Metal Porphyrins Research Articles

Colorimetric sensor array based on metal porphyrin Dye-Modified mesoporous silica nanospheres for quantitative detection of aflatoxin B1 in wheat

This study developed a novel colorimetric sensor array (CSA) based on mesoporous silica nanospheres (MSNs) for the quantitative detection of aflatoxin B1 (AFB1) in wheat. First, 12 kinds of nano-composite color-sensitive materials (Nano-CSMs) were prepared based on MSNs combined with metal porphyrin dyes, and their color-sensitive materials (CSMs) were modified. The volatile gas information of wheat samples with different degrees of mold was collected using two different sensor arrays, and the characteristic maps were visualized. Next, the genetic algorithm (GA) and particle swarm optimization (PSO) were used to screen the optimal characteristic components, and a support vector regression (SVR) model was established to achieve rapid quantitative detection of AFB1. The optimization results show that the SVR model based on Nano-CSA performed best, with a correlation coefficient (Rp) of 0.9754. The results show that the colorimetric sensor array modified by MSNSs has higher sensitivity and efficiency in the detection of AFB1 in wheat.

Quantum chemical analysis of porphyrin-based sensors: Adsorption and sensing capabilities of pure, protonated, and metallic porphyrins insights into volatile organic compounds (VOCs)

Quantum chemical analysis of porphyrin-based sensors: Adsorption and sensing capabilities of pure, protonated, and metallic porphyrins insights into volatile organic compounds (VOCs)

Biosensors for measuring nitric oxide NO levels in biosubstrates: a systematic analysis

Nitric oxide NO is a signaling molecule involved in numerous physical and pathological processes in biological systems. Highly sensitive sensor materials for measuring NO amounts in vivo in exhaled air and in body fluids (saliva, blood, urine) can be a useful tool in diagnostics and management of patients with bronchopulmonary, cardiovascular, neurological and tumor diseases. Several approaches to measuring NO in biosubstrates (including exhaled air) have been developed: fluorescence/chemiluminescence, electron spin resonance, electrochemical/amperometric (organic and inorganic) and enzymatic/protein sensors. Semiconductors, transition metal nitrides, phthalocyanine complexes, porphyrin and cobalamin derivatives with metals can serve as materials for NO sensors. Creating sensor materials based on vitamin B12 derivatives is an urgent research task in biomedicine. The article systematizes information on using various compounds as materials for NO-sensitive and selective sensors to measure/evaluate NO levels in various biosubstrates.

Covalent Organic Framework Controls the Aggregation of Metal Porphyrins for Enhanced Photocatalytic H2 Evolution.

Although different post modifications of covalent organic frameworks (COFs) have been developed for achieving hierarchical nanostructures and improved photocatalytic performance, the co-assemblies of COFs with small organic molecules were still rarely studied. Herein, COF/porphyrin composites, which were fabricated at room temperature, reveal that COFs surface can modulate the aggregation of metal porphyrins, which subsequently enhance the photocatalytic properties of COFs assemblies. Thus, the surface of COFs was decorated by porphyrins aggregations with varied thickness, dependent on the metal ions of porphyrins. Ni(II) meso-Tetra (4-carboxyphenyl) porphine (NiTCPP) formed discontinuous monolayer covering on COFs surface, while Pt(II) meso-Tetra (4-carboxyphenyl) porphine (PtTCPP) or Co(II) meso-Tetra (4-carboxyphenyl) porphine (CoTCPP) aggregated into multilayer coverage. Notably, even though NiTCPP did not show any advantages in terms of light absorption or HOMO/LUMO energy levels, COF/NiTCPP with the lowest porphyrin loading still exhibited the highest photocatalytic H2 evolution (29.71 mmol g-1 h-1), which is 2.5 times higher than that of COF/PtTCPP or COF/CoTCPP. These results open new possibilities for making highly efficient photocatalysts upon the co-assemblies of COFs with small organic molecules.

Iron-Catalyzed Cross-Electrophile Coupling for the Formation of All-Carbon Quaternary Centers.

Quaternary carbon centers are desirable targets for drug discovery and complex molecule synthesis, yet the synthesis of these motifs within traditional cross-coupling paradigms remains a significant challenge due to competing β-hydride elimination pathways. In contrast, the bimolecular homolytic substitution (SH2) mechanism offers a unique and attractive alternative pathway. Metal porphyrin complexes have emerged as privileged catalysts owing to their ability to selectively form primary metal-alkyl complexes, thereby eliminating the challenges associated with tertiary alkyl complexation with a metal center. Herein, we report an iron-catalyzed cross-electrophile coupling of tertiary bromides and primary alkyl electrophiles for the formation of all-carbon quaternary centers through a biomimetic SH2 mechanism.

