Search

The demetallation reaction of sulfanyl magnesium(II) porphyrazine with N-ethylphthalimide substituents, followed by remetallation with manganese(II) salts, yields the corresponding manganese(III) derivative (Pz3) with high efficiency. This novel manganese(III) sulfanyl porphyrazine was characterized by HPLC and analyzed using UV-Vis, MS, and FT-IR spectroscopy. Electrochemical experiments of Pz3 conducted in dichloromethane revealed electrochemical activity of the new complex due to both manganese and N-ethylphthalimide substituents redox transitions. Subsequently, Pz3 was deposited on multiwalled carbon nanotubes (MWCNTs), and this hybrid material was then applied to glassy carbon electrodes (GC). The resulting hybrid electroactive electrode material, combining manganese(III) porphyrazine with MWCNTs, showed a significant decrease in overpotential of H2O2 oxidation compared to bare GC or GC electrodes modified with only carbon nanotubes (GC/MWCNTs). This improvement, attributed to the electrocatalytic performance of Mn3+, enabled linear response and sensitive detection of H2O2 at neutral pH. Furthermore, a glucose oxidase (GOx)-containing biosensing platform was developed by modifying the prepared GC/MWCNT/Pz3 electrode for the electrochemical detection of glucose. The bioelectrode incorporating the newly designed Pz3 exhibited good activity in the presence of glucose, confirming effective electronic communication between the Pz3, GOx and MWCNT surface. The linear range for glucose detection was 0.2–3.7 mM. [ABSTRACT FROM AUTHOR]

The demetallation reaction of sulfanyl magnesium(II) porphyrazine with N-ethylphthalimide substituents, followed by remetallation with manganese(II) salts, yields the corresponding manganese(III) derivative (Pz3) with high efficiency. This novel manganese(III) sulfanyl porphyrazine was characterized by HPLC and analyzed using UV-Vis, MS, and FT-IR spectroscopy. Electrochemical experiments of Pz3 conducted in dichloromethane revealed electrochemical activity of the new complex due to both manganese and N-ethylphthalimide substituents redox transitions. Subsequently, Pz3 was deposited on multiwalled carbon nanotubes (MWCNTs), and this hybrid material was then applied to glassy carbon electrodes (GC). The resulting hybrid electroactive electrode material, combining manganese(III) porphyrazine with MWCNTs, showed a significant decrease in overpotential of H2O2 oxidation compared to bare GC or GC electrodes modified with only carbon nanotubes (GC/MWCNTs). This improvement, attributed to the electrocatalytic performance of Mn3+, enabled linear response and sensitive detection of H2O2 at neutral pH. Furthermore, a glucose oxidase (GOx)-containing biosensing platform was developed by modifying the prepared GC/MWCNT/Pz3 electrode for the electrochemical detection of glucose. The bioelectrode incorporating the newly designed Pz3 exhibited good activity in the presence of glucose, confirming effective electronic communication between the Pz3, GOx and MWCNT surface. The linear range for glucose detection was 0.2–3.7 mM.

The present study investigates four iron(II/III) porphyrazines with extending pyrrolyl peripheral substituents to understand the impact of introduced phenyl rings on the macrocycle's electrochemical and spectroelectrochemical properties as well as their activity in oxidation reactions. The electrochemical studies showed six well-defined redox processes and quasi-reversible one-electron transfers—two originating from the iron cation and four related to the ring. Adding phenyl rings to the periphery increased the electrochemical gap by 0.1 V. The UV–Vis spectra changes were observed at the applied potential of −1.3 V with the presence of additional red-shifted bands. The oxidizing studies showed increased efficiency in the oxidation reaction of the reference substrate in the cases of Pz1 and Pz2 in both studied oxygen atom donors. The calculated reaction rates in t-BuOOH were 12.0 and 15.0 mmol/min, respectively, for Pz1 and Pz2, compared to 6.4 for Pz3 and 1.8 mmol/min for Pz4. The study identified potential applications for these porphyrazines in mimicking cytochrome P450 prosthetic groups for oxidation and hydroxylation reactions in the future. [ABSTRACT FROM AUTHOR]

Photodynamic therapy is known as an effective primary and adjuvant anticancer treatment. Compounds with improved properties or additional modalities are still needed to create an 'ideal' photosensitizer. In this article, we review cyanoarylporphyrazine dyes for photodynamic (anticancer) therapy that we have synthesised to date. The review provides information on the chemistry of cyanoarylporphyrazines, photophysical properties, cellular uptake features and the use of various carriers for selective delivery of cyanoarylporphyrazines to the tumour. The potential of cyanoarylporphyrazines as photodynamic anti-tumour agents also has been evaluated. The most interesting feature of cyanoarylporphyrazines is the dependence of the fluorescence quantum yield and excited state lifetime on the viscosity of the medium, which makes it possible to use them as viscosity sensors in photodynamic therapy. In the future, we expect that the unique combination of photosensitizer and viscosity sensor properties of cyanoarylporphyrazines will provide a tool for dosimetry and tailoring treatment regimens in photodynamic therapy to the individual characteristics of each patient. [ABSTRACT FROM AUTHOR]

Background and Objectives: Bladder cancer is one of the ten most common cancers causing a high mortality rate. Photodynamic therapy (PDT) is one of the promising ways to treat this disease. To increase the effectiveness of PDT it is necessary to ensure selective delivery of photosensitizer to the tumor. Selective delivery systems such as nano- and microparticles of calcium carbonate in the polymorphic modification of vaterite are of great interest to solve this problem. Therefore, the aim of this study was to investigate submicron particles of vaterite as agents for selective delivery of photosensitizer PzBn on human bladder T24 cell culture. Materials and Methods: Calcium carbonate particles were obtained by mixing equimolar solutions of CaCl2 and Na2CO3 salts in the presence of glycerol. PzBn was immobilized by adsorbing the substance on preliminarily synthesized vaterite particles. The loading efficiency was evaluated using the spectrophotometric method. The experiments were carried out on the T24 human bladder carcinoma cell line. Intracellular localization was assessed using fluorescent laser confocal scanning microscopy. The study of the dynamics of PzBnVp accumulation by cells was carried out by spectrophotometry. Dark toxicity and photodynamic activity were analyzed using the MTT test. Results: The efficiency of loading porphyrazine into vaterite particles is over 9%. It has been shown that PzBnVp is characterized by rather rapid accumulation by T24 cells: the maximum accumulation is recorded already 30 minutes after its addition, after which the intensity of the fluorescence signal remains at a constant level for 5 hours of observation. It has been demonstrated that PzBnVp is characterized by low dark toxicity with high photodynamic activity. Conclusion: The possibility of loading vaterite particles with the photodynamic dye porphyrazine has been demonstrated. A high rate of entry of vaterite particles into the cell and the release of the loaded photosensitizer from particles and its subsequent redistribution over subcellular structures have been shown. The preservation of the photodynamic activity of porphyrazine in the composition of vaterite particles and the absence of dark toxicity in the studied concentration range have been demonstrated. Vaterite particles can be considered as promising agents for the selective delivery of porphyrazine to the tumor in order to increase the efficiency of photodynamic therapy.

