Showing papers on "Porphyrin published in 2011"
TL;DR: In this article, a Co(II/III)tris(bipyridyl)-based redox electrolyte was used in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8).
Abstract: The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co(II/III)tris(bipyridyl)–based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.
5,462 citations
Journal Article•
TL;DR: Mesoscopic solar cells that incorporate a Co(II/III)tris(bipyridyl)–based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer are reported, enabling attainment of strikingly high photovoltages approaching 1 volt.
Abstract: Simultaneous modification of the dye and redox shuttle boosts the efficiency of a dye-sensitized solar cell. The iodide/triiodide redox shuttle has limited the efficiencies accessible in dye-sensitized solar cells. Here, we report mesoscopic solar cells that incorporate a Co(II/III)tris(bipyridyl)–based redox electrolyte in conjunction with a custom synthesized donor-π-bridge-acceptor zinc porphyrin dye as sensitizer (designated YD2-o-C8). The specific molecular design of YD2-o-C8 greatly retards the rate of interfacial back electron transfer from the conduction band of the nanocrystalline titanium dioxide film to the oxidized cobalt mediator, which enables attainment of strikingly high photovoltages approaching 1 volt. Because the YD2-o-C8 porphyrin harvests sunlight across the visible spectrum, large photocurrents are generated. Cosensitization of YD2-o-C8 with another organic dye further enhances the performance of the device, leading to a measured power conversion efficiency of 12.3% under simulated air mass 1.5 global sunlight.
5,385 citations
TL;DR: Two types of covalent organic frameworks (COFs) having a porphyrin unit have been synthesized as discussed by the authors, and the two COFs have shown very high charge carrier mobility values (8.1 cm2 V−1 s−1).
Abstract: Two types (imine and boronate) of covalent organic frameworks (COFs) having a porphyrin unit have been synthesized. The two highly crystalline porphyrin COFs (COF-366 and COF-66) display excellent chemical and thermal stability and are permanently porous. Two-dimensional extended layered structures of the two COFs demonstrate very high charge carrier mobility values (8.1 cm2 V−1 s−1).
620 citations
TL;DR: Synchrotron X-ray diffraction measurements showed that NAFS-2 exhibits highly crystalline order in both the in-plane and out-of-plane orientations, which is a key issue for the future use of MOFs in potential applications in nanodevices.
Abstract: Layer-structured metal−organic framework (MOF) nanofilms (NAFS-2) consisting of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (H2TCPP) molecules and copper ion metal linkers were assembled on a gol...
275 citations
TL;DR: In this paper, a high-potential porphyrin is codeposited on TiO2 nanoparticles together with a Cp*-iridium water-oxidation catalyst to give a photoanode for a water splitting cell.
Abstract: A high-potential porphyrin is codeposited on TiO2 nanoparticles together with our Cp*–iridium water-oxidation catalyst to give a photoanode for a water-splitting cell. The photoanode optically resembles the porphyrin yet electrochemically responds like the Ir catalyst when it is immersed in aqueous solutions. Photoelectrochemical data show that illumination of the codeposited anode in water results in a marked enhancement and stability of the photocurrent, providing evidence for light-induced activation of the catalyst.
249 citations
TL;DR: Highly efficient porphyrin sensitizers with two phenyl groups at meso-positions of the macrocycle bearing two ortho-substituted long alkoxyl chains for dye-sensitized solar cells exhibit significantly enhanced photovoltaic performances.
246 citations
TL;DR: A cobalt(II) hangman porphyrin with a xanthene backbone and a carboxylic acid hanging group catalyzes the electrochemical production of hydrogen from benzoic and tosic acid in acetonitrile solutions and is shown to be exclusively involved in the generation of H(2) from weak acids.
Abstract: A cobalt(II) hangman porphyrin with a xanthene backbone and a carboxylic acid hanging group catalyzes the electrochemical production of hydrogen from benzoic and tosic acid in acetonitrile solutions. We show that CoIIH is exclusively involved in the generation of H2 from weak acids. In a stronger acid, a CoIIIH species is observed electrochemically, but it still needs to be further reduced to CoIIH before H2 generation occurs. Overpotentials for H2 generation are lowered as a result of the hangman effect.
235 citations
TL;DR: The synthesis, properties, and activity of CNC-Por (5) described herein serve as a benchmark toward the overall objectives of developing novel, potent, bioactive, photobactericidal materials that are effective against a range of bacteria, with potential utilization in the health care and food preparation industries.
207 citations
TL;DR: This feature article gives an account of the work in the past decade to develop synthetic methods for the A(x)- and ABCD-type porphyrins and their use as optical materials and photosensitizers.
