Showing papers on "Porphyrin published in 2017"
TL;DR: This Review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing high-performance ion chemosensors based on porphyrin analogues and other relevant compounds.
Abstract: Sensing of metal ions and anions is of great importance because of their widespread distribution in environmental systems and biological processes. Colorimetric and fluorescent chemosensors based on organic molecular species have been demonstrated to be effective for the detection of various ions and possess the significant advantages of low cost, high sensitivity, and convenient implementation. Of the available classes of organic molecules, porphyrin analogues possess inherently many advantageous features, making them suitable for the design of ion chemosensors, with the targeted sensing behavior achieved and easily modulated based on their following characteristics: (1) NH moieties properly disposed for binding of anions through cooperative hydrogen-bonding interactions; (2) multiple pyrrolic N atoms or other heteroatoms for selectively chelating metal ions; (3) variability of macrocycle size and peripheral substitution for modulation of ion selectivity and sensitivity; and (4) tunable near-infrared emission and good biocompatibility. In this Review, design strategies, sensing mechanisms, and sensing performance of ion chemosensors based on porphyrin analogues are described by use of extensive examples. Ion chemosensors based on normal porphyrins and linear oligopyrroles are also briefly described. This Review provides valuable information for researchers of related areas and thus may inspire the development of more practical and effective approaches for designing high-performance ion chemosensors based on porphyrin analogues and other relevant compounds.
463 citations
TL;DR: This review focuses on the postfunctionalization of porphyrins and related compounds through catalytic and stoichiometric organometallic methodologies, which allows chemists to construct a wide range of highly elaborated and complex p Morphyrin architectures.
Abstract: This review focuses on the postfunctionalization of porphyrins and related compounds through catalytic and stoichiometric organometallic methodologies. The employment of organometallic reactions has become common in porphyrin synthesis. Palladium-catalyzed cross-coupling reactions are now standard techniques for constructing carbon–carbon bonds in porphyrin synthesis. In addition, iridium- or palladium-catalyzed direct C–H functionalization of porphyrins is emerging as an efficient way to install various substituents onto porphyrins. Furthermore, the copper-mediated Huisgen cycloaddition reaction has become a frequent strategy to incorporate porphyrin units into functional molecules. The use of these organometallic techniques, along with the traditional porphyrin synthesis, now allows chemists to construct a wide range of highly elaborated and complex porphyrin architectures.
312 citations
TL;DR: The targeted synthesis of two 3D porphyrin-based COFs, starting from tetrahedral and square building blocks connected through [4 + 4] imine condensation reactions, shows enhanced photocatalytic activity compared with 3D-CuPor-COF, indicating the properties of 3D covalent organic frameworks can be tuned by metalation of p Morphyrin rings.
Abstract: The design and synthesis of three-dimensional covalent organic frameworks (3D COFs) bearing photoelectric units have been considered as a big challenge. Herein, for the first time, we reported the targeted synthesis of two 3D porphyrin-based COFs (3D-Por-COF and 3D-CuPor-COF), starting from tetrahedral (3D-Td) and square (2D-C4) building blocks connected through [4 + 4] imine condensation reactions. On the basis of structural characterizations, 3D-Por-COF and 3D-CuPor-COF are microporous materials with high surface areas, and are proposed to adopt a 2-fold interpenetrated pts topology with Pmc21 space group. Interestingly, both 3D COFs are photosensitive and can be used as heterogeneous catalyst for generating singlet oxygen under photoirradiation. However, 3D-Por-COF shows enhanced photocatalytic activity compared with 3D-CuPor-COF, indicating the properties of 3D porphyrin-based COFs can be tuned by metalation of porphyrin rings. The results reported here will greatly inspire us to design and synthesize...
311 citations
TL;DR: Interestingly, the Mn3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C-H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart.
