Showing papers on "Porphyrin published in 2022"

Porphyrin-based Framework Materials for Energy Conversion

Abstract: With the increasing demand for fuel causing serious environmental pollution, it is urgent to develop new and environmentally friendly energy conversion devices. These energy conversion devices, however, require good, inexpensive materials for electrodes and so on. The multifunctional properties of porphyrins enable framework materials (e.g., metal-organic frameworks and covalent organic frameworks) to be applied in energy conversion devices due to their simple synthesis, high chemical stability, abundant metallic active sites, adjustable crystalline structure and high specific surface area. Herein, the types of porphyrin structural blocks are briefly reviewed. They can be used as organic ligands or directly assembled with framework materials to generate high-performance electro-/photo-catalysts. These types of catalysts applied in electro-/photo-catalytic water splitting, electro-/photo-catalytic carbon dioxide reduction, and electrocatalytic oxygen reduction are also summarized and introduced. At the end of the article, we present the challenges of porphyrin-based framework materials in the above application and corresponding solutions. We expect porphyrin-based framework materials to flourish energy conversion in the coming years.

Selective photocatalytic CO2 reduction in aerobic environment by microporous Pd-porphyrin-based polymers coated hollow TiO2

Abstract: Direct photocatalytic CO2 reduction from primary sources, such as flue gas and air, into fuels, is highly desired, but the thermodynamically favored O2 reduction almost completely impedes this process. Herein, we report on the efficacy of a composite photocatalyst prepared by hyper-crosslinking porphyrin-based polymers on hollow TiO2 surface and subsequent coordinating with Pd(II). Such composite exhibits high resistance against O2 inhibition, leading to 12% conversion yield of CO2 from air after 2-h UV-visible light irradiation. In contrast, the CO2 reduction over Pd/TiO2 without the polymer is severely inhibited by the presence of O2 ( ≥ 0.2 %). This study presents a feasible strategy, building Pd(II) sites into CO2-adsorptive polymers on hollow TiO2 surface, for realizing CO2 reduction with H2O in an aerobic environment by the high CO2/O2 adsorption selectivity of polymers and efficient charge separation for CO2 reduction and H2O oxidation on Pd(II) sites and hollow TiO2, respectively.

Electron Donor–Acceptor Interface of TPPS/PDI Boosting Charge Transfer for Efficient Photocatalytic Hydrogen Evolution

Abstract: Charge separation efficiency of photocatalysts is still the key scientific issue for solar‐to‐chemical energy conversion. In this work, an electron donor–acceptor (D‐A) interface with high charge separation between TPPS (tetra(4‐sulfonatophenyl)porphyrin) and PDI (perylene diimide) is successfully constructed for boosting photocatalytic H2 evolution. The TPPS/PDI with D‐A interface shows excellent photocatalytic H2 evolution rate of 546.54 µmol h–1 (30.36 mmol h–1 g–1), which is 9.95 and 9.41 times higher than that of pure TPPS and PDI, respectively. The TPPS/PDI has a markedly stronger internal electric field, which is respectively 3.76 and 3.01 times higher than that of pure PDI and TPPS. The D‐A interface with giant internal electric field efficiently facilitates charge separation and urges TPPS/PDI to have a longer excited state lifetime than single component. The work provides entirely new ideas for designing materials with D‐A interface to realize high photocatalytic activity.

Fluorescence and Colorimetric Dual-Mode Ratiometric Sensor Based on Zr-Tetraphenylporphyrin Tetrasulfonic Acid Hydrate Metal-Organic Frameworks for Visual Detection of Copper Ions.

