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Showing papers on "Porphyrin published in 2010"


Journal ArticleDOI
TL;DR: A greatly enhanced photovoltaic performance is observed when the porphyrin dye is cosensitized with a metal-free dye that has a complementary spectral response.
Abstract: To dye for: A porphyrin chromophore, which is integrated into a donor-acceptor dye as a π-conjugated bridge (see picture), exhibits an unprecedented efficiency of 11 □ % when used as a photosensitizer in a double-layer TiO2 film. A greatly enhanced photovoltaic performance is observed when the porphyrin dye is cosensitized with a metal-free dye that has a complementary spectral response. © 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

775 citations


Journal ArticleDOI
TL;DR: In this article, a review summarizes recent advances in the use of porphyrins, phthalocyanines, and related compounds as components of solar cells, including organic molecular solar cells and dye-sensitized solar cells.
Abstract: This review summarizes recent advances in the use of porphyrins, phthalocyanines, and related compounds as components of solar cells, including organic molecular solar cells, polymer cells, and dye-sensitized solar cells. The recent report of a porphyrin dye that achieves 11% power conversion efficiency in a dye-sensitized solar cell indicates that these classes of compounds can be as efficient as the more commonly used ruthenium bipyridyl derivatives.

623 citations


Journal ArticleDOI
TL;DR: In this paper, a series of porphyrin dyes with an electron-donating group (EDG) attached at a meso-position (YD1-YD8) have been designed and synthesized for use as sensitizers in dye-sensitized solar cells (DSSC).
Abstract: A series of porphyrin dyes with an electron-donating group (EDG) attached at a meso-position (YD1–YD8) have been designed and synthesized for use as sensitizers in dye-sensitized solar cells (DSSC). The nature of the EDG exerts a significant influence on the spectral, electrochemical and photovoltaic properties of these sensitizers. Absorption spectra of porphyrins having an amino group show broadened Soret band and red-shifted Q bands with respect to those of reference porphyrin YD0. This phenomenon is more pronounced for porphyrins YD7 and YD8 that have a π-conjugated triphenylamine at the meso-position opposite the anchoring group. Upon introduction of an EDG at the meso-position, the potential for the first oxidation alters significantly to the negative whereas that for the first reduction changes inappreciably, indicating a decreased HOMO-LUMO gap. Results of density-functional theory (DFT) calculations support the spectroelectrochemical data for a delocalization of charge between the porphyrin ring and the amino group in the first oxidative state of diarylamino-substituted porphyrins YD1–YD4, which exhibit superior photovoltaic performance among all porphyrins under investigation. With long-chain alkyl groups on the diarylamino substituent, YD2 shows the best cell performance with JSC = 13.4 mA cm−2, VOC = 0.71 V, and FF = 0.69, giving an overall efficiency 6.6% of power conversion under simulated one-sun AM1.5 illumination.

244 citations


Journal ArticleDOI
TL;DR: In this article, a library of Co(II) hangman porphyrins was used to demonstrate that the four-electron four-proton catalytic reduction of oxygen to water in aqueous solution can be achieved at the single cobalt center of the hangman platform.
Abstract: Cobalt(II) hangman porphyrins are delivered from easily available starting materials, in two steps, in good yields, and with abbreviated reaction times. Selected compounds from a library of Co(II) hangman porphyrins immobilized on multiwall carbon nanotubes establish that the four-electron four-proton catalytic reduction of oxygen to water in aqueous solution can be achieved at the single cobalt center of the hangman platform. Reaction trends within the library reveal that the selective reduction of O2 to H2O occurs at electron deficient hangman porphyrin platforms possessing a distal group that is capable of proton transfer.