Abstract: A base-resistant porphyrin metal–organic framework (MOF), namely PCN-602 has been constructed with 12-connected [Ni8(OH)4(H2O)2Pz12] (Pz = pyrazolate) cluster and a newly designed pyrazolate-based porphyrin ligand, 5,10,15,20-tetrakis(4-(pyrazolate-4-yl)phenyl)porphyrin under the guidance of the reticular synthesis strategy. Besides its robustness in hydroxide solution, PCN-602 also shows excellent stability in aqueous solutions of F–, CO32–, and PO43– ions. Interestingly, the Mn3+-porphyrinic PCN-602, as a recyclable MOF catalyst, presents high catalytic activity for the C–H bond halogenation reaction in a basic system, significantly outperforming its homogeneous counterpart. For the first time, a porphyrinic MOF was thus used as an efficient catalyst in a basic solution with coordinating anions, to the best of our knowledge.
220 citations
TL;DR: A star-shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non-fullerene organic solar cells, which represents the highest photovoltaic performance based as the acceptor.
Abstract: A star-shaped electron acceptor based on porphyrin as a core and perylene bisimide as end groups was constructed for application in non-fullerene organic solar cells. The new conjugated molecule exhibits aligned energy levels, good electron mobility, and complementary absorption with a donor polymer. These advantages facilitate a high power conversion efficiency of 7.4 % in non-fullerene solar cells, which represents the highest photovoltaic performance based on porphyrin derivatives as the acceptor.
219 citations
TL;DR: Enhanced peroxidase-like activity of Por-ceria originated from synergistic effect of porphyrin and ceria, thereby explaining the high performance of Por -Ceria as an artificial enzyme mimicking peroxIDase.
Abstract: Hydrogen peroxide (H 2 O 2 ) is a key molecule in biology. As a byproduct of many enzymatic reactions, H 2 O 2 is also a popular biosensor target. We report the first use of uniform nanoparticles of porphyrin functionalized ceria (Por-Ceria) prepared by a one-step method, as a colorimetric probe in detection for H 2 O 2 . Por-ceria nanoparticles exhibited strong intrinsic peroxidase activity toward a classical peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H 2 O 2 . Enhanced peroxidase-like activity of Por-ceria originated from synergistic effect of porphyrin and ceria, thereby explaining the high performance of Por-Ceria as an artificial enzyme mimicking peroxidase. When coupled with glucose oxidase, glucose is detected. A detection limit of 1.9 × 10 −2 mM glucose with a linear range up to 0.15 mM.
189 citations
TL;DR: It is expected that the addendum of the imine based COF would not only enrich the structural variety but also help to understand the electrochemical behavior of these class of materials.
Abstract: A [2 + 2] Schiff base type condensation between 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAP) and 1,3,6,8-tetrakis (4-formylphenyl) pyrene (TFFPy) under solvothermal condition yields a crystalline, quasi-two-dimensional covalent organic framework (SB-PORPy-COF). The porphyrin and pyrene units are alternatively occupied in the vertex of 3D triclinic crystal having permanent microporosity with moderately high surface area (∼869 m2 g–1) and promising chemical stability. The AA stacking of the monolayers give a pyrene bridged conducting channel. SB-PORPy-COF has been exploited for metal free hydrogen production to understand the electrochemical behavior using the imine based docking site in acidic media. SB-PORPy-COF has shown the onset potential of 50 mV and the Tafel slope of 116 mV dec–1. We expect that the addendum of the imine based COF would not only enrich the structural variety but also help to understand the electrochemical behavior of these class of materials.
153 citations
TL;DR: This is the first example of a transition-metal complex for CO2 electroreduction catalysis with its metal center being redox-innocent under working conditions and chemical reduction of the zinc–porphyrin complex confirms that the reduction is ligand-based and the reduced species can react with CO2.
Abstract: Transition-metal-based molecular complexes are a class of catalyst materials for electrochemical CO2 reduction to CO that can be rationally designed to deliver high catalytic performance. One common mechanistic feature of these electrocatalysts developed thus far is an electrogenerated reduced metal center associated with catalytic CO2 reduction. Here we report a heterogenized zinc–porphyrin complex (zinc(II) 5,10,15,20-tetramesitylporphyrin) as an electrocatalyst that delivers a turnover frequency as high as 14.4 site–1 s–1 and a Faradaic efficiency as high as 95% for CO2 electroreduction to CO at −1.7 V vs the standard hydrogen electrode in an organic/water mixed electrolyte. While the Zn center is critical to the observed catalysis, in situ and operando X-ray absorption spectroscopic studies reveal that it is redox-innocent throughout the potential range. Cyclic voltammetry indicates that the porphyrin ligand may act as a redox mediator. Chemical reduction of the zinc–porphyrin complex further confirms...
