bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, characterization, electrical and dielectric permittivity measurements of 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanines
Authors: Salan Ümit , Altindal Ahmet , Bulut Mustafa , Bekaroğlu Özer
Published: July 2009

2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyanines were synthesized from 4-(4-amino-3-nitrophenoxy)phthalonitrile which was obtained from 4-nitro-1,2-dicyanobenzene and 4-amino-3-nitrophenol. 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyaninatocobalt(II) were synthesized in a one-step condensation reaction of ferrocenylaldehyde with 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyaninatocobalt(II), respectively. The novel compounds were characterized by elemental analysis, Inductively Coupled Plasma (ICP-MS), UV-vis, IR and 1 H NMR spectroscopy. The effects of temperature and frequency on the conduction properties (a.c. and d.c.) and the dielectric constant were studied on pellet samples of 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyanine, 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanine, 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyaninatocobalt(II) and 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyaninatocobalt(II), with evaporated, ohmic gold electrodes in the frequency range 40-105 Hz. and within the temperature range 290-400 K. Unlike many metallophthalocyanines, a variable-range hopping model is found to most appropriately fit the experimental conductivity data of 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyaninatocobalt(II), while for 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyaninatocobalt(II), thermally activated conduction with single activation energy is valid. Frequency and temperature dependence of the a.c conductivity were analyzed in terms of existing theory for 2,9,16,23-tetra-(4-amino-3-nitrophenoxy)phthalocyanine, 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanine, 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyaninatocobalt(II) and 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyaninatocobalt(II). It was found that the a.c. conductivity of the compounds depends on the frequency, obeying the empirical formula, σ ac = A ( T )ωs. The model parameters calculated are reasonable and consistent with the prediction of the correlated barrier hopping model for 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-ferrocenylimino-3-nitrophenoxy)phthalocyaninatocobalt(II) and the quantum mechanical tunneling model for 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyanine and 2,9,16,23-tetra(4-amino-3-nitrophenoxy)phthalocyaninatocobalt(II). The dielectric constant of the compounds increased with temperature and decreased with frequency in the investigated range.
Reactions of oxonium derivatives of (B12H12)2- with phenoles, and synthesis and photochemical properties of a phthalocyanine containing four (B12H12)2- groups
Authors: Semioshkin Andrej , Tsaryova Olga , Zhidkova Olga , Bregadze Vladimir , Wöhrle Dieter
Published: July 2009

The reactions of dodecahydro-closo-dodecaborate oxonium derivatives with various phenols resulted in phenoxy-undecahydro-closo-dodecaborates in high yields. Using this method, a phthalocyanine zinc(II) complex containing four ( B 12 H 12)2- species was prepared in high yield. The compound shows good photocatalytic activity. The combination of boron cages and phthalocyanines makes this compound useful for boron neutron capture therapy for cancer and photodynamic tumor therapy.
Photoinduced electron transfer processes in three component rotaxanes with porphyrins, [60]fullerene and triphenylamine
Authors: Sasabe Hisahiro , Furusho Yoshio , Sandanayaka Atula S.D. , Araki Yasuyuki , Kihara Nobuhiro , Mizuno Kazuhiko , Ogawa Akiya , Takata Toshikazu , Ito Osamu
Published: July 2009