Free‐Base Octaethylporphyrin on Au(111) as Heterogeneous Organic Molecular Electrocatalyst for Oxygen Reduction Reaction in Acid Media: An Electrochemical Scanning Tunneling Microscopy and Rotating Ring‐Disc Electrode Analyses

The oxygen reduction reaction (ORR) using metal porphyrin catalysts is currently widely explored. Conversely, metal‐free molecular systems are much less investigated, and there is limited information available for molecules such as nonmetalated macrocycles capable of catalyzing the ORR or other small molecules. Herein, the activity and selectivity of a heterogeneous organic molecular electrocatalyst, octaethylporphyrin (H2OEP), adsorbed on Au(111) toward ORR in acidic aqueous electrolyte are investigated. Electrochemical scanning tunneling microscopy (EC‐STM) is employed to monitor the molecular layer during the electrochemical process. Additionally, cyclic and linear sweep voltammetries are performed at still and rotating Pt/ring‐H2OEP‐functionalized Au(111)/disk electrodes to determine the activity and selectivity of the H2OEP monolayer toward ORR on Au(111). Based on EC‐STM and computation analysis, dioxygen electroreduction does not follow an inner‐sphere electron transfer reduction as seen in metal porphyrins, where a preliminary MO2 bond has to form, but it follows an outer‐sphere mechanism involving the precoordination of O2 induced by the protonated hydrogen of the macrocycle cavity.

Dual-doped metalloporphyrin MOFs-based nanoagent increases low-dose radiotherapy efficacy by apoptosis-ferroptosis for hepatocellular carcinoma

Radiotherapy (RT) represents a cornerstone therapeutic approach in clinical practice for locally control of hepatocellular carcinoma (HCC). However, its efficacy in treating liver cancer is significantly hampered by radiation resistance, which attributed to the insufficient reactive oxygen species (ROS) generation within the tumor microenvironment (TME). To augment RT efficacy, we have developed a novel radiosensitizer termed PTFM. The compound has the features of meso-tetra (4-carboxyphenyl) porphine (TCPP) porphyrin metal–organic frameworks (MOF, PCN-224(Fe)) co-doped with high-atomic element Ta. Under X-ray excitation, the porous PTFM acts as a proficient radio-sensitization, absorbs X-ray energy to promote hydroxyl radicals generation for RT, thereby disrupting the redox balance and intensifying the cytotoxic effect on tumor cells. The incorporation of Fe3+ into the macrocycle of TCPP within the MOFs shell, facilitates the reactions with GSH and H2O2 in the TME, leads to ROS production that promotes ferroptosis and apoptosis, while also releases O2 to alleviate tumor hypoxia. Furthermore, PTFM with thermo-metal serves as a dual-mode MR/CT imaging contrast agent, enabling precise RT monitoring and imaging guidance. In conclusion, the radiosensitizer we developed integrates dual-mode imaging capabilities and enhances RT sensitization for HCC through ROS-induced cell apoptosis and ferroptosis, thereby ameliorating tumor hypoxia.

Tunable Rectification in 2D Porphyrinic Metal–Organic Framework Nanosheets Molecular Heterojunctions

AbstractAs functional electrical devices advance, new strategies for regulating electrical properties are essential for achieving diverse electrical performance. In this study, molecular heterojunction rectifiers are constructed by connecting porphyrinic 2D metal–organic framework (2D MOF) nanosheets and oligophenylene thiols self‐assembled monolayers (OPT SAMs) within metal electrodes. The rectification characteristics can be tuned by the molecular length of OPT and the coordinated metal atom in the center of 2D MOFs. Specifically, a rectification ratio of more than 1.67 orders of magnitude is achieved in the heterojunction composed of 2D Zn‐TCPP MOF nanosheet (TCCP, tetrakis(4‐carboxyphenyl) porphyrin) and OPT3 SAM. Combining Kelvin probe force microscopy measurements and first‐principles calculations of the 2D MOF nanosheets, it elucidates that the rectification variations come from the adjustment of energy level alignment at OPT SAMs//2D MOF interface, leading to asymmetric charge transport with the voltage polarities. This strategy can be further extended to Cu‐MOF nanosheets, which also exhibit rectification behaviors when placed on OPT2 SAMs. This work provides a universal and flexible strategy for regulating the electrical behaviors of MOFs without the need for specific design and synthesis, paving the way for the development of MOF‐based functional electronic devices.