144 citations
TL;DR: Significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, theirUse in building multiporphyrin arrays for light-harvesting applications, their use as ligands to form interesting metal complexes, and also their use for several other studies.
Abstract: The heteroatom-containing porphyrin analogues or core-modified porphyrins that resulted from the replacement of one or two pyrrole rings with other five-membered heterocycles such as furan, thiophene, selenophene, tellurophene, indene, phosphole, and silole are highly promising macrocycles and exhibit quite different physicochemical properties compared to regular azaporphyrins. The properties of heteroporphyrins depend on the nature and number of different heterocycle(s) present in place of pyrrole ring(s). The heteroporphyrins provide unique and unprecedented coordination environments for metals. Unlike regular porphyrins, the monoheteroporphyrins are known to stabilize metals in unusual oxidation states such as Cu and Ni in +1 oxidation states. The diheteroporphyrins, which are neutral macrocycles without ionizable protons, also showed interesting coordination chemistry. Thus, significant progress has been made in last few decades on core-modified porphyrins in terms of their synthesis, their use in bui...
140 citations
TL;DR: In this article, a facile method to prepare porphyrin [5,10,15,20-Tetrakis (4-carboxyl phenyl)porphyrin] functionalized ZnS nanoparticles (H2TCPP-ZnS nanocomposites) under mild conditions was demonstrated.
Abstract: In this article, we demonstrated a facile method to prepare the porphyrin [5,10,15,20-Tetrakis (4-carboxyl phenyl)porphyrin] functionalized ZnS nanoparticles (H2TCPP-ZnS nanocomposites) under the mild conditions Porphyrin molecules serves as both a functional molecule and stabilizer TEM images showed that H2TCPP-ZnS nanocomposites are composed of nanoparticles with ca 5–8 nm in size The nanocomposites were for the first time developed as a peroxidase mimetic with catalytic activities and could catalyze the colorimetric reaction of H2O2 and 3,3′,5,5′-tetramethylbenzidine (TMB), where the oxidized TMB showed a typical absorption peak at 652 nm Kinetic analysis indicated that the catalytic behavior was in accordance with typical Michaelis–Menten kinetics Moreover, H2TCPP-ZnS nanocomposites could accelerate H2O2 to decompose into ·OH radicals The intrinsic peroxidase-like activity of H2TCPP-ZnS nanocomposites is due to the synergistic effect of H2TCPP as well as ZnS in the nanocomposites Based on these findings, a simple and sensitive colorimetric assay to detect H2O2 and glucose with a range of concentration from 001 to 006 mM and from 0005 to 05 mM, respectively In addition, this nanosensor can also be used for glucose detection in diluted serum
134 citations
TL;DR: This work not only sheds light on developing functional carbon dots, but also highlights the importance of special-structure precursor molecules in synthesizing functional CDs.
Abstract: Porphyrin-containing carbon dots (CDs) possess ultrasmall size, excellent water solubility, and photostability. These CDs can effectively generate cytotoxic singlet oxygen upon irradiation, and induce the cell apoptosis. Photodynamic ability of CDs inhibits the growth of hepatoma. This work not only sheds light on developing functional carbon dots, but also highlights the importance of special-structure precursor molecules in synthesizing functional CDs.
TL;DR: The current review aims to collect short information about photovoltaic performance and structure of porphyrin-based sensitizers used in dye-sensitized solar cells (DSSC).
Abstract: The current review aims to collect short information about photovoltaic performance and structure of porphyrin-based sensitizers used in dye-sensitized solar cells (DSSC). Sensitizer is the key component of the DSSC device. Structure of sensitizer is important to achieve high photovoltaic performance. Porphyrin derivatives are suitable for DSSC applications due to their thermal, electronic and photovoltaic properties. It describes some electrochemical and spectral properties as well as thestructure of porphyrin dyes used in dye based-solar cells.