218 citations


Journal ArticleDOI
02 Mar 2010-Langmuir
TL;DR: The 3-sensitized solar cell demonstrates higher solar spectral coverage, based on incident photon to current efficiency (IPCE) spectra, and an improved power conversion efficiency compared to that of the 2-s Sensitized cell.
Abstract: A zinc porphyrin derivative (2) and zinc porphyrin−bodipy dyad (3) have been prepared and applied to dye-sensitized solar cells (DSSCs). On the basis of absorption and fluorescence excitation spectra, dyad 3 efficiently transfers energy from the bodipy to zinc porphyrin constituent. The 3-sensitized solar cell demonstrates higher solar spectral coverage, based on incident photon to current efficiency (IPCE) spectra, and an improved power conversion efficiency (η = 1.55%) compared to that of the 2-sensitized cell (η = 0.84%). The better performance of the 3-sensitized cell is attributed largely to the gain in spectral absorbance provided by the bodipy constituent of 3. Also evident, however, are secondary effects reflecting (a) fill-factor improvement and (b) a slight gain in porphyrin red-edge absorbance due to bodipy-conjugate formation.

209 citations


Journal ArticleDOI
28 Oct 2010-ACS Nano
TL;DR: The ability of TMPyP-RGO to undergo photoinduced charge separation was further confirmed from the photoelectrochemical measurements and results are indicative of the electron transfer between photoexcited porphyrin and RGO.
Abstract: Photoexcited cationic 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP) undergoes charge-transfer interaction with chemically reduced graphene oxide (RGO). Formation of the ground-state TMPyP-RGO complex in solution is marked by the red-shift of the porphyrin absorption band. This complexation was analyzed by Benesi-Hildebrand plot. Porphyrin fluorescence lifetime reduced from 5 to 1 ns upon complexation with RGO, indicating excited-state interaction between singlet excited porphyrin and RGO. Femtosecond transient absorption measurements carried out with TMPyP adsorbed on RGO film revealed fast decay of the singlet excited state, followed by the formation of a longer-living product with an absorption maximum around 515 nm indicating the formation of a porphyrin radical cation. The ability of TMPyP-RGO to undergo photoinduced charge separation was further confirmed from the photoelectrochemical measurements. TMPyP-RGO coated conducting glass electrodes are capable of generating photocurrent under visible excitation. These results are indicative of the electron transfer between photoexcited porphyrin and RGO. The role of graphene in accepting and shuttling electrons in light-harvesting assemblies is discussed.

191 citations


Journal ArticleDOI
TL;DR: These multifunctional organometallic polyyne polymers exhibit convenient structural variability as well as optical and electronic properties, which renders them important for use in different research domains as chemical sensors and sensor protectors, as converters for light/electricity signals, and as patternable precursors to magnetic metal alloy nanoparticles.
Abstract: This review article surveys the electronic and photophysical properties of conjugated organometallic polymers built upon the title compound and its related derivatives focussing primarily on systems investigated in our laboratories. The general structure of the polymers is (trans-bis(para-ethynylbenzene)bis(phosphine)platinum(II)-G)(n) where G is a conjugated group such as thiophene, fluorene, carbazole, substituted silole, quinone derivative, and metalloporphyrin residue, or a non-conjugated main-group moiety. Systems based on substituted phenylene units and other related fused rings are also discussed. The phosphine ligands are generally triethyl- or tri-n-butylphosphine groups. These trans-platinum(II) polymers and the corresponding model compounds are compared to the corresponding ortho-derivatives in the quinone series, and the newly prepared paracyclophane-containing polymers. For the porphyrin series, a comparison of fully conjugated oligomers exhibiting the general structure (trans-bis(para-ethynyl(zinc(porphyrin)))bis(phosphine)platinum(II))(n) (i.e., the C(6) H(4) group is absent from the main chain) will be made. This contribution also includes a description of the properties of the mononuclear chromophore itself, properties that define those of the polymers. Potential applications with regard to electronic and optical devices will be highlighted. These soluble and stable materials feature both the processing advantages of polymers and the functionality provided by the presence of metal centers. These multifunctional organometallic polyyne polymers exhibit convenient structural variability as well as optical and electronic properties, which renders them important for use in different research domains as chemical sensors and sensor protectors, as converters for light/electricity signals, and as patternable precursors to magnetic metal alloy nanoparticles.