202 citations
TL;DR: A fused tetraanthracenylporphyrin is synthesized by oxidation of a meso-anthracENyl nickel(II) porphyrin with FeCl(3), which exhibits an intense red-shifted absorption spectrum.
Abstract: We have synthesized a fused tetraanthracenylporphyrin by oxidation of a meso-anthracenyl nickel(II) porphyrin with FeCl3. This compound exhibits an intense red-shifted absorption spectrum (λmax = 1417 nm; e = 1.2 × 105 M−1 cm−1) and a small electrochemical HOMO−LUMO gap (0.61 eV). The crystal structure shows that it forms π-stacked dimers with a short Ni···Ni distance (3.32 A).
183 citations
TL;DR: Electrochemistry, absorption, and fluorescence spectra indicate that the HOMO-LUMO gap of the nanoring is less than that of the linear hexamer and less than those of the corresponding polymer.
Abstract: Linear π-conjugated oligomers have been widely investigated, but the behavior of the corresponding cyclic oligomers is poorly understood, despite the recent synthesis of π-conjugated macrocycles such as [n]cycloparaphenylenes and cyclo[n]thiophenes. Here we present an efficient template-directed synthesis of a π-conjugated butadiyne-linked cyclic porphyrin hexamer directly from the monomer. Small-angle X-ray scattering data show that this nanoring is shape-persistent in solution, even without its template, whereas the linear porphyrin hexamer is relatively flexible. The crystal structure of the nanoring–template complex shows that most of the strain is localized in the acetylenes; the porphyrin units are slightly curved, but the zinc coordination sphere is undistorted. The electrochemistry, absorption, and fluorescence spectra indicate that the HOMO–LUMO gap of the nanoring is less than that of the linear hexamer and less than that of the corresponding polymer. The nanoring exhibits six one-electron reduc...
TL;DR: Findings indicate that the clay/porphyrin complexes are promising and prospective candidates to be used for construction of an efficient artificial light-harvesting system.
Abstract: The quantitative excited energy transfer reaction between cationic porphyrins on an anionic clay surface was successfully achieved. The efficiency reached up to ca. 100% owing to the “Size-Matching Rule” as described in the text. It was revealed that the important factors for the efficient energy transfer reaction are (i) suppression of the self-quenching between adjacent dyes, and (ii) suppression of the segregated adsorption structure of two kinds of dyes on the clay surface. By examining many different kinds of porphyrins, we found that tetrakis(1-methylpyridinium-3-yl) porphyrin (m-TMPyP) and tetrakis(1-methylpyridinium-4-yl) porphyrin (p-TMPyP) are the suitable porphyrins to accomplish a quantitative energy transfer reaction. These findings indicate that the clay/porphyrin complexes are promising and prospective candidates to be used for construction of an efficient artificial light-harvesting system.
TL;DR: In this article, the photometric properties of dye-sensitized solar cells were investigated and the overall efficiencies of the corresponding devices show a trend LD4 > LD3p > LD2 > LD 3a > LD1.
Abstract: Zinc porphyrins in a series bearing a phenylethynyl, naphthalenylethynyl, anthracenylethynyl, phenanthrenylethynyl or pyrenylethynyl substituent, denoted LD1, LD2, LD3a, LD3p or LD4, respectively, were prepared as photosensitizers for dye-sensitized solar cells. The overall efficiencies of the corresponding devices show a trend LD4 > LD3p > LD2 > LD3a > LD1. Significantly, LD4 features JSC/mA cm−2 = 19.627, VOC/V = 0.711, and FF = 0.721, giving an efficiency η = 10.06% of power conversion. This value is superior to that of a N719-based solar cell fabricated under similar experimental conditions. The remarkable performance of the LD4 cell is rationalized to be due to the broader and more red-shifted spectral feature that makes the IPCE spectrum to cover broadly across the entire visible region, 400–800 nm.
TL;DR: In this article, the synthesis of a porous organic polymer (POP) containing free-base porphyrin subunits has been accomplished by the condensation of a bis(phthalic acid)porphyrin with tetra(4-aminophenyl)methane.
Abstract: The synthesis of a porous organic polymer (POP) containing free-base porphyrin subunits has been accomplished by the condensation of a bis(phthalic acid)porphyrin with tetra(4-aminophenyl)methane. Metallation by post-synthesis modification affords microporous materials incorporating either Fe or Mn(porphyrins) that have been shown to be active catalysts for both olefin epoxidation and alkane hydroxylation.
TL;DR: The porphyrin/graphene sensor provided a unique platform in the analysis of nitroaromatic explosives for various security and environmental applications as mentioned in this paper, which showed an ultratrace detection of as low as 1.1% standard deviation for a series of 9 repetitive measurements.
