Manganese Tetraphenylporphyrin Research Articles

Manganese tetraphenylporphyrin and carbon nanocoil interface-based electrochemical sensing of tyrosine.

Tyrosine is one of the essential metabolites present in the human body for nutritional maintenance and normal physiological functioning. Its concentration in the body is crucial in predicting various hereditary, emotional, and physiological disorders. Therefore, quantitative monitoring of tyrosine in clinical samples is indispensable. We state the use of carbon nanocoils/manganese tetraphenylporphyrin convened glassy carbon electrode (CNC/MnTPP/GC) for the streamlined electrochemical sensing of tyrosine. Cutting-edge analytical techniques were employed to perform a comprehensive physicochemical analysis of the synthesized materials. To investigate the electrochemical properties, various techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy, and chronocoulometry were employed. CNC/MnTPP/GC displayed an optimal response at pH 5 and exhibited remarkable linearity within the concentration range of 0.05 to 100 μM for tyrosine. Using DPV, it demonstrated a low limit of detection (21 nM ± 1.17) and a sensitivity of 0.12 μA μM-1 cm-2. CNC/MnTPP/GC displayed excellent performance in terms of repeatability, reproducibility, and stability for up to 30 days, making it suitable for real-time analysis, particularly in the analysis of tyrosine in blood serum. Notably, CNC/MnTPP/GC showcased a superior detection limit compared to previously reported methods.

Fabrication of Mn-TPP/RGO Tailored Glassy Carbon Electrode for Doxorubicin Sensing.

Cancer is a long-standing disease, and the use of anticancer drugs can cause many different harmful side effects. Therefore, the quantitative analysis of anticancer drugs is crucial. Among all the analytical techniques that have been utilized for the detection of doxorubicin, electrochemical sensors have drawn exceptional consideration because they are simple, affordable, and highly sensitive. Manganese tetraphenylporphyrin decorated reduced graphene oxide (Mn-TPP/RGO), tetraphenylporphyrin decorated reduced graphene oxide (TPP/RGO), and reduced graphene oxide (RGO) nanostructure based glassy carbon electrodes (GCEs) were fabricated for the detection of doxorubicin (DOX). The synthesized materials were characterized by FTIR, scanning electron microscopy (SEM), ultraviolet-visible spectroscopy (UV/vis), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). Doxorubicin detection was performed using differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Among the prepared electrodes, Mn-TPP/RGO modified GCE gave an optimum peak current at pH 3. The Mn-TPP/RGO modified electrode showed significant linear response range (0.1-0.6 mM); effective sensitivity (112.09 μA mM-1 cm-2); low detection limit (63.5 μM); and excellent stability, selectivity, repeatability, and reproducibility toward doxorubicin. With differential pulse voltammetry, LoD and sensitivity were 27 μM and 0.174 μA μM-1 cm-2, respectively. Real sample analysis was also performed in human serum, and it depicted reasonable recovery results for spiked doxorubicin.

Development of a sensor-based fluorescent method for quality evaluation of used frying oils

The sensor-based fluorescent spectroscopy was developed for the rapid evaluation of oil quality at different frying stages. Manganese tetraphenylporphyrin was selected as the fluorescent sensor according to its sensitivity and selectivity to the oxidation products in frying oil. The performance of the selected fluorescent sensor was calculated based on density functional theory. The fluorescent sensor was then made to detect frying oil quality every 24 h within eighteen days. A fluorescence profile for each oil sample was obtained from the fluorescent sensor reacting with the oil sample. The feature data of fluorescence spectra were extracted using the parallel factor analysis algorithm. All oil samples were classified into three oxidation groups using principal component analysis and support vector machine algorithms. Finally, the classification algorithm of the support vector machine coupled with the genetic algorithm achieved the best classification accuracy of 96.67% and 93.33% in the training set and test set, respectively. The overall results demonstrated that this fluorescent sensor could successfully be applied in the discrimination of frying oil with different oxidation states.

Rapid Assessment of Total Polar Material in Used Frying Oils Using Manganese Tetraphenylporphyrin Fluorescent Sensor with Enhanced Sensitivity

Probe-based three-dimensional fluorescence spectroscopy was developed for the rapid assessment of frying oil quality. Tetraphenylporphyrin manganese (MnTPP) was selected due to its sensitivity and selectivity in response to dissolved organic matter, which is typically produced during the frying process of oil analyte. Parallel factor analysis (PARAFAC) was then performed to decompose three-dimensional fluorescence data for model construction. The digital data representing the change of the MnTPP-base fluorescent probe before and after exposure to dissolved organic matter were analyzed using support vector regression (SVR). SVR was then used for the construction of the regression model between the fluorescence data and the total polar material (TPM). The coefficients of determination (R2) in the training set (R2 = 0.9719) and the test set (R2 = 0.9699) were achieved to evaluate the robustness of the best models for TPM. This study demonstrated that the probe-based three-dimensional fluorescence spectroscopy is useful for assessing the quality of frying oil and perhaps could be used for other food products with high oil contents.

