Metal Porphyrins Research Articles

Zn–porphyrin metal–organic framework–based photoelectrochemical enzymatic biosensor for hypoxanthine

Zn–porphyrin metal–organic framework–based photoelectrochemical enzymatic biosensor for hypoxanthine

Photophysical characterization and in vitro anti-leishmanial effect of 5,10,15,20-tetrakis(4-fluorophenyl) porphyrin and the metal (Zn(II), Sn(IV), Mn(III) and V(IV)) derivatives.

In this report 5 compounds were synthesized and structural and their photophysical characterization was performed (ΦΔ and Φf). Furthermore, in this in vitro study, their biological activity against Leishmania panamensis was evaluated. The photophysical behavior of these compounds was measured and high ΦΔ and low Φf was observed. Besides, DFT quantum calculations on the electronic structures were performed. Finally, the biological activity was determined by means of the compounds capacity to inhibit the viability of parasites using the MTT assay. The inclusion of the metal ions substantially modified the photophysical and biological properties in comparison with the free metal porphyrin (1). In fact, Zn2+ porphyrin derivative (2) showed a marked decrease of Φf and increase of ΦΔ. In this sense, using TDDFT approaches, a luminescent process for Sn4+ derivative (3) was described, where emissive states involve the ML-LCT transition. So, this led to a decrease in the singlet oxygen production (0.82-0.67). Biological results showed that all compounds inhibit the viability of L. panamensis with high efficiency; the decrease in the viability was greater as the concentration of exposure increased. Finally, under light irradiation the IC50 of L. panamensis against the Zn(II)-porphyrin (2) and V(IV)-porphyrin (5) was lower than the IC50 of the Glucantime control (IC50 = 2.2 and 6.95μM Vs IC50 = 12.7μM, respectively). We showed that the use of porphyrin and metalloporphyrin-type photosensitizers with exceptional photophysical properties can be successful in photodynamic therapy (PDT) against L. panamensis, being the diamagnetic ion Zn2+ a candidate for the preparation of metalloporphyrins with high singlet oxygen production.

Different types of interactions between fullerene C60 and C70 anions and metal tetraphenylporphyrins in the (PMDAE+)(MIITPP)(Fullerene−)⋅Solvent complexes (M = Co, Mn, Zn) containing coordinating N, N, N, N‘, N‘-pentamethyldiaminoethane cations

Series of anionic salts of fullerenes C60 and C70 with different metal tetraphenylporphyrins, MIITPP, where M = Co, Mn and Zn, and N, N, N, N‘, N‘-pentamethyldiaminoethane cations (PMDAE+) has been obtained in a crystalline form. Composition of the complexes is (PMDAE+)⋅(MIITPP)(C60−)⋅XC6H4Cl2 (M = Co, X = 1.25 (1), M = Mn, X = 0.75 (2) and M = Zn, X = 0.75 (3)) and {(PMDAE+)⋅ZnIITPP}2⋅(C70−)2⋅4C6H4Cl2 (4). Both fullerene anion and nitrogen-containing PMDAE+ cation can coordinate to metal porphyrin competing with each other. Weak Co-C(C60−) coordination bond of 2.426(7) Å length (120 K) is formed in 1 whereas PMDAE+ cation only weakly coordinates to CoIITPP. Dissociation of Co-C(C60−) bond observed at 90–310 K is accompanied by a transition of 1 from singlet to triplet state with an energy gap of 574 ± 3 K. According to the calculations negative charge on C60− is only −0.548 due to electron transfer to the macrocyclic ligand through the cobalt atom. Charge transfer bands are observed in {CoIITPP(C60)}− at 700 and 1240 nm. On the contrary, PMDAE+ cations coordinate to MnIITPP and ZnIITPP in 2 and 3, respectively, with short M−N(PMDAE+) bonds of 2.27–2.33 Å length. In these cases fullerenes are preserved in the non-coordinated radical anion state. Fullerenes are arranged in closely packed π-stacking {C60•−}2 dimers with short interfullerene center-to-center distances of 9.92–9.95 Å. Nevertheless, the C60•− radical anions do not form intercage CC bonds down to 1.9 K. Strong antiferromagnetic coupling of spins is observed in the {C60•−}2 dimers of 3 with exchange interaction of J/kB = -21 K. Both {(PMDAE+)⋅MnIITPP} and C60•− species are paramagnetic in 2 having S = 5/2 and S = 1/2 spin states, respectively. These spins are coupled antiferromagnetically with Weiss temperature of −16 K. It is obvious that magnetic coupling occurs not only in the {C60•−}2 dimers but MnIITPP is also involved in this coupling. The C70•− radical anions are dimerized in 4 forming diamagnetic singly-bonded (C70−)2 dimers which manifest intense NIR absorption. As a result, complex 4 is EPR silent.

