Metal-free Porphyrazine Research Articles

Improved Electrochemical Hydrogen Peroxide Detection Using a Nickel(II) Phthalimide-Substituted Porphyrazine Combined with Various Carbon Nanomaterials.

A metal-free porphyrazine derivative with peripheral phthalimide substituents was metallated with a nickel(II) ion. The purity of the nickel macrocycle was confirmed using HPLC, and characterized by MS, UV-VIS, and 1D (1H, 13C) and 2D (1H-13C HSQC, 1H-13C HMBC, 1H-1H COSY) NMR techniques. The novel porphyrazine was combined with various carbon nanomaterials, such as carbon nanotubes-single walled (SWCNTs) and multi-walled (MWCNTs), and electrochemically reduced graphene oxide (rGO), to create hybrid electroactive electrode materials. The carbon nanomaterials' effect on the electrocatalytic properties of nickel(II) cations was compared. As a result, an extensive electrochemical characterization of the synthesized metallated porphyrazine derivative on various carbon nanostructures was carried out using cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). An electrode modified with carbon nanomaterials GC/MWCNTs, GC/SWCNTs, or GC/rGO, respectively, was shown to have a lower overpotential than a bare glassy carbon electrode (GC), allowing for the measurement of hydrogen peroxide in neutral conditions (pH 7.4). It was shown that among the tested carbon nanomaterials, the modified electrode GC/MWCNTs/Pz3 exhibited the best electrocatalytic properties in the direction of hydrogen peroxide oxidation/reduction. The prepared sensor was determined to enable a linear response to H2O2 in concentrations ranging between 20-1200 µM with the detection limit of 18.57 µM and sensitivity of 14.18 µA mM-1 cm-2. As a result of this research, the sensors produced here may find use in biomedical and environmental applications.

X-ray and NMR structural studies of the series of porphyrazines with peripheral pyrrolyl groups

Magnesium(II) and metal-free porphyrazines containing peripheral 2-methyl-5-phenyl- or 2,3,5-triphenyl-1H-pyrrol-1-yl substituents were synthesized and subjected to physicochemical characterization, including high-resolution mass spectrometry, nuclear magnetic resonance, HPLC purity analysis, and UV-Vis spectroscopy, accompanied by the aggregation study in dichloromethane and pyridine. Single crystals of magnesium(II) porphyrazines were subjected to X-ray structure analysis. The presence of atropisomers of magnesium(II) porphyrazines with peripheral 2-methyl-5-phenyl- or 2,3,5-triphenyl-1H-pyrrol-1-yl substituents was noticed in the NMR study and was confirmed by crystal structure determination. The NMR and X-ray data provided the evidence for the hindered rotation of the asymmetrical peripheral pyrrolyl substituents in magnesium(II) porphyrazines which resulted in obtaining compounds composed of different types of atropisomers, other than α4, preferentially α3β and αβαβ.

Metal-free and metallo-porphyrazines with eight [5-thiopentyl 2-methoxy-4,6-bis (trifluoromethyl) benzoate] substituent

ABSTRACTThe reaction of (5-hydroxypentylthio magnesium porphyrazine) with 2-methoxy-4,6-bis(trifluoromethyl)benzoic acid in DCCI and PTSA, esterified MgPz having [5-thiopentyl 2-methoxy-4,6-bis(trifluoromethyl)benzoate] substituent was obtained. Further reactions of the metal-free porphyrazine with M2+(Mg, Co, Cu, Zn, Fe) acetates have produced the metallo-porphyrazines. Finally, by the reaction of FePzCl with pyridine or pyrazine compounds, [FePz(py)2] and [FePz(pyz)]n complexes were prepared as the novel stable complexes, respectively. The target compounds have been characterized by using different spectroscopic methods such as FT-IR, UV-Vis, mass, 1H, 13C, and 19F NMR together with elemental analysis. The aggregation and the solubility features were indicated in various concentrations and solvents.