TL;DR: A porphyrinic metal-organic framework (MOF) is presented as a highly sensitive fluorescent probe targeting Cu(ii) ions with a fast response, leading to an outstanding detection limit performance of 67 nM among MOF-based materials.
TL;DR: This line of research will provide a strategy for germicides consisting of quaternary ammonium groups to fight against bacterial accumulation in the long term and holds huge potential for application in the real world.
Abstract: A series of supramolecular photosensitizers were fabricated from porphyrin derivatives (Por) containing quaternary ammonium groups with cucurbit[7]uril (CB[7]) based on host–guest interactions. The antibacterial activity of Por in the dark could be turned off upon binding with CB[7], whereas the antibacterial activity under white-light illumination could be turned on. In addition, its antibacterial efficiency could be greatly enhanced by introducing metal ions. When Pd(II) was introduced into porphyrin, its antibacterial efficiency was enhanced from 40 to 100%. It should be noted that these small molecules showed little to no cytotoxicity toward mammalian cells even at concentrations higher than those under the antibacterial condition studied. This line of research will provide a strategy for germicides consisting of quaternary ammonium groups to fight against bacterial accumulation in the long term and holds huge potential for application in the real world.
TL;DR: The porous property and solid skeleton of the CPF endow Fe2P/Fe4N@N-doped carbons with porous structure and a high degree of graphitization, which exhibited highly efficient multifunctional electrocatalytic performance for water splitting and oxygen electroreduction.
Abstract: A new porous covalent porphyrin framework (CPF) filled with triphenylphosphine was designed and synthesized using the rigid tetrakis(p-bromophenyl)porphyrin (TBPP) and 1,3,5-benzenetriboronic acid trivalent alcohol ester as building blocks. The carbonization of this special CPF has afforded coupled Fe2P and Fe4N nanoparticles embedded in N-doped carbons (Fe2P/Fe4N@N-doped carbons). This CPF serves as an “all in one” precursor of Fe, N, P, and C. The porous property and solid skeleton of the CPF endow Fe2P/Fe4N@N-doped carbons with porous structure and a high degree of graphitization. As a result, Fe2P/Fe4N@N-doped carbons exhibited highly efficient multifunctional electrocatalytic performance for water splitting and oxygen electroreduction. Typically, Fe2P/Fe4N@C-800, obtained at a heat-treatment temperature of 800 °C, showed an ORR half-wave potential of 0.80 V in alkaline media and 0.68 V in acidic media, close to that of commercial Pt/C catalysts. Fe2P/Fe4N@C-800 also displayed efficient OER and HER ac...
Journal Article•
TL;DR: It is found that a high-valent iron oxo porphyrin complex containing electron-donating substituents reacts fast with ROOH in a competitive reaction performed with a mixture of olefin and ROOh, whereas a high
TL;DR: New nanocomposite particles with self-assembled porphyrin arrays as the core surrounded by amorphous silica as the shell are reported, which can selectively destroy tumor cells upon receiving light irradiation.
Abstract: Structurally controlled nanoparticles, such as core–shell nanocomposite particles by combining two or more compositions, possess enhanced or new functionalities that benefited from the synergistic coupling of the two components. Here we report new nanocomposite particles with self-assembled porphyrin arrays as the core surrounded by amorphous silica as the shell. The synthesis of such nanocomposite nanoparticles was conducted through a combined surfactant micelle confined self-assembly and silicate sol–gel process using optically active porphyrin as a functional building block. Depending on kinetic conditions, these particles exhibit structure and function at multiple length scales and locations. At the molecular scale, the porphyrins as the building blocks provide well-defined macromolecular structures for noncovalent self-assembly and unique chemistry for high-yield generation of singlet oxygen for photodynamic therapy (PDT). On the nanoscale, controlled noncovalent interactions of the porphyrin buildin...
