Iron Tetrakis Research Articles

Design of the Functional Dialysis Membrane with a Catalase Pseudoactive Center on the Surface.

Here, we have designed a functional dialysis membrane with a catalase pseudoactive center on the surface. To make the catalase pseudoactive center, we have modified the regenerated cellulose dialysis membrane with methylated or octylated poly(1-vinylimidazole) (PVIm-Me or PVIm-Oc), followed by manganese or iron tetrakis(4-carboxyphenyl)porphyrin (Mn- or Fe-TCPP), using the layer-by-layer (LbL) method. As a result of the optimization, the dialysis membrane modified with 25 mol % methylated poly(1-vinylimidazole) [PVIm-Me(25)] and Mn-TCPP produced the highest amount of oxygen (O2) from hydrogen peroxide (H2O2) without the decomposition of Mn-TCPP. Conversely, Mn- and Fe-TCPP were decomposed under other experimental conditions in the presence of H2O2. These results suggest the conversion of H2O2 to O2 by catalase catalytic activity on the surface coated with PVIm-Me(25) and Mn-TCPP.

Two-Site Enhanced Porphyrinic Metal-Organic Framework Nanozymes and Nano-/Bioenzyme Confined Catalysis for Colorimetric/Chemiluminescent Dual-Mode Visual Biosensing.

The rational design of efficient nanozymes and the immobilization of enzymes are of great significance for the construction of high-performance biosensors based on nano-/bioenzyme catalytic systems. Herein, a novel V-TCPP(Fe) metal-organic framework nanozyme with a two-dimensional nanosheet morphology is rationally designed by using V2CTx MXene as a metal source and iron tetrakis(4-carboxyphenyl)porphine (FeTCPP) ligand as an organic linker. It exhibits enhanced peroxidase- and catalase-like activities and luminol-H2O2 chemiluminescent (CL) behavior. Based on the experimental and theoretical results, these excellent enzyme-like activities are derived from the two-site synergistic effect between V nodes and FeTCPP ligands in V-TCPP(Fe). Furthermore, a confined catalytic system is developed by zeolitic imidazole framework (ZIF) coencapsulation of the V-TCPP(Fe) nanozyme and bioenzyme. Using the acetylcholinesterase (AChE) as a model, our constructed V-TCPP(Fe)/AChE@ZIF confined catalytic system was successfully used for the colorimetric/CL dual-mode visual biosensing of organophosphorus pesticides. This work is expected to provide new insights into the design of efficient nanozymes and confined catalytic systems, encouraging applications in catalysis and biosensing.

On Some Topological Indices of Metal-Organic Frameworks

Topological indices are very important because they are used in the study of QSAR (Quantitative Structure–Activity Relationships) and QSPR (Quantitative Structure–Property Relationships) which are mathematical models that show the properties among physicochemical, environmental, and biological activity of a chemical structure. The chemical structure of a molecular graph is used to find the topological indices, which are widely used in theoretical chemistry, environmental chemistry, toxicology, and many others for correlation analysis. Topological indices are numerical values that helps us in measuring the physical and chemical properties of any molecule. In this article, we have calculated some degree-based topological indices of two categories of Metal-Organic Frameworks (MOFs), named as, CoBHT (cobalt butylated hydroxytoluene) and FeTPyP (Iron tetrakis pyridyl porphyrin)-CO (MOFs), also their graphical results are compared at the end.