Research progress of metalloporphyrin against neurodegen-erative diseases.

Neurodegenerative disorders are a group of diseases caused by the degeneration and apoptosis of neurons in the brain and spinal cord, which seriously affect human ability of motion perception, memory and cognition. Peroxynitrite can cause oxidative damage in the brain exhibiting neurotoxicity, and its excussive accumulation is closely related to neurodegenerative diseases. Therefore, effectively scavenging peroxynitrite may become a therapeutic strategy for neurodegenerative diseases. Due to their high peroxynitrite scavenging ability, some water-soluble metalloporphyrins have recently attracted much attention. Metalloporphyrins such as iron porphyrins and manganese porphyrins have certain neuroprotective effects, including inhibiting amyloid plaque accumulation, alleviating oxidative stress and neuroinflammatory damage, improving mitochondrial function and reducing neuronal apoptosis. However, there are certain limitations for metalloporphyrins as neuroprotective drugs, and some metal porphyrins have poor blood-brain barrier penetration. To overcome the obstacle, in addition to traditional synthesis processes, metalloporphyrins can also be prepared into nanoparticles to improve bioavailability in vivo. Here, we will review the mechanisms underlying the neuroprotective effects of metalloporphyrin and explore its therapeutic potential for neurodegenerative disorders.

Fabrication of Novel Porous Nano-pesticides by Modifying MPN onto Cu-TCPP MOFs to Enhance Bactericidal Efficacy and Modulate Its Bioavailability.

Nano-pesticides have attracted much attention in the field of agriculture, due to existing problems such as decreased bactericidal effect and poor adhesion. An environmentally friendly metal porphyrin (Cu-TCPP)-based nanocarrier pesticide release of diniconazole (DIN) was designed to enhance bactericidal efficacy and modulate its bioavailability in a multidimensional manner by constructing a metal phenolic network (MPN) encapsulation. The introduction of the MPN prevents the DIN from prematurely escaping from the Cu-TCPP@DIN@MPN in the environment and gives it strong interfacial adhesion to resist rain washing. The resulting Cu-TCPP@DIN@MPN nanoparticles (NPs) showed a lamellar stacked embedded structure, which improved the inhibition of Fusarium oxysporum (90.9%) and photostability (67.2%), while they do not affect healthy plant growth and meet the relevant food safety requirements for DIN residues. This work provides new ideas for the development of superior photostable, adhesive, rainwater erosion-resistant, and sustainable nanocarrier pesticides.

A novel ZIF-8 mediated nanocomposite colorimetric sensor array for rapid identification of matcha grades, validated by density functional theory

The rapid and intelligent assessment of matcha grades remains crucial in quality control. This study proposed a colorimetric sensor array (CSA) mediated with zeolitic imidazolate framework-8 (ZIF-8) to identify matcha grades. The ZIF-8 mediated CSA was innovatively developed by encapsulating the pH indicator and metal porphyrin within the ZIF-8 structure, improving their stability and functionality. ZIF-8 mediated CSA exhibited significantly increased sensitivity towards matcha samples driven by the preconcentration of volatile organic compounds (VOCs) facilitated by ZIF-8. As a result, the response signal values of the CSA increased by 1.13–4.75 times after ZIF-8 mediation. Subsequently, qualitative models for identifying matcha grades were established using K-Nearest Neighbor and Artificial Neural Network (ANN). The ANN model showed the higher discrimination accuracy. Compared with common CSA, the ANN model based on ZIF-8 mediated CSA achieved a better identification rate of 95 %, and recognition accuracy was improved by 7.5 % in the model. These results indicated that the ZIF-8 mediated CSA with a porous structure demonstrated enhanced specificity in capturing VOCs. Ultimately, the density functional theory has confirmed that the ZIF-8-mediated CSA exhibits high selectivity towards matcha's characteristic VOCs. These results highlight the potential of this novel CSA for the rapid identification and grading of matcha.

Imparting functionality into porphyrin metal–organic framework aerogels with uniform distributions for diversified applications

The incorporation of various functional nanoentities into pure metal–organic framework (MOF) aerogels can not only introduce additional functionality but also expands the application scenarios of MOF aerogels. Herein, a general and simple strategy for uniform incorporation of various functional nanomaterials into a porphyrin MOF aerogel is presented. Specifically, this strategy primarily involves the introduction of a surfactant polyvinylpyrrolidone (PVP) to disperse the nanomaterials in lipophilic solvents, followed by a direct solvothermal reaction with the precursors of the porphyrin MOF aerogel. Additionally, uniform aerogel composites consisting of two MOF components have also been developed by careful optimizing the reaction conditions. The resulting nanoentity@MOF aerogel composites exhibit positive properties that stem from the synergistic effects between the nanoentities and MOF aerogel, offering advanced applications in areas such as photochemical electrochemistry, adsorption and photodegradation, electrochemical oxygen reduction reaction, and fluorescence.

