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Macrocyclic Ligands and their metal Complexes.
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The fascinating structures of naturally occurring porphyrins and metalloporphyrins have been perfected by nature to give functional dyes par excellence. The important roles these tetrapyrrolic macrocycles play in vital biological processes, in particular photosynthesis (chlorophyll), oxygen transport (hemoglobin), oxygen activation (cytochrome), ha...
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While searching for adequate sol-gel methodologies for successfully trapping in monomeric and stable form either porphyrins or phthalocyanines, inside translucent monolithic silica xerogels, it was discovered that the interactions of these trapped tetrapyrrole macrocycles with Si-OH surface groups inhibit or spoil the efficient display of physicoch...
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Citations
... The results of the current study showed that the total peak area of milbemycin was increased from 2% in A. platensis powder (AP) to 66.68% in A. platensis nanoparticle (NAP). Porphyrin is a molecule (macrocyclic tetrapyrrole) that has great biological functions, particularly in the photosynthesis process, chemical sensors (Pogonin et al., 2015), photodynamic therapy (Mathai et al., 2007), energy conversion (Campbell et al., 2007), photonics (Yang et al., 1999), oxygen transport and activation (haemoglobin and cytochrome, respectively) (Chandra et al., 2000), and the creation of novel macro-heterocyclic functional materials (Pogonin et al., 2020). In the current study, the application of the top-down technique on A. platensis to produce nanoparticles could lead to the creation of new bioactive materials with the bonding form of copper complexe, copper-etioporphyrin II (metalloporphyrins) complexes, which are considered to be biologically important and represent approximately 11.06% of the total peak area ( Fig. 2 and Table 3). ...
The utilization of nanoparticle-based microalgae as aquaculture feed additives is a growing research trend. The present study examines the effect of conversion of Arthrospira platensis NIOF17/003 (AP) to nano-form on its phytochemical constituents, followed by a feeding experiment to investigate the dietary effect of nanoparticles of A. platensis, NAP (NAP0.25%, NAP0.5%, and NAP1%) on growth, feed utilization, and growth-related gene expression of Pacific white shrimp, Litopenaeus vannamei, comparing with negative (non-supplemented diet) and positive control (supplemented diet with normal Arthrospira). The shrimp postlarvae (0.124 ± 0.002 g) were allocated into glass aquaria (40 L; three aquaria per group) and fed the experimental diet for 90 days. The GC-Mass analysis revealed that the conversion of A. platensis to its nano-form induced notable phytochemical changes. The main phytochemicals of NAP were milbemycin B (66.68%), docosanoic acid, 1,2,3-propanetriyl ester (22.26%), and copper etioporphyrin (11.06%). The dietary supplementation of NAP in different levels improved all growth indices, survival, and feed utilization parameters compared to the negative and positive control at the same supplementation level. The weight gain, survival, and feed conversion ratio were improved by 66.11%, 23.51%, and 13.60%, respectively in group fed NAP1% supplemented diet compared to the negative control. The expression of IGF-I and IGF-II were upregulated with NAP supplementation in a dose-dependent manner. Therefore, the present study recommended the use of 1% NAP as dietary supplementation for improving growth, survival, and feed utilization of Pacific white shrimp.
... III), Mn (II o III), Sm (III), Eu (III), Pt (II), Si (II), Cr (III), Co (III), Fe (III), Cu (II), Pd (II), Rh (III), Sn (IV), Bi (III) y Sb (V)(135,155). ...