178 citations


Journal ArticleDOI
TL;DR: In this paper, porphyrin dyes with electron-donating groups (EDG) were synthesized for dye-sensitized solar cells (DSSC); their spectral, electrochemical and photovoltaic properties were investigated.
Abstract: Novel porphyrin dyes YD14–YD17 with a push-pull framework were synthesized for dye-sensitized solar cells (DSSC); their spectral, electrochemical and photovoltaic properties were investigated. The absorption bands of these porphyrin dyes are broadened and red-shifted upon introduction of electron-donating groups (EDG) to the meso-positions via extension of π-conjugation. Electrochemical tests show that the first oxidation for these porphyrins occurs at a potential greater than that of the I−/I3− redox couple, and attachment of EDGs to the periphery of the porphyrin facilitates electron abstraction. The photovoltaic measurements show that YD14 and YD17 have a power conversion efficiency of ∼7%. Introduction of EDGs to various meso-positions is demonstrated to be achievable, and porphyrin dyes with appropriate EDGs are promising candidates for highly efficient DSSCs.

161 citations


Journal ArticleDOI
TL;DR: A new method for the preparation of graphene has been developed via porphyrin exfoliation of graphite in NMP, which follows the intercalation of organic ammonium ions and shows undisturbed sp(2) carbon networks.

159 citations


Journal ArticleDOI
TL;DR: A porphyrin nanobarrel, 1, that can encapsulate C(60) effectively was prepared via a concise coupling route and the structures of both 1 and C( 60)@1 were confirmed by single-crystal X-ray diffraction analysis.
Abstract: A porphyrin nanobarrel, 1, that can encapsulate C60 effectively was prepared via a concise coupling route. The structures of both 1 and C60@1 were confirmed by single-crystal X-ray diffraction analysis.

153 citations


Journal ArticleDOI
TL;DR: The electron-transfer oxidation of TPZn(3) results in intramolecular pi-dimer formation between porphyrin moieties as indicated by electrochemical, vis-NIR, and ESR measurements.
Abstract: A novel porphyrin tripod (TPZn3) was synthesized via “click chemistry”. Three porphyrin moieties of TPZn3 are geometrically close and linked by a flexible linker. The electron-transfer oxidation of TPZn3 results in intramolecular π-dimer formation between porphyrin moieties as indicated by electrochemical, vis−NIR, and ESR measurements. The cyclic voltammogram of TPZn3 exhibited stepwise one-electron oxidation processes of three porphyrin moieties in the range from 0.58 to 0.73 V (vs SCE in CH2Cl2). When TPZn3 was oxidized by tris(2,2′-bipyridyl)-ruthenium(III) ([Ru(bpy)3]3+), the oxidized species (TPZn3)n+ (0 < n ≤ 3) exhibited a charge resonance band in the NIR region due to the π-dimer formation between porphyrin moieties. A supramolecular electron donor−acceptor system was also constructed using TPZn3. The flexible conformation of TPZn3 makes it possible to capture a fullerene derivative containing a pyridine moiety (PyC60) inside the cavity by π−π interactions as well as the coordination bond between...

Journal ArticleDOI
TL;DR: Among three noble-metal-free molecular devices (1-3) containing a porphyrin photosensitizer and a cobaloxime catalyst, the one with a zinc p Morphyrin unit displayed apparently higher efficiency for photoinduced H(2) production than complex 2 with a magnesium porphyrsin and 3 with a free-base porphYRin, possibly due to the formation of a TEAZnPor-Co triad in solution.

