Showing papers on "Porphyrin published in 2021"

Porphyrin-based frameworks for oxygen electrocatalysis and catalytic reduction of carbon dioxide

Abstract: Porphyrin-based frameworks, as specific kinds of metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in energy-related conversion processes, including the oxygen reduction reaction (ORR), oxygen evolution reaction (OER) and CO2 reduction reaction (CO2RR), and also in energy-related storage technologies such as rechargeable Zn-air batteries. This review starts by summarizing typical crystal structures, molecular building blocks, and common synthetic procedures of various porphyrin-based frameworks used in energy-related technologies. Then, a brief introduction is provided and representative applications of porphyrin-based frameworks in ORR, OER, Zn-air batteries, and CO2RR are discussed. The performance comparison of these porphyrin-based frameworks in each field is also summarized and discussed, which pinpoints a clear structure-activity relationship. In addition to utilizing highly active porphyrin units for catalytic conversions, regulating the porous structures of porphyrin-based frameworks will enhance mass transfer and growing porphyrin-based frameworks on conductive supports will accelerate electron transfer, which will result in the improvement of the electrocatalytic performance. This review is therefore valuable for the rational design of more efficient porphyrin-based framework catalytic systems in energy-related conversion and storage technologies.

Atomically Dispersed Iron Metal Site in a Porphyrin-Based Metal-Organic Framework for Photocatalytic Nitrogen Fixation.

Abstract: The rational design of photocatalysts for efficient nitrogen (N2) fixation at ambient conditions is important for revolutionizing ammonia production and quite challenging because the great difficulty lies in the adsorption and activation of the inert N2. Inspired by a biological molecule, chlorophyll, featuring a porphyrin structure as the photosensitizer and enzyme nitrogenase featuring an iron (Fe) atom as a favorable binding site for N2 via π-backbonding, here we developed a porphyrin-based metal-organic framework (PMOF) with Fe as the active center as an artificial photocatalyst for N2 reduction reaction (NRR) under ambient conditions. The PMOF features aluminum (Al) as metal node imparting high stability and Fe incorporated and atomically dispersed by residing at each porphyrin ring promoting the adsorption and the activation of N2, termed Al-PMOF(Fe). Compared with the pristine Al-PMOF, Al-PMOF(Fe) exhibits a substantial enhancement in NH3 yield (635 μg g-1cat.) and production rate (127 μg h-1 g-1cat.) of 82% and 50%, respectively, on par with the best-performing MOF-based NRR catalysts. Three cycles of photocatalytic NRR experimental results corroborate a stable photocatalytic activity of Al-PMOF(Fe). The combined experimental and theoretical results reveal that the Fe-N site in Al-PMOF(Fe) is the active photocatalytic center that can mitigate the difficulty of the rate-determining step in photocatalytic NRR. The possible reaction pathways of NRR on Al-PMOF(Fe) were established. Our study of porphyrin-based MOF for the photocatalytic NRR will provide insight into the rational design of catalysts for artificial photosynthesis.

Construction of Interfacial Electric Field via Dual-Porphyrin Heterostructure Boosting Photocatalytic Hydrogen Evolution

Abstract: A dual-porphyrin heterostructure is successfully constructed by coupling tetrakis (4-carboxyphenyl) zinc porphyrin (ZnTCPP) with tetrakis (4-hydroxyphenyl) porphyrin (THPP). The high photocatalytic H2 evolution rate of 41.4 mmol h-1 g-1 is obtained for ZnTCPP/THPP under full spectrum, which is ≈5.1 and ≈17.0 times higher than that of pure ZnTCPP and THPP, respectively. The significantly enhanced activity is mainly attributed to the giant interfacial electric field formed between dual porphyrins, which greatly facilitates efficient charge separation and transfer. Meanwhile, similar conjugated structures of dual porphyrins also provide proper interface match and decrease interface defects, thus inhibiting the recombination of photoproduced carriers. By rationally combining the appropriate band structures and high-quality interfacial contact of dual porphyrins, this work provides a fresh insight into the interfacial electric field construction to improve the photocatalytic performance.