Structural effects of metal porphyrins and metal corroles on the mechanisms of the oxygen reduction reaction

Structural effects of metal porphyrins and metal corroles on the mechanisms of the oxygen reduction reaction

Construction of ROS-balancing-engineered heterojunction photoswitch for achieving programmed inflammatory management and tissue regeneration

Early instigation and subsequent attenuation of inflammation are crucial for tissue regeneration, which poses a need for inflammatory regulation in the design of materials. In this work, a novel photocatalytic heterojunction consist of MXene, Zr-based porphyrinic metal–organic framework (named PCN-222), and Pt nanoparticles (termed MX/PCN@Pt HJs) is developed to achieve photo-controlled reactive oxygen species (ROS) generation and clearance. According to density function theory calculations and related experiments, the unique heterojunction formed by MXene and MOFs, abundant O2 adsorption sites of metal oxide clusters, and porous features of MOFs promoted the adsorption of active reactants and accelerated electron transfer, thereby exhibiting excellent photocatalytic performance. Meanwhile, the PCN-222 with superoxide dismutase (SOD) activity and Pt nanoparticles with catalase (CAT) activity endowed the MX/PCN@Pt HJs with SOD/CAT mimetic cascade performance. Through the photo-controlled regulation, the MX/PCN@Pt HJs acted as a photoswitch that flexibly achieved the switch between ROS generation and clearance. Effective production of ROS not only enabled antimicrobial activity but also contributed to a pro-inflammatory state; while the timely ROS scavenging activity effectively prevented the detrimental effects of sustained inflammation. Both in vitro and in vivo evaluations had confirmed the inflammatory modulation and tissue regeneration potency of the MX/PCN@Pt HJs based on the ROS-regulated strategy, which offer a vital understanding of the MOF-based photocatalytic heterojunction for programmed inflammatory regulation.

Cobalt (II) porphyrin nanoaggregates as sacrificial templates to improve the peroxidase-like activity of light-controlled TiO2-based nanozymes for colorimetric determination of amikacin

Although porphyrin modification can improve the peroxidase-like activity of some inorganic nanozymes, it is hardly studied that metal porphyrin self-assembled nanoaggregates as sacrificial templates to turn on the peroxidase-like activity of inorganic nanozymes under light illumination. In this work, cobalt (II) 5,10,15,20-Tetrakis (4-carboxylpheyl)porphyrin (CoTCPP) self-assembled nanoaggregates are firstly used as soft templates to prepare TiO2-based nanozymes with the enhanced peroxidase-like activity. Interestingly, CoTCPP nanoaggregates can be changed into Co oxide nanoparticles dispersed into the nanosphere composites. Furthermore, the peroxidase-like activity of CoTCPP-TiO2 nanospheres can be controlled by light illumination. Comparatively, CoTCPP-TiO2 nanoshperes exhibit the highest peroxidase-like activity of three nanospheres (CoTCPP-TiO2, H2TCPP-TiO2 and TiO2) with similar morphology under the light illumination. Other than the existence of oxygen vacancy, the formation of heterostructure between TiO2 and a small amount of Co3O4 are ascribed to increase the catalytic activity of CoTCPP-TiO2 composites. Thus, a facile and convenient colorimetric sensing platform has been constructed and tuned by light illumination for determining H2O2 and amikacin in a good linear range of 20–100 and 50–100 μM with a limit of detection (LOD) of 3.04 μM and 1.88 μM, respectively. The CoTCPP-TiO2 based colorimetric sensing platform has been validated by measuring the amikacin residue in lake water.

Electrolyte Composition‐Dependent Product Selectivity in CO2 Reduction with a Porphyrinic Metal–Organic Framework Catalyst

AbstractA copper porphyrin‐derived metal–organic framework electrocatalyst, FICN‐8, was synthesized and its catalytic activity for CO2 reduction reaction (CO2RR) was investigated. FICN‐8 selectively catalyzed electrochemical reduction of CO2 to CO in anhydrous acetonitrile electrolyte. However, formic acid became the dominant CO2RR product with the addition of a proton source to the system. Mechanistic studies revealed the change of major reduction pathway upon proton source addition, while catalyst‐bound hydride (*H) species was proposed as the key intermediate for formic acid production. This work highlights the importance of electrolyte composition on CO2RR product selectivity.