La leishmaniasis es una enfermedad parasitaria, que predispone un reto para los entes gubernamentales de cada región o país. Según la organización mundial de la salud al ser una enfermedad desatendida, se estima que 350 millones de personas están riesgo de padecerla; existiendo 12 millones de personas infectadas y reportándose 30000 defunciones por año. Diferentes estrategias se han diseñado para combatir esta problemática, centradas principalmente en prevención primaria, y en menor medida a la elaboración de terapias farmacológicas. Acciones que han sido poco eficientes para reducir las frecuencias y efectos de la enfermedad sobre la población mundial. En este sentido la generación de nuevos fármacos se presenta como un foco de vital importancia para su tratamiento. En este trabajo se evaluó el potencial farmacológico de fotosensibilizadores tipo porfirina y metaloporfirina frente a parásitos del género Leishmania mediante ensayos in vitro. Para tal fin se sintetizó un grupo de 23 compuestos tipo porfirina y metaloporfirina y seguido de esto se evaluaron sus propiedades fotodinámicas y biológicas. Con respecto al rendimiento cuántico de fluorescencia (Փf), los valores más bajos fueron para los compuestos TBrPP-Al (III), TEtPP, TBrPP-Ni (II), TFPP-V (III), mientras que para el rendimiento cuántico de producción de oxígeno singulete (ՓΔ), la TFPP presentó el valor más alto de las porfirinas. En general las metaloporfirinas de Zn (II) mejoraron significativamente el ՓΔ, mientras que los derivados metalados Sn (IV) disminuyeron dicho valor. Todos los compuestos presentaron buena fototoxicidad y baja toxicidad intrínseca frente a L. brasiliensis y L. panamensis. De todos los compuestos, los derivados metalados con Zn (II) presentaron los mejores resultados de letalidad frente a ambos parásitos, posiblemente relacionado con la producción de oxígeno singulete. Finalmente, en relación al tiempo de exposición para los ensayos biológicos irradiados, se encontró que los tiempos de exposición de 48 y 72 horas no presentaron diferencias significativas en las respuestas leishmanicida en comparación con la exposición a radiación durante 24 horas.
Palabras Clave: Fotosensibilizadores, Porfirina, metaloporfirina, fototóxico, Parásito, Leishmania, Oxígeno singulete, Terapia fotodinámica, CL50.
... Synthetic metal-porphyrin complexes cannot be enzymatically degraded to bile pigments by heme oxygenase and in vivo they might have dual actions both inducing expression and inhibiting activity of this enzyme, which can lead to different biological actions depending on the nature of the metalloporphyrin [25]. In addition to their possible therapeutic roles [26][27][28], some metalloporphyrins can also be naturally available in certain conditions, such as occurs with the ZnPP formed by ferrochelatase when iron levels are low [29,30]. Therefore, here we have studied the direct effect of a variety of porphyrins on ABCB10 activity. ...
Heme biosynthesis occurs through a series of reactions that take place within the cytoplasm and mitochondria, so intermediates need to move across these cellular compartments. However, the specific membrane transport mechanisms involved in the process are not yet identified. The ATP-binding cassette protein ABCB10 is essential for normal heme production, as knocking down this transporter in mice is embryonically lethal and accompanied by severe anemia plus oxidative damage. The role of ABCB10 is unknown, but given its location in the inner mitochondrial membrane, it has been proposed as a candidate to export either an early heme precursor or heme. Alternatively, ABCB10 might transport a molecule important for protection against oxidative damage. To help discern between these possibilities, we decided to study the effect of heme analogs, precursors, and antioxidant peptides on purified human ABCB10. Since substrate binding increases the ATP hydrolysis rate of ABC transporters, we have determined the ability of these molecules to activate purified ABCB10 reconstituted in lipid nanodiscs using ATPase measurements. Under our experimental conditions, we found that the only heme analog increasing ABCB10 ATPase activity was Zinc-mesoporphyrin. This activation of almost seventy percent was specific for ABCB10, as the ATPase activity of a negative control bacterial ABC transporter was not affected. The activation was also observed in cysteine-less ABCB10, suggesting that Zinc-mesoporphyrin’s effect did not require binding to typical heme regulatory motifs. Furthermore, our data indicate that ABCB10 was not directly activated by neither the early heme precursor delta-aminolevulinic acid nor glutathione, downsizing their relevance as putative substrates for this transporter. Although additional studies are needed to determine the physiological substrate of ABCB10, our findings reveal Zinc-mesoporphyrin as the first tool compound to directly modulate ABCB10 activity and raise the possibility that some actions of Zinc-mesoporphyrin in cellular and animal studies could be mediated by ABCB10.