Esterified porphyrazine complexes: Synthesis, characterization, aggregation behavior, and theoretical study

ABSTRACTMagnesium porphyrazine having eight 5-hydroxypentylthio groups at the peripheral positions, was synthesized from 2,3-bis(5-hydroxypentylthio) maleonitrile. By the esterification reaction of octakis(5-hydroxypentylthio) porphyrazinato] Mg(II) with 3,4,5-trimethoxybenzoic acid in dicyclohexylcarbodiimide and toluene-p-sulfonic acid, esterified MgPz appending [5-thiopentyl 2-methoxy-4,6-bis(trifluoromethyl) benzoate] substituent was obtained. Further reaction of the metal-free porphyrazine with Co(II), Cu(II), Zn(II), and Fe(II) acetates have produced the metallo-porphyrazines. By reacting FePzCl with pyridine or pyrazine, the monomeric bis-axial and the oligomeric complexes were synthesized as the novel stable complexes, respectively. Their characterizations were performed by using elemental analysis, FT-IR, 1H-NMR, 13C-NMR, mass and UV-Vis spectral data. The aggregation investigations carried out in different concentrations indicate that 3,4,5-trimethoxybenzyloxy-substituted porphyrazine compounds do not have any aggregation behavior in different concentrations. Quantum chemical computations were also done to the structural and electronic properties of target compounds.

Metallo-porphyrazines with eight [5-thiopentyl 3,4,5-tris(benzyloxy)benzoate] groups: Synthesis, characterization, aggregation, and solubility behavior

Metal-free and metallo-porphyrazines having eight 5-hydroxypentylthio units at the peripheral positions have been prepared from 2,3-bis(5-hydroxypentylthio)maleonitrile. By the esterification reaction of magnesium hydroxy-porphyrazine with 3,4,5-tris(benzyloxy)benzoic acid in dicyclohexylcarbodiimide and toluene-p-sulfonic acid, the reactivity of the hydroxypentyl units was indicated. On the other hand, iron porphyrazine derivatives with eight [5-thiopentyl 3,4,5-tris(benzyloxy)benzoate] groups attached to the periphery positions were synthesized. By the reaction of metal-free porphyrazine with iron (II) acetate and further processing with HCl solution, FePzCl was obtained. Finally, by reacting FePzCl with pyridine or pyrazine, [FePz(py)2] and [FePz(pyz)]n complexes were prepared, respectively. The characterizations of target complexes were carried out by utilizing different spectroscopic methods such as FT-IR, UV–vis, mass, 1H NMR, and 13C NMR together with elemental analysis.

Metal-free, metallo-, oligomeric, and monomeric porphyrazine complexes of (3-thiopropyl anthraquinone-2-carboxylate) units

Metal-free and several metallo-porphyrazines (M = Mg, 2H, Co, Cu, or Zn) carrying eight (3-thiopropyl anthraquinone-2-carboxylate) groups at the peripheral positions were synthesized from octakis(3-hydroxypropylthio)porphyrazinato] Mg(II). Symmetrically functionalized porphyrazines with eight ester units were soluble in common organic solvents. Chloro-octakis(3-thiopropyl anthraquinone-2-carboxylate) porphyrazinato iron(III) (FePzCl) was prepared by the reaction of metal-free porphyrazine with iron(II) acetate and further treatment with hydrochloric acid solution. The oligomeric structure [FePz(pyz)]n and the monomeric compound [FePz(py)2] were formed as stable complexes by reacting FePzCl with pyrazine and pyridine, respectively. The porphyrazine compounds were characterized by different spectroscopic methods.

The Extraction Ability and Sensitivity of Porphyrazine Derivatives Towards Some Transition Metal Cations

The synthesis of novel metal-free and magnesium porphyrazines, peripherally substituted with dithia-dioxa (S2O2) and tetrathia (S4) 14-membered macrocycles were performed by cyclotetramerization of (6Z)-1,3,4,9,10,12-hexahydro-2,5,8,11-benzo-dioxadithiacyclotetradecine-6,7-dicarbodinitrile (3) or (6Z)-1,3,4,9,10,12-hexahydro 2,5,8,11-benzotetrathiacyclotetradecine-6,7-dicarbodinitrile (5). The metal-free porphyrazines have been obtained by known route. The structure of compounds were characterized by elemental analysis and 1H, 13C NMR, IR, UV-vis, and MS spectral data. The solvent extraction properties of the synthesized compounds towards some metal cations, such as Ag(I), Hg(II), Cu(II), Mn(II), Cr(III), Ni(II), Pb(II), and Zn(II) have been investigated. The effect of Cu2+, Mn2+, Ni2+, Pb2+, Sr2+, Al3+, Zn2+, Ba2+, Cd2+, Co2+, Hg2+, and Ag+ ions on the absorption spectra of the compounds were investigated by means of spectrophotometric method. Magnesium porphyrazine with S2O2 (6) interacted within Hg2+ ion specifically of all the tested metal ions.