Manganese tetraphenylporphyrin bromide and iodide. Studies of structures and magnetic properties

Manganese tetraphenylporphyrin bromide and iodide Mn(TPP)X (X = Br, 2; I, 3; TPP2− = meso-tetraphenylporphyrinate) are synthetic analogs of Mn(III) geoporphyrins. Crystal structures of 2 and 3 with chloroform in the lattices, Mn(TPP)Br·CHCl3 (2·CHCl3), Mn(TPP)I·CHCl3 (3·CHCl3), Mn(TPP)I·CDCl3 (3·CDCl3 in a different space group from 3·CHCl3), Mn(TPP)I·1.5CHCl3 (3·1.5CHCl3), and 2 with dichloromethane in the lattice, Mn(TPP)Br·CH2Cl2 (2·CH2Cl2), have been determined by single-crystal X-ray diffraction at 100 K or 298 K. Hirshfeld surface analyses of the crystal structures of 2·CHCl3, 2·CH2Cl2, 3·CHCl3, 3·CDCl3 and 3·1.5CHCl3 have been performed. Surprisingly the Mn(III)–Br and Mn(III)–I bonds in Mn(TPP)X (2–3) are about 0.2 Å (8%) longer than Fe(III)–Br and Fe(III)–I bonds in S = 5/2 Fe(TPP)X (X = Br, 4; I, 5), although both Mn(III) and Fe(III) ions have the same radii. Magnetic properties of 2 and 3 have been studied by direct current (DC) and alternating current (AC) susceptibility measurements, high-field electron paramagnetic resonance (HFEPR), and inelastic neutron scattering (INS). With four unpaired electrons in Mn(TPP)X (X = Br, 2; I, 3), the bromide complex 2 in 2·CDCl3 possesses easy-axis anisotropy, as does the chloride analog Mn(TPP)Cl (1), with the axial (D) and rhombic (E) zero-field splitting parameters of D = –1.091(3) cm−1 and |E| = 0.087(2) cm−1. The iodide complex 3 in 3·CDCl3 becomes easy-plane with D = +1.30(1) cm−1 and |E| = 0.010(5) cm−1. Axial ZFS parameters D change from −2.290(5) cm−1 in 1, reported earlier, to −1.091(3) cm−1 in 2 and +1.30(1) cm−1 in 3.

Properties and degradation of manganese(III) porphyrin thin films formed by high vacuum sublimation

Manganese porphyrins are of interest due to the optical, electronic and magnetic properties of the central metal ion, coupled to the low bandgap of the polyaromatic ring. These attractive characteristics are harnessed in solutions or in ultra-thin films, such as, for example, self-assembled monolayers. However, for devices, thicker films deposited using a controlled and reproducible method are required. Here we present the morphological, structural, chemical and optical properties of manganese(III) tetraphenylporphyrin chloride (MnTPPCl) thin films deposited using organic molecular beam deposition, typically employed to process analogue molecules for applications such as organic photovoltaics. We find, using a combination of UV-vis and X-ray photoelectron spectroscopies, that the sublimation process leads to the scission of the Mn–Cl bond. The resultant film is a Mn(II)TPP:Mn(III)TPPCl blend where approximately half the molecules have been reduced. Following growth, exposure to air oxidizes the Mn(II)TPP molecule. Through quantitative analysis of the time-dependent optical properties, the oxygen diffusion coefficient (D) [Formula: see text] is obtained, corresponding to a slow bulk oxidation following fast oxidation of a 8-nm-thick surface layer. The bulk diffusion D is lower than for analogous polycrystalline films, suggestion that grain boundaries, rather than molecular packing, are the rate-limiting steps in oxidation of molecular films. Our results highlight that the stability of the axial ligands should be considered when depositing metal porphyrins from the vapor phase, and offer a solvent-free route to obtain reproducible and smooth thin films of complex materials for engineering film functionalities.

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.

Manganese-doped carbon quantum dots for fluorometric and magnetic resonance (dual mode) bioimaging and biosensing.