Ferrocene is useful in modern organometallic chemistry due to its versatile applications in material sciences, catalysis, medicinal chemistry, and diagnostic applications. The ferrocene moiety can potentially serve many purposes in therapeutics and diagnostics. In the course of this study, (6-bromo-1-oxohexyl)ferrocene was combined with dimercaptomaleonitrile sodium salt to yield a novel maleonitrile derivative. Subsequently, this compound was subjected to an autocyclotetramerization reaction using the Linstead conditions in order to obtain an octaferrocenyl-substituted magnesium(II) sulfanyl porphyrazine. Following that, both compounds—the maleonitrile derivative and the porphyrazine derivative—were subjected to physicochemical characterization using UV-Vis, ES-TOF, MALDI-TOF, and one-dimensional and two-dimensional NMR spectroscopy. Moreover, the sulfanyl porphyrazine was subjected to various photophysical studies, including optical absorption and emission measurements, as well as the evaluation of its photochemical properties. Values of singlet oxygen generation quantum yields were obtained in different organic solvents. The electrochemical properties of the synthesized compounds were studied using cyclic voltammetry. According to the electrochemical results, the presence of electron-withdrawing oxohexyl groups attached to ferrocene afforded significantly more positive oxidation potentials of the ferrocene-based redox process up to 0.34 V vs. Fc+/Fc. [ABSTRACT FROM AUTHOR]

By using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and OPBE/TZVP levels, the possibility of the existence of three Fe(V) complexes, each of which contains in the inner coordination sphere porphyrazine/trans-di[benzo]porphyrazine/tetra[benzo]porphyrazine (phthalocyanine), oxygen (O2−) and fluorine (F−) ions, was shown. Key geometric parameters of the molecular structure of these heteroligand complexes are given; it is noted that FeN4 chelate nodes, and all metal-chelate and non-chelate cycles in each of these compounds, are practically planar with the deviation from coplanarity, as a rule, by no more than 0.5°. Furthermore, the bond angles between two nitrogen atoms and an Fe atom are equal to 90°, or less than this by no more than 0.1°, while the bond angles between donor atoms N, Fe, and O or F, in most cases, albeit insignificantly, differ from this value. Nevertheless, the bond angles formed by Fe, O and F atoms are exactly 180°. It is shown that good agreement occurs between the structural data obtained using the above two versions of the DFT method. NBO analysis data for these complexes are presented; it is noted that, according to both DFT methods used, the ground state of the each of three complexes under consideration may be a spin quartet or spin doublet. Additionally, standard thermodynamic parameters of formation (standard enthalpy ∆fH0, entropy S0 and Gibbs's energy ∆fG0) for the macrocyclic compounds under consideration are calculated. [ABSTRACT FROM AUTHOR]

By using the data of the DFT quantum chemical calculation in the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of a manganese(VI) heteroligand complex containing porphyrazine or its tetra[benzo] derivative (phthalocyanine) and two oxygen (O2−) ligands, which is still unknown for this element, is shown. The parameters of the molecular structure, multiplicity of the ground state, NBO analysis data and standard thermodynamic parameters (enthalpy ΔH0f, entropy S0f and Gibbs's energy ΔG0f of formation) of each of these metal macrocyclic compounds are presented. Additionally, it is noted that, based on the totality of structural data obtained by the above versions of the DFT method, the existence of a similar complex of manganese with di[benzo] derivative of porhyrazine and two oxygen (O2−) ligands seems doubtful. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is a rapidly developing modality of primary and adjuvant anticancer treatment. The main trends today are the search for new effective photodynamic agents and the creation of targeted delivery systems with the function of controlling the release of the agent in the tumor. Recently, the new group of cyanoarylporphyrazine dyes was reported, which combine the properties of photosensitizers and sensors of the local microenvironment. Such unique characteristics allow the release of the photosensitizer from the transport carrier to be assessed in real time in vivo. The aim of the present work was to compare the photophysical and photobiological properties of tetra(2-naphthyl)tetracyanoporphyrazine and its newly synthesized Fe(II) complex. We have shown that the chelation of the Fe(II) cation with the porphyrazine macrocycle leads to a decrease in molar extinction and an increase in the quantum yield of fluorescence and photostability. We demonstrate that the iron cation significantly affects the rate of dye accumulation in cells, the dark toxicity and photodynamic activity, and the direction of the changes depends on the particular cell line. However, in all the cases, the photodynamic index of a metal complex was higher than that of a metal-free base. In general, both of the compounds were found to be very promising for PDT, including for the use with transport delivery systems, and can be recommended for further in vivo studies. [ABSTRACT FROM AUTHOR]