Metal-free, metallo-porphyrazines, monomeric bisaxial complex [FePz(py)2] and the bridged complex [FePz(pyz)]n with eight (4-thiobutyl 4-biphenylcarboxylate) groups

Metal-free and metallo-porphyrazines (M = Mg, Co, Cu, Zn, and ClFe) carrying eight hydroxybutylthio groups at peripheral positions were prepared from 2,3-bis(4-hydroxybutylthio) maleonitrile. The hydroxybutyl groups were incorporated by esterification of porphyrazine derivatives with 4-biphenylcarboxylic acid in the presence of dicyclohexylcarbodiimide and p-toluenesulfonic acid. Unlike the parent porphyrazine, the symmetrically functionalized porphyrazines with eight ester units were soluble in common organic solvents such as chloroform, dichloromethane, tetrahydrofuran, acetone, and toluene and insoluble in water and n-hexane. Chloro-octakis(4-thiobutyl 4-biphenylcarboxylate) porphyrazinato iron(III) (FePzCl) was prepared by the reaction of metal-free porphyrazine with iron(II) acetate and further treatment with HCl solution. The monomeric bisaxial complex [FePz(py)2] and the bridged complex [FePz(pyz)]n were formed as stable complexes by reacting FePzCl with pyridine and pyrazine, respectively. The newly synthesized compounds were characterized by elemental analysis, FT-IR, UV‒vis, mass, 1H and 13C NMR spectroscopy.

The synthesis and characterization of a shish kebab type oligomer with eight [3-thiopropyl 2-fluoro-5-(trifluoromethyl)phenylacetate] units

The functionality of hydroxypropylsulfanyl units of metal-free and metallo-porphyrazines, which are new compounds (M=2H, Mg, Co, Cu or Zn), has been produced by esterification with a carboxylate group such as 2-fluoro-5-(trifluoromethyl)phenylacetic acid. The symmetrically functionalized porphyrazines, with eight ester units, are soluble in common organic solvents such as chloroform, dichloromethane, tetrahydrofuran, dimethylsulfoxide, acetone and toluene, and insoluble in water and n-hexane. Chloro-octakis[3-thiopropyl 2-fluoro-5-(trifluoromethyl)phenylacetate] porphyrazinato iron(III) (FePzCl) was prepared by the reaction of the metal-free porphyrazine and iron(II) acetate, followed by treatment with HCl solution. The monomeric bis-axial complex [FePz(py)2], as well as the bridged complex [FePz(pyz)]n, were formed as stable complexes by reacting FePzCl with pyridine and pyrazine, respectively. The novel compounds have been characterized by several spectroscopic techniques, such as FT-IR, UV–Vis, mass, 1H, 13C and 19F NMR, and elemental analysis.

Highly symmetrical polyfluorinated porphyrazines

By cyclotetramerization of 2,3-bis[2-fluoro-5-(trifluoromethyl)benzylthio] maleonitrile in the presence of magnesium butanolate, magnesium porphyrazinate carrying eight (2-fluoro-5-(trifluoromethyl)benzylthio) functional groups on the periphery positions has been synthesized. Conversion of the magnesium porphyrazinate into the metal-free derivative was achieved by treatment with trifluoroacetic acid. Further reaction of this product with different metal (II) acetates have led to the metallo porphyrazines. Then, chloro-octakis [2-fluoro-5-(trifluoromethyl)benzylthio] porphyrazinato iron (III) (FePzCl) was prepared by the reaction of metal-free porphyrazine with iron (II) acetate and further treatment with HCl solution. The monomeric bisaxial complex FePz(py)2 as well as the bridged complex [FePz(pyz)]n were formed as stable complexes by reacting FePzCl with pyridine or pyrazine, respectively. These novel complexes were characterized by elemental analysis, together with FT-IR, 1H NMR, 13C NMR, 19F NMR, UV–vis and mass spectral data.

Synthesis and characterization of new metallo and metal-free porphyrazines containing dioxadithia (O2S2) and tetrathia (S4) macrocyclic moieties

Abstract The synthesis of new magnesium porphyrazines, peripherally substituted with 14-membered dioxa-dithia (O 2 S 2 ) and tetrathia (S 4 ) macrocycles has been accomplished by cyclotetramerization of (6Z)-1,3,4,9,10,12-hexahydro-2,5,8,11-benzodioxadithia-cyclotetradecine-6,7-dicarbonitrile ( 3 ) or (6Z)-1,3,4,9,10,12-hexahydro-2,5,8,11-benzotetrathiacyclotetradecine-6,7-dicarbonitrile ( 5 ) in the presence of magnesium butanolate. The precursors were prepared from disodium salt of dithiomaleonitrile and o -xylenebis(1-chloro-3-oxapentane) ( 2 ) or o -xylenebis(1-chloro-3-thiapentane) ( 4 ). The metal-free porphyrazines are obtained by the treatment of these magnesium porphyrazines with trifluoroacetic acid. These new compounds are characterized by a combination of elemental analysis and 1 H, 13 C NMR, IR, UV–vis and MS spectral data.