Ultra-fast photothermal-responsive Fe-TCPP-based thin-film nanocomposite membranes for ON/OFF switchable nanofiltration

• Fe-TCPP nanofibers based TFN nanofiltration membranes were prepared via IP. • Fe-TCPP nanofibers enhanced the permeance by improving the membrane hydrophilicity. • High permeation and dyes rejection were achieved. • Fe-TCPP based TFN membrane’s permeance was enhanced by light-illumination. Metal organic frameworks (MOFs) based Nanofiltration (NF) membranes have promising advantages in the separation of dyes and salts to purify the industrial polluted water. Herein, we report the synthesis of porphyrinic, porous and ultra-fast photothermal sensitive iron tetrakis(4-carboxyphenyl)porphyrin) (Fe-TCPP) MOFs nanofibers and the corresponding thin film nanocomposite (TFN) membranes by facile interfacial polymerization (IP). The Fe-TCPP nanofibers based TFN membrane enhances the pure water permeance to 28.1 L·m −2 ·h −1 ·bar −1 ( i.e., 3.5-fold higher than thin film composite (TFC)) by providing continuous hydrophilic flow pathways to permeate. The Fe-TCPP nanofibers contribute to the surface of TFN membrane, resulting not only fast permeation, but also ultra-high rejection of dyes i.e., 97.2%, 98.3% and 99.1% for Indocyanine Green, Brilliant Blue-R and Direct Red-80, respectively. Additionally, the TFN membrane also demonstrates 23–43 % salts rejection. Due to the ultra-fast photothermal responsive nature of Fe-TCPP nanofibers (88.4 °C increased temperature in 2 sec photo exposure), the water permeation of TFN NF membrane increases 30 % with 0.5 min under visible light-irradiation. This photo-induced ON/OFF separation is switchable. The enhanced permeation, high dyes rejection and photo-modulated ON/OFF nano-separation opens a new avenue for TCPP-based MOFs in the water purification technologies.

Superhydrophilic and Photothermal Fe-TCPP Nanofibrous Membrane for Efficient Oil-in-Water Nanoemulsion Separation.

Separation and purification of surfactant-stabilized oil-in-water nanoemulsions is a great environmental challenge. Membrane-based separation strategies are more effective over conventional methods in the treatment of nanoemulsion waste water. In this paper, we construct a superhydrophilic membrane by coating a thin photothermal-responsive iron tetrakis(4-carboxyphenyl)porphyrin (Fe-TCPP) nanofibrous metal organic framework (MOF) selective layer on a macroporous polyethersulfone membrane. The as-prepared membrane exhibits high separation performance of oil-in-water nanoemulsions with permeance of 46.4 L·m-2·h-1·bar-1 and separation efficiency of 99%. It also demonstrates nice anti-oil/ionic-fouling property, good recyclability, and desirable stability. The high separation performance is accredited to the superhydrophilicity, highly charged surface, and nanometer pore sizes of the Fe-TCPP nanofibrous membrane. Due to the unique photothermal property of Fe-TCPP nanofibers, the permeance can be enhanced more than 50% by visible light without deteriorating the rejection. This photo-stimuli MOF-based thin-layer membrane offers great potential for the generation of point-of-use water treatment devices.

Binary ionic iron(III) porphyrin nanostructured materials with catalase-like activity

Supramolecular structures were prepared in water by ionic self-assembly of oppositely charged iron(III) porphyrins and tested as a new class of catalase mimics. Iron(III) porphyrins carrying the positively charged groups, N-methyl-4-pyridinium (FeTMPyP), 4-pyridinium (FeTHPyP) and tetrafluoro-4-imidazoliumphenyl (FeTFHImP) were assembled with iron tetrakis(4-sulfonatophenyl)porphyrin (FeTSPP), at an optimized pH. The material with the best catalase activity (FeTHPyP:FeTSPP) showed 65-77 catalase units (U)/mg in the pH range 3.5-7.0, which was significantly higher than the 3 U/mg observed for the individual porphyrins. Analogous metal-free structures had no catalytic activity. Micro-scale structures with nanoscale features were observed by Scanning Electron Microscopy. Studies of the chemical composition of materials by X-ray Photoelectron Spectroscopy showed the formation of structures with a 1:1 ratio for (+):(‒) tectons. Characterization of particles in solution was carried out at different pH and before and after catalysis by UV-vis spectroscopy, Dynamic Light Scattering (measurement of hydrodynamic diameters) and Electrophoretic Light Scattering (measurement of zeta potentials).