Iron(III) porphyrazines containing peripheral 2,5-dimethyl-, 2-methyl-5-phenyl-, and 2,3,5-triphenyl-1H-pyrrol-1-yl substituents were synthesized and subjected to physicochemical characterization. This was accomplished by high-resolution mass spectrometry, nuclear magnetic resonance (as diamagnetic Fe(II) derivatives), HPLC purity analysis, and UV-Vis spectroscopy, accompanied by the solvation study in dichloromethane and pyridine. X-ray structure analysis was performed for a single crystal of the previously obtained 2,5-diphenyl-substituted derivative of porphyrazine complex (5d). The octahedral geometries of iron cation, present in the porphyrazine core, influenced the packing mode of molecules in the crystals. Mössbauer studies, performed for solid samples of iron porphyrazines, indicated that low-spin reduced iron states might occupy low- or high-symmetry binding sites. It was found that the hyperfine parameters and the subsequent contribution of the iron cations depend on the number of phenyl groups surrounding the pyrrolyl moiety. For iron(II) porphyrazine 2,3,5-triphenylpyrrol-1-yl substituents (5b), a high-spin ferrous state fraction was observed. Temperature-dependent measurements showed that the freed rotation of the peripheral porphyrazine ligands and the increased flexibility of the macrocycle ring result in the Fe2+ ion being stabilized in a diamagnetic state at a binding site of high symmetry at room temperature in the solid state. This process is most probably stimulated by the range of collective motions of the polymeric ribbons consisting of iron(II) porphyrazines observed in the X-ray. [ABSTRACT FROM AUTHOR]

The present study investigates four iron(II/III) porphyrazines with extending pyrrolyl peripheral substituents to understand the impact of introduced phenyl rings on the macrocycle’s electrochemical and spectroelectrochemical properties as well as their activity in oxidation reactions. The electrochemical studies showed six well-defined redox processes and quasi-reversible one-electron transfers—two originating from the iron cation and four related to the ring. Adding phenyl rings to the periphery increased the electrochemical gap by 0.1 V. The UV–Vis spectra changes were observed at the applied potential of −1.3 V with the presence of additional red-shifted bands. The oxidizing studies showed increased efficiency in the oxidation reaction of the reference substrate in the cases of Pz1 and Pz2 in both studied oxygen atom donors. The calculated reaction rates in t-BuOOH were 12.0 and 15.0 mmol/min, respectively, for Pz1 and Pz2, compared to 6.4 for Pz3 and 1.8 mmol/min for Pz4. The study identified potential applications for these porphyrazines in mimicking cytochrome P450 prosthetic groups for oxidation and hydroxylation reactions in the future.

Magnesium(II) sulfanyl porphyrazine with peripheral morpholinethoxy substituents was embedded on the surface of titanium(IV) dioxide nanoparticles. The obtained nanocomposites were characterized with the use of particle size and distribution (NTA analysis), electron microscopy (SEM), thermal analysis (TGA), FTIR–ATR spectroscopy, and X-ray powder diffraction (XRD). The measured particle size of the obtained material was 327.4 ± 15.5 nm. Analysis with XRD showed no visible changes in the crystallinity of the material after deposition of porphyrazine on the TiO2 surface. However, SEM images revealed noticeable changes in the morphology of the obtained hybrid material: higher aggregation and less ordered structure of the aggregates. The TGA analysis revealed the lost 3.6% (0.4 mg) of the mass of obtained material in the range 250–550 °C. In the FTIR–ATR analysis, C-H stretching vibratins in the range of 3000–2800 cm−1, originating from porphyrazine moieties, were detected. The photocatalytic applicability of the nanomaterial was assessed in photodegradation studies of methylene blue and bisphenol A as reference environmental pollutants. In addition, the photocatalytic degradation of carbamazepine with porphyrazine/TiO2 hybrids as photocatalysts was studied, accompanied by an HPLC chromatography assessment of photodegradation. In total, 43% of the initial concentration was achieved in the case of bisphenol A, after 4 h of irradiation, whereas 57% was achieved in the case of carbamazepine. In each photodegradation reaction, the activity of the obtained photocatalytic nanomaterial was proved with almost linear degradation. The photodegradation reaction rate constants were calculated, and revealed 5.75 × 10−5 s−1 for bisphenol A and 5.66 × 10−5 s−1 for carbamazepine. [ABSTRACT FROM AUTHOR]

Ferrocene is useful in modern organometallic chemistry due to its versatile applications in material sciences, catalysis, medicinal chemistry, and diagnostic applications. The ferrocene moiety can potentially serve many purposes in therapeutics and diagnostics. In the course of this study, (6-bromo-1-oxohexyl)ferrocene was combined with dimercaptomaleonitrile sodium salt to yield a novel maleonitrile derivative. Subsequently, this compound was subjected to an autocyclotetramerization reaction using the Linstead conditions in order to obtain an octaferrocenyl-substituted magnesium(II) sulfanyl porphyrazine. Following that, both compounds—the maleonitrile derivative and the porphyrazine derivative—were subjected to physicochemical characterization using UV-Vis, ES-TOF, MALDI-TOF, and one-dimensional and two-dimensional NMR spectroscopy. Moreover, the sulfanyl porphyrazine was subjected to various photophysical studies, including optical absorption and emission measurements, as well as the evaluation of its photochemical properties. Values of singlet oxygen generation quantum yields were obtained in different organic solvents. The electrochemical properties of the synthesized compounds were studied using cyclic voltammetry. According to the electrochemical results, the presence of electron-withdrawing oxohexyl groups attached to ferrocene afforded significantly more positive oxidation potentials of the ferrocene-based redox process up to 0.34 V vs. Fc+/Fc.

A new supramolecular electrocatalyst for Oxygen Evolution Reaction (OER) was synthesized from a central multibridging cobalt tetrapyridylporphyrazine (CoTPyPz) species by attaching four [Ru(bpy)2Cl]+ groups. Both CoTPyPz and the tetraruthenated cobalt porphyrazine species, TRuCoTPyPz, form very homogenous molecular films just by dropcasting their methanol solutions onto GCE electrodes. Such films exhibited low overpotentials for O2 evolution, e.g., 560 e 340 mV, respectively, displaying high stability, typically exceeding 15 h. The kinetic parameters obtained from the Tafel plots showed that the peripheral complexes are very important for the electrocatalytic activity. Hyperspectral Raman images taken along the electrochemical process demonstrated that the cobalt center is the primary active catalyst site, but its performance is enhanced by the ruthenium complexes, which act as electron-donating groups, in the supramolecular system. [ABSTRACT FROM AUTHOR]