Specifics of singlet molecular oxygen photogeneration by copper porphyrazines

As applied to the photodynamic properties of porphyrazines, one of their crucial characteristics is the capacity for photochemical generation of sin glet molecular oxygen (О2, Δg), which involves energy transfer from the excited triplet molecules of these compounds to the dissolved molecular oxygen of air. The О2 yield provides indirect infor mation on the properties of excited triplet states of porphyrazines. As distinct from metal free por phyrazines and their compounds with metals in sta ble oxidation states, such as zinc and aluminum, porphyrazines containing a copper atom exhibit an ambiguous photochemical behavior [3, 5]. Detailed study of the reasons for such a behavior of copper porphyrazines provides deeper insight into the specific features of their photochemical prop erties and advances the solution of the problem of their practical use.

Synthesis and electron donating property of novel porphyrazines containing tetrathiacrown ether-linked tetrathiafulvalene moieties

Abstract Novel magnesium and metal-free porphyrazines (4 and 5) containing four peripheral tetrathiacrown ether-linked tetrathiafulvalene moieties have been synthesized and characterized. Their solution electrochemical data showed two reductive and three oxidative processes within a −1500 mV to +1500 mV potential window. UV/Vis spectroscopy and electron paramagnetic resonance (EPR) measurements reveal the formation of a charge-transfer complex between porphyrazine 4 with F4TCNQ. The single-crystal structure of the TTF-dicyanocrown ether 3 is presented.

Octakis (9-anthracenylmethylthio) Iron Porphyrazine Derivatives

Chloro[octakis(9-anthracenylmethylthio)porphyrazinato]iron(III), ([FePzCl]), was prepared by the reaction of metal-free porphyrazine with iron(II) acetate and further treatment with HCl solution. The monomeric bisaxial complex [FePz(py)2] as well as the bridged complex [FePz(pyz)] n were formed as stable complexes by reacting [FePzCl] with pyridine or pyrazine, respectively. These novel complexes were characterised by elemental analysis, together with FT-IR, 1H NMR, UV-Vis and mass spectral data.

Synthesis of polyphenylene dendrimeric tetrapyrazinoporphyrazines

In this study, new tetrapyrazinoporphyrazine derivatives containing both flexible (linear) and more rigid (dendritic) groups were synthesized. The absorption spectra of Mg-porphyrazines 5a and 5b showed that the splitted Q band at 653 and 736 nm caused the coupling of the transition moment between a pair (or more) of chromophores. The absorption spectra of metal-free porphyrazines 6 exhibited a well-resolved splitting of the Q x /Q y band in the 651–679 nm region and a broad B band in the 377 nm region. Synthesized tetrapyrazinoporphyrazine metal and metal-free complexes were characterized by UV–visible spectroscopy, MALDI-TOF-Ms (matrix-assisted laser desorption ionization time-of-flight mass) spectroscopy and 1H NMR spectroscopy.

Absorption, luminescence, and Raman spectroscopic properties of thin films of benzo-annelated metal-free porphyrazines

Thin film properties of the set of metal-free linearly benzo-annelated porphyrazines, tetra( tert-butyl)porphyrazine ( tBu-TAPH 2), tetra( tert-butyl)phthalocyanine ( tBu-PcH 2), tetra( tert-butyl)naphthalocyanine ( tBu-NpH 2), and octaphenyltetraanthraporphyrazine (AnH 2) were studied by laser excitation using micro-Raman and -luminescence spectroscopy. With the exception of tBu-TAPH 2 all compounds are characterized by a broad absorption pattern mainly due to excitonic coupling. A strong bathochromic energy shift for the Q-band absorption per annelated benzo-moiety was found in solution as well as in the solid state in going from tBu-TAPH 2 to AnH 2. Films of tBu-TAPH 2, tBu-PcH 2, and tBu-NpH 2 exhibit a single broad featureless luminescence band with a large Stokes shift, which originates from an excitonic state. In addition, tBu-TAPH 2 and tBu-NpH 2 exhibit photoluminescence peaks emerging from monomer-like molecules. These porphyrazines are the only ones known to show two luminescence peaks each. A systematic decrease in luminescence efficiency of thin films is observed and can be attributed to exciton coupling and migration leading to efficient quenching of the radiative decay channels. It also allows for Raman spectroscopic characterization of the thin films and for the case of tBu-NpH 2 in highly concentrated solutions.The different resonance Raman spectra of the compounds can be used as fingerprint for distinguishing the degree of benzo-annelation.