A Minireview on Porphyrin and Phthalocyanine Based Catalysts for Electrocatalytic Synthesis of Ammonia

AbstractAmmonia (NH3) is an important raw material in the chemical industry, but the synthesis of NH3 by the traditional Haber‐Bosch process will increase the carbon footprint. Therefore, it is necessary to develop sustainable routes for NH3 production. New NH3 production schemes, including nitrogen reduction (N2RR), nitrite reduction (NO2RR), and nitrate reduction (NO3RR), have been proposed. Porphyrins and phthalocyanines are macrocyclic compounds with a central metal ion coordinated with nitrogen. The metal centers in these catalysts play a crucial role in binding and activating nitrogen, nitrite, and nitrate. Their unique structure allows for effective electron transfer and catalytic activation in NH3 synthesis. Recently, metal porphyrin and phthalocyanine based catalysts have been demonstrated to be efficient in catalyzing N2RR, NO2RR, and NO3RR. Unfortunately, there is no review focusing on such macrocyclic catalysts for the electrocatalytic synthesis of NH3. In this review, we discuss the electrocatalytic reduction performances and summarize the key factors and reaction mechanisms that affect the catalytic performance of metal porphyrin and phthalocyanine based catalyst systems. This review helps to design more effective new electrocatalysts for NH3 synthesis.

Revealing the potential-determining steps of reduction of nitrate to ammonia on transition metal porphyrins catalysts

The reduction reaction of nitrate (NO3RR) to ammonia by electrocatalytic methods is a promising method for sustainable ammonia synthesis, yet it remains a great challenge. In this work, we report a class of transition metal coordination porphyrins (TM-PP) as a cost-effective, high activity and selectivity electrocatalysts for NO3RR. By large-scale density functional theory calculations, our investigation into the catalytic mechanism of TM-PP sheds light on the underlying principles of their enhanced activity. It's worth noting that through systematic study of potential-determining steps, we proposed for the first time that the Gibbs free energy change of the 7th step (*NOH→*N) reaction can serve as an effective catalytic descriptor for NO3RR and unveiled its underlying mechanism. We theoretically demonstrate that Mo-PP and Ru-PP stand out among 23 TM-PP and showcasing superior performance supported by systematic analyses of kinetics, thermodynamics, and electrochemical stabilities. Mo-PP boast a significantly reduced additional voltage requirement of merely –0.16 V compared to existing catalysts. Furthermore, both Mo-PP and Ru-PP demonstrate the capacity to suppress the competing HER and effectively prevent the generation of by-products. Overall, our work presents a promising NO3RR catalyst with great potential for practical applications and provides valuable insights into the NO3RR intricate mechanisms.

Synthesis of Hetero-Trimetal Porphyrin Nanobelts.

This work reported "trinitarian" porphyrin nanobelts, contained hetero-trimetal ions. The high-resolution mass spectrometry and X-ray crystallography proved PNBNiCuPd consisting of three different bent porphyrin(2.1.2.1) metal complex moieties. The redox properties indicate porphyrin nanobelts demonstrate the multielectron donating and accepting properties, more than nine redox processes.

Investigation of demetallization of Ni and V in crude oil using spherical polyelectrolyte brushes with adjuvant

Nickel and vanadium in crude oil adversely affects the quality of petroleum coke and refining process. Polymer brushes bearing high-density ligands have shown promising nickel removal ability. In this work, submicron polybutadiene (PB) grafted by aminodithio- carbamate acrylamide (PAMDTC@PB) was prepared and characterized by the infrared spectroscopy, dynamic light scattering, and elemental analysis. Based on results of molecular simulation, PAMDTC was selected as ligand molecule at first. Then the nickel and vanadium removal rates by PAMDTC@PB and traditional polyacrylic acid brushes (PAA@PB) were evaluated through the electric desalination process, both in the model and real oil samples. The result shows that S atom in AMDTC is most likely to chelate with metal porphyrin compounds and AMDTC molecule presents highest chelating activity. Compared with PAA@PB, the removal rate of Ni and V porphyrin compounds with the aid of PAMDTC@PB increases significantly, with an optimized removal rate of 46.91 % and 56.81 %. To achieve better metal removal efficiency and higher utilization rate of prepared polymer brushes, sodium dimethyl dithiocarbamate (SDD) is introduced into the electric desalination process as a adjuvant. The results indicate that the addition of SDD leads to a increment of 10–30 % to the removal rate of Ni and V and a reduction of brush dosage by 200–400 ppm in the electric desalination process, exhibiting great potential of industrial applications of novel desalination process with adjuvant.