Manganese-doped carbon quantum dots (MnCQDs) were prepared through one-step hydrothermal method using citric acid and manganese tetraphenyl porphyrin as carbon sources in aqueous media. The structure of MnCQDs was confirmed by TEM, XRD, and XPS.The MnCQDs display a typical excitation-dependent emission behavior and exhibit bright green luminescence (with a peak at 482nm) under UV irradiation (365nm) and a fluorescence quantum yield of 13%. The MnCQDs can be used as a fluorescent probe for ferric ion in aqueous solution with a 220nM detection limit. The MTT assay demonstrated the low cytotoxicity of MnCQDs towards HeLa cells. Due to the excitation-dependent emission properties, MnCQDs can be used as a multi-color (blue, green, and red) bioimaging agent in cancer cells and in living zebrafish. The application of MnCQDs as selective biosensing probe for Fe3+ was also realized in cells and zebrafish mode. Because of the existence of paramagnetic ions, MnCQDs demonstratean enhanced magnetic resonance (MR) signal. Thus, the MnCQDs can serve as a positive contrast agent for MR imaging. Graphical abstract Schematic presentation of the preparation of luminescent manganese-doped carbon quantum dots (MnCQDs). MnCQDs showed good magnetic resonance effect and can be used as a fluorescence probe for the detection of Fe3+ in HeLa cells and zebrafish.

Combined optical and electronic paper-nose for detection of volatile gases

In this work, a paper-based optoelectronic sensor (paper-nose) is presented for sensing volatile gases in air. The proposed optoelectronic sensor is a combination of both colorimetric (optical) and chemiresistive (electronic) sensor arrays in order to improve the selectivity of the paper-nose in the complex air background. The optical sensors are based on chemoresponsive dyes, namely Reichardt's dye (2,6-diphenyl-4-(2,4,6-triphenyl-1-pyridinio)phenolate), bromocresol purple, methyl red, bromothymol blue, brilliant yellow and manganese tetraphenylporphyrin (Mn-TPP). The chemiresistive sensors are based on nanomaterials, such as carbon nanotubes (CNT), PEDOT:PSS, graphite, and an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI). Sensor is fabricated through direct handwriting of sensing materials using a pen on paper without the need of expensive cleanroom facilities. The optoelectronic sensor is tested in ambient air with different volatile gases such as methanol, ammonia, toluene, acetone and ethanol and their mixtures of varying concentrations. The detected electrical and optical responses together form a unique signature for each volatile gas and its mixture. Support-vector machine (SVM) is applied for target classification and detection. From the SVM result, it is found that better discriminative power is achieved by combining optical and electrical responses.

Detection of Trimethylamine Based on a Manganese Tetraphenylporphyrin Optical Waveguide Sensing Element.

The sensitive detection of trimethylamine has been accomplished by using a homogeneous optical waveguide sensor system. Also the sensor can be easily fabricated by using tetraphenylporphyrin manganese (MnTPP) as sensitive materials to detect different volatile organic compounds (VOC). NMR (1H-NMR), field-emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet-visible (UV-vis) instrumental means were used to characterize its structure. Gas-sensing measurements indicated that the sensing element has shown good selectivity, high sensitivity and a low detection limit level of 0.1 ppm to trimethylamine (TMA) with the presence of interference gases at room temperature. For a range of trimethylamine concentrations from 0.1 to 1000 ppm, the sensor has shown a short response time. Also the response time and recovery time are 1.5 and 50 s, respectively. Simulation experiments (dichloromethane, chloroform and carbon tetrachloride were selected as interference gases) showed little interference with its gas sensing. That may provide an ideal candidate for detecting the freshness of fish and seafood.

Isolating O-O Bond Activation with Manganese Porphyrins

The oxygen reduction reaction (ORR) is catalyzed by manganese(II) tetraphenyl porphyrin (Mn(II)TPP) in the presence of Brønsted acids (HAs). Analysis of the catalytic wave in the cyclic voltammogram of the ORR reaction leads to the proposal two equivalents of HA drives the formation of the initial oxygen adduct, followed by oxygen-oxygen bond activation. An analogous hangman Mn(II) TPP compound has been prepared and characterized. For this ORR catalyst, an acidic proton is provided intramolecularly, and the HA order is reduced to one equivalent. Our data supports a model where one HA is used to stabilize the oxygen bound to the reduced hangman Mn(II) porphyrin platform; one HA is not needed as an internal hydrogen bond may be formed with the hanging acid group. The O–O bond cleavage requires an external HA for the rate-determining step, thus offering a rare example where the O–O bond activation of an ORR process is isolated and captured.

