Phthalocyanine Precursors Research Articles

Synthesis and Characterization of Vanadium Nitride/Carbon Nanocomposites.

The present work focuses on the synthesis of a vanadium nitride (VN)/carbon nanocomposite material via the thermal decomposition of vanadyl phthalocyanine (VOPC). The morphology and chemical structure of the synthesized compounds were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoemission spectroscopy (XPS). The successful syntheses of the VOPC and non-metalated phthalocyanine (H2PC) precursors were confirmed using FTIR and XRD. The VN particles present a needle-like morphology in the VN synthesized by the sol-gel method. The morphology of the VN/C composite material exhibited small clusters of VN particles. The XRD analysis of the thermally decomposed VOPC indicated a mixture of amorphous carbon and VN nanoparticles (VN(TD)) with a cubic structure in the space group FM-3M consistent with that of VN. The XPS results confirmed the presence of V(III)-N bonds in the resultant material, indicating the formation of a VN/C nanocomposite. The VN/C nanocomposite synthesized through thermal decomposition exhibited a high carbon content and a cluster-like distribution of VN particles. The VN/C nanocomposite was used as an anode material in LIBs, which delivered a specific capacity of 307 mAh g-1 after 100 cycles and an excellent Coulombic efficiency of 99.8 at the 100th cycle.

Gem-Dibromovinyl phthalonitriles: synthesis, structure elucidation, Hirshfeld surface analysis and energy framework calculations

A series of versatile phthalocyanine precursors, consisting of gem-dibromovinyl phthalonitrile derivatives, were synthesized and characterized by various spectroscopic and X-ray crystallographic techniques.

Highly Efficient Electrochemical Sensing of Acetaminophen by Cobalt Oxide-Embedded Nitrogen-Doped Hollow Carbon Spheres.

With respect to sensor application investigations, hollow mesoporous carbon sphere-based materials of the spinel type of cobalt oxide (Co3O4) and heteroatom-doped materials are gaining popularity. In this contribution, dopamine hydrochloride (DA) and cobalt phthalocyanine (CoPc) precursors were employed to construct a highly homogeneous Co3O4-embedded N-doped hollow carbon sphere (Co3O4@NHCS) by a straightforward one-step polymerization procedure. The resulting Co3O4@NHCS materials may effectively tune the surface area, defect sites, and doping amount of N and Co elements by altering the loading amount of CoPc. The relatively high surface area, greater spherical wall thickness, enriched defect sites, and better extent of N and Co sites are all visible in the best 200 mg loaded Co3O4@NHCS-2 material. This leads to significant improvement in pyridine and graphitic N site concentrations, which offers exceptional electrochemical performance. Electrochemical analysis was used to study the electrocatalytic activity of Co3O4@NHCSs towards the sensing of pharmacologically active significant compounds (acetaminophen). Excellent sensor properties include the linear range (0.001-0.2 and 1.0-8.0 mM), sensitivity, limit of detection (0.07 and 0.11 μM), and selectivity in the modified Co3O4@NHCSs/GCE. The authentic sample (acetaminophen tablet) produces a satisfactory result when used practically.

Electrochemical and in-situ spectroelectrochemical properties of novel (5-(tert-butyl)-2-((3,4-dicyanophenoxy)methyl)phenyl)methanolate substituted mononuclear metal phthalocyanines

This work involves the synthesis and characterization of metallic (Co, Fe, Mn, Ni, Zn) ball-type phthalocyanine precursors by using novel 4,4′-(((4-(tert-butyl)-1,2-phenylene)bis-(methylene))bis(oxy))diphthalonitrile starting compound. The classical oxo-bridge in phthalocyanines was altered with the -OCH2- bridge first time for these ball-type phthalocyanine precursors, and the effects of this change on the chemical, physical and spectral features of phthalocyanine complexes were investigated, in the study. The redox properties of phthalocyanines were researched by electrochemical and in situ spectroelectrochemical measurements on a Pt working electrode in non-aqueous medium. The color changes involved in the redox processes were observed via in situ electrocolorimetric techniques. Electrochemical and UV–Vis spectral measurements exhibited that the compounds had reversible and serial one-electron reduction and oxidation processes. Furthermore, they also had nitrile reduction processes because of opened nitrile groups located at peripheral tails of the phthalocyanine complexes. The plentiful redox conducts of the complexes such as Pc ring based and/or central redox active metal-based reduction and oxidation reactions at low potentials showed that these complexes can be used as functional materials. Because of the apparent spectral and net color changes, the complexes are suitable for utilization in electrochromic devices. Moreover, their rich redox features are a sign of their high electrocatalytic activity for oxygen reduction.

