Tetraphenylporphyrin Complexes Research Articles

Intricacies of Mass Transport during Electrocatalysis: A Journey through Iron Porphyrin-Catalyzed Oxygen Reduction.

Electrochemical steps are increasingly attractive for green chemistry. Understanding reactions at the electrode-solution interface, governed by kinetics and mass transport, is crucial. Traditional insights into these mechanisms are limited, but our study bridges this gap through an integrated approach combining voltammetry, electrochemical impedance spectroscopy, and electrospray ionization mass spectrometry. This technique offers real-time monitoring of the chemical processes at the electrode-solution interface, tracking changes in intermediates and products during reactions. Applied to the electrochemical reduction of oxygen catalyzed by the iron(II) tetraphenyl porphyrin complex, it successfully reveals various reaction intermediates and degradation pathways under different kinetic regimes. Our findings illuminate complex electrocatalytic processes and propose new ways for studying reactions in alternating current and voltage-pulse electrosynthesis. This advancement enhances our capacity to optimize electrochemical reactions for more sustainable chemical processes.

Exploring copper (II) porphyrin complexes and their derivatives for electrochemical analysis and biological assessment in the study of breast cancer (MCF-7) cell lines

In this study, several derivatives of tetraphenylporphyrin were synthesized, each with unique meso-substituent groups including phenyl, methoxyphenyl, butyloxyphenyl, octyloxyphenyl, and dectyloxyphenyl. Additionally, their corresponding copper complexes were prepared and thoroughly characterized. The structural confirmation of all compounds was established through CHN elemental analysis, mass spectrometry, and FT-IR spectroscopy. As the number of carbon atoms in the alkyl long-chain increased, a slight red shift in the electronic absorption band was observed, which was attributed to the electronic influence of the alkyl group. DFT analysis indicated that electron density predominantly localized on the porphyrin ring of both the metal free porphyrins and copper (II) porphyrin complexes, with relatively low electron density in the p orbital of the meso-aryl long-chain substituent group. EPR spectroscopy of the Copper (II) ion complexes revealed signals, indicating their paramagnetic properties. Additionally, the Copper (II) tetraphenylporphyrin (CuTPP) complexes displayed two reversible oxidation peaks at +0.97 V and +1.35 V, whereas other derivatives exhibited lower oxidation potentials. The cytotoxicity of these compounds against MCF-7 cell lines was assessed using MTT assay, revealing cytotoxic effects in all cases. Among them, Copper (II) tetrakis (4-methyloxyphenyl)porphyrin (CuTOMPP) demonstrated the highest potential, with an IC50 value of 32.07 μg/mL.

Metal-TPP (5,10,15,20-tetraphenylporphyrin) complex compounds as dye sensitizer in dye sensitized solar cells

The excessive exploitation of fossil fuels requires humans to look for alternative renewable energy sources that are environmentally friendly such as DSSC. DSSC is a solar cell technology that can convert photon energy in sunlight into electrical energy. This research aims to study the performance of complex compounds synthesized from tetraphenylporphyrin (TPP) ligands with metal ions Cr(III), Mn(II) and Fe(III) and applied as dye sensitizers in Dye Sensitized Solar Cell (DSSC). Metal-TPP complexes have been successfully synthesized using the Adler method. The formation of metal-TPP complex compound is indicated by the characterization result using UV–Vis spectrophotometer, FTIR, conductometer test and the observed MLCT phenomenon. In a dye sensitizer application, the performance of the Cr(III)-TPP complex compound shows a short circuit current density value (Jsc) of 8.0 mA/cm2 with an open circuit voltage (Voc) of 0.62 V and an efficiency value (ƞ) of 9.13 %. The Mn(II)-TPP complex compound shows that the short circuit current density value (Jsc) of 8.0 mA/cm2 with an open circuit voltage (Voc) of 0.64 V and an efficiency value (ƞ) of 9.16 %. The Fe(III)-TPP complex compound shows that the short circuit current density value (Jsc) of 8.0 mA/cm2 with an open circuit voltage (Voc) of 0.64 V and an efficiency value (ƞ) of 9.36 %.