Journal ArticleDOI
TL;DR: In this paper, the effects of substituent number and position of the diarylamino groups on the optical, electrochemical, and photovoltaic properties of the porphyrins for the first time were evaluated.
Abstract: We have prepared meso-bis(diarylamino)-substituted porphyrins (cis-ZnP and trans-ZnP), meso-diarylamino-substituted porphyrin (mono-ZnP), and porphyrin reference without the meso-diarylamino group (ZnP) to evaluate the effects of substituent number and position of the diarylamino groups on the optical, electrochemical, and photovoltaic properties of the porphyrins for the first time With increasing the number of the diarylamino groups, the light-harvesting properties were improved in the visible region The optical and electrochemical HOMO−LUMO gaps were parallel to those estimated by DFT calculations The photovoltaic properties were compared under the optimized conditions in which a sealed device structure with TiCl4-treated, TiO2 double layers was used The power conversion efficiency (η) was in the order of the trans-ZnP (38%) < ZnP (44%) < cis-ZnP (55%) < mono-ZnP (65%) sensitized TiO2 cells The low light-harvesting efficiency (LHE) rather than the high adsorbed photon-to-current efficiency (AP

Journal ArticleDOI
TL;DR: Due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP-O(2) complex and its reduction by ferrocene.
Abstract: Molecular electrocatalysis for oxygen reduction at a polarized water/1,2-dichloroethane (DCE) interface was studied, involving aqueous protons, ferrocene (Fc) in DCE and amphiphilic cobalt porphyrin catalysts adsorbed at the interface. The catalyst, (2,8,13,17-tetraethyl-3,7,12,18-tetramethyl-5-p-aminophenylporphyrin) cobalt(II) (CoAP), functions like conventional cobalt porphyrins, activating 02 via coordination by the formation of a superoxide structure. Furthermore, due to the hydrophilic nature of the aminophenyl group, CoAP has a strong affinity for the water/DCE interface as evidenced by lipophilicity mapping calculations and surface tension measurements, facilitating the protonation of the CoAP-O-2 complex and its reduction by ferrocene. The reaction is electrocatalytic as its rate depends on the applied Galvani potential difference between the two phases.

Journal ArticleDOI
TL;DR: The crystal structure of the fully fused bis-anthracene porphyrin shows that it has a regular planar pi-system.

Journal ArticleDOI
TL;DR: In this article, a combined multimethod experimental and theoretical study of the geometric and electronic properties of Co-tetraphenyl-porphyrin Co-TPP molecules adsorbed on a Ag111 surface is presented.
Abstract: We present a combined multimethod experimental and theoretical study of the geometric and electronic properties of Co-tetraphenyl-porphyrin Co-TPP molecules adsorbed on a Ag111 surface. Scanning tunneling microscopy STM topographs reveal that Co-TPP forms highly regular arrays with a square unit cell. Hereby, the Co-TPP molecules do not occupy a unique adsorption site on the Ag111 atomic lattice. The central Co atom of the Co-TPP is found to reside predominantly above fcc and hcp hollow sites of the substrate, as determined from the photoelectron diffraction patterns. A strong adsorption-induced deformation of Co-TPP involving a saddle-shaped macrocycle is evidenced by high-resolution STM images and quantified by near-edge x-ray absorption fine-structure measurements. By scanning tunneling spectroscopy we resolved discrete molecular electronic states and mapped the pertaining spatial charge-density distribution. Specifically, we discuss the interaction of orbitals originating from the Co-metal center with the porphyrin macrocycle and show that the varying adsorption sites induce a modulation in the Co-TPP lowest unoccupied molecular orbital. These findings are corroborated by density-functional-theory calculations.

Journal ArticleDOI
TL;DR: The meso-meso-linked porphyrin dimer (YDD1) exhibited the best photovoltaic performance with power conversion efficiency 5.2% under AM 1.5G one solar illumination.