Abstract: Porphyrin functionalized graphene is used to electrochemically detect nitroaromatic explosives. It is found that synergistic effects from the specific good adsorptive properties of porphyrin and the large electroactive surface area and fast charge transfer of graphene contribute to the sensitive detection. The porphyrin/graphene sensor shows an ultratrace detection of as low as 1 ppb of 2,4-dinitrotoluene, 0.5 ppb of 2,4,6-trinitrotoluene, 1 ppb of 1,3,5-trinitrobenzene and 2 ppb of 1,3-dinitrobenzene respectively and good reproducibility within 5.1 % standard deviation for a series of 9 repetitive measurements. The porphyrin/graphene sensor provides a unique platform in the analysis of nitroaromatic explosives for various security and environmental applications.
TL;DR: In this article, a comprehensive photophysical study is reported on a family of π-extended platinum(II) porphyrin complexes, including tetraarylbenzo-, tetraarylnaphtho-, and tetrasylbenzo, which exhibits efficient phosphorescence at 773, 890, and 1020 nm in the near-infrared region.
Abstract: A comprehensive photophysical study is reported on a family of π-extended platinum(II) porphyrin complexes. The platinum(II) complexes are synthesized from the corresponding free base porphyrins by treatment with platinum(II) acetate in hot benzonitrile, affording the complexes in considerably higher yield than by reaction with platinum(II) chloride. A quantitative study of the absorption and luminescence properties of the metalloporphyrins is presented. A series including tetraarylbenzo-, tetraarylnaphtho-, and tetraarylanthroporphyrin exhibits efficient phosphorescence at 773, 890, and 1020 nm in the near-infrared region, with quantum yields of 0.35, 0.15, and 0.08, respectively. The triplet lifetimes and phosphorescence yields decrease with increasing emission wavelength, consistent with energy gap law behavior. A set of six Pt-tetrabenzoporphyrins (TBPs) with different meso-substituents were examined. The Pt-TBPs exhibit efficient phosphorescence with λmax ∼ 770 nm and with a quantum yield ranging fro...
TL;DR: The quenching of fluorescence (or phosphorescence) and reduced lifetimes suggest excited state energy/electron transfer between graphene and the covalently attached TPP (or PdTPP) molecules.
Abstract: Two types of graphene-based hybrid materials, graphene-TPP (TPP=tetraphenylporphyrin) and graphene-PdTPP (PdTPP=palladium tetraphenylporphyrin), were prepared directly from pristine graphene through one-pot cycloaddition reactions. The hybrid materials were characterized by thermogravimetric analysis (TGA), by TEM, by UV/Vis, FTIR, Raman, and luminescence spectroscopy, and by fluorescence/phosphorescence lifetime measurements. The presence of the covalent linkages between graphene and porphyrin was confirmed by FTIR and Raman spectroscopy and further supported by control experiments. The presence of TPP (or PdTPP) in the hybrid material was demonstrated by UV/Vis spectroscopy, with TGA results indicating that the graphene-TPP and graphene-PdTPP hybrid materials contained approximately 18% TPP and 20% PdTPP. The quenching of fluorescence (or phosphorescence) and reduced lifetimes suggest excited state energy/electron transfer between graphene and the covalently attached TPP (or PdTPP) molecules.
TL;DR: A historical perspective highlights the importance of spectroscopic methods for biochemical studies in general, and especially for heme enzymes, where the presence of the heme iron and porphyrin macrocycle provides rich variety of specificSpectroscopic markers available for monitoring chemical transformations and transitions between active intermediates of catalytic cycle.
TL;DR: It is concluded that ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes and that mutant alleles of GUN4 and Mg-chelatase genes cause sensitivity to intense light by a mechanism that is potentially complex.
Abstract: The GENOMES UNCOUPLED4 (GUN4) protein stimulates chlorophyll biosynthesis by activating Mg-chelatase, the enzyme that commits protoporphyrin IX to chlorophyll biosynthesis. This stimulation depends on GUN4 binding the ChlH subunit of Mg-chelatase and the porphyrin substrate and product of Mg-chelatase. After binding porphyrins, GUN4 associates more stably with chloroplast membranes and was proposed to promote interactions between ChlH and chloroplast membranes-the site of Mg-chelatase activity. GUN4 was also proposed to attenuate the production of reactive oxygen species (ROS) by binding and shielding light-exposed porphyrins from collisions with O₂. To test these proposals, we first engineered Arabidopsis thaliana plants that express only porphyrin binding-deficient forms of GUN4. Using these transgenic plants and particular mutants, we found that the porphyrin binding activity of GUN4 and Mg-chelatase contribute to the accumulation of chlorophyll, GUN4, and Mg-chelatase subunits. Also, we found that the porphyrin binding activity of GUN4 and Mg-chelatase affect the associations of GUN4 and ChlH with chloroplast membranes and have various effects on the expression of ROS-inducible genes. Based on our findings, we conclude that ChlH and GUN4 use distinct mechanisms to associate with chloroplast membranes and that mutant alleles of GUN4 and Mg-chelatase genes cause sensitivity to intense light by a mechanism that is potentially complex.