A sulfanyl porphyrazine derivative with peripheral phthalimide moieties was metallated with cobalt(II) and iron(II) metal ions. The purity of the macrocycles was confirmed by HPLC, and subsequently, compounds were characterized using various analytical methods (ES-TOF, MALDI-TOF, UV–VIS, and NMR spectroscopy). To obtain hybrid electroactive electrode materials, novel porphyrazines were combined with multiwalled carbon nanotubes. The electrocatalytic effect derived from cobalt(II) and iron(II) cations was evaluated. As a result, a significant decrease in the overpotential was observed compared with that obtained with bare glassy carbon (GC) or glassy carbon electrode/carbon nanotubes (GC/MWCNTs), which allowed for sensitive determination of hydrogen peroxide in neutral conditions (pH 7.4). The prepared sensor enables a linear response to H2O2 concentrations of 1–90 µM. A low detection limit of 0.18 μM and a high sensitivity of 640 μA mM−1 cm−2 were obtained. These results indicate that the obtained sensors could potentially be applied in biomedical and environmental fields. [ABSTRACT FROM AUTHOR]

Fused aromatic networks (FANs) have been studied in efforts to overcome the low physicochemical stability of metal–organic frameworks (MOFs) and covalent organic frameworks (COFs), while preserving crystallinity. Herein, we describe the synthesis of a highly stable and crystalline FAN (denoted as Pz‐FAN) using pyrazine‐based building blocks to form porphyrazine (Pz) linkages via an irreversible reaction. Unlike most COFs and FANs, which are synthesized from two different building blocks, the new Pz‐FAN is formed using a single building block by self‐cyclotetramerization. Controlled and optimized reaction conditions result in a highly crystalline Pz‐FAN with physicochemical stability. The newly prepared Pz‐FAN displayed a high magnitude (1.16×10−2 S cm−1) of proton conductivity compared to other reported FANs and polymers. Finally, the Pz‐FAN‐based membrane was evaluated for a proton‐exchange membrane fuel cell (PEMFC), which showed maximum power and current densities of 192 mW cm−2 and 481 mA cm−2, respectively. [ABSTRACT FROM AUTHOR]

• MAOS approach was applied in the cross-coupling reactions leading to porphyrazines. • MAOS approach was used in the Paal-Knorr reaction towards diaminomaleonitriles. • Optical and electrochemical properties of porphyrazines were assessed. Cross-coupling Suzuki-Miyaura reaction using Microwave Assisted Organic Synthesis (MAOS) approach of phenylboronic acid and magnesium(II) porphyrazines with peripheral dimethylamino and 3,4-dibromo-2,5-diphenylpyrrol-1-yl or 3-bromo-2,4,5-triphenylpyrrol-1-yl groups led to magnesium(II) porphyrazines with dimethylamino and 2,3,4,5-tetraphenylpyrrol-1-yl groups. MAOS approach was also used in the Paal-Knorr reaction to synthesise the modified diaminomaleonitrile intermediates. All intermediates and macrocycles were characterized using UV-Vis, 1H and 13C NMR spectroscopy, as well as ES or MALDI MS spectrometry. The optical and electrochemical properties of obtained porphyrazine macrocycles were assessed. It was found that the susceptibility of new macrocycles to oxidation/reduction processes analyzed by cyclic and differential pulse voltammetry depended on the presence of bromide and the number of phenyl substituents in the macrocyclic periphery. [ABSTRACT FROM AUTHOR]

By using quantum chemical calculation data obtained by the DFT method with the B3PW91/TZVP and OPBE/TZVP levels, the possibility of the existence of three Fe(V) complexes, each of which contains in the inner coordination sphere porphyrazine/trans-di[benzo]porphyrazine/tetra[benzo]porphyrazine (phthalocyanine), oxygen (O2−) and fluorine (F−) ions, was shown. Key geometric parameters of the molecular structure of these heteroligand complexes are given; it is noted that FeN4 chelate nodes, and all metal-chelate and non-chelate cycles in each of these compounds, are practically planar with the deviation from coplanarity, as a rule, by no more than 0.5°. Furthermore, the bond angles between two nitrogen atoms and an Fe atom are equal to 90°, or less than this by no more than 0.1°, while the bond angles between donor atoms N, Fe, and O or F, in most cases, albeit insignificantly, differ from this value. Nevertheless, the bond angles formed by Fe, O and F atoms are exactly 180°. It is shown that good agreement occurs between the structural data obtained using the above two versions of the DFT method. NBO analysis data for these complexes are presented; it is noted that, according to both DFT methods used, the ground state of the each of three complexes under consideration may be a spin quartet or spin doublet. Additionally, standard thermodynamic parameters of formation (standard enthalpy ∆fH0, entropy S0 and Gibbs’s energy ∆fG0) for the macrocyclic compounds under consideration are calculated.

By using the data of the DFT quantum chemical calculation in the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of a manganese(VI) heteroligand complex containing porphyrazine or its tetra[benzo] derivative (phthalocyanine) and two oxygen (O2−) ligands, which is still unknown for this element, is shown. The parameters of the molecular structure, multiplicity of the ground state, NBO analysis data and standard thermodynamic parameters (enthalpy ΔH0f, entropy S0f and Gibbs’s energy ΔG0f of formation) of each of these metal macrocyclic compounds are presented. Additionally, it is noted that, based on the totality of structural data obtained by the above versions of the DFT method, the existence of a similar complex of manganese with di[benzo] derivative of porhyrazine and two oxygen (O2−) ligands seems doubtful.

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.

Photodynamic therapy (PDT) is a rapidly developing modality of primary and adjuvant anticancer treatment. The main trends today are the search for new effective photodynamic agents and the creation of targeted delivery systems with the function of controlling the release of the agent in the tumor. Recently, the new group of cyanoarylporphyrazine dyes was reported, which combine the properties of photosensitizers and sensors of the local microenvironment. Such unique characteristics allow the release of the photosensitizer from the transport carrier to be assessed in real time in vivo. The aim of the present work was to compare the photophysical and photobiological properties of tetra(2-naphthyl)tetracyanoporphyrazine and its newly synthesized Fe(II) complex. We have shown that the chelation of the Fe(II) cation with the porphyrazine macrocycle leads to a decrease in molar extinction and an increase in the quantum yield of fluorescence and photostability. We demonstrate that the iron cation significantly affects the rate of dye accumulation in cells, the dark toxicity and photodynamic activity, and the direction of the changes depends on the particular cell line. However, in all the cases, the photodynamic index of a metal complex was higher than that of a metal-free base. In general, both of the compounds were found to be very promising for PDT, including for the use with transport delivery systems, and can be recommended for further in vivo studies.