Abstract: As a special heavy metal ion, copper ions (Cu2+) play an indispensable role in the fields of environmental protection and safety. Their excessive intake not only easily leads to diseases but also affects human health. Therefore, it is particularly important to construct a facile, effective, and highly selective Cu2+ probe. Herein, a novel Zr-tetraphenylporphyrin tetrasulfonic acid hydrate (TPPS) metal-organic framework (ZTM) was fabricated using TPPS as the ligand and exhibited strong red fluorescence with a high quantum yield of 12.22%. In addition, we designed a ratiometric fluorescent probe by introducing green fluorescein isothiocyanate (FITC), which was not subject to environmental interference and had high accuracy. When exposed to different amounts of Cu2+, the fluorescence emission at 667 nm from ZTMs is remarkably quenched, while that at 515 nm from FITC is enhanced, accompanied by a change in the solutions' fluorescence color from red to green under a UV lamp. Besides, the ZTMs solutions display an excellent ratiometric colorimetric response for Cu2+ and produce an obvious color change (from green to colorless) that is visible to the naked eye. The fabricated ZTMs@FITC fluorescent probe exhibits distinguished performance for Cu2+ detection with linear ranges of 0.1 to 5 μM and 5 to 50 μM, as well as a low detection limit of 5.61 nM. Moreover, a colorimetric sensor based on ZTMs exhibits a good linear range from 0.1 to 20 μM for Cu2+ with the detection limit of 4.96 nM. Furthermore, the dual-signal ratiometric sensor has significant specificity for Cu2+ and is successfully applied for monitoring Cu2+ in water samples, which proves its practical application value in the environment and biological systems.

Covalently anchoring covalent organic framework on carbon nanotubes for highly efficient electrocatalytic CO2 reduction

Abstract: Porphyrin-based covalent organic frameworks (Por-COF) nanosheets were vertically anchored on carbon nanotubes (CNT) with covalent connection for efficient electrocatalytic CO 2 reduction reaction (CO 2 RR). The CNT not only acts as ideal carriers for the dispersion of Pro-COF but also facilitates electron transfer along porphyrin planes to immobilized metal active sites. As a result, covalently linked MWCNT-Por-COF-M (M: Co, Ni, Fe) display improved electrocatalytic CO 2 -to-CO activity and selectivity compared to pure Por-COF-M and MWCNT@Por-COF-M without covalent connection between two components. In particular, MWCNT-Por-COF-Co exhibits superior activity (FE CO : 99.3%), higher partial current density and good durability in 0.5 M KHCO 3 by H-type cell, while MWCNT-Por-COF-Cu exhibits the highest CH 4 faradaic efficiency of 71.2% in 1.0 M KOH by flow cell. The results of HRTEM and Auger spectrum revealed that the high performance of MWCNT-Por-COF-Cu could be attributed to the generated Copper-based nanoclusters during the electrocatalytic CO 2 RR process. • Por-COF nanosheets were vertically anchored on carbon nanotubes by covalent connection. • Covalently linked MWCNT-Por-COF-M display improved electrocatalytic CO 2 RR activity and selectivity. • MWCNT-Por-COF-Co exhibits remarkable activity (FE CO : 99.3%). • MWCNT-Por-COF-Cu exhibits the highest CH 4 faradaic efficiency of 71.2%.

Au-activated N motifs in non-coherent cupric porphyrin metal organic frameworks for promoting and stabilizing ethylene production

Abstract: Direct implementation of metal-organic frameworks as the catalyst for CO2 electroreduction has been challenging due to issues such as poor conductivity, stability, and limited > 2e- products. In this study, Au nanoneedles are impregnated into a cupric porphyrin-based metal-organic framework by exploiting ligand carboxylates as the Au3+ -reducing agent, simultaneously cleaving the ligand-node linkage. Surprisingly, despite the lack of a coherent structure, the Au-inserted framework affords a superb ethylene selectivity up to 52.5% in Faradaic efficiency, ranking among the best for metal-organic frameworks reported in the literature. Through operando X-ray, infrared spectroscopies and density functional theory calculations, the enhanced ethylene selectivity is attributed to Au-activated nitrogen motifs in coordination with the Cu centers for C-C coupling at the metalloporphyrin sites. Furthermore, the Au-inserted catalyst demonstrates both improved structural and catalytic stability, ascribed to the altered charge conduction path that bypasses the incoherent framework. This study underlines the modulation of reticular metalloporphyrin structure by metal impregnation for steering the CO2 reduction reaction pathway.