TL;DR: In this article, a novel zinc porphyrin dyes for use in dye-sensitized solar cells (DSSCs) have been synthesized, which are based on a molecular design that relies on donor−π-acceptor interactions.
Abstract: Novel zinc porphyrin dyes for use in dye-sensitized solar cells (DSSCs) have been synthesized. These dyes are based on a molecular design that relies on donor−π–acceptor interactions, a concept implemented by introducing a bis(4-tert-butylphenyl)amino group at the meso position of the porphyrin opposite to what are 2-propenoic or 2,4-pentadienoic acid anchoring groups at the β-pyrrolic positions. Incorporating an electron-donating group (i.e., the diarylamine) on the porphyrin core serves as the considerable electronic coupling between the donor site and porphyrin core, and hence, the HOMO–LUMO energy gap is decreased. This change is reflected in the remarkable red shift and broadening of the absorption spectra relative to an unfunctionalized parent system. This substitution, in conjunction with functionalization with carboxylic acid moieties on the β-pyrrolic positions, also provides what is an effectively aligned donor−π–acceptor dipolar architecture. This, in turn, gives rise to advantageous charge-tra...
TL;DR: In this article, three new solution-processable platinum polyyne polymers containing zinc(II) porphyrinate chromophores P1, P2, and P3 and their corresponding dinuclear model complexes were synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum (II) chloride precursor and each of the respective bis(ethynyl)-zinc(porphyrin) metalloligands.
Abstract: Three new solution-processable platinum(II) polyyne polymers containing zinc(II) porphyrinate chromophores P1, P2, and P3 and their corresponding dinuclear model complexes were synthesized via the CuI-catalyzed dehydrohalogenation reaction of the platinum(II) chloride precursor and each of the respective bis(ethynyl)-zinc(porphyrin) metalloligands The thermal, photophysical (absorption, excitation and emission spectra), electrochemical, and photovoltaic properties of P1–P3 were investigated These results are also correlated by time-dependent density functional theory (TDDFT) calculations The computations corroborate the presence of moderate conjugation in the π-systems, somewhat more accentuated for P3 where more favorable dihedral angles between the porphyrin and thiophene rings are noted Moreover, the computed excited states are predicted to be π–π* in nature with some charge transfer components from the trans-[−C≡CPt(L)2C≡C−]n unit to the porphyrin rings The optical bandgaps range from 193 to 20
TL;DR: In this article, different chemical strategies were demonstrated for access to unsymetrically substituted porphyrin rings with nonequivalent β or meso substituents for optical limiting and photodynamic therapy.
TL;DR: In this article, the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane was investigated using phase-modulation 2D fluorescence spectroscopy (PM-2D FS).
Abstract: By applying a phase-modulation fluorescence approach to 2D electronic spectroscopy, we studied the conformation-dependent exciton coupling of a porphyrin dimer embedded in a phospholipid bilayer membrane. Our measurements specify the relative angle and separation between interacting electronic transition dipole moments and thus provide a detailed characterization of dimer conformation. Phase-modulation 2D fluorescence spectroscopy (PM-2D FS) produces 2D spectra with distinct optical features, similar to those obtained using 2D photon-echo spectroscopy. Specifically, we studied magnesium meso tetraphenylporphyrin dimers, which form in the amphiphilic regions of 1,2-distearoyl-sn-glycero-3-phosphocholine liposomes. Comparison between experimental and simulated spectra show that although a wide range of dimer conformations can be inferred by either the linear absorption spectrum or the 2D spectrum alone, consideration of both types of spectra constrain the possible structures to a “T-shaped” geometry. These experiments establish the PM-2D FS method as an effective approach to elucidate chromophore dimer conformation.
TL;DR: In this article, a review of supermolecular electron-donor-acceptor ensembles with porphyrin dyes covalently linked to fullerene is presented.
TL;DR: Organic light-emitting diodes incorporating linear and cyclic porphyrin hexamers which have red-shifted emission are reported which have high photoluminescence quantum efficiency when using additives to prevent aggregation and achieving high color purity near-infrared electroluminescent.