Electron transfer processes occurring through-space and through-bond were studied for novel mechanically linked triad [2]rotaxanes, which contain a porphyrin (MP) unit as a pendant and [60]fullerene ( C 60) and triphenylamine ( TPA ) moieties as stopper groups at the axle ends (abbreviated as ( MP ; C 60- TPA ) rot+ with MP = H 2 P or ZnP . The photophysical properties were investigated by means of time-resolved fluorescence and transient absorption measurements with changing solvent polarity. The charge separation took place mainly via(1 MP *; C 60- TPA ) rot+ and ( MP ;1 C 60*- TPA ) rot + in polar solvents. Within the charge-separated states of triads ( MP ; C 60- TPA ) rot +, hole-shift and/or back electron transfer took place competitively. The lifetime of the charge separation state of ( ZnP ; C 60- TPA ) rot+ was similar to that of dyad ( C 60- TPA ) rot+ (140 ns in dimethylformamide), whereas that of ( H 2 P ; C 60- TPA ) rot + was as long as 230 ns, suggesting two final charge separation states such as ( MP ; C 60•-- TPA •+) rot + and ( MP •+; C 60•-- TPA ) rot+ depending on the kind of porphyrin.
An extremely long-lived charge-separated state of zinc tetraphenylporphyrin coordinated with pyridylnaphthalene-diimide
Authors: Saito Kenji , Kashiwagi Yukiyasu , Ohkubo Kei , Fukuzumi Shunichi
Published: July 2009

The nitrogen of pyridylnaphthalenediimide ( PyNIm ) coordinates to the metal center of zinc tetraphenylporphyrin ( ZnTPP ) to form a donor-acceptor complex: ZnTPP-PyNIm . Formation of the ZnTPP-PyNIm complex was probed by UV-vis, fluorescence and NMR spectra. The fluorescence of ZnTPP is strongly quenched and the fluorescence lifetime is shortened significantly in the complex. The transient absorption spectrum of the charge-separated state ( ZnTPP •+- PyNIm •-) is successfully detected by laser flash photolysis measurements of the ZnTPP-PyNIm system in benzonitrile. The charge-separated state of the complex produced by the photoinduced electron transfer has the longest lifetime, (450 μs) at 288 K, ever reported for donor-acceptor systems linked covalently or non-covalently in solution. However, when benzonitrile is replaced by benzene, the triplet excited state (3 ZnTPP* ), rather than the charge-separated state, is formed upon laser excitation of the ZnTPP-PyNIm complex, due to the lower energy of (3 ZnTPP* ) compared to the charge-separated state in benzene.
Chemical transformation of 1,2-oxazinochlorin derivatives: synthesis and X-ray crystal structure of a novel porphyrin-porphyrin dimer with a condensed cyclohexane ring
Authors: Morozova Yuliya V. , Yashunsky Dmitry V. , Starikova Zoya A. , Ponomarev Gelii V.
Published: July 2009

Base-assisted ring opening in 1,2-oxazinochlorin derivatives led selectively to the corresponding meso-cyanohydroxychlorin derivatives. The latter could then undergo acid-mediated carbocation formation followed by nucleophilic treatment to give different products, depending on the nature of the nucleophile reagent. Treatment of (E)- and/or (Z)-2-ethylidene-3-hydroxy-5-cyano-3,7,8,12,13,17,18-heptaethylchlorin nickel complex with a mixture of 5% trifluoroacetic acid and dichloromethane yielded a novel type porphyrin-porphyrin dimer with a condensed cyclohexane ring in an almost quantitative yield. The structure of this dimer was determined by single crystal X-ray analysis.
Synthetic porphyrins in experimental photodynamic therapy induce a different antitumoral effect
Authors: Neagu Monica , Manda Gina , Constantin Carolina , Radu Eugen , Ion Rodica-Mariana
Published: July 2009