Covalently anchoring covalent organic framework on carbon nanotubes for highly efficient electrocatalytic CO2 reduction

Abstract: Porphyrin-based covalent organic frameworks (Por-COF) nanosheets were vertically anchored on carbon nanotubes (CNT) with covalent connection for efficient electrocatalytic CO2 reduction reaction (CO2RR). The CNT not only acts as ideal carriers for the dispersion of Pro-COF but also facilitates electron transfer along porphyrin planes to immobilized metal active sites. As a result, covalently linked MWCNT-Por-COF-M (M: Co, Ni, Fe) display improved electrocatalytic CO2-to-CO activity and selectivity compared to pure Por-COF-M and MWCNT@Por-COF-M without covalent connection between two components. In particular, MWCNT-Por-COF-Co exhibits superior activity (FECO: 99.3%), higher partial current density and good durability in 0.5 M KHCO3 by H-type cell, while MWCNT-Por-COF-Cu exhibits the highest CH4 faradaic efficiency of 71.2% in 1.0 M KOH by flow cell. The results of HRTEM and Auger spectrum revealed that the high performance of MWCNT-Por-COF-Cu could be attributed to the generated Copper-based nanoclusters during the electrocatalytic CO2RR process.

Visible-LED-light-driven photocatalytic synthesis of N-heterocycles mediated by a polyoxometalate-containing mesoporous zirconium metal-organic framework

Abstract: A mesoporous metal-organic framework with photothermal properties, namely PCN-222, was solvothermally synthesized from meso-tetra(4-carboxyphenyl)porphyrin and zirconium chloride employing both benzoic acid (BA) and trifluoroacetic acid (TFA) as modifiers. The MOF material subsequently served as a porous support for a polyoxometalate (POM), H3PW12O40, via a facile impregnation method which rendered a novel porous POM@PCN-222 composite. The solid was characterized by FT-IR, PXRD, SEM/EDX, TGA/DSC, ICP-OES, UV–Vis DRS, cyclic voltammetry (CV), and BET surface area. The one-pot synthesis of N-heterocycles (pyridine derivatives) was investigated utilizing the hybrid material via one-pot pseudo four-component reaction between aromatic aldehydes, methyl acetoacetate and ammonium acetate promoted under visible LED light irradiation in the presence of molecular oxygen as green oxidant. Products were selectively formed in good yields in the presence of the recyclable heterogeneous solid. Remarkably, POM@PCN-222 showed a superior performance for this procedure as compared to both unfunctionalized MOF and POM. The photosensitizer and photothermal properties of the porphyrin linkers combined with Lewis acidic sites derived from PW12 and Zr6-nodes were responsible for the observed excelling performance. To understand the mechanism, control investigations, electron paramagnetic resonance (EPR) analysis and FT-IR reaction monitoring were performed. The work discloses, for the first time, a simple and environmentally friendly approach for the direct production of pyridines via one-pot thermo-photocatalytic approach using a novel POM-modified MOF in the absence of any chemical additive.

Porphyrin-Based COF 2D Materials: Variable Modification of Sensing Performances by Post-Metallization.

Abstract: 2D nanomaterials with flexibly modifiable surface are extremely desired for various applications, especially in room temperature chemiresistive gas sensing. Here, we have prepared a series of COF 2D nanomaterials (porphyrin-based COF nanosheets (NS)) that enabled highly sensitive and specific-sensing of NO 2 at room temperature. Different from the traditional 2D sensing materials, H 2 -TPCOF was designed with largely reduced interlayer interaction and predesigned porphyrin rings as modifiable sites on its surfaces for post-metallization. After post-metallization, the metallized M-TPCOF (M = Co and Cu) showed remarkably improved sensing performances. Among them, Co-TPCOF exhibited highly specific sensing toward NO 2 with one of the highest sensitivity in all reported 2D materials and COF materials, ultra-low limit-of-detection of 6.8 ppb and fast response/recovery. This work might shed light on designing and preparing a new type of surface-highly-modifiable 2D material for various chemistry applications.