Tetraiodophthalocyanines: Simple and convenient synthetic protocol and structural modification via Sonogashira cross-coupling reaction

Planar and sandwich-type iodo-substituted phthalocyanines – precursors for cross-coupling reactions were synthesized starting from 4-iodophthalonitrile via a novel user-friendly synthetic strategy. For this purpose, 4-iodophthalonitrile was prepared following the multi-step protocol, including nonclassical version of diazotization/iodination reaction in the presence of p-toluenesulfonic acid. Tetraiodophthalocyaninato Zinc(II) was obtained using a solvent-free microwave-assisted synthesis. For the first time, the polyphosphoric acid was applied to the demetallation of halogen-substituted phthalocyanine complex. Under these conditions, demetallation of Zinc(II) complex occurred in a good yield without the oxidation of peripheral iodogroups. The Sonogashira cross-coupling reaction between the 2(3),9(10),16(17),23(24)-tetraiodophthalocyanine and model (trimethylsilyl)acetylene resulted in a target compound in a high yield (94%). The versatility of iodo-substituted phthalocyanine precursors was demonstrated on the examples of the synthesis of novel tetra-(3-hydroxyprop-1-yn-1-yl)- phthalocyaninato Zinc (II) (52% yield), bis[tetra(2-trimethyhilyethynyl)phthalocyaninato] Lutetium (III) (45% yield). Target compounds were identified by nuclear magnetic resonance, infrared spectroscopy, and mass spectrometry. UV–Vis properties of target compounds were investigated and compared with literature data. The key compounds were characterized by elemental analysis.

Iron–Cobalt-Based Materials: An Efficient Bimetallic Catalyst for Ammonia Synthesis at Low Temperatures

Ammonia is one of the most commonly produced chemicals in the industry. As a result, ∼1–2% of the world’s electrical energy is used, and it produces ∼1.5–2% of global CO2 emissions. Therefore, developing efficient catalysts at milder conditions is highly desirable. Here, efficient iron/cobalt catalysts for ammonia synthesis are prepared with different Fe/Co ratios from phthalocyanine precursors, resulting in Fe–Co bimetallic nanoparticles embedded in a porous carbon–nitrogen matrix. The incorporation of Co to the Fe catalyst up to 20% wt of Co leads to ∼40% enhancement in the activity compared to the monometallic Fe-based catalyst. Interestingly, catalysts exhibit excellent activity even at low temperatures (350 °C). Ea for the most efficient 6K–FePc80CoPc20 catalyst is found to be 29 kJ·mol–1, suggesting facile activation of N2 at low temperatures. An in-depth kinetic study revealed that introducing Co in the Fe catalysts drastically tuned the surface of the catalyst by weakening the various NHx retarding species. Density functional theory calculations confirm the thermodynamic feasibility for introducing 25% of Co at surface Fe sites. This indicates that the presence of Co on the surface draws negative charges from neighboring Fe sites, making the exposed Fe sites neutral and more favorable for N2 activation on the bimetallic K2O/Co–Fe catalyst and displaying a more thermodynamically feasible energy profile as compared to the pristine K2O/Fe catalyst.

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.

Edge-Functionalized Polyphthalocyanine Networks with High Oxygen Reduction Reaction Activity.

Two-dimensional (2D) conjugated aromatic networks (CAN) have been fabricated by ball milling of polymeric cobalt phthalocyanine precursors edge-functionalized with different aromatic acid anhydride substituents. The optimal CAN, obtained by using tetraphenylphthalic anhydride, consists of uniform and thin (2.9 nm) layers with a high BET surface (92 m2 g-1), resulting in well-defined Co-N4 active sites with a high degree of exposure. Thence, this material exhibits excellent electrocatalytic oxygen reduction reaction (44 mA mgcat.-1). Compared to a benchmark Pt/C catalyst, this value denotes 1.2- and 6.0-fold enhancements, respectively, in terms of the mass of Pt and total Pt/C. When utilized as air electrode catalysts in Zn-air batteries, this material provides a maximum areal power density (137 mW cm-2) and mass power density (0.68 W mgcat.-1), values which also clearly surpass those of benchmark Pt/C catalyst. This support-free and pyrolysis-free strategy developed in this work delivers a novel route for the applications of 2D materials in clean energy conversion and storage.