Direct electrochemical DNA biosensor based on reduced graphene oxide and metalloporphyrin nanocomposite

A novel electrochemical DNA sensor based on self-assembled nanocomposite of a π-conjugated structure of reduced graphene oxide (RGO) and a modified manganese (III) tetraphenylporphyrin (MnTPP) was described. The composite MnTPP/RGO was formed through π−π stacking interactions between aromatic rings of graphene sheets and porphyrin macrocycle. Porphyrin molecules are versatile compounds that are easily functionalized with numerous reactive groups and also capable of incorporating many redox metals for electrochemical characterization. In this work, we synthesized the 5-[4-(4-carboxypropanoxy)phenyl]-10,15,20-triphenylporphyrin functionalized with a carboxylic group designed for covalent attachment of 5′-amino single-strand DNA through stable amide link. The MnTPP/RGO platform was characterized by Fourier Transform infrared spectroscopy (FT-IR), UV–visible spectroscopy and electrochemical methods. We demonstrated that the two-dimensional structure and conjugated system of graphene allowed strong interactions of metalloporphyrins and their immobilization on the surface of graphene without loss structural and conductive properties of the graphene. Electrochemical investigations performed by square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) provided that the RGO possessed excellent conductivity and facilitated the electron transfer of redox species. DNA immobilization and hybridization with complementary sequences lead to the change of electrochemical MnTPP/RGO properties. EIS demonstrated an increase of impedance after DNA probe grafting and hybridization. A detection limit of 6×10−14M has been calculated and a dynamic range of 100aM to 10pM has been shown. Selectivity of the biosensors has been investigated in presence of non-complementary and one-mismatched DNA sequence.

Sensitive and Selective Determination of Riboflavin in Food and Pharmaceutical Samples Using Manganese (III) Tetraphenylporphyrin Modified Carbon Paste Electrode

A chemically modified electrode was constructed by incorporating manganese (III) tetraphenyl porphyrine into a carbon paste matrix. The modified electrode was used as a sensitive electrochemical sensor for measuring of riboflavin. The constructed electrode exhibited catalytic properties for the electro-oxidation of riboflavin and lowered the over potential for the oxidation of this compound; consequently, the corresponding peak currents of riboflavin increased significantly. The modified electrode showed a near-Nernstian behavior for electro-oxidation of riboflavin hence, it could be a suitable voltammetric sensor for the fast and easy determination of riboflavin. A linear response in concentration range 1.0 × 10−8 – 1.0 × 10−5 M was obtained with a detection limit of 8.0 × 10−9 M (S /n = 3) for the determination of riboflavin. The electrode showed long-term stability and the standard deviation of the slope obtained after repeated calibration during a period of 3 months was 3.5% (n = 10). The modified electrode was used for differential pulse voltammetric determination of riboflavin in pharmaceutical and food samples.

Manganese(III) Tetraphenylporphyrin Encapsulated by Ion-Modified Hexagonal Mesoporous Silica With Unexpected Enhanced Epoxidation Selectivity

Tetraphenylporphyrin manganese (III) chloride (Mn-TPP) was encapsulated into hexagonal mesoporous silica (HMS) modified by different Lewis acid ions Al, Ti, Zr, and W, which have been tested for selective oxidation of unsaturated olefins and more challenged fatty acid esters under mild condition. Pure W-HMS support displayed no epoxidation activity under the present condition; nonetheless, an unexpected enhanced selectivity for Mn-TPP/W-HMS (90%) with respect to the other samples, especially to homogenous Mn-TPP, indicated the promoted role of W ions over the support. In addition, TG analysis and wetting contact angle measurement were determined in order to reveal the hydrophobic nature of heterogeneous materials, which has been preliminarily scrutinized as the factor influencing catalytic selectivity. That is, Mn-TPP/W-HMS exhibited around 90% selectivity because of a better hydrophobic nature.

Synthesis of conjugated Mn porphyrin polymers with p-phenylenediamine building blocks and efficient aerobic catalytic oxidation of alcohols

A series of conjugated metalloporphyrin polymers (MnP-AMPs) were synthesized based on Buchwald-Hartwig aromatic amination with p-phenylenediamine and manganese tetraphenylporphyrin as building blocks, and N-heterocyclic carbene-palladium complex as catalyst. Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy and transmission electron microscopy showed that MnP-AMPs had large surface areas and uniform pore sizes. The stable porous and superreticular conjugated structure of MnP-AMP further activated manganese ions in the porphin ring compared with those in the original monomanganeseporphyrin. Moreover, introducing CN bonds in MnP-AMP increased its polarity and affinity to alcohols, so MnP-AMP exhibited high catalytic activity when applied to aerobic oxidation of alcohols. For the catalysis of selective oxidation of benzyl alcohol to benzaldehyde with air, the conversion and aldehyde selectivity both reached up to 100% under mild condition in acetonitrile at 40°C. MnP-AMP also remained stable in oxidation reaction system and still had high catalytic activity after several recycles.