Porphyrin framework-derived N-doped porous carbon-confined Ru for NH₃BH₃ methanolysis: the more pyridinic-N, the better

Abstract: Ultrafine Ru NPs encapsulated in a pyridinic-N-rich N-doped porous carbon derived from the pyrolysis of a new porphyrin framework were firstly fabricated for hydrogen generation.

Controlling the length of porphyrin supramolecular polymers via coupled equilibria and dilution-induced supramolecular polymerization

Abstract: Multi-component systems often display convoluted behavior, pathway complexity and coupled equilibria. In recent years, several ways to control complex systems by manipulating the subtle balances of interaction energies between the individual components have been explored and thereby shifting the equilibrium between different aggregate states. Here we show the enantioselective chain-capping and dilution-induced supramolecular polymerization with a Zn2+-porphyrin-based supramolecular system when going from long, highly cooperative supramolecular polymers to short, disordered aggregates by adding a monotopic Mn3+-porphyrin monomer. When mixing the zinc and manganese centered monomers, the Mn3+-porphyrins act as chain-cappers for Zn2+-porphyrin supramolecular polymers, effectively hindering growth of the copolymer and reducing the length. Upon dilution, the interaction between chain-capper and monomers weakens as the equilibria shift and long supramolecular polymers form again. This dynamic modulation of aggregate morphology and length is achieved through enantioselectivity in the aggregation pathways and concentration-sensitive equilibria. All-atom and coarse-grained molecular simulations provide further insights into the mixing of the species and their exchange dynamics. Our combined experimental and theoretical approach allows for precise control of molecular self-assembly and chiral discrimination in complex systems.

Controlling the length of porphyrin supramolecular polymers via coupled equilibria and dilution-induced supramolecular polymerization

Abstract: Multi-component systems often display convoluted behavior, pathway complexity and coupled equilibria. In recent years, several ways to control complex systems by manipulating the subtle balances of interaction energies between the individual components have been explored and thereby shifting the equilibrium between different aggregate states. Here we show the enantioselective chain-capping and dilution-induced supramolecular polymerization with a Zn2+-porphyrin-based supramolecular system when going from long, highly cooperative supramolecular polymers to short, disordered aggregates by adding a monotopic Mn3+-porphyrin monomer. When mixing the zinc and manganese centered monomers, the Mn3+-porphyrins act as chain-cappers for Zn2+-porphyrin supramolecular polymers, effectively hindering growth of the copolymer and reducing the length. Upon dilution, the interaction between chain-capper and monomers weakens as the equilibria shift and long supramolecular polymers form again. This dynamic modulation of aggregate morphology and length is achieved through enantioselectivity in the aggregation pathways and concentration-sensitive equilibria. All-atom and coarse-grained molecular simulations provide further insights into the mixing of the species and their exchange dynamics. Our combined experimental and theoretical approach allows for precise control of molecular self-assembly and chiral discrimination in complex systems.

Visible-LED-light-driven photocatalytic synthesis of N-heterocycles mediated by a polyoxometalate-containing mesoporous zirconium metal-organic framework