The aim of the study was to investigate the influence of discrete structural differences in synthetic porphyrins on the antineoplastic effect induced in myelocitic cell line K562 after experimental photodynamic therapy procedure. For this study, we used 5,10,15,20-tetra(1-naphthyl)porphyrin, 5,10,15,20-tetra(4-sulfonatophenyl)porphyrin and their Zn complexes. For all these compounds, the following photodynamic therapy parameters were optimized: cell concentration, dye loading concentration, loading time and irradiation procedure. The non-toxic doses of porphyrins were different according to their structure: for 5,10,15,20-tetra(1-naphthyl)porphyrin compounds, the dose was of 10 μg.mL-1, and for 5,10,15,20-tetra(4-sulfonatophenyl)porphyrin compounds, the dose was 20 μg.mL-1. Cell functionality was assessed as membrane integrity, viability, and number of metabolically active cells. Photodynamic cell degradation kinetics showed that during irradiation tumor cells are actively destroyed, in contrast to unloaded cells. K562 cells loaded with the above-mentioned compounds and subjected to irradiation, displayed lower proliferative capacity compared to the control, for a period of 72 h after irradiation. The proliferative capacity of K562 cell line was more strongly inhibited by the 5,10,15,20-tetra(1-naphthyl)porphyrin family of compounds than by the 5,10,15,20-tetra(4-sulfonatophenyl)porphyrin family. The tested synthetic porphyrins showed effective antineoplastic activity against K562 leukemia cells in our in vitro photodynamic therapy experimental model.
Application of Ru(II)porphyrin complexes as epoxidation catalyst of olefins
Authors: Babakhani Rezvan , Bahadoran Farzad , Safari Nasser
Published: July 2009

Two complexes of ruthenium(II) carbonyl tetraphenyl- and tetramesytilporphyrins were used as catalysts for epoxidation of olefins using metachloroperbenzoic acid and iodosylbenzene, as oxidants. Better results were obtained with the ( TPP ) RuCO catalyst in the presence of metachloroperbenzoic acid; however, iodosylbenzene showed higher yields than metachloroperbenzoic acid for some aromatic olefins. The effect of imidazole axial base was also investigated. Two different pathways are proposed based on these two oxygen atom transfer agents.
Inhibition of aggregation of meso-tetra(4-sulfonatophenyl)-porphyrin (H4TPPS) by urea
Authors: Rahman Mahmudur , James Harmon H.
Published: July 2009

The inhibition of the formation of J-aggregates of meso-tetra(4-sulfonatophenyl)-porphyrin ( H 4 TPPS ) by urea is investigated spectroscopically by absorbance, fluorescence, and fluorescence lifetime techniques. In 8 M urea at pH 2 with 0.1 M NaCl , diacid TPPS ( H 4 TPPS ) exists as a monomer up to 75 μM H 4 TPPS where the absorbance is linearly dependent on porphyrin concentration. The extinction coefficient of monomeric H 4 TPPS in 8 M urea at pH 2 with 0.1 M NaCl at 438 nm is 4.43 × 105 M -1. cm -1. No aggregation peaks at 491 nm and 708 nm are found in the 0.5-75 μM concentration range. Aggregated H 4 TPPS (10 μM) molecules in pH 2 buffer dissociate to monomers when the temperature is raised to 65°C. In D 2 O at pH 2, no aggregation is observed. These spectral observations suggest that the H 4 TPPS aggregation involves intermolecular hydrogen bonding.
Protoporphyrin IX and heme binding properties of Staphylococcus aureus IsdC
Authors: Pluym Mark , Vermeiren Christie L. , Mack John , Heinrichs David E. , Stillman Martin J.
Published: July 2009

Staphylococcus aureus is a human pathogen that results in numerous infections in hospital settings and recently also in the wider community. Its antibiotic resistant forms are causing considerable alarm. A series of surface-anchored proteins that have heme uptake and transport properties have been reported. Through the use of absorption and magnetic circular dichroism spectroscopies and mass spectrometry, the iron-free, protoporphyrin IX and the iron-containing, heme-binding characteristics of bacterial rIsdC have been obtained. Mass spectrometry showed that following isolation and purification, the rIsdC is bound predominantly to protoporphyrin IX and to a lesser extent heme, unlike the case of rIsdA, which binds predominantly heme. Magnetic circular dichroism analysis provided further information regarding porphyrin binding because the characteristic magnetic circular dichroism band envelopes for the iron-free protoporphyrin IX and the iron-containing heme can be clearly distinguished in the spectrum of the rIsdC. Analysis of these spectral data showed that the minor heme component exists as a high-intermediate spin state ferric heme when bound to rIsdC, similar to the high-spin ferric heme reported for the rIsdA protein.
On the mechanism of boron-subphthalocyanine chloride formation
Authors: Claessens Christian G. , González-Rodríguez David , McCallum Charles M. , Nohr Ronald S. , Schuchmann Heinz-Peter , Torres Tomás
Published: July 2009