Synthesis and Aggregation of Tetrathiafulvalene-Annulated Porphyrazines

Magnesium(II)-porphyrazine (4) was prepared via a Mg-butoxide templated macrocyclization of 2,3-dicyano-6,7-dibutylthiotetrathiafulvalene in buthanol, and then 4 was converted to metal-free porphyrazine (5) by treatment with trifluoroacetic acid in the dark. 5 reacted with excess zinc acetate to give zinc(II)-porphyrazine (6) in the chlorobenzene. Their structure has been characterized by 1 H NMR, MALDI-TOF-MASS, UV-VIS, ESR and EA, and self-assembly behavior of 4 was studied with the help of TEM and DLS data. 4 self-assembled to spherical aggregates in toluene.

X-ray photoelectron spectroscopy of metal free porphyrazine, phthalocyanine and naphthalocyanine: density functional calculations

A theoretical investigation of the core-level electronic structure of metal free porphyrazine, phthalocyanine and naphthalocyanine based on density functional theory has been conducted. The sign-reversed energies of the N 1s orbital with small discrepancy of about 8 eV are reported, which is improved compared with that of previous SCF/DZ and SCF/DZP calculations, 25 eV. The sign-reversed energies of the C 1s orbital for these three compounds are reported for the first time also with discrepancy of about 8 eV. Our result has demonstrated that density functional calculations at B3LYP/6–31G(d) level are more suitable for studying the absolute core-level energies of phthalocyanine and its analogues and/or derivatives than SCF calculations, in addition to giving reasonable result on the relative changes in the core-level energies. A comparison between the core-level molecular orbital and X-ray photoelectron spectroscopy (XPS) properties for these molecules is made. The effect of extended π-electron conjugation on the N XPS properties of these compounds is discussed. The data of the C 1s orbital reported in the present work will be helpful for future experimental and theoretical XPS research works on these compounds.

Geometry and electronic structure of metal free porphyrazine, phthalocyanine and naphthalocyanine as well as their magnesium complexes

A theoretical investigation of the fully optimized geometries and electronic structures of metal free porphyrazine, phthalocyanine and naphthalocyanine as well as their magnesium derivatives based on density functional theory has been conducted. The optimized geometry at density functional theory level for naphthalocyanine is reported for the first time. A comparison between the different molecules for the geometry, molecular orbital and atom charge is made. The substituent effect of extended π-electron conjugation on the molecular structure of these compounds is discussed.

Photophysical properties of benzoannelated metal-free phthalocyanines

Symmetrically (1–4) and unsymmetrically (5–7) benzoannelated metal-free porphyrazines bearing tert-butyl substituents have been investigated in regard to their photophysical properties and their splitting behavior of the Q-band. Q-band splitting in the series of symmetrical tetraazaporphyrine (1), tetrabenzoporphyrazine (2), tetranaphthoporphyrazine (3), is decreased from ΔQ ∼2000 to ∼0cm−1 while the tetraanthraporphyrazine system (4) shows a low splitting of about ΔQ=265cm−1 again. In the unsymmetrically substituted series in going from tribenzomononaphthoporphyrazine (6) (ΔQ=903cm−1) to tribenzomonoanthraporphyrazine (7) (ΔQ=875cm−1) Q-band splitting is very similar while tribenzoporphyrazine (5) (ΔQ=2073cm−1) exhibits a drastic increase. In the series 1–4, fluorescence lifetimes 2.6, 5.5, 3.0, 0.5ns, fluorescence quantum yields 0.17, 0.44, 0.19, 0.01 and singlet oxygen quantum yields 0.53, 0.21, 0.03, <10−4 were determined. Fluorescence lifetimes of 5–7 are in the range 3.1–4.7ns. The absorption- and fluorescence spectra as well as the fluorescence lifetimes of the separated isomers of 5 do not differ.