TL;DR: In this paper, seven D−π-A porphyrin dyes (LG1,LG7) were engineered with 3-ethynyl phenothiazine tethered at the meso-position and π-spacers, such as 4-ethyl phenyl, 5-thynylthiophene (LG2), 5-ynyl furan (LG3), 2,1,3-benzothiadiazole (BTD)-phenyl (LG6), and BTD-thiophenes (LG7
Abstract: Porphyrins are major sensitizers in dye-sensitized solar cells (DSSCs) and result in very high power conversion efficiency; however, aggregation tendency and visible range absorption prevent realistic applications. Thus, designing of novel porphyrins based sensitizers is essential to resolve the current existing issues. In this context, seven D−π–A porphyrin dyes (LG1–LG7) engineered with 3-ethynyl phenothiazine tethered at the meso-position and π-spacers, such as 4-ethynyl phenyl (LG1), 5-ethynylthiophene (LG2), 5-ethynyl furan (LG3), 2,1,3-benzothiadiazole (BTD)–phenyl (LG6), and BTD–thiophene (LG7), were incorporated between porphyrin macrocycle and anchoring carboxylic acid. Similarly, π-spacers 4-ethynyl phenyl (LG4) and 4-ethynylthiophene (LG5) were functionalized between porphyrin and anchoring cyanoacrylic acid. LG5 and LG6 showed significant near-infrared absorption resulting in the highest efficiency of 10.20% and 9.64% among other derivatives. UV–vis-NIR absorption, cyclic voltammetry, and dens...
TL;DR: A substituted tetraphenyl iron porphyrin, bearing positively charged trimethylammonio groups at the para position of each phenyl ring, demonstrates its ability as a homogeneous molecular catalyst to selectively reduce CO2 to CO under visible light irradiation in organic media without the assistance of a sensitizer and no competitive hydrogen evolution for several days.
TL;DR: The photoresponse of N2 covers the whole visible wavelength range (400-650 nm), with a maximum quantum efficiency of more than twice that of a bis(dipyrrinato)zinc(II) complex nanosheet without porphyrin.
Abstract: New bis(dipyrrinato)zinc(II) complex micro- and nanosheets containing zinc(II) porphyrin (N2) are synthesized. A liquid/liquid interface method between dipyrrin porphyrin ligand L2 and zinc acetate produces N2 with a large domain size. N2 can be layered quantitatively onto a flat substrate by a modified Langmuir–Schafer method. N2 deposited on a SnO2 electrode functions as a photoanode for a photoelectric conversion system. The photoresponse of N2 covers the whole visible wavelength range (400–650 nm), with a maximum quantum efficiency of more than twice that of a bis(dipyrrinato)zinc(II) complex nanosheet without porphyrin.
TL;DR: The chemistry of annulated isomeric, expanded, and contracted porphyrins started flourishing recently with considerable efforts over the past few years, as evidenced by an increasing number of publications.
Abstract: Compared to porphyrin, its isomeric, expanded, and contracted analogues are less well explored. This contrast is found to be even more drastic in the case of their peripherally annulated counterparts. Nevertheless, the chemistry of annulated isomeric, expanded, and contracted porphyrins started flourishing recently with considerable efforts over the past few years, as evidenced by an increasing number of publications. While keeping the essence of porphyrins, these annulated versions exhibit quite unique properties that have no precedence in their nonannulated counterparts. An in-depth update of research carried out so far in this emerging area will be presented in this review.
TL;DR: The combined spectroscopic and computational investigations reveal that the reduction is ligand-centered and that [Fe(TPP)]2- is best formulated as an intermediate-spin Fe(II) center that is antiferromagnetically coupled to a porphyrin diradical anion, yielding an overall singlet ground state.
Abstract: Iron porphyrins can act as potent electrocatalysts for CO2 functionalization. The catalytically active species has been proposed to be a formal Fe(0) porphyrin complex, [Fe(TPP)]2– (TPP = tetraphenylporphyrin), generated by two-electron reduction of [FeII(TPP)]. Our combined spectroscopic and computational investigations reveal that the reduction is ligand-centered and that [Fe(TPP)]2– is best formulated as an intermediate-spin Fe(II) center that is antiferromagnetically coupled to a porphyrin diradical anion, yielding an overall singlet ground state. As such, [Fe(TPP)]2– contains two readily accessible electrons, setting the stage for CO2 reduction.
TL;DR: In this article, the effect that Fe substitutions have on the electronic properties of porphyrin-based metal organic frameworks has been investigated using computer simulations based on density functional theory.