A series of calcium carbonate particles with sizes of 500 ± 80 and 200 ± 90 nm were obtained using mass crystallization in aqueous salt solutions by varying the reaction conditions and adding glycerol or a combination of polyethylene glycol, polysorbat-80 and cell cultural medium to the reaction volume. Calcium carbonate nanoparticles of 50 ± 30 nm in diameter were synthesized within the pores of mesoporous silica particles with a subsequent etching out of the template material. A complete characterization of the particles was carried out using scanning and transmission electron microscopy, X-ray powder diffraction, and dynamic and electrophoretic light scattering. CaCO3 particles were loaded with anticancer drugs, porphyrazine and doxorubicin, with an encapsulation efficiency of 2–5 and 4–11 wt.%, respectively. The spontaneous release at pH 7 reached 15%, and when the particles are dissolved at pH 4, the release was about 45% of the substance during the day, regardless of the encapsulated substance. Functionalization of the surface of calcium carbonate particles with a biocompatible Pluronic-folic acid conjugate did not affect the particle size distribution and aggregative stability for all three samples. The effect of coatings on the rate of internalization and accumulation of particles by cells expressing folic acid receptors was established. It was also shown that the internalization of 50 ± 30 nm particles was more active than other samples.

Iron(III) porphyrazines containing peripheral 2,5-dimethyl-, 2-methyl-5-phenyl-, and 2,3,5-triphenyl-1H-pyrrol-1-yl substituents were synthesized and subjected to physicochemical characterization. This was accomplished by high-resolution mass spectrometry, nuclear magnetic resonance (as diamagnetic Fe(II) derivatives), HPLC purity analysis, and UV-Vis spectroscopy, accompanied by the solvation study in dichloromethane and pyridine. X-ray structure analysis was performed for a single crystal of the previously obtained 2,5-diphenyl-substituted derivative of porphyrazine complex (5d). The octahedral geometries of iron cation, present in the porphyrazine core, influenced the packing mode of molecules in the crystals. Mössbauer studies, performed for solid samples of iron porphyrazines, indicated that low-spin reduced iron states might occupy low- or high-symmetry binding sites. It was found that the hyperfine parameters and the subsequent contribution of the iron cations depend on the number of phenyl groups surrounding the pyrrolyl moiety. For iron(II) porphyrazine 2,3,5-triphenylpyrrol-1-yl substituents (5b), a high-spin ferrous state fraction was observed. Temperature-dependent measurements showed that the freed rotation of the peripheral porphyrazine ligands and the increased flexibility of the macrocycle ring result in the Fe2+ ion being stabilized in a diamagnetic state at a binding site of high symmetry at room temperature in the solid state. This process is most probably stimulated by the range of collective motions of the polymeric ribbons consisting of iron(II) porphyrazines observed in the X-ray.

Magnesium(II) sulfanyl porphyrazine with peripheral morpholinethoxy substituents was embedded on the surface of titanium(IV) dioxide nanoparticles. The obtained nanocomposites were characterized with the use of particle size and distribution (NTA analysis), electron microscopy (SEM), thermal analysis (TGA), FTIR–ATR spectroscopy, and X-ray powder diffraction (XRD). The measured particle size of the obtained material was 327.4 ± 15.5 nm. Analysis with XRD showed no visible changes in the crystallinity of the material after deposition of porphyrazine on the TiO2 surface. However, SEM images revealed noticeable changes in the morphology of the obtained hybrid material: higher aggregation and less ordered structure of the aggregates. The TGA analysis revealed the lost 3.6% (0.4 mg) of the mass of obtained material in the range 250–550 °C. In the FTIR–ATR analysis, C-H stretching vibratins in the range of 3000–2800 cm−1, originating from porphyrazine moieties, were detected. The photocatalytic applicability of the nanomaterial was assessed in photodegradation studies of methylene blue and bisphenol A as reference environmental pollutants. In addition, the photocatalytic degradation of carbamazepine with porphyrazine/TiO2 hybrids as photocatalysts was studied, accompanied by an HPLC chromatography assessment of photodegradation. In total, 43% of the initial concentration was achieved in the case of bisphenol A, after 4 h of irradiation, whereas 57% was achieved in the case of carbamazepine. In each photodegradation reaction, the activity of the obtained photocatalytic nanomaterial was proved with almost linear degradation. The photodegradation reaction rate constants were calculated, and revealed 5.75 × 10−5 s−1 for bisphenol A and 5.66 × 10−5 s−1 for carbamazepine.

[Display omitted] • Deprotonation/protonation and dehydrogenation/hydrogenation are crucial characteristics and common reaction of porphyrins and porphyrinoids. • The most fundamental impact is believed on the molecular configuration and electronic distribution to weaken the molecular aromaticity, or even transform to anti-aromaticity have always been of interest. • In this study, taking porphyrazine as the object, we used the classical aromaticity descriptors to discuss the main conjugated paths and compare aromaticity in terms of magnetic property, geometric structure and electronic delocalization upon the deprotonation/protonation and dehydrogenation/hydrogenation. • The molecular UV–vis spectra were simulated theoretically and the frontier orbitals excitation characteristics were analyzed to identify the aromaticity modulation effect. It is found that the aromaticity of porphyrazine is modulated with the number of H or H+ regulation in the molecular structure, the photophysical properties of each molecule change significantly • Particularly, as the parent of the star molecule phthalocyanine, this work on the aromaticity regulation of PZ will play a forward-looking role in the theoretical and experimental exploration of the physical and chemical properties of phthalocyanine and its derivatives. Deprotonation/protonation is crucial characteristics of porphyrins and porphyrinoids solutions, and dehydrogenation/hydrogenation is also a common reaction in porphyrinoids synthesis as well. These processes fundamentally impact the molecular configuration and electronic distribution, leading to the weakening of molecular aromaticity, and this transformation may even result in the anti-aromaticity of the system. In this study, taking porphyrazine as the object, we used the classical aromaticity descriptors to discuss the main conjugation pathways and compare aromaticity in terms of magnetic property, geometric structure and electronic delocalization upon the deprotonation/protonation and dehydrogenation/hydrogenation. The molecular UV–vis spectra were simulated theoretically, and the frontier orbitals excitation characteristics were analyzed to identify the aromaticity modulation effect. It is found that the aromaticity of porphyrazine is modulated with the number of H or H+ regulations in the molecular structure, the photophysical properties of each molecule change significantly. [ABSTRACT FROM AUTHOR]