Abstract: A mesoporous metal-organic framework with photothermal properties, namely PCN-222, was solvothermally synthesized from meso-tetra(4-carboxyphenyl)porphyrin and zirconium chloride employing both benzoic acid (BA) and trifluoroacetic acid (TFA) as modifiers. The MOF material subsequently served as a porous support for a polyoxometalate (POM), H3PW12O40, via a facile impregnation method which rendered a novel porous [email protected] composite. The solid was characterized by FT-IR, PXRD, SEM/EDX, TGA/DSC, ICP-OES, UV–Vis DRS, cyclic voltammetry (CV), and BET surface area. The one-pot synthesis of N-heterocycles (pyridine derivatives) was investigated utilizing the hybrid material via one-pot pseudo four-component reaction between aromatic aldehydes, methyl acetoacetate and ammonium acetate promoted under visible LED light irradiation in the presence of molecular oxygen as green oxidant. Products were selectively formed in good yields in the presence of the recyclable heterogeneous solid. Remarkably, [email protected] showed a superior performance for this procedure as compared to both unfunctionalized MOF and POM. The photosensitizer and photothermal properties of the porphyrin linkers combined with Lewis acidic sites derived from PW12 and Zr6-nodes were responsible for the observed excelling performance. To understand the mechanism, control investigations, electron paramagnetic resonance (EPR) analysis and FT-IR reaction monitoring were performed. The work discloses, for the first time, a simple and environmentally friendly approach for the direct production of pyridines via one-pot thermo-photocatalytic approach using a novel POM-modified MOF in the absence of any chemical additive.

Visible Light Driven Photocatalytic CO2 Reduction to CO/CH4 using Metal-Organic 'Soft' Coordination Polymer Gel.

Abstract: The self-assembly of well-defined and astutely designed, low molecular weight gelator (LMWG) based linker with a suitable metal ion is a promising method for preparing photocatalytically active coordination polymer gels. Here, we report the design, synthesis, and gelation behaviour of a tetrapodal LMWG based on a porphyrin core connected to four terpyridine units (TPY-POR) through amide linkages. The self-assembly of TPY-POR LMWG with Ru II ions results in a Ru-TPY-POR coordination polymer gel (CPG), with a nanoscroll morphology. Ru-TPY-POR CPG exhibits efficient CO 2 photoreduction to CO (3.5 mmol g -1 h -1 ) with >99% selectivity in the presence of triethylamine (TEA) as sacrificial electron donor. Interestingly, in the presence of 1-benzyl-1,4-dihydronicotinamide (BNAH) with TEA as the sacrificial electron donor, the 8e - /8H + photoreduction of CO 2 to CH 4 is realized with >95 % selectivity (6.7 mmol g -1 h -1 ). In CPG, porphyrin acts as a photosensitizer and covalently attached [Ru(TPY) 2 ] 2+ acts as a catalytic center as demonstrated by femtosecond transient absorption (TA) spectroscopy. Further, combining information from the in situ DRIFT spectroscopy and DFT calculation, a possible reaction mechanism for CO 2 reduction to CO and CH 4 was outlined.

Boosting photo-Fenton process enabled by ligand-to-cluster charge transfer excitations in iron-based metal organic framework

Abstract: Iron-based metal organic frameworks (MOFs) are widely adopted to mediate heterogeneous photo-Fenton reaction, but poor charge separation efficiency in iron-oxo clusters of MOF usually results in the dull Fe(III)/Fe(II) transformation. In this study, ligand-to-cluster charge transfer (LCCT) excitations were first introduced to photo-Fenton process toward accelerating Fe(III)/Fe(II) transformation by constructing new iron-based MOF nanorods with porphyrin ligand (Fe-TCPP). Fe-TCPP with LCCT excitations showed a maximum kinetic constant of 0.23 min-1 for ciprofloxacin (CIP) degradation at neutral pH under visible light irradiation, which is remarkably better than most of the state-of-the-art photocatalysts. Experimental and theoretical analyses collaboratively verify that LCCT excitations within Fe-TCPP dramatically accelerate Fe(III)/Fe(II) transformation, which generate more ∙OH for quick CIP elimination. Additionally, this LCCT excitations strategy is also effective for the photo-Fenton-like system induced by copper-based MOFs. Our study presents a novel strategy to intensify MOFs based photo-Fenton/Fenton-like processes, upon which the high-efficiency contaminant removal is expected.