A mechanistic study of chloroboron subphthalocyanine (SubPc) formation from phthalonitrile and BCl 3 in aromatic solvents such as p-xylene or toluene suggests that rearrangement of the initial phthalonitrile- BCl 3 adduct produces (1 Z )-3-chloro-N-(dichloroboryl)-1 H -isoindol-1-imine 3, following rearrangement of the initial phthalonitrile- BCl 3 adduct. From three molecules of (1 Z )-3-chloro-N-(dichloroboryl)-1 H -isoindol-1-imine 3, by successive addition, the dichlorosubstituted macrocycle 7 is formed. Quantum-chemical computation shows that the postulated elementary reaction steps leading up to the formation of the SubPc-precursor macrocycle are indeed exothermic, or at least kinetically allowed. The formation of the SubPc is concluded by the elimination of chlorine which is probably catalyzed by BCl 3 in a concerted process which might be represented as: dichlorosubstituted macrocycle 7 + BCl 3 → SubPc · Cl + + BCl 4- → SubPc + Cl 2 + BCl 3. The chlorine formed may be photolytically affected if the reaction is carried out under ordinary laboratory lighting (fluorescent lamps), giving rise to a free-radical chain reaction involving the solvent. Alternatively, molecular chlorine may react with aromatic solvents such as toluene and p-xylene in a Friedel-Crafts-type reaction catalyzed by BCl 3. In this way, such solvents which are reactive in both ways can protect the reactant phthalonitrile, the reaction intermediates, and the product SubPc from degradation by chlorination.
Supramolecular interactions of conjugated Zn- and protonated porphyrin polymer with carbon nanotubes
Authors: Cheng Fuyong , Adronov Alex
Published: July 2009

The interaction of a highly soluble conjugated Zn -porphyrin containing polymer with a surface of single-walled carbon nanotubes, producing a soluble polymer-nanotube complex, is reported. We found that successful complexation required the addition of trifluoroacetic acid to the solvent tetrahydrofuran in order to disrupt solvent-porphyrin coordination that prohibits close interaction of the polymer with the nanotube surface. In the presence of trifluoroacetic acid, the complex remained soluble even after excess free polymer was removed from solution, and could be centrifuged at high speed with no observable sedimentation. Furthermore, the polymer-nanotube assembly resulted in enhanced planarization and conjugation within the porphyrin polymer, which was observed via a 127 nm bathochromic shift of the Q-band absorption in the UV-vis spectrum. In addition, removal of the Zn atoms and protonation of the porphyrin repeat units under acidic conditions resulted in a polycationic polymer that also forms strong interactions with carbon nanotubes which result in soluble supramolecular complexes. Control experiments with the Zn -porphyrin monomer indicated that homogeneous solutions could be prepared by sonication, but the monomer-nanotube interactions were weak and resulted in nanotube precipitation within minutes. Atomic force microscopy and transmission electron microscopy studies indicated that the polymer is capable of exfoliating large nanotube bundles into individual tubes and small bundles that are coated in polymer.
Metal phthalocyanine showing four-peak Q-band similar to metal-free phthalocyanines: nickel 1,4-di(trifluorosulfonyl)-phthalocyanine
Authors: Nakai Katunori , Usami Jyo , Kobayashi Nagao
Published: July 2009