Peculiarities of fluoride activation of porphyrin and phthalocyanine catalysts by the example of zirconium and hafnium in the production of cyclic carbonates

In this work, we have shown that fluoride additives can increase the catalytic activity of even 5- and 6-period metal complexes. Using tetraphenylporphyrin and phthalocyanine hafnium complexes as an example we were able to lower catalyst loading to 500 ppm. It was found out that after reaction tetraphenylporphyrin complex decomposed with the formation of meso‑tetraphenylporphyrin. Such process did not occur with the phthalocyanine complex. Moreover, in the presence of the fluoride additive hafnium tetrachloride showed high catalytic activity similar to both tetraphenylporphyrin and phthalocyanine comlpexes.

Metalloporphyrin doped rice husk-based biomass porous carbon materials as high performance electrocatalyst for oxygen reduction reaction in Zn-Air battery

Rice husk (RH) is one of the most abundant biomass having a unique natural structure. Herein, the highly porous rice husk carbon material (RHC) has been prepared. After loading metal (Fe, Co, Mn, Cu) complex of tetra-phenylporphyrin (TPP) and the followed calcination, a new kind of metal-nitrogen-carbon (M-N-C) electrocatalyst (MTPP/RHC) for the oxygen reduction reaction (ORR) was obtained. It was found that all prepared catalysts showed good ORR performance and the activity follows an order of Fe > Co > Mn > Cu catalyst. The best FeTPP/RHC catalyst exhibited an ORR activity with a half-wave potential of 0.88 V (Eonset = 0.96 V) and excellent long-term stability (97% retention after 30000s). In the constructed zinc-air battery, it even showed a higher specific capacity (766 mAh/g) and superior reversibility than commercial Pt/C catalysts. This work provides a new practical protocol for ORR electrocatalysts.

Mechanistic Insights into Photochemical CO2 Reduction to CH4 by a Molecular Iron-Porphyrin Catalyst.

Iron tetraphenylporphyrin complex modified with four trimethylammonium groups (Fe-p-TMA) is found to be capable of catalyzing the eight-electron eight-proton reduction of CO2 to CH4 photochemically in acetonitrile. In the present work, density functional theory (DFT) calculations have been performed to investigate the reaction mechanism and to rationalize the product selectivity. Our results revealed that the initial catalyst Fe-p-TMA ([Cl-Fe(III)-LR4]4+, where L = tetraphenylporphyrin ligand with a total charge of -2, and R4 = four trimethylammonium groups with a total charge of +4) undergoes three reduction steps, accompanied by the dissociation of the chloride ion to form [Fe(II)-L••2-R4]2+. [Fe(II)-L••2-R4]2+, bearing a Fe(II) center ferromagnetically coupled with a tetraphenylporphyrin diradical, performs a nucleophilic attack on CO2 to produce the 1η-CO2 adduct [CO2•--Fe(II)-L•-R4]2+. Two intermolecular proton transfer steps then take place at the CO2 moiety of [CO2•--Fe(II)-L•-R4]2+, resulting in the cleavage of the C-O bond and the formation of the critical intermediate [Fe(II)-CO]4+ after releasing a water molecule. Subsequently, [Fe(II)-CO]4+ accepts three electrons and one proton to generate [CHO-Fe(II)-L•-R4]2+, which finally undergoes a successive four-electron-five-proton reduction to produce methane without forming formaldehyde, methanol, or formate. Notably, the redox non-innocent tetraphenylporphyrin ligand was found to play an important role in CO2 reduction since it could accept and transfer electron(s) during catalysis, thus keeping the ferrous ion at a relatively high oxidation state. Hydrogen evolution reaction via the formation of Fe-hydride ([Fe(II)-H]3+) turns out to endure a higher total barrier than the CO2 reduction reaction, therefore providing a reasonable explanation for the origin of the product selectivity.