An all-organic 0D/2D supramolecular porphyrin/g-C3N4 heterojunction assembled via π-π interaction for efficient visible photocatalytic oxidation

Abstract: Herein, an all-organic self-assembled tetra(4-carboxylphenyl)porphyrin (SA-TCPP)/oxidized g-C3N4 (O-CN) heterojunction photocatalyst was successfully synthesized through an in-situ electrostatic method. As a nanocrystalline supramolecular semiconductor, SA-TCPP could sufficiently contact with the surface of O-CN nanosheets, resulting in a 0D/2D assembling heterostructure via π-π interaction. The full-spectrum responsive property of SA-TCPP could enhance the light-harvesting ability of O-CN to generate more photogenerated carries, which was a driving force for photocatalytic reaction. The well-matched band structures and the π-π interaction between SA-TCPP and O-CN could give rise to a built-in electric field and electron delocalization effect to promote the interfacial charge transfer. A large amount of highly oxidative reactive species (h+, O2− and 1O2) also could make a great contribution to the strong oxidation capacity of the heterojunction system. Compared with O-CN and SA-TCPP, SA-TCPP/O-CN exhibited greatly improved visible photocatalytic oxidation performance towards pollutants degradation, oxygen evolution and disinfection. The apparent rate constant (k) of SA-TCPP/O-CN-40% for bisphenol A degradation was 3.7 times as high as that of O-CN, while the corresponding k for phenol degradation were about 2.5 times faster than that of SA-TCPP. The oxygen evolution rate of SA-TCPP/O-CN-40% were 4.7 and 2.7 times higher than those of O-CN and SA-TCPP, respectively. Additionally, the bactericidal efficiency of SA-TCPP/O-CN-40% (62.5 %) against Staphylococcus aureus cells within 8 min was also more outstanding than those of O-CN (negligible) and SA-TCPP (55.6 %). Therefore, the enhanced photocatalytic oxidation activities of SA-TCPP/O-CN heterojunction were ascribe to the synergistic effect between O-CN and SA-TCPP.

In Situ Porphyrin Substitution in a Zr(IV)-MOF for Stability Enhancement and Photocatalytic CO 2 Reduction

Abstract: Despite numerous inherent merits of metal-organic frameworks (MOFs), structural fragility has imposed great restrictions on their wider involvement in many applications, such as in catalysis. Herein, a strategy for enhancing stability and enabling functionality in a labile Zr(IV)-MOF has been proposed by in situ porphyrin substitution. A size- and geometry-matched robust linear porphyrin ligand 4,4'-(porphyrin-5,15-diyl)dibenzolate (DCPP2- ) is selected to replace the 4,4'-(1,3,6,8-tetraoxobenzo[lmn][3,8]phenanthroline-2,7(1H,3H,6H,8H)-diyl)dibenzoate (NDIDB2- ) ligand in the synthesis of BUT-109(Zr), affording BUT-110 with varied porphyrin contents. Compared to BUT-109(Zr), the chemical stability of BUT-110 series is greatly improved. Metalloporphyrin incorporation endows BUT-110 MOFs with high catalytic activity in the photoreduction of CO2 , in the absence of photosensitizers. By tuning the metal species and porphyrin contents in BUT-110, the resulting BUT-110-50%-Co is demonstrated to be a good photocatalyst for selective CO2 -to-CO reduction, via balancing the chemical stability, photocatalytic efficiency, and synthetic cost. This work highlights the advantages of in situ ligand substitution for MOF modification, by which uniform distribution and high content of the incoming ligand are accessible in the resulting MOFs. More importantly, it provides a promising approach to convert unstable MOFs, which mainly constitute the vast MOF database but have always been neglected, into robust functional materials.

Bioinspired Applications of Porphyrin Derivatives.