... However, because of the van der Waals interaction, sheets of the graphene tends to combine or restack to make graphite that may have adverse effect on the catalytic activity [16]. To avoid the aggregation of the graphene, an aromatic macro cyclic molecule having nitrogen atoms like metal derivatives of porphyrin or phthalocyanines having a cloud of delocalized π-electrons, that can be combined to graphene via π-π conjugation [17]. In recent studies, it have been proved that the introduction of the graphene or carbon nanotubes within the macromolecules like phthalocyanines can improve their catalytic properties by providing good electron mobility and high electron conductivity [18,19]. ...
Herein, we reported the development of tetramethoxyphenylporphyrin (CoTPP)/reduced graphene (rGO)/multiwalled carbon nanotubes (MWCNTs) composite via an ultrasonic treatment. The engineered composite was characterized by different analytical techniques like scanning electron microscopy (SEM), energy dispersive X-ray (EDX), ultraviolet–visible spectroscopy (UV–Vis) and Fourier transform infrared spectroscopy (FT-IR). The synthesized composite was tested for the catalytic degradation of methylene blue (MB) under solar irradiation and the electrochemical performance of the CoTPP/rGO/MWCNTs was also investigated in alkaline media by using cyclic voltammetry (CV). The photodegradation efficiency of prepared CoTPP/rGO/MWCNTs composite is 92% degradation of MB in water within 60 min irradiation. The results of the cyclic voltammogram showed that the onset potential value was -0.4 V while peak potential value of CoTPP-rGO/CNTs was -0.59 V. The high onset peak potential values and the current values of the CoTPP/rGO/MWCNTs make it a promising candidate as a catalyst for ORR.
... However, the complex manganese (II)-porphyrins does not appear to be significantly studied and interpreted despite the importance of this complex in the biological fields (e.g., enzymatic and catalytic reactions). [19][20][21] Interestingly, when porphyrins coordination occurs, two negative charges appeared following the removal of two protons from the nitrogen atoms of pyrrole. [22][23][24][25] Therefore, we think that manganese (II) is more appropriate for the porphyrin complexation than manganese (III) and that the manganese (II)-porphyrin is the most interesting ionophore, especially in terms of stability. ...
Equilibrium adsorbed amounts of manganese on porphyrins were determined at 288 K and 308 K using the quartz crystal microbalance strategy. The experimental measurements were achieved in order to compare the adsorption capacities of the tetratolylporphyrin and the tetraphenylporphyrin for ionophore investigation. The aim of this work is to examine these isotherms at the ionic scale in order to elucidate physical clarifications about the microscopic interactions between the manganese ions and the two complexing porphyrins (TTP and TPP). Indeed, statistical physics formalism is employed by the intermediate of the parameters contained in the expressions of the single-layer and the quadruple-layer models to evaluate the materials employed for ionophore fabrication. Results indicated that high attraction was shown between manganese ions and the sites of tetratolylporphyrins. Energetic investigation (through statistical physics approach and density functional theory method) revealed that the Mn–TTP complex was chemically bonded. The interpretation of the van der Waals parameters confirms the highest stability of the Mn(Cl)2–TTP among all complexes. This study contributes new tips on the theoretical and the experimental understanding of ionophore adsorption. The novel results of this research are the Mn(Cl)2 is the most useful adsorbate material because chlorine ions do not have any impact on the complexation mechanism and the tetratolylporphyrin is the finest complexing adsorbent in terms of stability.
... [8] Most of the clinical applications of porphyrins and metalloporphyrins are due to the macrocyclic aromatic structure. [9] In the free form, it is assumed that only 18 of the 22 π electrons are conjugated, which are responsible for the characteristic redox and electronic properties. [9] Various systems of porphyrins and nanoparticles have been obtained. ...
... [9] In the free form, it is assumed that only 18 of the 22 π electrons are conjugated, which are responsible for the characteristic redox and electronic properties. [9] Various systems of porphyrins and nanoparticles have been obtained. During the last years, several gold (III) complexes with strong donor ligands, such as porphyrins, have been reported to have good stability and strong antitumor activity. ...