Journal ArticleDOI
TL;DR: In this article, a tin porphyrin (SnP)-sensitized TiO2 system in the wide pH range (pH 3 − 11) was successfully produced under visible light irradiation in a SnP-sensited TiO 2 system.
Abstract: Hydrogen was successfully produced under visible light irradiation in a tin porphyrin (SnP)-sensitized TiO2 system in the wide pH range (pH 3–11) although SnP hardly adsorbs on TiO2. The number of H2 produced in the SnP/TiO2 system after 9 h irradiation corresponds to the turnover number of 410. The apparent photonic efficiency for H2 evolution was estimated to be 35% with the monochromatic radiation of 550 ± 10 nm. The photochemical production of hydrogen is mediated through the formation of the π-radical anion (SnP˙−) that subsequently transfers electron to TiO2. The photogenerated SnP˙− was monitored by transient absorption spectroscopy and its lifetime is long enough to survive the slow diffusion from the solution bulk to the TiO2 surface, which makes the adsorption of SnP on TiO2 not required for hydrogen production. This is clearly contrasted with the common ruthenium complex-sensitized TiO2 system where the adsorption of the sensitizer complex is essentially required and the hydrogen production is limited to the acidic condition where the adsorption of the sensitizers on TiO2 is allowed. The photocatalytic activity of SnP was mainly attributed to the Q-band (500–650 nm), not to the Soret band (420–430 nm) of which absorption intensity is much higher.

Journal ArticleDOI
TL;DR: The enhanced stabilization of the gold(III) ion and the ease of structural modification render porphyrins an attractive ligand system in the development of physiologically stable gold( III) complexes with anticancer and anti-angiogenic activities.
Abstract: In the design of physiologically stable anticancer gold(III) complexes, we have employed strongly chelating porphyrinato ligands to stabilize a gold(III) ion [Chem. Commun. 2003, 1718; Coord. Chem. Rev. 2009, 253, 1682]. In this work, a family of gold(III) tetraarylporphyrins with porphyrinato ligands containing different peripheral substituents on the meso-aryl rings were prepared, and these complexes were used to study the structure-bioactivity relationship. The cytotoxic IC(50) values of [Au(Por)](+) (Por=porphyrinato ligand), which range from 0.033 to >100 microM, correlate with their lipophilicity and cellular uptake. Some of them induce apoptosis and display preferential cytotoxicity toward cancer cells than to normal noncancerous cells. A new gold(III)-porphyrin with saccharide conjugation [Au(4-glucosyl-TPP)]Cl (2a; H(2)(4-glucosyl-TPP)=meso-tetrakis(4-beta-D-glucosylphenyl)porphyrin) exhibits significant cytostatic activity to cancer cells (IC(50)=1.2-9.0 microM) without causing cell death and is much less toxic to lung fibroblast cells (IC(50)>100 microM). The gold(III)-porphyrin complexes induce S-phase cell-cycle arrest of cancer cells as indicated by flow cytometric analysis, suggesting that the anticancer activity may be, in part, due to termination of DNA replication. The gold(III)-porphyrin complexes can bind to DNA in vitro with binding constants in the range of 4.9 x 10(5) to 4.1 x 10(6) dm(3) mol(-1) as determined by absorption titration. Complexes 2a and [Au(TMPyP)]Cl(5) (4a; [H(2)TMPyP](4+)=meso-tetrakis(N-methylpyridinium-4-yl)porphyrin) interact with DNA in a manner similar to the DNA intercalator ethidium bromide as revealed by gel mobility shift assays and viscosity measurements. Both of them also inhibited the topoisomerase I induced relaxation of supercoiled DNA. Complex 4a, a gold(III) derivative of the known G-quadruplex-interactive porphyrin [H(2)TMPyP](4+), can similarly inhibit the amplification of a DNA substrate containing G-quadruplex structures in a polymerase chain reaction stop assay. In contrast to these reported complexes, complex 2a and the parental gold(III)-porphyrin 1a do not display a significant inhibitory effect (<10%) on telomerase. Based on the results of protein expression analysis and computational docking experiments, the anti-apoptotic bcl-2 protein is a potential target for those gold(III)-porphyrin complexes with apoptosis-inducing properties. Complex 2a also displays prominent anti-angiogenic properties in vitro. Taken together, the enhanced stabilization of the gold(III) ion and the ease of structural modification render porphyrins an attractive ligand system in the development of physiologically stable gold(III) complexes with anticancer and anti-angiogenic activities.