Abstract: Porphyrin derivatives are ubiquitous in nature and have important biological roles, such as in light harvesting, oxygen transport, and catalysis. Owing to their intrinsic π-conjugated structure, porphyrin derivatives exhibit characteristic photophysical and electrochemical properties. In biological systems, porphyrin derivatives are associated with various protein molecules through noncovalent interactions. For example, hemoglobin, which is responsible for oxygen transport in most vertebrates, consists of four subunits of a globular protein with an iron porphyrin derivative prosthetic group. Furthermore, noncovalently arranged porphyrin derivatives are the fundamental chromophores in light-harvesting systems for photosynthesis in plants and algae. These biologically important roles originate from the functional versatility of porphyrin derivatives. Specifically, porphyrins are excellent host compounds, forming coordination complexes with various metal ions that adds functionality to the porphyrin unit, such as redox activity and additional ligand binding at the central metal ion. In addition, porphyrins are useful building blocks for functional supramolecular assemblies because of their flat and symmetrical molecular architectures, and their excellent photophysical properties are typically utilized for the fabrication of bioactive functional materials. In this Account, we summarize our endeavors over the past decade to develop functional materials based on porphyrin derivatives using bioinspired approaches. In the first section, we discuss several synthetic receptors that act as artificial allosteric host systems and can be used for the selective detection of various chemicals, such as cyanide, chloride, and amino acids. In the second section, we introduce multiporphyrin arrays as mimics of natural light-harvesting complexes. The active control of energy transfer processes by additional guest binding and the fabrication of organic photovoltaic devices using porphyrin derivatives are also introduced. In the third section, we introduce several types of porphyrin-based supramolecular assemblies. Through noncovalent interactions such as metal-ligand interaction, hydrogen bonding, and π-π interaction, porphyrin derivatives were constructed as supramolecular polymers with formation of fiber or toroidal assembly. In the last section, the application of porphyrin derivatives for biomedical nanodevice fabrication is introduced. Even though porphyrins were good candidates as photosensitizers for photodynamic therapy, they have limitations for biomedical application owing to aggregation in aqueous media. We suggested ionic dendrimer porphyrins and they showed excellent photodynamic therapy (PDT) efficacy.

Metalloporphyrin-based D-A type conjugated organic polymer nanotube for efficient photocatalytic degradation

Abstract: A series of porphyrin-based D-A type conjugated organic polymer (COP) nanotubes MTAPP-BT (M= H2, Zn, Cu, Fe) were synthesized through acid-catalyzed Schiff base reaction between metalloporphyrins (MTAPP) and benzothiadiazole (BT) units. Among them, CuTAPP-BT shows superior photocatalytic activity and recyclability for bisphenol A (BPA) degradation. The transfer and separation of photo-induced carriers can be significantly improved through the metal-to-ligand charge transfer (MLCT) and electron push-pull effect between porphyrin units (electron donor, D) and benzothiadiazole moieties (acceptor, A). The nanotube structure exposed abundant active sites and improved the adsorption capacity for BPA through the π-π interaction and surface hydrogen bond. The possible mechanism of photocatalytic degradation for BPA over CuTAPP-BT was proposed based on molecular orbital (MO) theory. This investigation will provide a new insight about design and synthesis of novel D-A type COPs with enhanced photocatalytic activities.

Porphyrin-Based Metal-Organic Framework Probe: Highly Selective and Sensitive Fluorescent Turn-On Sensor for M3+ (Al3+, Cr3+, and Fe3+) Ions.

Abstract: The development of porphyrin-based metal-organic frameworks (MOFs) has attracted significant interest in the scientific community in recent years because of their versatile applications particularly in optical and electronic fields. In this study, a highly selective and sensitive fluorescent turn-on sensor using a porphyrinic MOF, Tb-TCPP, is presented, which displays a 10-fold fluorescence enhancement in the presence of Al3+, Cr3+, and Fe3+ ions. The detection limit is in the nM region. For the Al3+ ion, it could be visually detected at concentrations as low as 5 mM within 15 min. Tb-TCPP could also be used as an indicator for acidic or alkaline solutions at pH values of >9 and <3. The studies on the detection mechanism illustrate that cation exchange proceed between Tb-TCPP and these M3+ ions, and consequently, energy transfer from TCPP to Tb3+ is suppressed and π*-π energy transfer of the porphyrin ligand is significantly enhanced.

Graphene Quantum Dots with Pyrrole N and Pyridine N: Superior Reactive Oxygen Species Generation Efficiency for Metal-Free Sonodynamic Tumor Therapy.

Abstract: Those responsible for the development of sonosensitizers are faced with a dilemma between high sonosensitization efficacy and good biosecurity that limited the development of sonodynamic therapy (SDT). Herein, inspired by the intriguing therapeutic features of SDT and the potential catalytic activity of graphene quantum dots, the potential of N-doped graphene quantum dots (N-GQDs) to act as a sonosensitizer is demonstrated. The superior sonosensitization effect of N-GQDs is believed to be three to five times higher than that of traditional sonosensitizers (such as porphyrin, porphyrin Mn, porphyrin Zn, TiO2 , etc.). More importantly, the sonochemical mechanism of N-GQDs is revealed. Pyrrole N and pyridine N are believed to form catalytic centers in sonochemical processing of N-GQDs. This knowledge is important from the perspective of understanding the structure-dependent SDT enhancement of carbon nanostructure. Moreover, N-GQDs modified by folic acid (FA-N-GQDs) show a high marker rate for tumor cells (greater than 96%). Both in vitro and in vivo therapeutic results have exhibited high tumor inhibition efficiency (greater than 90%) of FA-N-GQDs as sonosensitizers while the oxidative stress response of tumor cells is activated through the PEX pathway and induced apoptosis via the p53 pathway.