... The porphyrin ring has a strong stability against concentrated acids such as sulfuric acid that cannot break apart the highly stable structure of porphyrins. 52 The other form of bonding takes place when the metallic element is present in an imperfect aromatic structure as a heteroatom filling the gaps and holes that apparently were made during the formation of crude oil in the reservoir in an extremely high-pressure and hightemperature condition. 51 The metal content of asphaltenes is usually measured by atomic absorption or mass spectroscopy. ...
... This observed higher capacitance and decreased Rct further supports the presence of an enormous number of electrocatalytic active sites in 3h-N-GNS and their electrical conductivity. 52 This observation demonstrates the importance of pyridinic and pyrrolic nitrogen atoms embedded in the crystalline graphene nanosheets. We further calculated the electrochemical active surface area (ECSA) by impedance method. ...
Asphaltene deposition causes many difficulties and imposes challenging flow assurance problems for the oil industry throughout the globe. Asphaltenes are the heaviest and most polarizable fraction of crude oil. They have a high tendency to destabilize and deposit in the wellbore, oil reservoir formations, transportation pipelines, surface facilities, and heat exchangers. The significant difficulties associated with asphaltene deposition can cost oil companies millions of dollars each year. This problem will almost certainly become worse as the oil industry is moving towards production from deep-water reservoirs and implementation of the enhanced oil recovery by miscible gas injections. Despite the tremendous efforts and studies undertaken over the past decades, a full understanding of asphaltene behavior and its inherent physical and chemical characteristics has not been achieved. More importantly, the successful utilization of this problematic but high potential material has not been extensively explored.
In this dissertation, a series of comprehensive experimental methods were presented to better understand and predict the occurrence and the scale of asphaltene deposition. As a part of these methods, a novel NIR spectroscopy technique was developed to accurately monitor the kinetics of asphaltene
precipitation and aggregation in crude oil systems. The effects of different variables, such as temperature, the driving force towards precipitation, and the addition of commercial chemical dispersant were evaluated. Unlike currently available techniques, this new method is fast and simple: it requires less than 2 ml of sample for each measurement, with the capability of performing experiments at high temperatures. The amount of precipitated asphaltene can be easily estimated by using a newly developed method called “Absorbance Ratio”, in which the light transmittance values from the spectroscopy experiments are readily translated into precipitated asphaltene amounts. These simple and quick lab-scale experiments facilitate establishing modeling tools to scale the asphaltene precipitation and aggregation parameters to real-field, high-pressure, and high-temperature conditions.
Furthermore, the potential production of carbon-based nanoparticles from asphaltenes was investigated in this work. To achieve this goal, first, a physical spray drying method was developed, in which fully dissolved asphaltene solutions were sprayed on a hot surface in order to evaporate the solvent quickly. Once the solvent evaporated, individual asphaltene nanoparticles with a high association tendency could be separated and deposited on the substrate. Scanning electron microscopy (SEM) results showed that asphaltene nanospheres as small as 20 nm in diameter were generated. The impact of different variables, such as temperature, type of the hot surface, and the asphaltene solution concentration on the size and morphology of the particles, were also discussed. Additionally, a new method of chemical oxidation by a concentrated nitric acid, followed by heat treatment was applied to asphaltenes.
This oxidation reaction resulted in water-soluble and photoluminescent carbon-based nanoparticles. In this new method, the nitric acid used for oxidation could be recycled and reused as well.