Abstract: Here we report organic light-emitting diodes incorporating linear and cyclic porphyrin hexamers which have red-shifted emission (λPL = 873 and 920 nm, respectively) compared to single porphyrin rings as a consequence of their extended π-conjugation. We studied the photoluminescence and electroluminescence of blends with poly(9,9′-dioctylfluorene-alt-benzothiadiazole), demonstrating a high photoluminescence quantum efficiency of 7.7% for the linear hexamer when using additives to prevent aggregation and achieving high color purity near-infrared electroluminescence.
TL;DR: In this article, a template-directed synthesis of rotaxanes was proposed for creating complex interlocked structures directly from simple starting materials using a radial hexa-pyridyl template.
Abstract: [2]Rotaxanes consisting of butadiyne-linked porphyrin dimers threaded through a phenanthroline-containing macrocycle, can be synthesised by an active-metal template directed copper-mediated Glaser coupling, in yields of up to 61%, without requiring a large excess of the macrocycle. The crystal structure of one of these rotaxanes confirms that the macrocycle is clasped around the centre of the porphyrin dimer. A radial hexa-pyridyl template was used to convert the alkyne-terminated [2]rotaxane into a [4]catenane cyclic porphyrin hexamer in 62% yield, viapalladium-catalysed Glaser coupling. The related [7]catenane porphyrin dodecamer complex was also isolated as a by-product of this cyclisation, in 6% yield. These results illustrate the scope of template-directed synthesis for creating complex interlocked structures directly from simple starting materials.
TL;DR: Study of the polymers formed in reactions involving Al-alkoxide initiators and PPN(+) salts by mass spectrometry indicate that one chain is grown per Al center, compared with earlier studies where the reactions display first order kinetics in the metal complex.
Abstract: The reactivities of aluminum(III) complexes LAlX, where L = 5,10,15,20-tetraphenylporphyrin (TPP), 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TFPP), and 2,3,7,8,12,13,17,18-octaethylporphyirn (OEP) and X = Cl or OEt, have been studied with respect to their ability to homopolymerize propylene oxide (PO) and copolymerize PO and CO(2) to yield polypropylene oxide (PPO) and polypropylene carbonate (PPC), respectively, with and without the presence of a cocatalyst, namely, 4-dimethylaminopyridine (DMAP) or a PPN(+) salt where the anion is Cl(-) or N(3)(-). In the presence of a cocatalyst (0.5 equiv), the TFPP complex is the most active in copolymerization to yield PPC, with the latter being effective even at 10 bar CO(2). An increase in the PPN(+)X(-)/[Al] ratio decreases the rate of PPC formation and favors the formation of propylene carbonate, (PC). Studies of the polymers formed in reactions involving Al-alkoxide initiators and PPN(+) salts by mass spectrometry indicate that one chain is grown per Al center. These results are compared with earlier studies where the reactions display first order kinetics in the metal complex.
TL;DR: The boron dipyrrin (Bodipy) chromophore was combined with either a free-base or a Zn porphyrin moiety, via an easy synthesis involving a cyanuric chloride bridging unit, yielding dyads Bodipy-H(2)P (4) and BodipY-ZnP (5).
Abstract: The boron dipyrrin (Bodipy) chromophore was combined with either a free-base or a Zn porphyrin moiety (H2P and ZnP respectively), via an easy synthesis involving a cyanuric chloride bridging unit, yielding dyads Bodipy-H2P (4) and Bodipy-ZnP (5). The photophysical properties of Bodipy-H2P (4) and Bodipy-ZnP (5) were investigated by UV-Vis absorption and emission spectroscopy, cyclic voltammetry, and femtosecond transient absorption spectroscopy. The comparison of the absorption spectra and cyclic voltammograms of dyads Bodipy-H2P (4) and Bodipy-ZnP (5) with those of their model compounds Bodipy, H2P, and ZnP shows that the spectroscopic and electrochemical properties of the constituent chromophores are essentially retained in the dyads indicating negligible interaction between them in the ground state. In addition, luminescence and transient absorption experiments show that excitation of the Bodipy unit in Bodipy-H2P (4) and Bodipy–ZnP (5) into its first singlet excited state results in rapid Bodipy to po...
TL;DR: A brief survey of the development of meso-meso-linked porphyrin arrays can be found in this paper, along with a discussion of the evolution of transition metal-catalyzed functiona.
Abstract: After a brief survey of our efforts in the development of novel porphyrinoids that include meso–meso-linked porphyrin arrays, meso-aryl expanded porphyrins, and transition-metal-catalyzed functiona...