Construction of Electrochemical Aptamer Sensor Based on Pt-Coordinated Titanium-Based Porphyrin MOF for Thrombin Detection.

In this work, a Pt-coordinated titanium-based porphyrin metal organic framework (Ti-MOF-Pt) was prepared by embedding single-atom Pt through strong interactions between the four pyrrole nitrogen atoms in the rigid backbone of the porphyrin. The synthesized Ti-MOF-Pt was characterized by TEM, XRD, FTIR and BET. Then, the Ti-MOF-Pt has been used for glassy carbon electrode surface modification and consequently used for construction of a thrombin aptamer sensor. The high surface area provides by MOF and excellent electrochemical property provided by Pt enhance the sensing performance. After optimization of amount of aptamer, hybridization time and specific reaction time, the fabricated aptamer sensor exhibited a linear relationship with the logarithm of the thrombin concentration in the range of 4 pM to 0.2 μM. The detection limit can be calculated as 1.3 pM.

Metal center regulation of the porphyrin unit in covalent organic polymers for boosting the photocatalytic CO2 reduction activity

Regulating the porphyrin's metal center of metalloporphyrin(MPor)/Ru(ii)-pincer complex(RuN3) covalent organic polymers (COPs) effectively boosted the CO2 photoreduction by promoting charge separation and sacrificial electron donor oxidation.

A new porphyrinic vanadium-based MOF constructed from infinite V(OH)O4 chains: syntheses, characterization and photoabsorption properties

A new porphyrinic vanadium-based metal–organic framework (MOF), namely V-MOF-10 [V2(OH)2(H2TCPP)], constructed from {V(OH)O4}∞ chains and 4-tetracarboxyphenylporphyrin linkers, was synthesized by a solvothermal procedure.

Unveiling the mechanism of the photocatalytic reduction of CO2to formate promoted by porphyrinic Zr-based metal–organic frameworks

A complete picture of the reaction mechanism driving the photocatalytic reduction of CO2into formate promoted by the Zr-based porphyrinic MOF-545 in CH3CN/TEOA solutions is provided for the first time by combining experimental and computational approaches.

NiFe-mixed metal porphyrin aerogels as oxygen evolution reaction catalysts in alkaline electrolysers.

Aerogels are a very interesting group of materials owing to their unique physical and chemical properties. In the context of electrocatalysis, the focus has been on their physical properties, and they have been used primarily as catalyst supports so far. In this work, we synthesized porphyrin aerogels containing Ni and NiFe mixed metal materials and studied them as catalysts for the oxygen evolution reaction (OER). Different Ni : Fe ratios were synthesized and studied in electrochemical cells, and DFT calculations were conducted in order to gain insight into their behavior. The activity trends were dependent on the metal ratios and differ from known NiFeOOH materials due to the change in the oxidation states of the metals to higher numbers. Herein, we show that Ni and Fe have a synergistic effect on the OER, despite being structurally separated. They are connected electronically, though, through a large organic aromatic system that facilitates electron sharing between them. Among the mixed metal porphyrin aerogels, the best ratio was found to be Ni : Fe = 35 : 65, in contrast to oxide/oxyhydroxide materials in which a ratio of 80 : 20 was found to be ideal.

Mitigating the photodegradation of all-inorganic mixed-halide perovskite nanocrystals by ligand exchange.

We show that the decomposition of caesium lead halide perovskite nanocrystals under continuous X-ray illumination depends on the surface ligand. For oleic acid/oleylamine, we observe a fast decay accompanied by the formation of elemental lead and halogen. Upon surface functionalization with a metal porphyrin derivative, the decay is markedly slower and involves the disproportionation of lead to Pb0 and Pb3+. In both cases, the decomposition is preceded by a contraction of the atomic lattice, which appears to initiate the decay. We find that the metal porphyrin derivative induces a strong surface dipole on the nanocrystals, which we hold responsible for the altered and slower decomposition pathway. These results are important for application of lead halide perovskite nanocrystals in X-ray scintillators.