Electrocatalytic oxidation of dopamine based on non-covalent functionalization of manganese tetraphenylporphyrin/reduced graphene oxide nanocomposite

In the present work, a reduced graphene oxide (RGO) supported manganese tetraphenylporphyrin (Mn-TPP) nanocomposite was electrochemically synthesized and used for the highly selective and sensitive detection of dopamine (DA). The nuclear magnetic resonance, scanning electron microscopy and elemental analysis were confirmed the successful formation of RGO/Mn-TPP nanocomposite. The prepared RGO/Mn-TPP nanocomposite modified electrode exhibited an enhanced electrochemical response to DA with less oxidation potential and enhanced response current. The electrochemical studies revealed that the oxidation of the DA at the composite electrode is a surface controlled process. The cyclic voltammetry, differential pulse voltammetry and amperometry methods were enable to detect DA. The working linear range of the electrode was observed from 0.3 to 188.8μM, limit of detection was 8nM and the sensitivity was 2.606μAμM−1cm−2. Here, the positively charged DA and negatively charged porphyrin modified RGO can accelerate the electrocatalysis of DA via electrostatic attraction, while the negatively charged ascorbic acid (AA) repulsed by the negatively charged electrode surface which supported for good selectivity. The good recovery results obtained for the determination of DA present in DA injection samples and human pathological sample further revealed the good practicality of RGO/Mn-TPP nanocomposite film modified electrode.

Influence of the Outer Ligands on Metal-to-Ligand Charge Transfer in Solvated Manganese Porphyrins.

Two manganese porphyrin complexes, manganese tetraphenylporphyrin chloride (MnTPP-Cl) and manganese octaethylporphyrin chloride (MnOEP-Cl), exhibit distinctive spectral features of metal-to-ligand charge-transfer (MLCT) when dissolved in dichloromethane, characterized by resonant inelastic X-ray scattering at the Mn L-edge and N K-edge. The metal-ligand orbital mixing that mediates the MLCT is analyzed with the help of density functional theory/restricted open-shell configuration interaction singles calculations. On the basis of experimental and theoretical analyses, the distinctive MLCT is argued to originate from alteration of the porphyrin outer ligands: phenyl groups in MnTPP-Cl and ethyl groups in MnOEP-Cl.

Catalytic properties of the homologous series of the β-brominated-pyrrole manganese(III) tetraphenylporphyrins

A homologous series of β-brominated Mn-porphyrins were prepared and their catalytic activities were investigated in the oxidation of cyclooctene with urea hydrogen peroxide (UHP). The highest conversion of cyclooctene with UHP in ethanol was obtained in the presence of β-tetra-brominated meso-tetraphenylporphyrinatomanganese(III) acetate (MnTPPBr4(OAc)). Therefore MnTPPBr4(OAc) has been selected for oxidation of different alkenes and alkanes. In order to achieve maximum conversion, the effect of different parameters such as solvent, temperature, amount of oxidant, acetic acid as oxidant activator and also the amount of axial base as co-catalyst were investigated.

Effect of L-cysteine on the oxidation of cyclohexane catalyzed by manganeseporphyrin.

Effect of L-cysteine as the cocatalyst on the oxidation of cyclohexane by tert-butylhydroperoxide (TBHP) catalyzed by manganese tetraphenylporphyrin (MnTPP) has been investigated. The results showed that L-cysteine could moderately improve the catalytic activity of MnTPP and significantly increase the selectivity of cyclohexanol. Different from imidazole and pyridine, the L-cysteine may perform dual roles in the catalytic oxidation of cyclohexane. Besides as the axial ligand for MnTPP, the L-cysteine could also react with cyclohexyl peroxide formed as the intermediate to produce alcohol as the main product.

The first manganese N-confused porphyrins catalyzed oxidation of alkene

A series of N-methyl N-confused porphyrin manganese complexes (3a–3f) were synthesized and characterized by UV–vis, XPS, HR-MS and cyclic voltammetry. These complexes were utilized to catalyze the styrene oxidation. It turned out their catalytic activities were comparable with manganese tetraphenylporphyrin (MnTPP). Among all investigated manganese N-confused porphyrins, the most electron deficient 3f exhibited the best catalytic activity for the alkene oxidation. The proposed mechanism for the catalytic oxidation has also been described.