Design, synthesis, characterization of peripherally tetra-pyridine-triazole-substituted phthalocyanines and their inhibitory effects on cholinesterases (AChE/BChE) and carbonic anhydrases (hCA I, II and IX).

In this study, phthalocyanine precursors (5 and 9) and 1,2,3-triazole-substituted metal-free and metallo phthalocyanines (9a-c) were designed and synthesized for the first time and evaluated in vitro for key molecular targets. The structures of the novel compounds were characterized via FT-IR, 1H/13C NMR, UV-Vis, and mass spectroscopy. The inhibitory activities of the compounds were tested against human carbonic anhydrase isoforms hCA I, II (cytosolic, ubiquitous isozymes), and IX (transmembrane, cancer-associated isozyme) and cholinesterases (AChE and BChE, which are associated with Alzheimer's disease). Among the three phthalocyanines and starting compounds, 9b showed the most interesting profile as a nanomolar selective inhibitor of hCA I (Ki = 37.2 nM) and 9c showed the most effective inhibitory effect on hCA II, IX, AChE and BChE (Ki = 41.9, 27.4, 5.8 and 45.8 nM, respectively). This study is also the first example of cancer-associated isozyme hCA IX inhibition by phthalocyanines.

Development of catalysts for ammonia synthesis based on metal phthalocyanine materials

Highly efficient and very stable iron and/or cobalt-based catalysts for the ammonia synthesis reaction were synthesized by one-step pyrolysis of metal phthalocyanine precursors.

Covalent functionalization of graphene oxide with hyperbranched lanthanum phthalocyanines for improving optical limiting

Abstract Two graphene oxide (GO)-based nanohybrid materials possessing axially covalent linkages to lanthanum phthalocyanines (LaPc-GO) and hyperbranched lanthanum phthalocyanines (HBLaPc-GO) were prepared. Significant fluorescence quenching demonstrates electron transfer between lanthanum phthalocyanine precursors and GO. At the identical mass concentration of 0.1 mg mL−1, all the hybrids show stronger nonlinear optical (NLO) performance than the individual components, ascribed to a combination of nonlinear scattering and two-photon absorption with reverse saturable absorption and the photoinduced electron or energy transfer from the electron donor phthalocyanine moiety to the acceptor graphene. Due to the better dispersion and the more flexible electron/energy transfer, the HBLaPc-GO exhibits a stronger optical limiting response (the normalized transmittances decrease to 49%) and a larger nonlinear extinction coefficient (1.48 cm GW−1) than that of LaPc-GO hybrid.

Phthalocyanine Precursors To Construct Atomically Dispersed Iron Electrocatalysts

Carbon materials embedded with atomically dispersed metal sites have recently demonstrated intriguing performance as electrocatalysts. However, it remains challenging to construct abundant single m...

Low-Cost Sulfonated Phthalocyanines-Derived Hierarchical Porous Co-Cu-N-S-Doped Carbons for Efficient Oxygen Electroreduction

Low-cost commercial sulfonated phthalocyanines were converted into a series of porous multi-doped carbons with Co/Cu and N/S heteroatoms (Co-Cu-N-S-Cs). The water-soluble sulfonated copper (II) phthalocyanines and sulfonated cobalt (II) phthalocyanines could be coated on commercial silica nano-spheres with the interlinking of the acidized chitosan polymers, and the direct pyrolysis of such composites produced hierarchical porous carbons with abundant multi-doped sites. The Co-Cu-N-S-Cs exhibited the efficient electro-catalytic performance for oxygen reduction reaction (ORR) in both alkaline and acidic electrolytes. In particular, the ORR half-wave potential over Co-Cu-N-S-C-900 reached 0.85 V in 0.1 M KOH, 10 mV higher than Pt/C (20 wt%) electro-catalysts. Co-Cu-N-S-C-900 also demonstrated better stability and methanol-tolerance properties, in contrast to commercial Pt/C catalysts (JM, 20wt%). The mixed using of sulfonated Cu and Co phthalocyanine precursors help to balance the graphitization-related electron transportation and doping defects-related active site density in Co-Cu-N-S-C-900. These results indicated that low-cost and high-efficency multi-doped carbon-based electrocatalysts for ORR could be facile prepared using commercial sulfonated phthalocyanines.