Stereoselective On-Surface Cyclodehydrofluorization of a Tetraphenylporphyrin and Homochiral Self-Assembly.

The thermally induced cyclodehydrofluorization of iron tetrakis(pentafluorophenyl)porphyrin proceeded highly stereoselectively to give a prochiral product on a gold surface in an ultrahigh vacuum, whereas dehydrocyclization of the respective iron tetrakisphenylporphyrin did not show such selectivity. Stereoselectivity was predominantly observed for closely packed layers, which is an indication of intermolecular cooperativity and steric constraints induced by adjacent species. Density functional theory identified intermolecular packing constraints as the origin of such selectivity during the reaction. Scanning tunneling microscopy revealed the formation of an enantiomerically pure two-dimensional self-assembly as a conglomerate of mirror domains. On-surface two-dimensional topochemistry, as reported herein, may open new routes for stereoselective synthesis.

Stereoselective On‐Surface Cyclodehydrofluorization of a Tetraphenylporphyrin and Homochiral Self‐Assembly

AbstractThe thermally induced cyclodehydrofluorization of iron tetrakis(pentafluorophenyl)porphyrin proceeded highly stereoselectively to give a prochiral product on a gold surface in an ultrahigh vacuum, whereas dehydrocyclization of the respective iron tetrakisphenylporphyrin did not show such selectivity. Stereoselectivity was predominantly observed for closely packed layers, which is an indication of intermolecular cooperativity and steric constraints induced by adjacent species. Density functional theory identified intermolecular packing constraints as the origin of such selectivity during the reaction. Scanning tunneling microscopy revealed the formation of an enantiomerically pure two‐dimensional self‐assembly as a conglomerate of mirror domains. On‐surface two‐dimensional topochemistry, as reported herein, may open new routes for stereoselective synthesis.

Mesoporous chitosan‐immobilized iron tetrakis(4‐carboxyphenyl)porphyrin as a model of cytochrome P‐450 enzyme for oxidation of ethylbenzene

Mesoporous chitosan‐grafted iron tetra (4‐carboxyphenyl) porphyrin catalyst (Fe TCPP/mesp‐CTS) was prepared and investigated as a practical model for the nano‐cavity and coordinate regulation‐catalysis(CRC) function in cytochrome P‐450 enzyme. Fe TCPP/mesp‐CTS was characterized by X‐ray Diffraction(XRD), Thermogravimetry(TG), Ultraviolet–visible spectroscopy(UV‐Vis), Ultraviolet–visible–Diffuse reflectance spectroscopy(UV‐DRS), Scanning electron microscope (SEM), Fourier transform infrared spectroscopy(FT‐IR), and X‐ray photoelectron spectroscopy(XPS) techniques. The catalytic activity of Fe TCPP/mesp‐CTS for ethylbenzene oxidation was investigated and it was proved to be a better catalyst than Fe TCPP/macp‐CTS based on the ethylbenzene conversion, turnover numbers(TON), and the reusability. These results are attributed to the mesocavity and CRC of amino group in Fe TCPP/mesp‐CTS. The highest ethylbenzene conversion and yields of ketone and alcohol were 24.4% and 18.2%, respectively.

A Reactive Oxygen/Nitrogen Species Sensor Fabricated from an Electrode Modified with a Polymerized Iron Porphyrin and a Polymer Electrolyte Membrane.