5,10,15,20-tetrakis (4-carboxylphenyl) porphyrin functionalized NiCo2S4 yolk-shell nanospheres: Excellent peroxidase-like activity, catalytic mechanism and fast cascade colorimetric biosensor for cholesterol

Abstract: 5,10,15,20-tetrakis (4-carboxylphenyl) porphyrin functionalized NiCo2S4 yolk-shell nanospheres (Por-NiCo2S4) were fabricated by a facile and efficient solvothermal strategy and demonstrated to possess excellent peroxidase-like activity. Compared with pure NiCo2S4 nanospheres, Por-NiCo2S4 exhibits the superior peroxidase activity, which was evaluated by the fast oxidation of 3,3′,5,5′-tetramethylbenzidine (a chromogenic substrate, TMB) by H2O2 to form the blue product (oxTMB) only in 10 s. The systematic studies including radical scavenger, fluorescence probe, and electrochemical experiments confirm that superoxide free radicals ( O2−) play a key role in catalytic reactions, in addition to the synergistic effect of holes (h+). Based on the developed peroxidase activity of Por-NiCo2S4, and combined with cholesterol oxidase (Chox), a fast cascade reaction sensing platform has been constructed to quantitatively determination cholesterol in a wide linear range of 0.1−9.0 mM with the detection limit of 19.36 μM. The Por-NiCo2S4 based colorimetric biosensing platform has been used for determining the levels of total cholesterol in serum samples, indicating Por-NiCo2S4 is expected to be used as the promising materials for fast visual colorimetry in clinical medical detection.

Green CoNi2S4/porphyrin decorated carbon-based nanocomposites for genetic materials detection

Abstract: A one-pot synthesis method was conceptualized and implemented to develop green carbon-based nanocomposites working as biosensors. Porphyrin was synthesized to adorn the surface of nanocomposites making them highly sensitive for giving rise to π-π interactions between the genetic materials, proteins and porphyrin rings. The hydrogen bond formed between the proteins (analytes) and the nitrogen in the porphyrin structure as well as the surface hydroxyl groups was equally probable. In this context, different forms of porphyrins were incorporated to explore the interrelationship between the surface morphology and the ability of detection of genetic material and/or proteins by the aid of the synthesized structures. This phenomenon was conceptualized to optimize the interactions between the biomolecules and the substrate by reaching significant biosensor application in the presence of Anti-cas9 protein and sgRNA (concentration changed between 10 and 500 n mol/L). Almost full quenching of fluorescence emission was observed after addition of 300 n mol/L of Anti-cas9 protein and 250 n mol/L of sgRNA. Surprisingly, CoNi2S4 provided 12%–29% cytotoxicity in both HEK-293 and PC12 cell lines.

Can N, S Cocoordination Promote Single Atom Catalyst Performance in CO 2 RR? Fe-N 2 S 2 Porphyrin versus Fe-N 4 Porphyrin

Abstract: Single atom catalysts (SACs) are promising electrocatalysts for CO2 reduction reaction (CO2 RR), in which the coordination environment plays a crucial role in intrinsic catalytic activity. Taking the regular Fe porphyrin (Fe-N4 porphyrin) as a probe, the study reveals that the introduction of opposable S atoms into N coordination (Fe-N2 S2 porphyrin) allows for an appropriate electronic structural optimization on active sites. Owing to the additional orbitals around the Fermi level and the abundant Fe d z 2 orbital occupation after S substitution, N, S cocoordination can effectively tune SACs and thus facilitating protonation of intermediates during CO2 RR. CO2 RR mechanisms lead to possible C1 products via two-, six-, and eight-electron pathways are systematically elucidated on Fe-N4 porphyrin and Fe-N2 S2 porphyrin. Fe-N4 porphyrin yields the most favorable product of HCOOH with a limiting potential of -0.70 V. Fe-N2 S2 porphyrin exhibits low limiting potentials of -0.38 and -0.40 V for HCOOH and CH3 OH, respectively, surpassing those of most Cu-based catalysts and SACs. Hence, the N, S cocoordination might provide better catalytic environment than regular N coordination for SACs in CO2 RR. This work demonstrates Fe-N2 S2 porphyrin as a high-performance CO2 RR catalyst, and highlights N, S cocoordination regulation as an effective approach to fine tune high atomically dispersed electrocatalysts.