High-efficiency copper-based electrocatalysts for oxygen electroreduction by heating metal-phthalocyanine at superhigh temperature

The highly efficient Cu-based ORR catalysts (Cu–N–C) were obtained by the pyrolysis of mesoporous KIT-6 silica-supported phthalocyanines at superhigh temperature (1000 °C). The prepared Cu–N–C catalyst was demonstrated as one of the best Cu-based electrocatalysts for ORR, with 0.82 V half-wave potential in 0.1 M KOH and 0.72 V half-wave potential in 0.1 M HClO4. It showed the competitive ORR activity to high-performance Fe- or Co-based carbon catalysts. Moreover, the ORR catalytic performance of Cu–N–C could be further enhanced by co-doping few Fe species (Fe–Cu–N–C) into the carbon framework. It revealed about 30 mV higher half-wave potential and better stability than Cu–N–C catalyst in both alkaline and acidic media. Cu–N–C and Fe–Cu–N–C electrocatalysts could be produced at a scale of over 15 g by facilely enlarging the amount of phthalocyanine precursors. The high-efficiency ORR performance and scalable synthesis of Cu–N–C and Fe–Cu–N–C catalysts enabled them to be the potential substitutes to Pt-based electrocatalyst for ORR.

Synthesis, characterization and aggregation and fluorescence properties of novel highly soluble zinc phthalocyanines bearing tetrakis-4-(3-(piperidin-1-yl)phenoxy) with tetra and dodecachloro substituents

The synthesis of two new phthalocyanine precursors 4-(3-(piperidin-1-yl)phenoxy) with mono (2) and trichloro (3) substituents were carried out in this work. Cyclotetramerization of these precursors with zinc acetate gave novel tetrakis-4-(3-(piperidin-1-yl)phenoxy) with tetra (4) and dodecachloro (5) substituted zinc phthalocyanines. The synthesized new compounds were characterized using FT-IR, 1H NMR, electronic absorption spectroscopy, mass spectra and elemental analysis. The aggregation behavior of zinc phthalocyanines 4 and 5 was investigated in different concentrations of dichloromethane (DCM). Zinc phthalocyanines 4 and 5 showed good solubility in different organic solvents such as DCM, CHCl3, THF, benzene and toluene. Further, the aggregation behavior of zinc phthalocyanines 4 and 5 was studied before and after the addition of Triton X100. Further, the fluorescence quantum yields of zinc phthalocyanines 4 and 5 were calculated in the presence and absence of Triton X100.

Water soluble quarternizable gallium and indium phthalocyanines bearing quinoline 5-sulfonic acid: Synthesis, aggregation, photophysical and electrochemical studies

Abstract In this work, we have presented the synthesis, characterization, photophysical properties and electrochemical characterization of new tetra α and β-substituted indium and gallium phthalocyanines MPcX(α- or β-HQSA) 4 {M = Ga(III) ( 3 ) ( 4 ) and In(III) ( 5 ) ( 6 ); X = Cl} attached with 1-hydroxy quinoline-5-sulfonic acid groups on non-periphery and their water-soluble quaternized counterpart. The non-periphery substituted phthalocyanines with axially counter chlorine anion exhibit high solubility and low aggregation tendency owing to bulky HQSA steric hindrance moieties. The novel phthalocyanine precursors, 3, 4, 5, 6 synthesis, characterization, photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence quantum yields and flouresans behavior) of their peripherally tetra substituted gallium and indium phthalocyanines are reported in this study. The new compounds ( 3, 4, 5, 6 ) have been characterized by using spectroscopic methods, FT-IR, 1 H NMR spectroscopy, electronic spectroscopy and Maldi-TOF spectra in addition to elemental analysis. General trends focus on fluorescence, photodegradation and singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO), water (H 2 O). The nature of the substituent and solvent effect on the photophysical and photochemical parameters of the substituted phthalocyanines ( 3, 4, 5, 6 ) are also reported. The effect of point of substitution on the electrochemical properties of newly synthesized phthalocyanine compounds, periphery (β-) and non-periphery (α-) substituted with 8-hydroxyquinoline-5-sulfonic acid group were evaluated.