Construction of a two-dimensional artificial antioxidase for nanocatalytic rheumatoid arthritis treatment

Abstract: Constructing nanomaterials mimicking the coordination environments of natural enzymes may achieve biomimetic catalysis. Here we construct a two-dimensional (2D) metal-organic framework (MOF) nanosheet catalyst as an artificial antioxidase for nanocatalytic rheumatoid arthritis treatment. The 2D MOF periodically assembles numbers of manganese porphyrin molecules, which has a metal coordination geometry analogous to those of two typical antioxidases, human mitochondrial manganese superoxide dismutase (Mn-SOD) and human erythrocyte catalase. The zinc atoms of the 2D MOF regulate the metal-centered redox potential of coordinated manganese porphyrin ligand, endowing the nanosheet with both SOD- and catalase-like activities. Cellular experiments show unique anti-inflammatory and pro-biomineralization performances of the 2D MOF, while in vivo animal model further demonstrates its desirable antiarthritic efficacy. It is expected that such a nanocatalytic antioxidation concept may provide feasible approaches to future anti-inflammatory treatments.

Boosting photo-Fenton process enabled by ligand-to-cluster charge transfer excitations in iron-based metal organic framework

Abstract: Iron-based metal organic frameworks (MOFs) are widely adopted to mediate heterogeneous photo-Fenton reaction, but poor charge separation efficiency in iron-oxo clusters of MOF usually results in the dull Fe(III)/Fe(II) transformation. In this study, ligand-to-cluster charge transfer (LCCT) excitations were first introduced to photo-Fenton process toward accelerating Fe(III)/Fe(II) transformation by constructing new iron-based MOF nanorods with porphyrin ligand (Fe-TCPP). Fe-TCPP with LCCT excitations showed a maximum kinetic constant of 0.23 min-1 for ciprofloxacin (CIP) degradation at neutral pH under visible light irradiation, which is remarkably better than most of the state-of-the-art photocatalysts. Experimental and theoretical analyses collaboratively verify that LCCT excitations within Fe-TCPP dramatically accelerate Fe(III)/Fe(II) transformation, which generate more ∙OH for quick CIP elimination. Additionally, this LCCT excitations strategy is also effective for the photo-Fenton-like system induced by copper-based MOFs. Our study presents a novel strategy to intensify MOFs based photo-Fenton/Fenton-like processes, upon which the high-efficiency contaminant removal is expected.

Structural Regulation of Coupled Phthalocyanine–Porphyrin Covalent Organic Frameworks to Highly Active and Selective Electrocatalytic CO2 Reduction

Abstract: Covalent organic frameworks (COFs) have been applied as potential electrocatalysts for CO2 reduction reaction (CO2RR) due to their adjustable architecture and porous feature. Herein, tetraanhydrides of 2,3,9,10,16,17,23,24‐octacarboxyphthalocyanine cobalt(II) (CoTAPc) are used as nodes to couple with 5,15‐di(4‐aminophenyl)‐10,20‐diphenylporphyrin (DAPor) or 5,15,10,20‐tetrayl(4‐aminophenyl)porphyrin (TAPor) via imidization reaction to fabricate novel coupled phthalocyanine–porphyrin Type 1:2 (CoPc‐2H2Por) or Type 1:1 (CoPc‐H2Por) COFs. Electrocatalytic CO2RR experiments show that both Type 1:2 and Type 1:1 COFs exhibit the maximum Faraday efficiency over 90% with high stability, while the Type 1:2 COF (CoPc‐2H2Por) delivers lower overpotential, higher current density, and CO selectivity than Type 1:1 COF (CoPc‐H2Por) and CoPc monomer. Theoretical and experimental results reveal that the better CO2RR activity of CoPc‐2H2Por than CoPc‐H2Por can be attributed to its larger pore size and conjugate structure, which then cause more efficient electron transfer, adsorption/activation of CO2, faster mass transfer, and reaction kinetics. This work provides a new idea in the structural design of COF‐based electrocatalyst for efficient CO2RR.