We have developed an electrochemical reactive oxygen/nitrogen species sensor that can detect superoxide anion radicals (O2-•) and nitric oxide (NO). The reactive oxygen/nitrogen species sensor was fabricated by surface modification of an electrode with polymerized iron tetrakis(3-thienyl)porphyrin (FeT3ThP), and it can detect either O2-• or NO by switching the applied potential. Furthermore, we fabricated a sensor with improved selectivity by coating a Nafion® film onto the poly(FeT3ThP)-modified electrode. An interference current caused by NO2- was seen for the poly(FeT3ThP)-modified electrode, while the interference current was significantly reduced at the Nafion®/poly(FeT3ThP)-modified electrode, leading to improved selectivity for NO detection. The current response at the Nafion®/poly(FeT3ThP)-modified electrode exhibited good linearity in the O2-• and NO concentration ranges 1.3 - 4.1, and 0.5 - 10 μM, respectively. The Nafion®/poly(FeT3ThP)-modified and poly(FeT3ThP)-modified electrodes are highly versatile, because these electrodes can detect either O2-• or NO by switching the applied potential. Since the Nafion®/poly(FeT3ThP)-modified and poly(FeT3ThP)-modified electrodes contain no bio-derived compounds, the reactive oxygen/nitrogen species sensor should be safe even when it is used in vivo.

Molecular Catalysis of O2 Reduction by Iron Porphyrins in Water: Heterogeneous versus Homogeneous Pathways.

Despite decades of active attention, important problems remain pending in the catalysis of dioxygen reduction by iron porphyrins in water in terms of selectivity and mechanisms. This is what happens, for example, for the distinction between heterogeneous and homogeneous catalysis for soluble porphyrins, for the estimation of H2O2/H2O product selectivity, and for the determination of the reaction mechanism in the two situations. With water-soluble iron tetrakis(N-methyl-4-pyridyl)porphyrin as an example, procedures are described that allow one to operate this distinction and determine the H2O2/H2O product ratio in each case separately. It is noteworthy that, despite the weak adsorption of the iron(II) porphyrin on the glassy carbon electrode, the contribution of the adsorbed complex to catalysis rivals that of its solution counterpart. Depending on the electrode potential, two successive catalytic pathways have been identified and characterized in terms of current-potential responses and H2O2/H2O selectivity. These observations are interpreted in the framework of the commonly accepted mechanism for catalytic reduction of dioxygen by iron porphyrins, after checking its compatibility with a change of oxygen concentration and pH. The difference in intrinsic catalytic reactivity between the catalyst in the adsorbed state and in solution is also discussed. The role of heterogeneous catalysis with iron tetrakis(N-methyl-4-pyridyl)porphyrin has been overlooked in previous studies because of its water solubility. The main objective of the present contribution is therefore to call attention, by means of this emblematic example, to such possibilities to reach a correct identification of the catalyst, its performances, and reaction mechanism. This is a question of general interest, so that reduction of dioxygen remains a topic of high importance in the context of contemporary energy challenges.

Iron and manganese (III) porphyrin covalently bound to poly(acryloyl chloride) as biomimetic heterogeneous catalysts for alkene epoxidation by NaIO4: advantage of iron (III) porphyrin and significance of nitrogen donor axial ligands

Poly(acrylic acid) (PAA) was converted to poly(acryloyl chloride) (PAC) by thionyl chloride and the prepared PAC was used as support for iron tetrakis(4-benzylamine)porphyrin (Fe(TBaminP)OAc). The Fe-porphyrin was covalently bound to the PAC to produce Fe(TBaminP)OAc@PAC as reusable heterogeneous catalysts for alkene epoxidation with sodium periodate (NaIO4). The newly synthesized Fe catalyst was characterized by FT-IR, EDX, SEM and TEM techniques. A similar procedure was followed for synthesis and characterization of Mn(TBaminP)OAc@PAC using Mn(TBaminP)OAc and PAC. The Fe and Mn content of the catalysts were measured by atomic absorption spectroscopy (AAS). We have found that among Mn(TBaminP)OAc, Fe(TBaminP)OAc (heterogeneous catalysts), Mn(TBaminP)OAc@PAC and Fe(TBaminP)OAc@PAC (homogenous catalysts) the later is the best catalyst for alkene epoxidation by NaIO4 in CH3CN/H2O. The epoxidation reactions are sensitive to the nature and concentration of nitrogen donor axial ligands (i.e., imidazole) and the activity of the catalysts and the epoxidation yields increased with using such ligands in the reaction mixture. The Fe(TBaminP)OAc@PAC was found to be a stable catalyst and can be recycled for at least four times without considerable loss of catalytic activity.