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporphyrin: Analysis of the Data of Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy

Features of the Electronic and Local Atomic Structures of Erbium Complexes of Tetraphenylporphyrin: Analysis of the Data of Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy

A Feature of the Crystalline and Amorphous Structure of Ultra Thin Fibers Based on Poly(3-hydroxybutyrate) (PHB) Containing Minor Concentrations of Hemin and a Complex of Tetraphenylporphyrin with Iron.

Comprehensive studies combining X-ray diffraction analysis, thermophysical, dynamic measurements by probe method and scanning electron microscopy have been carried out. The peculiarity of the crystalline and amorphous structure of ultra-thin fibers based on poly(3-hydroxybutyrate) (PHB) containing minor concentrations (0–5%) of a gene and a tetraphenylporphyrin (TFP) complex with iron (in the form of FeCl) are considered. When these complexes are added to the PHB fibers, the morphology of the fibers change: a sharp change in the crystallinity and molecular mobility in the amorphous regions of PHB is observed. When adding a gel to the fibers of PHB, a significant decrease in the degree of crystallinity, melting enthalpy, and correlation time can be observed. The reverse pattern is observed in a system with the addition of FeCl-TFP—there is a significant increase in the degree of crystallinity, melting enthalpy and correlation time. Exposure of PHB fibers with gemin in an aqueous medium at 70 °C leads to a decrease in the enthalpy of melting in modified fibers—to an increase in this parameter. The molecular mobility of chains in amorphous regions of PHB/gemin fibers increases at the same time, a nonlinear dependence of changes in molecular dynamics is observed in PHB/FeCl-TFP fibers. Ozonolysis has a complex effect on the amorphous structure of the studied systems. The obtained fibrous materials have bactericidal properties and should be used in the creation of new therapeutic systems of antibacterial and antitumor action.

Cobalt(II)-tetraphenylporphyrin-catalysed carbene transfer from acceptor-acceptor iodonium ylides via N-enolate-carbene radicals.

Square-planar cobalt(II) systems have emerged as powerful carbene transfer catalysts for the synthesis of numerous (hetero)cyclic compounds via cobalt(III)-carbene radical intermediates. Spectroscopic detection and characterization of reactive carbene radical intermediates is limited to a few scattered experiments, centered around monosubstituted carbenes. Here, we reveal the formation of disubstituted cobalt(III)-carbene radicals derived from a cobalt(II)-tetraphenylporphyrin complex and acceptor-acceptor λ3-iodaneylidenes (iodonium ylides) as carbene precursors and their catalytic application. Iodonium ylides generate biscarbenoid species via reversible ligand modification of the paramagnetic cobalt(II)-tetraphenylporphyrin complex catalyst. Two interconnected catalytic cycles are involved in the overall mechanism, with a monocarbene radical and an N-enolate-carbene radical intermediate at the heart of each respective cycle. Notably, N-enolate formation is not a deactivation pathway but a reversible process, enabling transfer of two carbene moieties from a single N-enolate-carbene radical intermediate. The findings are supported by extensive experimental and computational studies.

Characteristics of the Parameters of Superfine Fibers of Poly(3-hydroxybutyrate) Modified with Tetraphenylporphyrin

Structural-dynamic studies combining X-ray diffraction analysis, thermophysical measurements (DSC), X-ray diffraction analysis, probe EPR method, and scanning electron microscopy are performed. The structural and dynamic characteristics of electrospun superfine fibers based on poly-(3-hydroxybutyrate) (PHB) containing a low concentration of the tetraphenylporphyrin complex (TPP) (0–5%) are considered. It is shown that the addition of tetramethylporphyrin complexes to PHB fibers changes the morphology, a slight decrease in crystallinity is observed, and the molecular mobility in the amorphous regions of the polymer slows down. The temperature action on the fibers (annealing at 140°C) leads to a sharp increase in crystallinity and molecular mobility in the amorphous regions of poly(3-hydroxybutyrate)—TPP fibers. Exposure to an aqueous medium at 70°C is accompanied by a sharp decrease in the enthalpy of melting and an increase in the molecular mobility of chains in the amorphous regions of the fiber.