Porphyrin-Based Metal-Organic Frameworks for Efficient Photocatalytic H2 Production under Visible-Light Irradiation.

Abstract: Metal-organic frameworks (MOFs) are important photocatalytic materials for H2 production. To clarify the structure-function relationship and improve the photocatalytic activity, herein we explored a series of porphyrin-based zirconium MOFs (PCN-H2/Ptx:y, where x:y = 4:1, 3:2, 2:3, and 0:1) containing different ratios of H2TCPP and PtIITCPP [TCPP = tetrakis(4-carboxyphenyl)porphyrinate] as isostructural ligands and Zr6 clusters as nodes. Under visible-light irradiation, PCN-H2/Pt0:1 shows the highest average H2 evolution reaction rate (351.08 μmol h-1 g-1), which decreases along with lowering of the ratio of PtIITCPP in the PCN-H2/Ptx:y series. The differences in photocatalytic activity are attributed to more uniformly dispersed Pt2+ ions in PCN-H2/Pt0:1, which promotes charge transfer from porphyrins (photosensitizers) to PtII ions (catalytic centers), leading to efficient charge separation in the MOF materials. The bifunctional MOFs with photosensitizers and catalytic centers provide new insight for the design and application of porphyrin-based photocatalytic systems for visible-light-driven H2 production.

Resolving deactivation pathways of Co porphyrin-based electrocatalysts for CO2 reduction in aqueous medium

Abstract: Carbon-supported first-row transition metal complexes drive electroreduction of CO2 to CO in aqueous medium with remarkable activity and selectivity. However, their durability under negative potent...

Rational design of iridium–porphyrin conjugates for novel synergistic photodynamic and photothermal therapy anticancer agents

Abstract: Near-infrared (NIR) emitters are important probes for biomedical applications. Nanoparticles (NPs) incorporating mono- and tetranuclear iridium(III) complexes attached to a porphyrin core have been synthesized. They possess deep-red absorbance, long-wavelength excitation (635 nm) and NIR emission (720 nm). TD-DFT calculations demonstrate that the iridium–porphyrin conjugates herein combine the respective advantages of small organic molecules and transition metal complexes as photosensitizers (PSs): (i) the conjugates retain the long-wavelength excitation and NIR emission of porphyrin itself; (ii) the conjugates possess highly effective intersystem crossing (ISC) to obtain a considerably more long-lived triplet photoexcited state. These photoexcited states do not have the usual radiative behavior of phosphorescent Ir(III) complexes, and they play a very important role in promoting the singlet oxygen (1O2) and heat generation required for photodynamic therapy (PDT) and photothermal therapy (PTT). The tetranuclear 4-Ir NPs exhibit high 1O2 generation ability, outstanding photothermal conversion efficiency (49.5%), good biocompatibility, low half-maximal inhibitory concentration (IC50) (0.057 μM), excellent photothermal imaging and synergistic PDT and PTT under 635 nm laser irradiation. To our knowledge this is the first example of iridium–porphyrin conjugates as PSs for photothermal imaging-guided synergistic PDT and PTT treatment in vivo.

How Aromatic Are Molecular Nanorings? The Case of a Six-Porphyrin Nanoring*.

Abstract: Large conjugated rings with persistent currents are novel promising structures in molecular-scale electronics. A six-porphyrin nanoring structure that allegedly sustained an aromatic ring current involving 78π electrons was recently synthesized. We provide here compelling evidence that this molecule is not aromatic, contrary to what was inferred from the analysis of 1 H-NMR data and computational calculations that suffer from large delocalization errors. The main reason behind the absence of an aromatic ring current in these nanorings is the low delocalization in the transition from the porphyrins to the bridging butadiyne linkers, which disrupts the overall conjugated circuit. These results highlight the importance of choosing a suitable computational method to study large conjugated molecules and the appropriate aromaticity descriptors to identify the part of the molecule responsible for the loss of aromaticity.