Journal ArticleDOI
TL;DR: The electron-withdrawing nature of the NMI group makes the diiron complex among the most easily reduced hydrogenase mimics reported to date.
Abstract: Diiron complexes modeled on the active site of the [FeFe] hydrogenases having the general formula [Fe(2)(mu-R)(CO)(6-n)(L)(n)], where commonly R = alkyl or aryl dithiolate and L = CO, CN(-), or PR(3), are a promising class of catalysts for use in photodriven H(2) production. However, many of these catalysts are difficult to photoreduce using chromophores that absorb visible light. Here we report the synthesis and spectroscopic characterization of a naphthalene-4,5-dicarboximide-1,8-dithiolate diiron complex [NMI-Fe(2)S(2)(CO)(6), 1] and a covalently linked, fixed-distance zinc 5,10,15-tri-n-pentyl-20-phenylporphyrin-NMI-Fe(2)S(2)(CO)(6) donor-acceptor dyad (2). The electron-withdrawing nature of the NMI group makes the diiron complex among the most easily reduced hydrogenase mimics reported to date (-0.74 V vs SCE). In the presence of triflic acid, the cyclic voltammogram of 1 showed an increase in current at the first reduction wave at -0.78 V and a new reduction wave at -1.4 V. As the acid concentration was increased, the current at -0.78 V remained constant while the current at -1.4 V increased significantly, which is consistent with a catalytic proton reduction process. Selective photoexcitation of the Zn porphyrin in 2 with 553 nm, 110 fs laser pulses in both toluene and CH(2)Cl(2) yielded transient absorption spectra showing a distinct peak at 616 nm, which has been assigned to [NMI-Fe(2)S(2)(CO)(6)](-*) on the basis of spectroelectrochemical measurements on 1. The 616 nm peak was used to monitor the charge separation (CS) and charge recombination (CR) dynamics of 2, which yielded tau(CS) = 12 +/- 1 ps and tau(CR) = 3.0 +/- 0.2 ns in toluene and tau(CS) = 24 +/- 1 ps and tau(CR) = 57 +/- 1 ps in CH(2)Cl(2). Photoexcitation of the disulfide precursor to 2 in both toluene and CH(2)Cl(2) produced only the singlet and triplet excited states of the Zn porphyrin, showing that electron transfer is favorable only when the diiron complex is present. Photoexcitation of 2 in the presence of trifluoroacetic acid was shown to generate H(2).

Journal ArticleDOI
TL;DR: A comprehensive analysis and comparison of the various strategies for ABCD-type porphyrins is given in this article, which is suitable for the preparation of porphrin derivatives for many divergent applications ranging over amphiphilic porphyn for photodynamic therapy, push-pull systems for optical applications and chiral systems useful in catalysis to donor-acceptor systems suitable for electron-transfer studies.

Journal ArticleDOI
TL;DR: A cyclic porphyrin trimer has been synthesized which has a high affinity for fullerenes and the solvent dependence of the association constants shows that solvation of both the guest and the host influence the binding strength.

Journal ArticleDOI
TL;DR: The porphyrin-cyclodextrin conjugates were prepared and tested for selective and effective multifunctional drug delivery and therapy and the combined effect of chemotherapy and photodynamic therapy is demonstrated by in vitro and in vivo studies.
Abstract: The porphyrin−cyclodextrin conjugates were prepared and tested for selective and effective multifunctional drug delivery and therapy. The porphyrin receptor system combines efficient binding of the selected drug to the cyclodextrin cavity and photosensitizing properties of the porphyrin moiety with high accumulation of the whole complex in cancer tissue. The combined effect of chemotherapy and photodynamic therapy is demonstrated by in vitro and in vivo studies.