A sulfanyl porphyrazine derivative with peripheral phthalimide moieties was metallated with cobalt(II) and iron(II) metal ions. The purity of the macrocycles was confirmed by HPLC, and subsequently, compounds were characterized using various analytical methods (ES-TOF, MALDI-TOF, UV–VIS, and NMR spectroscopy). To obtain hybrid electroactive electrode materials, novel porphyrazines were combined with multiwalled carbon nanotubes. The electrocatalytic effect derived from cobalt(II) and iron(II) cations was evaluated. As a result, a significant decrease in the overpotential was observed compared with that obtained with bare glassy carbon (GC) or glassy carbon electrode/carbon nanotubes (GC/MWCNTs), which allowed for sensitive determination of hydrogen peroxide in neutral conditions (pH 7.4). The prepared sensor enables a linear response to H2O2 concentrations of 1–90 µM. A low detection limit of 0.18 μM and a high sensitivity of 640 μA mM−1 cm−2 were obtained. These results indicate that the obtained sensors could potentially be applied in biomedical and environmental fields.

A new supramolecular electrocatalyst for Oxygen Evolution Reaction (OER) was synthesized from a central multibridging cobalt tetrapyridylporphyrazine (CoTPyPz) species by attaching four [Ru(bpy)2Cl]+ groups. Both CoTPyPz and the tetraruthenated cobalt porphyrazine species, TRuCoTPyPz, form very homogenous molecular films just by dropcasting their methanol solutions onto GCE electrodes. Such films exhibited low overpotentials for O2 evolution, e.g., 560 e 340 mV, respectively, displaying high stability, typically exceeding 15 h. The kinetic parameters obtained from the Tafel plots showed that the peripheral complexes are very important for the electrocatalytic activity. Hyperspectral Raman images taken along the electrochemical process demonstrated that the cobalt center is the primary active catalyst site, but its performance is enhanced by the ruthenium complexes, which act as electron-donating groups, in the supramolecular system.

Molecular structure calculations of macrotetracyclic metal complexes containing a scan-dium(III) ion, a macrocyclic (N,N,N,N)-donor ligand (porphyrazine, trans-dibenzoporphyrazine, tetrabenzoporphyrazine), and a F− anion were carried out at the OPBE/TZVP level of the density functional theory. The most important bond lengths, bond angles, and non-bond angles in these heteroligand metal complexes were determined. All complexes have distorted tetragonal-pyramidal structures where the complex-forming agent ScIII is above the basal plane formed by the donor nitrogen atoms. The distance between the ScIII atom and the basal plane somewhat decreases in the order porphyrazine—trans-dibenzoporphyrazine—tetrabenzopor-phyrazine. Although all six-membered metal chelate rings in each complex are identical to one another, none of them is planar; on the contrary, all five-membered rings are planar. The standard enthalpies, entropies, and Gibbs energies of formation of the metal complexes in question were determined. Different metal complexes are characterized by different numerical values of the same thermodynamic parameters. [ABSTRACT FROM AUTHOR]

In this paper, we introduce a fluorescent dye 1, which is able to detect selectively Pd2+ by a clear fluorescence enhancement (FE) in THF. In the presence of eight Pd2+ equivalents, we observed a fluorescence enhancement factor (FEF) of 28.3. The high Pd2+ induced FEF can be explained by an off switching of multiple quenching processes within 1 by Pd2+. In the free dye 1 a photoinduced electron transfer (PET) and energy transfer (ET) takes place and quenches the anthracenic fluorescence. The coordination of eight Pd2+ units by the alkylthio‐substituted porphyrazine receptor suppresses the PET and ET quenching process and the anthracenic fluorescence is switched on. [ABSTRACT FROM AUTHOR]

The effect of chemical modification of the tetrapyrrole macrocycle structure on the spectral, acid–base, and complexing properties of tetrakis[5,6-bis(4-tert-butylphenyl)pyrazino]porphyrazine, tetra(4-tert-butyl)phthalocyanine, and octakis(4-tert-butylphenyl)porphyrazine in acetonitrile at 298–318 K has been studied by 1H NMR, electronic spectroscopy, and mass spectrometry. The obtained results can be used in the design of macrocyclic tetrapyrrole functional materials with desired physicochemical properties. [ABSTRACT FROM AUTHOR]

The molecular structures of (6666) macrotetracyclic (M(IV) chelates (M = Ti, V, Cr, Mn, Fe, Co, Ni, Cu) with the (NNNN)-donor ligand porphyrazine and the oxo ligand have been calculated by the DFT OPBE/TZVP method. Selected bond lengths and bond and nonbonded angles in the complexes have been reported. The standard enthalpies, entropies, and Gibbs energies of formation of these compounds have been calculated. All these complexes have a structure of a distorted tetragonal pyramid, where the complex-forming M(IV) atom is located above the base formed by the donor nitrogen atoms. It has been demonstrated that all six-membered metal chelate rings in each of these structures are identical to each other both in the sum of their bond angles and in their set, although none of them is flat. The images of the molecular structures of some of these coordination compounds are presented. [ABSTRACT FROM AUTHOR]