Post-synthetically modified metal-porphyrin framework GaTCPP for carbon dioxide adsorption and energy storage in Li-S batteries.

Lithium–sulphur batteries attract increasing interest due to their high theoretical specific capacity, advantageous economy, and “eco-friendliness”. In this study, a metal–organic framework (MOF) GaTCPP containing a porphyrinic base ligand was used as a conductive additive for sulphur. GaTCPP was synthesized, characterized, and post-synthetically modified by the transition metal ions (Co2+/Ni2+). The doping of GaTCPP ensured an increase in the carbon dioxide adsorption capacities, which were measured under different conditions. Post-synthetic modification of GaTCPP with Co2+/Ni2+ ions has been shown to increase carbon dioxide storage capacity from 22.8 wt% for unmodified material to 23.1 wt% and 26.5 wt% at 0 °C and 1 bar for Co2+ and Ni2+-doped analogues, respectively. As a conductive part of cathode material, MOFs displayed successful sulphur capture and encapsulation proven by stable charge/discharge cycle performances, high-capacity retention, and coulombic efficiency. The electrodes with pristine GaTCPP showed a discharge capacity of 699 mA h g−1 at 0.2C in the fiftieth cycle. However, the doping of GaTCPP by Ni2+ has a positive impact on the electrochemical properties, the capacity increased to 778 mA h g−1 in the fiftieth cycle at 0.2C.

Distortion-driven spin switching in electron-doped metal porphyrins

Different conformers can be stabilized for flexible porphyrins upon electron doping. The metastable flat conformer relaxes to the energetically favored distorted form, inducing spin switching in the chelated nickel ion.

Selection of Aptamer for N-Methyl Mesoporphyrin IX to Develop Porphyrin Metalation DNAzyme.

Mesoporphyrin IX (MPIX) contains a planar macrocycle center that can interact with various divalent metal ions through the exposed binding sites, leading to the metalation of MPIX. The DNA aptamers for porphyrin molecules usually display different catalytic functions (termed deoxyribozymes or DNAzymes), which can accelerate such chemical reactions. Inspired by this, an affinity chromatography selection approach was designed for identifying a porphyrin metalation DNAzyme. In our experiment, N-methyl mesoporphyrin IX (NMM), an analog of MPIX, is used as the target molecule, owing to its stable and high fluorescence enhancement after combining with specific oligonucleotides. Our results showed that the selected aptamer Nm1 is capable of binding to NMM with a low micromolar dissociation constant (0.75±0.08μM) and displays a catalytic activity for MPIX metalation with 3.3-fold rate enhancement. The protocol for isolation of such a porphyrin metalation DNAzyme is described in detail here.

A two-dimensional Bi-based porphyrin metal–organic framework photocatalyst for white light-driven selective oxidation of sulfides

A single crystal of a Bi-based porphyrin metal–organic framework was synthesized by a hydrothermal method. It exhibited significant photocatalytic activity for the selective oxidation of sulfides, maintaining high activity after 10 catalytic cycles.

Mixed-metal Zr/Ti MIL-173 porphyrinic metal–organic frameworks as efficient photocatalysts towards solar-driven overall water splitting

A hydrolytically stable metal–organic framework containing Ti(iv) and porphyrinic linkers allows a photoinduced charge separation process for the photocatalytic overall water splitting reaction.

Bidirectional Light-Driven Ion Transport through Porphyrin Metal–Organic Framework-Based van der Waals Heterostructures via pH-Induced Band Alignment Inversion

Bidirectional Light-Driven Ion Transport through Porphyrin Metal–Organic Framework-Based van der Waals Heterostructures via pH-Induced Band Alignment Inversion

Molecular Structure of Nickel Octamethylporphyrin-Rare Experimental Evidence of a Ruffling Effect in Gas Phase.

The structure of a free nickel (II) octamethylporphyrin (NiOMP) molecule was determined for the first time through a combined gas-phase electron diffraction (GED) and mass spectrometry (MS) experiment, as well as through quantum chemical (QC) calculations. Density functional theory (DFT) calculations do not provide an unambiguous answer about the planarity or non-planar distortion of the NiOMP skeleton. The GED refinement in such cases is non-trivial. Several approaches to the inverse problem solution were used. The obtained results allow us to argue that the ruffling effect is manifested in the NiOMP molecule. The minimal critical distance between the central atom of the metal and nitrogen atoms of the coordination cavity that provokes ruffling distortion in metal porphyrins is about 1.96 Å.