Journal ArticleDOI
TL;DR: Two novel "extended-arms" porphyrins, TetbpyPP and TedabpyPP, in which four peripheral bpy fragments are connected to the meso positions of the macrocycle through flexible linkers of different length and hydrophilicity are reported.
Abstract: We report here two novel "extended-arms" porphyrins, TetbpyPP and TedabpyPP, in which four peripheral bpy fragments are connected to the meso positions of the macrocycle through flexible linkers of different length and hydrophilicity We describe also the new, water-soluble, tetracationic conjugate [TedabpyPP{Ru([9]aneS3)Cl}(4)][Cl](4) (6) Compound 6 belongs to the series of cationic Ru-porphyrin conjugates 1-5, each bearing four peripheral Ru(II) half-sandwich coordination compounds, that we recently prepared as potential photosensitizing chemotherapeutic agents The in vitro cell growth inhibition of conjugates 1-6 toward MDA-MB-231 human breast cancer cells and HBL-100 human nontumorigenic epithelial cells are reported, together with the phototoxic effects of 1, 4, and 6 on MDA-MB-231 cells All conjugates have IC(50) values in the low micromolar range that decrease by 1 order of magnitude upon irradiation of cell cultures with visible light The most promising compounds 1 and 6 are phototoxic at low light and drug doses

Journal ArticleDOI
TL;DR: The ability to alter the electronic and photophysical properties of these solids and to vary cooperative interactions between the porphyrin subunits raises the possibility of producing binary solids with tunable functionality.
Abstract: Microscale four-leaf clover-shaped structures are formed by self-assembly of anionic and cationic porphyrins. Depending on the metal complexed in the porphyrin macrocycle (Zn or Sn), the porphyrin cores are either electron donors or electron acceptors. All four combinations of these two metals in cationic tetra(N-ethanol-4-pyridinium)porphyrin and anionic tetra(sulfonatophenyl)porphyrin result in related cloverlike structures with similar crystalline packing indicated by X-ray diffraction patterns. The clover morphology transforms as the ionic strength and temperature of the self-assembly reaction are increased, but the structures maintain 4-fold symmetry. The ability to alter the electronic and photophysical properties of these solids (e.g., by altering the metals in the porphyrins) and to vary cooperative interactions between the porphyrin subunits raises the possibility of producing binary solids with tunable functionality. For example, we show that the clovers derived from anionic Zn porphyrins (elect...

Journal ArticleDOI
TL;DR: The picket-fence porphyrin could serve as an efficient species to functionalize graphene for electronic and optical applications and showed excellent electrocatalytic activity toward the reduction of chlorite, thus leading to highly sensitive amperometric biosensing at low applied potential.
Abstract: Reduced graphene oxide (RGO) was prepared and functional- ized with picket-fence porphyrin, 5,10,15,20-tetrakis (aaaa-2-trismethyl- Anyl) porphyrin ironA pentachloride (FeTMAPP), through p-p interactions. The resulting nanocomposite was characterized by atomic force microscopy (AFM); trans- mission electron microscopy (TEM); contact angle measurements; and fluo- rescence, Raman, and UV/Vis absorp- tion spectroscopy. On account of the introduction of positively charged FeT- MAPP, the functionalized RGO showed good dispersion in aqueous so- lution. The RGO could greatly acceler- ate the electron transfer of FeTMAPP to produce a well-defined redox couple of Fe III /Fe II at 0.291 and 0.314 V. Due to the synergic effect between RGO and the porphyrin, the nanocom- posite showed excellent electrocatalytic activity toward the reduction of chlor- ite, thus leading to highly sensitive am- perometric biosensing at low applied potential. The biosensor for chlorite showed a linear range from 5.0 � 10 8 to 1.2 � 10 4 mol L 1 with a detection limit of 2.4 � 10 8 mol L 1 at a signal-to- noise ratio of 3. The picket-fence por- phyrin could serve as an efficient spe- cies to functionalize graphene for elec- tronic and optical applications.