Moreover, the utilization of asphaltenes in two different areas of electrocatalysis and energy storage was pursued. To achieve these ideas, asphaltene samples were converted into nitrogen-doped graphene-like nanosheets (N-GNS) and highly porous activated carbons. These novel nanomaterials with exceptional properties, such as high surface area, good conductivity, high porosity, and ion mobility, were tested as catalysts for hydrogen evolution reactions and as electrodes for supercapacitors. The N-GNS sample, due to its high electrochemical active surface area (ECSA), presence of a mixture of porous structures, uniform layers, and effective doping of nitrogen atoms within the carbon matrix, was considered as an excellent candidate for the hydrogen evolution reaction (HER). The results illustrated a significant catalytic performance from the N-GNS sample when used as a catalyst in hydrogen evolution reactions. In addition, a novel method was developed to chemically transform asphaltenes into highly porous activated carbon with an interconnected honeycomb-like structure. The obtained activated carbon illustrated an impressive, ultra-high surface area of 3868 m2/g. The results of the study indicate that this new technique not only allowed a greater yield of asphaltene-derived activated porous carbon output as compared to the conventional activation method, but also created a mixture of microporous and mesoporous networks, which demonstrated favorable properties for supercapacitor applications.
Finally, the hydrophobicity of asphaltenes was utilized in modifying commercially available melamine sponges to transform them into hydrophobic and oleophilic absorbent materials. The asphaltene-coated sponges showed excellent selectivity towards organic solvents and repelled water as soon as they came into contact with the liquids. In addition, the robust and flexible physical structure of sponges would enable them to be used multiple times. Overall, it was shown that the asphaltene-coated sponges, due to their impressive selectivity, high absorption capacity and good recyclability, could be promising candidates for large scale removal of oil spills and other organic liquids from water.
Ultimately, the findings presented in this dissertation suggest that what is currently considered an undesirable fraction of crude oil, which has a tendency to deposit in wellbores, pipelines, and downstream facilities, can be repurposed into a desirable material with remarkable properties for nanoparticles fabrication, electrocatalysis, energy storage, oil spill removal, and other applications.
... However, as we will show below (Table 7), this interpretation is not fully holding true for the insertion of Cu(II) that is much less sensitive to the acidity of the environment at which metal insertion is still observed. Our results vary significantly from those by James and co-workers who reported the inability to insert zinc into TPP using ZnO or [Zn 5 (CO 3 ) 2 (OH) 6 ], even upon the addition of small amounts of solvent (DMF, MeOH, or H 2 O). 15b Our utilization of a more aggressive planetary mill instead of the shaker mill used by James and co-workers might be source of the observed differences. ...
Building on a proof of concept study that showed the possibility of the mechanochemical insertion of some M(II) metals into meso-tetraphenylporphyrin using a ball mill as an alternative to traditional solution-based methods, we present here a detailed study of the influence of the many experimental variables on the reaction outcome performed in a planetary mill. Using primarily the mechanochemical zinc, copper, and magnesium insertion reactions, the scope and limits of the type of porphyrins (electron-rich or electron-poor meso-tetraarylporphyrins, synthetic or naturally occurring octaalkylporphyrins, and meso-triphenylcorrole) and metal ion sources suitable for this metal insertion modality were determined. We demonstrate the influence of the experimental metal insertion parameters, such as ball mill speed and reaction time, and investigated the often surprising roles of a variety of grinding agents. Also, the mechanochemical reaction conditions that remove zinc from a zinc porphyrin complex or exchange it for copper were studied. Using some standardized conditions, we also screened the feasibility of a number of other metal(II) insertion reactions (VO, Ni, Fe, Co, Ag, Cd, Pd, Pt, Pb). The underlying factors determining the rates of the insertion reactions were found to be complex and not always readily predictable. Some findings of fundamental significance for the mechanistic understanding of the mechanochemical insertion of metal ions into porphyrins are highlighted. Particularly the mechanochemical insertion of Mg(II) is a mild alternative to established solution methods. The work provides a baseline from which the practitioner may start to evaluate the mechanochemical metal insertion into porphyrins using a planetary ball mill.
... An intense absorption band called B band or Soret band between 350 and 500 nm resulting from a ground state to second excited singlet state (S 0 →S 2 ) with molar absorption coefficient 10 5 M −1 cm −1 and a less intense band known as Q-band observed from 500 to 750 nm resulting from ground state to first excited state (S 0 →S 1 ) with molar absorption coefficient 10 4 M −1 cm −1 [23]. Insertion of a metal ion into the porphyrin cavity or the protonation of the nitrogen atoms or variation of the peripheral substituents may result in a change in the wavelength and intensity of the absorption spectrum [24]. ...