NADPH Oxidase–Derived Peroxynitrite Drives Inflammation in Mice and Human Nonalcoholic Steatohepatitis via TLR4-Lipid Raft Recruitment

The molecular events that link NADPH oxidase activation and the induction of Toll-like receptor (TLR)-4 recruitment into hepatic lipid rafts in nonalcoholic steatohepatitis (NASH) are unclear. We hypothesized that in liver, NADPH oxidase activation is key in TLR4 recruitment into lipid rafts, which in turn up-regulates NF-κB translocation to the nucleus and subsequent DNA binding, leading to NASH progression. Results from confocal microscopy showed that liver from murine and human NASH had NADPH oxidase activation, which led to the formation of highly reactive peroxynitrite, as shown by 3-nitrotyrosine formation in diseased liver. Expression and recruitment of TLR4 into the lipid rafts were significantly greater in rodent and human NASH. The described phenomenon was NADPH oxidase, p47phox, and peroxynitrite dependent, as liver from p47phox-deficient mice and from mice treated with a peroxynitrite decomposition catalyst [iron(III) tetrakis(p-sulfonatophenyl)porphyrin] or a peroxynitrite scavenger (phenylboronic acid) had markedly less Tlr4 recruitment into lipid rafts. Mechanistically, peroxynitrite-induced TLR4 recruitment was linked to increased IL-1β, sinusoidal injury, and Kupffer cell activation while blocking peroxynitrite-attenuated NASH symptoms. The results strongly suggest that NADPH oxidase-mediated peroxynitrite drove TLR4 recruitment into hepatic lipid rafts and inflammation, whereas the invivo use of the peroxynitrite scavenger phenylboronic acid, a novel synthetic molecule having high reactivity with peroxynitrite, attenuates inflammatory pathogenesis in NASH.

A zinc sulfide-supported iron tetrakis (4-carboxyl phenyl) porphyrin catalyst for aerobic oxidation of cyclohexane

Fe TCPP/ZnS catalyst, which possessed much higher catalytic activity than Fe TCPP, was conveniently prepared and was easily recovered by simple isolation from the reaction mixture, and it was a promising catalyst in industrial applications.

Superoxide Anion Radical Sensor Using GC Electrode Modified with Heparin/PEDOT and Polymerized Iron Porphyrin

Blood coagulation on the electrode surface is a serious problem for a superoxide anion radical (O2−∙) sensor because it causes deterioration of the current signal especially in vivo. In order to solve this problem, we have developed iron porphyrin-based O2−∙ sensors immobilizing heparin, which is an anti-thrombotic compound, on the surface. In the present study, we immobilized heparin with a polyethylenedioxythiophene (PEDOT) matrix on poly[iron tetrakis(3-thienyl)porphyrin]-modified glassy carbon (GC) electrode, and the stability of the modified sensor to blood coagulation was investigated. The PEDOT matrix was found to be more effective for stable electrochemical detection of O2−∙ after immersion in a fibrinogen/thrombin solution for two weeks, while serious electrode fouling due to blood clot formation was occurred at a sensor using a polypyrrole matrix after immersion in the solution for one week.

