoII (Pc-4), CuII (Pc-5), ZnII (Pc-6), MnIIICl (Pc-7) and metal-free (Pc-8) were synthesized. The spectral properties of all compounds were accomplished by using prevalent spectroscopic techniques. Electrochemistry of metallophthalocyanines (MPcs) were studied with cyclic voltammetry (CV) and square wave voltammetry (SWV) to determine the redox mechanism of the complexes. In situ spectroelectrochemical characterizations were also performed to support the redox mechanism and to determine opto-electronic responses of the electrogenerated MPc species.

Synthesis, electrochemical and spectroelectrochemical properties of novel soluble peripheral tetra triazole substituted CoII, CuII, MnIIICl and TiIVO phthalocyanines

This paper reports the synthesis, electrochemical and spectroelectrochemical properties of peripherally tetra-substituted metallophthalocyanines (M = CoII, CuII, MnIIICl and TiIVO) which contain 4-(3,4-dimethoxyphenethyl)-5-ethyl-2H-1,2,4-triazol-3(4H)-one. The precursor phthalonitrile compound (3) for the phthalocyanine formation was synthesized in the first step. Subsequently, related metallophthalocyanine complexes of cobalt(II) (3-Co), copper(II) (3-Cu), manganese(III) (3-Mn) and oxo-titanium(IV) (3-Ti) were synthesized. The characterization of all these compounds was accomplished using prevalent spectroscopic techniques. Electrochemical characterization of the metallophthalocyanines (MPcs) bearing redox active Co2+ and Mn3+ metal centers, in addition to the redox inactive Cu2+ ion, were performed to investigate the effects of electron transfer reactions from the metal center on the redox features of the Pc ring. While the CuPc (3-Cu) illustrated three Pc based reduction reactions and one Pc based oxidation reaction, incorporation of redox active Co2+ and Mn3+ metal centers instead of Cu2+ increased the redox richness of the complexes, with additional metal based reduction and oxidation reactions. While the CoPc (3-Co) gave one metal-based reduction and one metal based oxidation reaction, in addition to the redox processes of Pc ring, the MnClPc (3-Mn) gave to two metal-based reduction reactions. All the redox processes had almost chemically and electrochemically reversible character, except those observed at the solvent windows. An in situ spectroelectrochemistry technique was used for the assignment of the redox couples and to determine the optical responses of the electrogenerated species.

Electrical, thermal behaviors and synthesis of intramolecular cobalt phthalocyanine with single-chain polymer structure

Firstly, poly[4-(4-vinylbenzyl)oxy)phthalonitrile]-co-styrene, [poly(VBOP-co-St], which is used as a linear copolymer precursor containing phthalonitrile pendant group was prepared from copolymerization of VBOP and St by atom transfer radical polymerization method at 110 °C. Then, complex synthesis of cobalt phthalocyanine in the single-chain polymer (SCP-CoPc complex) via the intramolecular macrocyclization reaction of cobalt and phthalonitrile group in poly(VBOP-co-St) was carried out at 150 °C in the presence of excess cyclohexanol. Both linear copolymer precursor and formation of cobalt phthalocyanine within a single-chain polymer were confirmed by FT-IR, 1H-NMR, 13C-NMR and UV/Vis spectroscopy techniques. Particularly, the formation of SCP-CoPc complex was characterized by almost disappearance of –C≡N band at 2230 cm−1 of the FT-IR and appearance of Q band around 672 nm and the B band in the near UV region at 350 nm of UV/Vis spectroscopy. The pure poly(VBOP-co-St), SCP-CoPc complex and the residue SCP-CoPc complex heated to 500 °C were characterized by SEM images, and the element analyses were estimated from X-ray energy dispersive spectroscopy (X-ray EDS). The EDS elemental analysis results of the residual of SCP-CoPc complex degraded to 500 °C showed that CoO [cobalt(II)oxide] compound occurred. The thermal properties of poly(VBOP-co-St) and SCP-CoPc complex were investigated through thermogravimetric analysis and differential scanning calorimeter. The conducting nanographene-based SCP-CoPc composites were prepared. DC and AC electrical conductivity and dielectric properties were investigated. The ac dielectric measurements of poly(VBOP-co-St), SCP-CoPc complex and composites were investigated at room temperature between 100 and 20 kHz depending on the alternating current conductivities. Also, the activation energy profile of SCP-CoPc/4% (by wt) nanographene composite was revealed by measuring the DC conductivity of individual composite material.