Abstract: Photocatalysts based on metal-organic frameworks (MOFs) are very promising due to a combination of high tuneability and convenient porous structure Introducing porphyrin units within MOFs is a potential route to engineer these natural photosynthesis molecular catalysts into artificial photosynthesis heterogeneous catalysts Using computer simulations based on density functional theory, we explore how to modify the electronic structure of porphyrin-based MOFs to make them suitable for the photocatalysis of solar fuel synthesis via water splitting or carbon dioxide reduction In particular, we have investigated the effect that Fe substitutions have on the electronic properties of porphyrin-based metal organic frameworks By aligning the electron levels with a vacuum reference, we show that Fe at the porphyrin metal centre has the effect of slightly raising the position of the valence band edge, whereas Fe at the octahedral metal node has the ability to significantly lower the position of the conduction band edge on the absolute scale Iron is therefore a very useful dopant to engineer the band structure and alignment of these MOFs We find that the porphyrin-based structure with Al in the octahedral sites and Zn in the porphyrin centres has a band gap that is slightly too wide to take advantage of visible-light solar radiation, while the structure with Fe in the octahedral sites has bandgaps that are too narrow for water splitting photocatalysis We then show that the optimal composition is achieved by partial substitution of Al by Fe at the octahedral sites, while keeping Zn at the porphyrin centres Our study demonstrates that porphyrin-based MOFs can be engineered to display intrinsic photocatalytic activity in solar fuel synthesis reactions
TL;DR: In this article, a cost-effective iron porphyrin (FePor)-based covalent organic polymer (COP), FePor-TFPA-COP, through an easy aromatic substitution reaction between pyrrole and tris(4-formylphenyl)amine (TFPA), was synthesized.
Abstract: Herein, we synthesized a cost-effective iron porphyrin (FePor)-based covalent organic polymer (COP), FePor-TFPA-COP, through an easy aromatic substitution reaction between pyrrole and tris(4-formylphenyl)amine (TFPA). The triangular pyramid-shaped, N-centric structure of TFPA facilitated the formation of FePor-TFPA-COP with three-dimensional porous structure, larger surface area, and abundant surface catalytically active sites. FePor-TFPA-COP exhibited strong intrinsic peroxidase activity toward a classical peroxidase substrate, 3,3′,5,5′-tetramethylbenzidine (TMB), in the presence of H2O2. Compared with horseradish peroxidase (HRP), FePor-TFPA-COP exhibited several advantages such as easy storage, high sensitivity, and prominently chemical and catalytic stability under the harsh conditions, which guaranteed the accuracy and reliability of measurements. Utilizing the excellent catalytic activity, a FePor-TFPA-COP-based colorimetric immunoassay was first established for α-fetoprotein (AFP) detection and sh...
TL;DR: These results provide a novel approach for developing efficient porphyrin dyes by introducing chains into the suitable position of the auxiliary benzothiadiazolyl moiety to suppress dye aggregation, without seriously aggravating distortion of the dye molecules.
Abstract: Donor−π–acceptor-type porphyrin dyes have been widely used for the fabrication of efficient dye-sensitized solar cells (DSSCs) owing to their strong absorption in the visible region and the ease of modifying their chemical structures and photovoltaic behavior. On the basis of our previously reported efficient porphyrin dye XW11, which contains a phenothiazine-based electron donor, a π-extending ethynylene unit, and an auxiliary benzothiadiazole acceptor, we herein report the syntheses of novel porphyrin dyes XW26–XW28 by introducing one or two alkyl/alkoxy chains into the auxiliary acceptor. The introduced chains can effectively suppress dye aggregation. As a result, XW26–XW28 show excellent photovoltages of 700, 701, and 711 mV, respectively, obviously higher than 645 mV obtained for XW11. Nevertheless, the optimized structures of XW26 and XW27 exhibit severe distortion, showing large dihedral angles of 57.2° and 44.0°, respectively, between the benzothiadiazole and benzoic acid units, resulting from the...