Сравнительный структурно-динамический анализ ультратонких волокон поли-(3-гидроксибутирата), модифицированного комплексами тетрафенилпорфирина с металлами

Проведены комплексные исследования, сочетающие рентгеноструктурный анализ, термофизические, динамические измерения зондовым методом и сканирующую электронную микроскопию. Рассмотрена особенность кристаллической и аморфной структуры ультратонких волокон на основе поли(3-гидроксибутирата) (ПГБ), содержащего минорные концентрации (0–5%) комплексов тетрафенилпорфирина (ТФП) с марганцем (в форме MnCl2 ), цинком и железом (в форме FeCl3 ). Показано, что при добавлении в волокна ПГБ указанных комплексов меняется морфология волокон, наблюдается изменение кристалличности и замедление молекулярной подвижности в плотных и рыхлых аморфных областях ПГБ в следующей последовательности: ПГБ/ТФП, ПГБ/Zn–ТФП, ПГБ/MnCl2 –ТФП, FeCl3 –ТФП. Температурное воздействие на волокна (их отжиг при 140°С) приводит к резкому росту кристалличности и молекулярной подвижности в аморфных областях волокон. Их экспозиция в водной среде при 70°С приводит к росту энтальпии плавления и замедлению молекулярной динамики только в исходном ПГБ, но к значительному снижению энтальпии в модифицированных волокнах. Молекулярная подвижность цепей в аморфных областях при этом возрастает. Полученные волокнистые материалы обладают бактерицидными свойствами и должны найти применение при создании новых терапевтических систем антибактериального и противоопухолевого действия.

Composites based on polylactide and manganese (III) tetraphenylporphyrin. Influence of concentration on the structure and properties

The bactericidal action of porphyrin has a very promising potential for medical applications. Therefore, composite materials based on L-Polylactide and manganese (III) chloride tetraphenylporphyrin were prepared. The aim of this work was to study the effects of the concentration of tetraphenylporphyrin on the structural features and mechanical properties of these composites. The concentration of the filler in the composites was in the range of 0.1–2 wt%. The sizes of the tetraphenylporphyrin microinclusions (15–40 μm) were determined using optical microscopy. It was found that the phase transition temperatures of polylactide in the presence of tetraphenylporphyrin varied by 1–2 °C, and the crystallinity degree increased by 4–5% in the composites compared with the pure polylactide. Using the method of electron paramagnetic resonance at 70 °C, an increase in the segmental mobility of the polymer matrix was detected as the tetraphenylporphyrin concentration in the composites was increased. The addition of manganese (III) chloride tetraphenylporphyrin complex microinclusions in the composites slightly enhanced the tensile strength and elongation at break of the polylactide matrix. Thus, the effects of the porphyrin manganese complex on the polylactide matrix and the properties of the composites were shown.

Metallo‐Corroles Supported on Carbon Nanostructures as Oxygen Reduction Electrocatalysts in Neutral Media

In this work, we report the investigation of Fe and Co triphenylcorrole complexes supported on two different carbon supports as eletrocatalysts for the ORR in neutral pH media, comparing their performances with the corresponding tetraphenylporphyrin complexes. Cyclic voltammetry experiments were acquired in neutral phosphate buffer demonstrating that corroles exhibit a superior catalytic activity towards ORR than porphyrins, as demonstrated by more positive oxygen reduction peak potential (Epr) and half‐wave potential (E1/2) values of corroles. Also, iron complexes performed better than cobalt ones, showing an ORR activity even superior to that of platinum taken as reference, as demonstrated by RDE experiments. We investigated the role of the axial ligand on the ORR activity of the macrocycles, and we found that Epr and E1/2 values are more positive along the series: PPh3Co < py2Co = µ‐oxoFe2 < FeCl. By contrast, there was not much difference in activity supporting the porphyrinoids on carbon nanotubes or carbon black pearls, indicating that the effect of carbon support is less important to that of the axial ligand. The results allowed pointing at iron corroles as a promising class of molecular catalysts for application as cathodes in biolectrochemical systems at neutral pH, such as microbial fuel cells.