Synthesis, spectroscopic properties, thermal properties and aggregation behaviors of macrogol-substituted phthalocyanines

The synthesis, characterization, spectroscopic data, solubility and aggregation behaviors depend on the solvents of metalled (Co, Cu, Ni, Zn) and metal free pegylated phthalocyanines (Pcs) were reported. Precursor phthalonitrile compound (4) for phthalocyanine formation was synthesized by nucleophilic substitution reaction between tetraethylene glycol substituted phthalonitrile (2) and tetraethylene glycol monotosylate (3). Related phthalocyanines (4-H, 4-Co, 4-Cu, 4-Ni, and 4-Zn) were characterized by FT-IR, 1H NMR, 13C NMR, and UV–Vis spectroscopies and elemental analysis. Thermal stabilities of the phthalocyanines were determined in the range between room temperature and 1000 °C. Pegylated phthalocyanines showed high solubility in water and common organic solvents including methanol, ethanol, acetone, pyridine, 1,4-dioxane, dimethylformamide, dimethylsulfoxide, dichloromethane, and chloroform. Aggregation states of all phthalocyanines were investigated in the aforementioned solvents using UV–Vis spectroscopy method. All phthalocyanines were especially found highly aggregated in their aqueous solutions.

Synthesis of a N-doped mesoporous carbon as an efficient electrocatalyst for oxygen reduction

A facile and effective approach was developed for the preparation of mesoporous Fe-NC by pyrolyzing the mixture of FeCl2, urea, (NH4)2MoO7, phthalic anhydride and SBA-15, during which the in-situ formation of iron phthalocyanine is confirmed. The obtained catalyst exhibits high catalytic activity towards ORR, whose half-wave potential can be 53 mV more positive than that of commercial Pt/C catalyst. Besides, the catalyst also exhibits high selectivity of four electron path, along with excellent stability and methanol tolerance in alkaline media. Based on the characterization results, we suggest, the higher surface areas, highly porous structures induced by SBA-15 addition, as well as high graphitic N content should be the proper origins for its outstanding catalytic performance.

Supramolecular Arrangement of Iron Phthalocyanine in Langmuir-Schaefer and Electrodeposited Thin Films.

The supramolecular arrangement in thin film technology has been explored through different deposition techniques aiming to control the film properties at the molecular level. We report on the formation of iron phthalocyanine (FePc) films using both Langmuir-Schaefer (LS) and electrodeposition methods. The multilayer formation was monitored with ultraviolet-visible absorption spectroscopy (UV-vis) and electrochemical measurements. According to Raman spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), the surface morphology of electrodeposited films is more homogeneous than LS films at micro and nanometer scales. From FTIR spectroscopy, the FePc molecules in the electrodeposited films are oriented preferentially with the macrocycle parallel to the substrate surface (flat-on), while a slight tilt is suggested in LS films, being both films crystalline. Therefore, the use of different deposition techniques allowed the fabrication of thin films from FePc with distinct supramolecular arrangements, leading to distinct electrochemical properties. For instance, the electrodeposited films show higher surface coverage, suggesting a more compact structure, which favors the charge transfer and smaller energy gap. The possibility of tuning some properties according to deposition technique for the same material can help the development of technological applications such as electronic or sensing devices.

Regioregular Phthalocyanines Substituted with Bulky Donors at Non-Peripheral Positions.

Three regioregular phthalocyanines (1-3) were synthesized selectively by the cyclic tetramerization of phthalonitriles bearing a bulky diarylamine substituent at the next position of nitrile. The steric repulsion at the tetramerization of bulky phthalonitriles allowed for the selective formation of regioregular phthalocyanines as confirmed by NMR and single crystal X-ray structural analyses. The absorption spectrum of 1 substituted with di(4-tert-butylphenyl)amine groups at the non-peripheral positions showed a non-split Q-band at 764 nm, which was redshifted by 83 nm compared with that of metal free phthalocyanine (H2 Pc). The TD-DFT calculation and electrochemical studies prove that the substitution of diarylamine groups at the α-positions effectively destabilizes the HOMO energy level, which causes a large redshift of the Q-band. Moreover, 1 can generate a one-electron oxidation species through chemical oxidation. The Q-band position of 2 bearing 4,4'-dimetoxyphenylamine units was further shifted by 10 nm compared with that of 1. In addition, 3 having carbazole units showed a small redshift of the Q-band relative to H2 Pc. The hole-mobility of 2 in thin film was determined to be 1.1×10-5 cm V-1 s-1 by using a space charge limited current method. A perovskite solar cell employing 2 as a hole-transporting layer gave an efficiency of 5.1 % under standard global 100 Wcm-2 AM 1.5 G illumination.