TL;DR: An iron-substituted tetraphenyl porphyrin bearing positively charged trimethylammonio groups at the para position of each phenyl ring catalyzes the photoinduced conversion of CO2 through visible-light irradiation in aqueous solutions with the assistance of purpurin, a simple organic photosensitizer.
Abstract: An iron-substituted tetraphenyl porphyrin bearing positively charged trimethylammonio groups at the para position of each phenyl ring catalyzes the photoinduced conversion of CO2 . This complex is water soluble and acts as a molecular catalyst to selectively reduce CO2 into CO under visible-light irradiation in aqueous solutions (acetonitrile/water=1:9 v/v) with the assistance of purpurin, a simple organic photosensitizer. CO is produced with a catalytic selectivity of 95 % and turnover number up to 120, illustrating the possibility of photocatalyzing the reduction of CO2 in aqueous solution by using visible light, a simple organic sensitizer coupled to an amine as a sacrificial electron donor, and an earth-abundant metal-based molecular catalyst.
TL;DR: Mechanistic investigations of CO2 reduction by iron porphyrin complexes in situ and chemical principles governing the rate and selectivity of reduction of small molecules like O2, CO2, NOx, and SOx may be quite similar in nature.
Abstract: ConspectusReactivity as well as selectivity are crucial in the activation and electrocatalytic reduction of molecular oxygen. Recent developments in the understanding of the mechanism of electrocatalytic O2 reduction by iron porphyrin complexes in situ using surface enhanced resonance Raman spectroscopy coupled to rotating disc electrochemistry (SERRS-RDE) in conjunction with H/D isotope effects on electrocatalytic current reveals that the rate of O2 reduction, ∼104 to 105 M–1 s–1 for simple iron porphyrins, is limited by the rate of O–O bond cleavage of an intermediate ferric peroxide species (FeIII–OOH). SERRS-RDE probes the system in operando when it is under steady state such that any intermediate species that has a greater rate of formation relative to its rate of decay, including the rate determining species, would accumulate and can be identified. This technique is particularly well suited to investigate iron porphyrin electrocatalysts as the intense symmetric ligand vibrations allow determination ...
TL;DR: Experimental data and theoretical calculations indicate that the distal triazole residues, once protonated, enhance the proton affinity of the iron center via formation of a dihydrogen bond with an Fe(III)-H- intermediate.
Abstract: Iron porphyrin complexes with second-sphere distal triazole residues show a hydrogen evolution reaction (HER) catalyzed by the Fe(I) state in both organic and aqueous media, whereas an analogous iron porphyrin complex without the distal residues catalyzes the HER in the formal Fe(0) state. This activation of the Fe(I) state by the second-sphere residues lowers the overpotential of the HER by these iron porphyrin complexes by 50%. Experimental data and theoretical calculations indicate that the distal triazole residues, once protonated, enhance the proton affinity of the iron center via formation of a dihydrogen bond with an Fe(III)–H– intermediate.
TL;DR: Insight is provided into the photosensitizing ability of the polymer in addition to its ability to firmly harbor nanoparticles onto its surface as compared to the parent precursors.
TL;DR: This review will focus on the attempted synthesis of antiaromatic isophlorin ever since its conception, and along with the synthetic details, the structural, electronic, and redox properties of isophloin and its expanded derivatives will be elaborated.
Abstract: Ever since the discovery of the porphyrin ring in “pigments of life”, such as chlorophyll and hemoglobin, it has become a prime synthetic target for optoelectronic properties and in the design of metal complexes. During one such early expedition on the synthesis of porphyrin, Woodward proposed that condensing pyrrole with an aldehyde under acidic conditions yields the “precursor” porphyrinogen macrocycle. Its four-electron oxidation leads to the “transitory” 20π isophlorin, which undergoes subsequent two-electron oxidation to form the 18π “porphyrin”. Due to its fleeting lifetime, it has been a synthetic challenge to stabilize the tetrapyrrolic isophlorin. This macrocycle symbolizes the antiaromatic character of a porphyrin-like macrocycle. In addition, the pyrrole NH also plays a key role in the proton-coupled, two-electron oxidation of isophlorin to the aromatic porphyrin. However, a major aspect of its unstable nature was attributed to its antiaromatic character, which is understood to destabilize the ...