Facile, liquid phase preparation of copper phthalocyanine microcrystals by means of thermal conversion of the dimethoxy-substituted solvent soluble phthalocyanine precursors

A simple procedure for the preparation of microcrystals of insoluble copper phthalocyanine (CuPc) by thermolysis of a dimethoxy-substituted precursor has been developed. Although the morphologies of the resultant microcrystals are practically independent from initial solution concentrations higher than ca. 0.03 mM of the dimethoxy-precursor, crystals with increased width are obtained with increasing the initial concentration of the precursor.

Novel highly soluble fluoro, chloro, bromo-phenoxy-phenoxy substituted zinc phthalocyanines; synthesis, characterization and photophysicochemical properties

The three new phthalocyanine precursors, 4-[4-(bromo phenoxy)phenoxy]phthalonitrile, 4-[4-(chlorophenoxy)phenoxy]phthalonitrile, 4-[4-(flourophenoxy)phenoxy]phthalonitrile (1, 2 and 3) were synthesized and characterized. The photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence quantum yields and fluorescence behavior) of their peripherally tetra substituted zinc phthalocyanines (4)-tetra[bromo phenoxy]phthalocyaninato zinc(II), (4)-tetra[chlorophenoxy]phthalocyaninato zinc(II), (4)-Tetra [flourophenoxy]phthalocyaninato zinc(II) (4, 5 and 6) were reported for the first time. The new compounds (1–6) were characterized by using spectroscopic methods, FT-IR, 1H NMR spectroscopy, electronic spectroscopy and mass spectra as well as elemental analysis. General trends focus on fluorescence, photodegradation and singlet oxygen quantum yields of these compounds in dimethylsulfoxide (DMSO), dimethylformamide (DMF) and tetrahydrofuran (THF). The nature of the substituent and solvent effects on the photophysical and photochemical parameters of the chloro, fluoro, bromo-phenoxy-phenoxy substituted phthalocyanines (4, 5 and 6) was also reported.

Effect of Chain Length on Thermal Conversion of Alkoxy-Substituted Copper Phthalocyanine Precursors

A series of dialkoxy-substituted copper phthalocyanine (CuPc) precursors (4a-4d) have been prepared by treating phthalonitrile with the corresponding lithium alkoxide under mild conditions. The precursors exhibited high solubilities in common organic solvents, including acetone, toluene, tetrahydrofuran (THF), CH(2)Cl(2), and CHCl(3). Elongation of the alkoxy chains improved the solubilities of the precursors effectively, and accordingly, the butoxy-substituted derivative (4d) showed the highest solubility among 4a-4d. X-ray crystallography clarified that the conjugated skeletons of 4a-4d are all isostructural, and have two alkoxy groups in a syn-conformation fashion, leading to highly bent structures. Thermal conversions of the precursors examined by thermogravimetry (TG) and differential thermal analysis (DTA) demonstrate that 4a was converted into CuPc via two distinct exothermic processes in the 200-250 °C temperature range, while 4d exhibits only one exothermic signal in the DTA. In the field emission scanning electron microscopy (FESEM) images of 4a, the presence of two types of distinct crystal morphology (prismatic and plate-like crystals) can be recognized, implying that the two observed exothermic processes in the DTA can be attributed to the different crystal morphologies of the samples rather than the step-by-step elimination of the alkoxy groups. The thermal formation of CuPc from the precursors has been unambiguously confirmed by X-ray powder diffraction, UV-vis spectroscopy, and elemental analysis. The precursors were converted into CuPc at lower temperature with increasing chain length, presumably because of the increased void volume in the crystals. Thermal conversion performed in the solution phase results in a bright blue-colored solution with prominent absorption bands in the 650-700 nm region, strongly supporting the formation of CuPc.

The synthesis of some phthalocyanines derived from bulky substituted phthalonitriles

Phthalocyanine precursors were prepared by displacement of the –CH proton in 1-chloro-3,4-dicyano-6-(1,1-dicarbethoxymethyl) benzene with 1-(chloromethyl)-2-methyl benzene and 1-(chloromethyl)-4-methyl benzene. Metallo-phthalocyanines were obtained by cyclotetramerization in the presence of template metal salts {Zn(CH 3COO) 2, CoCl 2, CuCl 2, and Pb(CH 3COO) 2·3H 2O} that possessed substituents to enhance the solubility of the macrocycle and reduce its propensity to aggregate in solution. The structures of the newly synthesized molecules were proposed according to elemental analysis and 1H NMR, FT-IR, Micro-TOF mass, MALDI-TOF mass and UV–vis spectral data.