Thermal selectivity of intermolecular versus intramolecular reactions on surfaces.

On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure.

New soluble octakis-substituted Co(II) phthalocyanines: Synthesis, spectra, supramolecular chemistry

The synthesis of (Octakis(3,5-di-tert-butylphenoxy)phthalocyaninato) cobalt(II) (CoPc(3,5-di-tBuPhO)8) was reported. The new phthalocyanine complex was characterized by UV–vis, IR, 1H NMR and mass spectra and elemental analysis. The supramolecule formation reactions of CoPc(3,5-di-tBuPhO)8 with pyridine (Py) and 2′-(4-pyridyl)-5′-(2-pyridyl)-1′-(3-pyridylmethyl)pyrrolidino[3′,4′:1,2][60]fullerene (Py3F) were studied in toluene by methods of chemical kinetics and thermodynamics, UV, visible, IR and 1H NMR spectroscopy. The addition of pyridine results in single-stage equilibrium between the donor-acceptor complex 1:1 and the initial cobalt phthalocyanine. The reaction with the substituted fullerene goes to the formation of phthalocyanine - fullerene 1:1 supramolecule in the kinetic mode. The product of supramolecular complexation were identified by spectral methods.

Colored single-chain polymeric nanoparticles via intramolecular copper phthalocyanine formation

Colored single-chain polymeric nanoparticles were synthesized by intramolecular formation of copper phthalocyanines from polystyrene-co-poly[4-((4-vinylbenzyl)oxy)phthalonitrile] under diluted conditions.

COMPLEX FORMATION OF 1,4-DIAZABICYCLO[2.2.2]OCTANE WITH COPPER(II) TETRASULFOPHTHALOCYANINE IN WATER SOLUTION

Information about copper tetrasulfophthalocyanine self-association in water solution and about complex formation process of it with DABCO is obtained. Formation of phthalocyanine π-π dimers is confirmed. Formation of monoligand complex CuPc-DABCO is shown. Formation of sandwich-type dimers is not detected.

Formation of phthalocyanines deprotonated forms and their interaction with Zn Ions in the system 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile at 298 K

The formation of deprotonated forms of tetra(t-butyl)phthalocyanine ((H2tButPc) and octa(pentoxy)-phthalocyanine (H2OAmPc) in the system acetonitrile-1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) at 298 K was studied by the method of spectrophotometric titration. With increasing DBU concentration sequential formation occurs of both mono- and douby deprotonated forms. The introduction of pentoxy groups into the fused benzene rings leads to a significant decrease in the acidity of the tetrapyrrole macrocycle compared with the tert-butyl substitution. The interaction of douby deprotonated forms of the phthalocyanines with zinc diacetate leads to the formation of metal complexes, the chelation constant of the latter is shown to correlate with the acidity of NH-protons in the nucleus of the macrocycle. For the chelation of more acidic tetra(t-butyl)-phthalocyanine an equimolar concentrations of zinc diacetate is sufficient, while the less acidic octa(pentoxy)-phthalocyanine requires almost 6-fold excess.

EPR investigation of the origin of the magnetic field effect on the dimerization of aluminum(III) and gallium(III) phthalocyanine chlorides in film structures

The origin of the magnetic field effect on the dimerization of aluminum(III) and gallium(III) phthalocyanine chloride films is revealed. The EPR technique is employed to demonstrate that the dimerization of the above coordination compounds occurs via a free radical pathway with the formation of phthalocyanine and OH radicals, thus resulting in the appearance of the magnetic moment in the studied compounds.

Interplay of cleaning and de-doping in oxygen plasma treated high work function indium tin oxide (ITO)

Indium tin oxide (ITO) is extensively used as a transparent electrode in photovoltaic cells and organic light emitting diodes. High surface work function (WF) of ITO is a crucial parameter for enhanced device performance. The ITO WF is usually around 4.3eV without any surface treatment. With surface treatments ITO WF, as high as 5.4eV has been reported. We designed a surface treatment method with which we achieved substantially high ITO surface work function of over 6.1eV. We observed changes in valence electronic structure and core levels, apart from surface cleaning. We also investigated interface formation of copper phthalocyanine (CuPc) on the high WF ITO. In the proximity of the interface the highest occupied energy level of CuPc was observed to be almost pinned to the Fermi level. We fabricated three simple devices with no to high treatment. The device results were observed to be consistent with the findings of electronic energy level alignment.

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

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