... An intense absorption band called B band or Soret band between 350 and 500 nm resulting from a ground state to second excited singlet state (S0→S2) with molar absorption coefficient 10 5 M −1 cm −1 and a less intense band known as Q-band observed from 500 to 750 nm resulting from ground state to first excited state (S0→S1) with molar absorption coefficient 10 4 M −1 cm −1 [23]. Insertion of a metal ion into the porphyrin cavity or the protonation of the nitrogen atoms or variation of the peripheral substituents may result in a change in the wavelength and intensity of the absorption spectrum [24]. Freebase porphyrins can form a complex with various metal cations and can adopt a wide variety of conformation: planar, domed, saddled, ruffled, etc. Depending on the size of coordinating metal cations, metalloporphyrins are of two types. ...
In recent years, scientific advancements have constantly increased at a significant rate in the field of biomedical science. Keeping this in view, the application of porphyrins and metalloporphyrins in the field of biomedical science is gaining substantial importance. Porphyrins are the most widely studied tetrapyrrole-based compounds because of their important roles in vital biological processes. The cavity of porphyrins containing four pyrrolic nitrogens is well suited for the binding majority of metal ions to form metalloporphyrins. Porphyrins and metalloporphyrins possess peculiar photochemical, photophysical, and photoredox properties which are tunable through structural modifications. Their beneficial photophysical properties, such as the long wavelength of emission and absorption, high singlet oxygen quantum yield, and low in vivo toxicity, have drawn scientists’ interest to discover new dimensions in the biomedical field. Applications of porphyrins and metalloporphyrins have been pursued in the perspective of contrast agents for magnetic resonance imaging (MRI), photodynamic therapy (PDT) of cancer, bio-imaging, and other biomedical applications. This review discusses photophysics and the photochemistry of porphyrins and their metal complexes. Secondly, it explains the current developments and mode of action for contrast agents for MRI. Moreover, the application of porphyrin and metalloporphyrin-based molecules as a photosensitizer in PDT of cancer, the mechanism of the generation of reactive oxygen species (ROS), factors that determine the efficiency of PDT, and the developments to improve this technology are delineated. The last part explores the most recent research and developments on metalloporphyrin-based materials in bio-imaging, drug delivery, and the determination of ferrochelatase in bone marrow indicating their prospective clinical applications.
... [36][37][38]43,44 For example, metalloporphyrins, nicknamed the pigments of life, contain large aromatic systems that are necessary for photosynthesis, oxygen transport, and electron transfer in several enzymes. 45 Effective models of quantum chemistry should be able to represent aromaticity in complex chemicals like these. ...
A collection of new approaches to building and training neural networks, collectively referred to as deep learning, are attracting attention in theoretical chemistry. Several groups aim to replace computationally expensive ab initio quantum mechanics calculations with learned estimators. This raises questions about the representability of complex quantum chemical systems with neural networks. Can local-variable models efficiently approximate nonlocal quantum chemical features? Here, we find that convolutional architectures, those that only aggregate information locally, cannot efficiently represent aromaticity and conjugation in large systems. They cannot represent long-range nonlocality known to be important in quantum chemistry. This study uses aromatic and conjugated systems computed from molecule graphs, though reproducing quantum simulations is the ultimate goal. This task, by definition, is both computable and known to be important to chemistry. The failure of convolutional architectures on this focused task calls into question their use in modeling quantum mechanics. To remedy this heretofore unrecognized deficiency, we introduce a new architecture that propagates information back and forth in waves of nonlinear computation. This architecture is still a local-variable model, and it is both computationally and representationally efficient, processing molecules in sublinear time with far fewer parameters than convolutional networks. Wave-like propagation models aromatic and conjugated systems with high accuracy, and even models the impact of small structural changes on large molecules. This new architecture demonstrates that some nonlocal features of quantum chemistry can be efficiently represented in local variable models.