Iridium Tetra(4‐carboxyphenyl) Porphyrin, Calix[4]pyrrole and Tetraphenyl Porphyrin Complexes as Potential Hydrogenation Catalysts

Here we report the preparation of first examples of iridium‐based organometallic macromolecules, viz., iridium‐tetra (4‐carboxyphenyl)porphyrin (IrTCPP), iridium‐calix[4]pyrrole (IrCP) iridium‐tetraphenylporphyrin (IrTPP), which are effective catalysts for hydrogenation of levulinic acid (LA) to γ‐valerolactone (GVL) and 1,4‐pentanediol under base free conditions. The turnover number in the range of 1220–2850 is evident for the chosen reaction using iridium macromolecule based catalysts. The heterogenization of homogeneous IrTCPP, IrCP, and IrTPP result in stable reactivity of the catalysts for several runs.

Physical and Chemical Properties of Polyporphyrin Films Based on the Mn Complexes of Amino-Substituted Tetraphenylporphyrin

The article presents the results of the study of electrochemical deposition and the physicochemical properties of polyporphyrin films deposited on glassy carbon, platinum, and ITO electrodes. Electropolymerization of Mn(III) 5,10,15,20-tetrakis(3-aminophenyl)porphyrin chloride from different solvents and in different deposition modes is carried out. In the process of electrooxidation of porphyrin monomer in solutions of dichloromethane and ethanol, polyporphyrin films are formed on the working electrode in the potential range from 0 to +2 V. The electropolymerization process is studied using the quartz microbalance method. The physicochemical properties of the films are studied using various methods: UV-VIS spectrophotometry, IR spectroscopy, scanning electron microscopy, atomic force microscopy, photo-EMF method. The number of electrons participating in the electropolymerization process is determined. Spectral methods show that a porphyrin structure is retained in the film, and in the process of electropolymerization, it is possible to incorporate μ-oxodimers into the composition of the film. It is found that the obtained polyporphyrin films possess semiconductor properties.

Comparative Structural Dynamic Analysis of Ultrathin Fibers of Poly-(3-Hydroxybutyrate) Modified by Tetraphenyl–Porphyrin Complexes with the Metals Fe, Mn, and Zn

Comparative Structural Dynamic Analysis of Ultrathin Fibers of Poly-(3-Hydroxybutyrate) Modified by Tetraphenyl–Porphyrin Complexes with the Metals Fe, Mn, and Zn

Ultrafine Fibers of Poly-(3-Hydroxybutyrate) with Zinc–Tetraphenylporphyrin Obtained by Electrospinning

Ultrathin fibers of poly(3-hydroxybutyrate) (PHB) with a zinc–tetraphenylporphyrin complex (0-5%) were obtained by electrospinning. Optical microscopy, differential scanning calorimetry, electron paramagnetic resonance, and x-ray structural analysis were used to study the structure of the fibers. It was shown that addition of the ZnTPP complex to the PHB fiber increases the crystallinity and lowers the molecular mobility in the amorphous regions of the polymer. The action of heat on the fiber (annealing at 140°C) leads to significant increase of crystallinity and molecular mobility in the amorphous regions of fibers of PHB and of PHB with 1% of ZnTPP. With 3-5% content of the complexes the crystallinity of the fiber is substantially reduced. The results of the work make it possible to recommend the investigated materials for biomedical application as matrices with antibacterial activity