Polythiophene hybrid film with zirconium–porphyrin metal–organic framework for improved charge carrier transport and NO2 gas sensing

Noxious gas sensors based on polymer thin films are attracting increasing attention because of their unique advantages. However, polymeric gas sensors usually exhibit low sensitivity and slow response rates for target gas molecules. These drawbacks are attributed to the poor charge transport in polymer active layers and to a structural limit resulting from the use of thick semiconductor films because of low charge carrier density. In this study, we examined the electrical and physical properties of Fe porous coordination network 222 (PCN-222) and explored its potential as an analyte interacting material inserted into a polymer active layer. The morphologies, molecular structures, and electrical characteristics of PCN-222/polythiophene blend films were systematically examined. The superior electrical characteristic of the PCN-222 enhanced the field-effect mobility in the polythiophene transistors. In addition, transistor-based sensors with the PCN-222/polythiophene blend films also showed significantly enhanced nitrogen dioxide sensing characteristics, including an enhanced responsivity, response rate. The improved sensing performance was due to the porous structures and large specific surface area of the PCN-222. These results provide useful guidelines for the application of transistor-type gas sensor based on metal–organic framework/polymer semiconductor blend films.

Complexes of Transition Metals with Petroleum Porphyrin Ligands: Preparation and Evaluation of Catalytic Ability

In the present work, the first data on the catalytic activity of d-metal complexes of petroleum porphyrins obtained via two-stage re-metallization (acid demetallization with subsequent metalation) of high-purity petroleum vanadyl porphyrins are presented. During acid demetallization of petroleum vanadyl porphyrins, the highest yield (49%) and spectral purity of free petroporphyrin bases were achieved with concentrated sulfuric acid and a diluted solution of vanadyl porphyrins in chloroform. In the series of divalent cations of Mn, Fe, Co, Ni, Cu, and Zn, only the last four metals are complexed with demetallated petroporphyrins without significant changes in their component composition, whereas the interaction with Mn and Fe cations causes an evident structural transformation or even full degradation of petroporphyrin macrocycles, respectively. The composition and spectral purity of petroleum porphyrin-containing reactants and products were analyzed by FT-IR, UV-Vis, NMR, and MALDI-TOF mass spectroscopic methods. The obtained petroporphyrin-based d-metal complexes were assayed by the reaction of 2-mercaptoethanol oxidative dimerization, in which the copper porphyrins exhibited the highest catalytic activity.

Electrodeposition of films of individual 5,10,15,20-tetrakis(3-aminophenyl)porphyrin metal complexes and their composite for electrocatalytic oxygen reduction

Carbon-based materials are common and quite promising for such industrial applications as power generation using electrochemical and electrocatalytic processes and can be successfully used as electrode substrates. The effectiveness of carbonaceous materials can be improved by modifying the electrode surface with phthalocyanine and porphyrin metal complexes possessing electrocatalytic properties. In this work, polyporphyrin films were obtained on a glassy carbon electrode from individual 5,10,15,20-tetrakis(3-aminophenyl)porphyrin metal complexes and a composite of two Fe and Mn metal complexes. The polymerization was carried out by the electrochemical method. The results of the evaluation of the polyporphyrin catalytic activity in oxygen electroreduction reactions achieved by different methods are in good agreement with each other and indicate higher catalytic activity of the composite of the two metal complexes than the films of individual porphyrins, which indicates the synergistic effect.

On‐Surface Synthesis of Porphyrin‐Complex Multi‐Block Co‐Oligomers by Defluorinative Coupling

AbstractOn‐surface chemical reaction has become a very powerful technique to synthesize nanostructures by linking small molecules in the bottom‐up approach. Given the fact that most reactants are simultaneously activated at certain temperatures, a sequential reaction in a controlled way has remained challenging. Here, we present an on‐surface synthesis of multi‐block co‐oligomers from trifluoromethyl (CF3) substituted porphyrin metal complexes. The oligomerization on Au(111) is demonstrated with a combination of bond‐resolved scanning probe microscopy and density functional theory (DFT) calculations. Even after the first oligomerization of single monomer unit, the termini of the oligomer keep the CF3 group, which can be used as a reactant for further coupling in a sequential order. Consequently, copper, cobalt, and palladium complexes of bisanthracene‐fused porphyrin oligomers were linked with each other in a designed order.