The electrochemical properties of a modified electrode covered with 2‐[2‐(4‐nitrophenoxy)ethoxy]ethylthio‐substituted porphyrazine/single‐walled carbon nanotube hybrids were investigated. The electrochemical study revealed that the electrode mechanism is more complex in acidic conditions in comparison to neutral buffer. According to our study, the nitro groups constituting the part of porphyrazine substituents can be electrochemically reduced to the corresponding hydroxylamine moieties; surprisingly, however, the latter can be additionally transformed to o‐aminophenol/o‐iminoquinone groups, but only in acidic conditions. The electrode covered with hybrid material was used in the electrocatalytic oxidation of NADH. According to these results, it seems that after the electrochemical activation of the electrode material, 2‐[2‐(4‐nitrophenoxy)ethoxy]ethylthio‐substituted porphyrazine reveals strong electrocatalytic behavior towards NADH oxidation, owing to the appearance of reversible surface‐anchored o‐aminophenol/o‐iminoquinone intermediate redox couples. In the amperometric determination, the limit of detection (LOD) and limit of quantification (LOQ) of NADH were calculated and found to be LOD=0.16 and LOQ=0.48 μM. Moreover, the relative standard deviation of the response was 3.32 %, indicating excellent reproducibility. Thus, the novel electrode based on 2‐[2‐(4‐nitrophenoxy)ethoxy]ethylthio‐substituted porphyrazine and single‐walled carbon nanotubes present an interesting opportunity in the fields of electroanalytical and biosensing applications, and can be considered for amperometric NADH determination. [ABSTRACT FROM AUTHOR]

The molecular structures of heteroligand (6666)macrotetracyclic chelates of M(III) (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, or Cu) with porphyrazine (an (NNNN)-donating ligand) and F– ion are calculated by the DFT OPBE/TZVP method. The key bond lengths, bond angles, and nonbonded angles in these complexes are reported. The standard enthalpies, entropies, and Gibbs free energies of formation are calculated for the complexes. All complexes have a slightly distorted tetragonal-pyramidal geometry, where the complex former M(III) is to some degree raised above the pyramid base made up of the donor nitrogen atoms. Characteristically, all 6-membered metal chelate rings in these metal chelates are identical to one another both in terms of the sum of bond angles and in their varieties. [ABSTRACT FROM AUTHOR]

Tetrakis{5,6-bis(4-tert-butylphenyl)pyrazino[2,3-c]}porphyrazine and tetra(4-tert-butyl)phthalocyanine have been synthesized, and their acid–base properties and electronic absorption and fluorescence spectra in acetonitrile and toluene at 298 and 295 K, respectively, have been studied. The synthesized compounds have been identified by electronic absorption and1H NMR spectroscopy and mass spectrometry. The effect of substituents in the molecular fragments of the macrocycle on the electronic and optical properties of the synthesized compounds has been estimated. [ABSTRACT FROM AUTHOR]

Based on the quantum-chemical calculation using the Density Functional Theory (DFT) method, the existence possibility of zinc heteroligand complexes with porphyrazine and its analogs – trans-di[benzo]porphyrazine or phthalocyanine and oxo ligands with an oxidation state of IV which is unknown for this element, was shown. The data on the structural parameters and multiplicity of the ground state of these complexes were presented. Comments on Inorganic Chemistry Volume ......., Issue ......., Pages .......... (2020). About of Possibility of Existence of Zn(IV) Oxidation State in Heteroligand Complexes with Porphyrazine, trans-Di[benzo]porphyrazine, Phthalocyanine and Oxo Ligands: Quantum-Chemical Review. Oleg V. Mikhailov, Denis V. Chachkov [ABSTRACT FROM AUTHOR]

The prospective strategy for treatment of cancer is based on the application of nano-sized macromolecular carriers, which are able penetrate inside and can be accumulated within tumor tissue. In this work graft copolymers of cellulose and poly(methacrylic acid) has been prepared and tested as a nanocontainers for the delivery of drug to tumor. For this purpose, two derivatives of porphyrazine suitable for photodynamic cancer therapy were loaded into prepared polymer brush. Fluorescence imaging was applied for monitoring of accumulation of porphyrazine in the CT26 murine colon carcinoma. The selective accumulation of cellulose brush loaded with porphyrazine in tumor was demonstrated by fluorescence intensity contrast between the tumor area and normal tissues. The tumor growth rate after photodynamic therapy were assessed and inhibition of its growth was revealed.

Aza-porphyrinoids exhibit distinct spectral properties in UV-Vis, and they are studied in applications such as photosensitizers in medicine and catalysts in technology. The use of appropriate peripheral substituents allows the modulation of their physicochemical properties. Phthalocyanine and sulfanyl porphyrazine octa-substituted with 4-(butoxycarbonyl)phenyloxy moieties were synthesized and characterized using UV-Vis and NMR spectroscopy, as well as mass spectrometry. A comparison of porphyrazine with phthalocyanine aza-porphyrinoids revealed that phthalocyanine macrocycle exhibits higher singlet oxygen generation quantum yields, reaching the value of 0.29 in DMF. After both macrocycles had been deposited on titanium dioxide nanoparticles P25, the cytotoxicities and photocytotoxicities of the prepared materials were studied using a Microtox® acute toxicity test. The highest cytotoxicity occurred after irradiation with a red light for the material composed of phthalocyanine deposited on titania nanoparticles.

The Knudsen effusion method with mass spectrometric control of the vapor composition was used to study the possibility of a congruent transition to the gas phase and to estimate the enthalpy of sublimation of metal-free tetrakis(1,2,5-thiadiazolo)porphyrazine and its nickel complex (H2TTDPz and NiTTDPz, respectively). The geometrical and electronic structure of H2TTDPz and NiTTDPz in ground and low-lying excited electronic states were determined by DFT calculations. The electronic structure of NiTTDPz was studied by the complete active space (CASSCF) method, following accounting dynamic correlation by multiconfigurational quasi-degenerate second-order perturbation theory (MCQDPT2). A geometrical structure of D2h and D4h symmetry was obtained for H2TTDPz and NiTTDPz, respectively. According to data obtained by the MCQDPT2 method, the nickel complex possesses the ground state 1A1g, and the wave function of the ground state has the form of a single determinant. Electronic absorption and vibrational (IR and resonance Raman) spectra of H2TTDPz and NiTTDPz were studied experimentally and simulated theoretically.