SPECTRAL INVESTIGATIONS OF COBALT PORPHYRINATES INTERACTION WITH RADICAL POLYMERIZATION INITIATORS

The article presents the results of the kinetics study of the cobalt porphyrins interaction with radical polymerization initiators – benzoyl peroxide and lauryl peroxide – in solution by the spectrophotometric method. From disparate literature data, it is known that some metalloporphyrins can interact with benzoyl peroxide to form the tautomers of porphyrins – isoporphyrins. These compounds have a number of specific properties, for example, it can be catalysts of various processes. Perhaps the isoporphyrins formation is the reason for high activity of the initiating systems “cobalt porphyrin – benzoyl peroxide” in the polymerization of vinyl monomers. Cobalt(II)complexes of tetraphenylporphyrin, tetra-para-methoxyphenylporphyrin, 5,15-bis(4´-tert-butylphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra-p-butylporphyrin were selected as the objects of this study. The influence of the porphyrin ligand structure on the formation of cobalt isoporphyrins was estimated. The interaction of cobalt (II) tetraphenylporphyrin and cobalt (II) tetra-para-methoxyphenylporphyrin with peroxides showed changes in the electronic absorption spectra of metalloporphyrins: deformation of the Soret band, reduction of the absorption band in the visible region, and the appearance of absorption bands in the near IR region. These changes are characteristic for metalloisoporphyrins. Data on the interaction of cobalt porphyrins with lauryl peroxide were obtained for the first time. The formation of isoporphyrins is possible with the different ratio of concentrations of reagents: with a lack of peroxide, with equimolar ratio, and also with a significant (100-fold) excess of peroxide. When 5,15-bis (4´-tert-butylphenyl)-3,7,13,17-tetramethyl-2,8,12,18-tetra-p-butylporphyrinate cobalt (II) reacted with peroxides, no isoporphyrinates were observed. The article presents the effective reaction rate constants of the cobalt isoporphyrinates formation at 25 °C. It is shown that the structure of both cobalt porphyrinates and organic peroxides affects the possibility and rate of isoporphyrins formation.

Effect of the Addition of Iron(III) Tetraphenylporphyrin Complex on the Structure of Poly(3-hydroxybutyrate) Fibers Prepared by Electrospinning

Ultrathin fibers of poly(3-hydroxybutyrate) biopolymer, containing 1–5 wt % iron(III) tetraphenylporphyrin complex, were prepared by electrospinning. The intermolecular interaction of fiber components was studied by UV spectroscopy. Paramagnetic reaction sites in the mixtures were revealed by magnetic resonance. The structure of crystalline and amorphous domains of the fibers was studied by differential scanning calorimetry, X-ray diffraction analysis, spin-probe ESR, and scanning electron microscopy. Introduction of the complex into poly (3-hydroxybutyrate) fibers leads to an increase in the crystallite size and to a considerable increase in the degree of crystallinity; the molecular mobility in the amorphous domains of the polymers decreases. Thermal annealing at 140°C leads to a sharp increase in the crystallinity and to a decrease in the molecular mobility in amorphous domains of poly(3-hydroxybutyrate). Ozonolysis of the fibers at a short treatment time (up to 5 h) causes sharp deceleration of the molecular mobility; at longer ozonation of the fibers, the mobility increases. The fibrous materials obtained exhibit bactericidal properties and can be used for developing antibacterial and antitumor therapeutic systems.

Ab initio study of C20 nanocluster effects on electrochemical properties of tetraphenylporphyrin

The Density Functional Theory (DFT) method was employed to study the properties of the C[Formula: see text] complex with tetraphenylporphyrin (TPP). Calculations were performed in vacuum and in the presence of different solvents. Strong interaction between the C[Formula: see text] cluster and TPP molecule was observed. To understand the effect of C[Formula: see text] on electrochemical properties of TPP, electron transfers from and toward the porphyrin and C[Formula: see text]-TPP complex were studied. It was shown that the presence of C[Formula: see text] influences the electron transfer reaction toward the porphyrin molecule and causes transfer of one and two electrons to C[Formula: see text]-porphyrin, which is more favorable compared with porphyrin alone. However, C[Formula: see text] has slight effect on electron transfer from porphyrin and on positive ion formation. The effect of solvent type on electron transfer energy was studied for these reactions, and it was shown that solvents with higher permittivity have lower electron transfer reaction energy, which may be predicted from ionic character of the products.