Journal ArticleDOI
TL;DR: The synthesis of the first tricationic water-soluble porphycene and its basic photochemical properties are reported, which successfully tested for in vitro photoinactivation of different Gram-positive and Gram-negative bacteria, as well as a fungal species (Candida) in a drug-dose and light-dose dependent manner.
Abstract: Structures of typical photosensitizers used in antimicrobial photodynamic therapy are based on porphyrins, phthalocyanines, and phenothiazinium salts, with cationic charges at physiological pH values. However, derivatives of the porphycene macrocycle (a structural isomer of porphyrin) have barely been investigated as antimicrobial agents. Therefore, we report the synthesis of the first tricationic water-soluble porphycene and its basic photochemical properties. We successfully tested it for in vitro photoinactivation of different Gram-positive and Gram-negative bacteria, as well as a fungal species (Candida) in a drug-dose and light-dose dependent manner. We also used the cationic porphycene in vivo to treat an infection model comprising mouse third degree burns infected with a bioluminescent methicillin-resistant Staphylococcus aureus strain. There was a 2.6-log(10) reduction (p < 0.001) of the bacterial bioluminescence for the PDT-treated group after irradiation with 180 J·cm(-2) of red light.


Journal ArticleDOI
TL;DR: The formation of a long-lived charge-separated state of a self-assembled donor-acceptor tetrad, formed by axial coordination of a fulleropyrrolidine appended with an imidazole coordinating ligand to the zinc center of a subphthalocyanine-triphenylamine-zinc porphyrin, as a charge-stabilizing antenna reaction center mimic in toluene.
Abstract: We report here the formation of a long-lived charge-separated state of a self-assembled donor-acceptor tetrad, formed by axial coordination of a fulleropyrrolidine appended with an imidazole coordinating ligand (C(60)Im) to the zinc center of a subphthalocyanine-triphenylamine-zinc porphyrin (SubPc-TPA-ZnP), as a charge-stabilizing antenna reaction center mimic in toluene. The subphthalocyanine and triphenylamine entities, with their high-energy singlet states, act as an energy-transferring antenna unit to produce a singlet zinc porphyrin. The formation constant for the self-assembled tetrad was determined to be 1.0 x 10(4) M(-1), suggesting a moderately stable complex formation. The geometric and electronic structures of the covalently linked SubPc-TPA-ZnP triad and self-assembled SubPc-TPA-ZnP:C(60)Im tetrad were examined by using an ab initio B3LYP/6-31G method. The majority of the highest occupied frontier molecular orbital was found over the ZnP and TPA entities, whereas the lowest unoccupied molecular orbital was located over the fullerene entity, suggesting the formation of the radical-ion pair (SubPc-TPA-ZnP(*+):C(60)Im(*-)). The redox measurements revealed that the energy level of the radical-ion pair in toluene is located lower than that of the singlet and triplet states of the zinc porphyrin and fullerene entities. The femtosecond transient absorption measurements revealed fast charge separation from the singlet porphyrin to the coordinated C(60)Im with a lifetime of 1.1 ns. Interestingly, slow charge recombination (1.6 x 10(5) s(-1)) and the long lifetime of the charge-separated state (6.6 micros) were obtained in toluene by utilizing the nanosecond transient measurements.

Journal ArticleDOI
TL;DR: In this paper, the superoxide radical anion O2− from tetra(4-carboxyphenyl)porphyrin (TCPP) adsorbed on TiO2 in DMSO and irradiated by visible light was studied using EPR spectroscopy.
Abstract: The generation of superoxide radical anion O2− from tetra(4-carboxyphenyl)porphyrin (TCPP) adsorbed on TiO2 in DMSO and irradiated by visible light was studied using EPR spectroscopy and 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as spin trap. A chemical filter was used to remove light with wave lengths <500 nm. A multiline EPR spectrum was observed, characteristic of a mixture of two adducts, the first corresponding to DMPO–O2− and the second to the so-called nitroxide-like radical. Hyperfine coupling constants determined for the DMPO–O2− adduct are: aN = 14.1 G, aHβ = 10.8 G and aHγ = 1.4 G, and for the nitroxide-like radical adduct aN = 14 G. An increased intensity of the EPR lines corresponding to the nitroxide-like radical adduct was observed under irradiation without chemical filter, which suggests a possible DMPO–O2− decomposition. No singlet oxygen could be detected by EPR spectroscopy using 2,2,6,6-tetramethyl-4-piperidone (TEMP) as spin trap and by chemical trapping using anthracene as the trap.