Cationic Metalloporphyrins Imobilized in Faujasite Zeolites as a Cytochrome P-450 Mimic

Metalloporphyrins immobilized into NaY zeolite are described as catalysts for hydrocarbon oxyfuntionalization. Manganese(III) and iron(III)tetrakis(4-N-methylpyridyl)-porphyrin (MnP1 and FeP1), and manganese(III) and iron(III) tetrakis(4-N-benzylpiridil)-porphyrin (MnP2 and FeP2) were impregnated (MnP1-NaYimp, FeP1-NaYimp, MnP2-NaYimp, FeP2-NaYimp, respectively) and encapsulated (MnP1-NaY, FeP1-NaY, MnP2-NaY and FeP2-NaY) into the NaY zeolite. These catalysts were used in the oxidation of (Z)-cyclooctene, cyclohexane, and adamantane by iodosylbezene (PhIO). These systems were able to epoxidize (Z)-cyclooctene with cis-epoxycyclooctane yields as high as 100%. By using cyclohexane and adamantane as substrate, the susceptibility of the benzyl groups on the porphyrin ring of the MnP materials, led to a different distribution of the oxidized products. With FePs, this susceptibility was not detected because the species responsible for the oxidations, FeIV(O)P·+, is more active than MnV(O)P. In conclusion, cationic metalloporphyrins immobilized into NaX zeolites, are good cytochrome P-450 models is less polar solvents since the selectivity of the system indicates the “in cage” solvent oxygen rebound oxidative process.

Plasmonic nanoparticle networks formed using iron porphyrin molecular bridges

The adsorption orientation of the iron(III) tetrakis(1-methyl-4-pyridyl)porphine (FeTMPyP) μ-oxo-bridged dimer species located in the inter-particle gap of solid gold nanosphere (SGN) and hollow gold nanosphere (HGN) networks was studied using a combination of linear extinction and surface-enhanced Raman Scattering (SERS) measurements. Nanoparticle aggregation was accomplished by μM additions of iron porphyrin to the colloidal SGN and HGN solutions. Aggregation was monitored by measuring the UV-Visible-NIR extinction spectra of the nanoparticle systems; a broadened and red-shifted localized surface plasmon resonance (LSPR), relative to the LSPR of the isolated nanoparticles, indicated aggregate formation. In conjunction with the LSPR extinction measurements, wavelength-dependent SERS measurements were used to determine the orientation of the FeTMPyP with respect to the SGN and HGN surfaces.

Multilayer Photovoltaic Structures Based on Tetrathiadiazoloporphyrazine/ Subphthalocyanine Heterojunction

Multilayered thin-film structures incorporating a planar junction of two molecular semiconductors, subphthalocyanine (SubPc) and iron tetrakis(1,2,5-thiadiazolo)porphyrazine (FeTTDPz) were fabricated using vacuum evaporation technique. Photovoltaic properties of such structures were tested. The open circuit voltage measured under illumination was equal to 0.4 V indicating that FeTTDPz may readily be used in planar heterojunction photovoltaic cell as n-type semiconductor, instead of conventional acceptor fullerene.

Iron(iii) tetrakis(pentafluorophenyl)porpholactone catalyzes nitrogen atom transfer to CC and C–H bonds with organic azides

We have demonstrated that iron porpholactones could be effective catalysts for nitrogen atom transfer reactions such as aziridination of alkenes and amidation of alkanes using organic azides.

Production of polycyclic aromatic hydrocarbon metabolites from a peroxynitrite/iron(III) porphyrin biomimetic model and their mutagenicities

Some polycyclic aromatic hydrocarbons (PAHs) are typical promutagens that require metabolic activation to exhibit their mutagenicities and carcinogenicities. The metabolites of three PAHs, pyrene (PY), fluoranthene (FLU), and benzo[a]pyrene (BaP), produced from the peroxynitrite/T(p-Cl)PPFeCl(peroxynitrite/(chloride)iron(III)tetrakis(p-chlorophenyl)porphyrin) system, have been identified with high-performance liquid chromatography coupled with electron spray ionization tandem mass spectrometry. The results demonstrated that three major metabolites were the quinone group, OH group, and nitro group. In the Ames test, all three PAH metabolites became mutagenic without using the enzymatic activating system, whereas their parents did not show positive results. Cell transformation assay indicated that 1,3-nitro-BaP and BaP metabolites produced from this biomimetic system have more serious effects in inducing cancer than the BaP parent.