The syntheses, spectral UV–Vis, NMR, and electrochemical as well as photocatalytic properties of novel magnesium(II) and zinc(II) symmetrical sulfanyl porphyrazines with 2-(morpholin-4-yl)ethylsulfanyl peripheral substituents are presented. Both porphyrazine derivatives were synthesized in cyclotetramerization reactions and subsequently embedded on the surface of commercially available P25 titanium(IV) oxide nanoparticles. The obtained macrocyclic compounds were broadly characterized by ESI MS spectrometry, 1D and 2D NMR techniques, UV–Vis spectroscopy, and subjected to electrochemical studies. Both hybrid materials, consisting of porphyrazine derivatives embedded on the titanium(IV) oxide nanoparticles’ surface, were characterized in terms of particle size and distribution. Next, they were subjected to photocatalytic studies with 1,3-diphenylisobenzofuran, a known singlet oxygen quencher. The applicability of the obtained hybrid material consisting of titanium(IV) oxide P25 nanoparticles and magnesium(II) porphyrazine derivative was assessed in photocatalytic studies with selected active pharmaceutical ingredients, such as diclofenac sodium salt and ibuprofen.

Based on the results of a quantum chemical calculation using the DFT method, the possibility of the existence of a copper heteroligand complex with porphyrazine and two fluoride ions with an oxidation state of IV that is unusual for this element has been shown. Also, data on the structural parameters and multiplicity of the ground state of this complex have been presented. Unlabelled Image • We studied macrocyclic Cu(IV) complex with porphyrazine and two fluorine ligands. • We calculated molecular structure of this complex by two versions of DFT method. • We found that coplanar structure of macrocycle takes place for the given complex. • We calculated bond lengths, bond and torsion angles of the given Cu(IV) complex. • In addition, we calculated standard thermodynamic parameters of this complex. [ABSTRACT FROM AUTHOR]

The first examples of diboron complexes of the tetrapyrroles octaethylporphyrazine (OEPz) and 2,9,16,23‐tetra‐t‐butyl‐phthalocyanine (Pc) are reported, counterpoints to the better known monoboron tripyrroles, subporphyrazine and subphthalocyanine. Two stereochemical possibilities are observed, with cisoid‐B2OF2(OEPz), both cisoid‐B2OPh2(OEPz) and transoid‐B2OPh2(OEPz), transoid‐B2OF2(Pc) and cisoid‐B2OPh2(Pc) having been isolated and characterised, including structure determinations for the OEPz complexes. This variation in stereochemistry, which can be extended to include the previously reported transoid‐B2OF2(porphyrin), cisoid‐[B2OF2(corrole)]−, and both transoid‐ and cisoid‐B2OF2(calixphyrin), prompted a wider DFT study to elucidate the factors influencing the stereochemical preferences. This shows that the cisoid/transoid preference is correlated to the ease with which the macrocycle accommodates a rectangularly distorted N4 cavity. [ABSTRACT FROM AUTHOR]

Abstract The adsorption of a porphyrazine (a tetraazaporphyrin) on the surfaces of Pt nanoparticles enhanced the activity of the oxygen reduction reaction (ORR) of the Pt catalysts for use in a polymer electrolyte fuel cell (PEFC). The apparent electrochemically active surface area was significantly decreased upon adsorption of the organic macrocycle. The promotion of the ORR was ascribed to the enhanced activity of the residual Pt surface area. Cyclic voltammograms under argon atmosphere and CO stripping voltammetry indicate that the porphyrazine impedes the generation of OH adsorbed on the surface of Pt. Other π-conjugated aromatic compounds tested did not increase (but rather, inhibited) the ORR activity. It should be noted that the porphyrazine, comparably large in size relative to the Pt nanoparticles, enhanced the catalytic activity of the Pt surface. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Porphyrazines containing peripheral bulky pyrrolyl substituents were synthesized. • Porphyrazines were subjected to detailed NMR and X-ray studies. • Atropisomers of porphyrazines with peripheral pyrrolyl substituents were found. Abstract Magnesium(II) and metal-free porphyrazines containing peripheral 2-methyl-5-phenyl- or 2,3,5-triphenyl-1 H -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-1 H -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. [ABSTRACT FROM AUTHOR]

Electronic and geometric structures of Y, La and Lu complexes with porphyrazine (Pz) and tetrakis(1,2,5-thiadiazole)porphyrazine (TTDPz) were investigated by density functional theory (DFT) calculations and compared. The nature of the bonds between metal atoms and nitrogen atoms has been described using the analysis of the electron density distribution in the frame of Bader’s quantum theory of atoms in molecule (QTAIM). Simulation and interpretation of electronic spectra were performed with use of time-dependent density functional theory (TDDFT) calculations. Description of calculated IR spectra was carried out based on the analysis of the distribution of the potential energy of normal vibrations by natural vibrational coordinates.

Based on the results of a quantum chemical calculation using the DFT method with the OPBE/TZVP and B3PW91/TZVP levels, the possibility of the existence of three cobalt heteroligand complexes containing in the inner coordination sphere porphyrazine, di[benzo]- and tetra[benzo]porphyrazine, and two oxygen (O2−) ions with probable oxidation state VI of Co, which is unknown for this element at the present time, was shown. Data on the structural parameters are presented. It was shown that CoN4 chelate nodes as well as all metal-chelate and non-chelate cycles in each of these complexes, were strictly planar. Besides, the bond angles formed by two donor nitrogen atoms and a Co atom were close or equal to 90°, while the bond angles formed by donor atoms N, Co, and O, in most cases, albeit insignificantly, differed from this value. Good agreement between the calculated data obtained using the above two versions of the DFT method was found. Standard thermodynamic parameters of formation (standard enthalpy ΔH0f, 298, entropy S0f, 298 and Gibbs’s energy ΔG0f, 298) for the indicated complexes were presented too.

Electronic and geometric structures of Ca(II) and Zn(II) complexes with porphyrazine (Pz) and tetrakis(1,2,5-thiadiazole)porphyrazine (TTDPz) were investigated by density functional theory (DFT) calculations and compared. The perimeter of the coordination cavity was found to be practically independent on the nature of a metal and a ligand. According to the results of the natural bond orbital (NBO) analysis and quantum theory of atoms in molecules (QTAIM) calculations, Ca–N bonds possess larger ionic contributions as compared to Zn–N. The model electronic absorption spectra obtained with the use of time-dependent density functional theory (TDDFT) calculations indicate a strong bathochromic shift (~70 nm) of the Q-band with a change of Pz ligand by TTDPz for both Ca and Zn complexes. Additionally, CaTTDPz was synthesized and its electronic absorption spectrum was recorded in pyridine and acetone.