Nickel phthalocyanines ( NiPc ) substituted by trifluorosulfonyl or trimethylsilylethynyl groups have been prepared and characterized using NMR and electronic absorption spectroscopy. In particular, when trifluorosulfonyl groups are introduced to two, so-called, α-benzo positions of one benzene ring of the Pc skeleton, the Q-band splits similarly to the Q-bands of metal-free phthalocyanines. The splitting width of the Q-bands can be interpreted as due mainly to splitting of the LUMOs by the substituents, although splitting between the HOMO-1 and HOMO-2 is also effective to a lesser extent.
Synthesis and characterization of a hexaphyrin(1.0.1.0.0.0) bearing both meso- and β-substituents
Authors: Sessler Jonathan L. , Melfi Patricia J. , Lynch Vincent M.
Published: July 2009

The synthesis of an isoamethyrin-type expanded porphyrin bearing both meso- and β-substituents is presented. The diprotonated form of this macrocycle was characterized by conventional spectroscopic means and via a single crystal X-ray diffraction analysis. This species is observed to adopt a planar conformation in the solid state. Nonetheless, the inner ring current, as inferred from 1 H NMR spectroscopic studies, is found to be severely diminished as compared to isoamethyrin, by the presence of the two meso-phenyl moieties. A second crystal structure, in which a molecule of water is hydrogen-bound to a pyrrole NH , was also solved.
Light harvesting porphyrin-crown ether conjugates: toward artificial photosynthetic systems
Authors: Solladié Nathalie , Rein Régis , Walther Mathieu
Published: July 2009

In this paper we report on our ongoing progress in the preparation of artificial photosynthetic systems through the preparation of light harvesting multi-porphyrins. The synthesis of these antennae is described herein and the energy transfer capabilities of these devices demonstrated. A terminal porphyrin/crown ether conjugate has been maintained in each case to ensure a coordination site for the complexation of an ammonium/ C 60 derivative, which could be chosen as the electron acceptor partner for the preparation of artificial photosynthetic systems.
Photocurrent generation by benzoporphyrin films prepared by a solution process
Authors: Yamada Hiroko , Kamio Naoko , Ohishi Akihiro , Kawano Manami , Okujima Tetsuo , Ono Noboru
Published: July 2009

Tetrabenzoporphyrin films on indium-tin-oxide electrodes were prepared by continuous spin-coating of indium-tin-oxide electrodes with a soluble precursor, tetrabicyclo[2.2.2]octadiene-fused porphyrin, and subsequent thermal conversion of the precursor to tetrabenzoporphyrin by annealing the modified electrodes. When the tetrabenzoporhyrin-modified indium-tin-oxide working electrode was irradiated in a three-electrode system, using Pt as a counter electrode and Ag / Ag + as a reference electrode in the presence of hexyl viologen as an electron acceptor, a cathodic photocurrent was observed. A double layer structure consisting of tetrabenzoporphyrin and [6,6]-phenyl- C 61 butyric acid methyl ester (PCBM) films and a triple layer structure consisting of tetrabenzoporphyrin; a mixture of tetrabenzoporphyrin and PCBM; and PCBM films were also prepared on indium-tin-oxide electrodes by repeated spin-coating. The incident photon to photocurrent efficiency values of up to 6.8% were obtained for the triple layer structure, in which the mixed layer contained tetrabenzoporphyrin and PCBM molecules in a 7:3 ratio. Action spectra of the triple layer structure showed that visible light from 380 to 700 nm sensitized the system for photocurrent generation.
Noncovalent porphyrin-functionalized single-walled carbon nanotubes: solubilization and spectral behaviors
Authors: Murakami Hiroto , Nakamura Genki , Nomura Takuro , Miyamoto Takeshi , Nakashima Naotoshi
Published: July 2009

We describe the solubilization/dispersion of as-produced and purified single-walled carbon nanotubes (raw-SWNTs and p-SWNTs) with protoporphyrin IX derivatives and tetraphenylporphyrin iron(III) chloride, the spectral behavior of the octaalkylporphyrins-solubilized shortened-SWNTs (s-SWNTs), and the electrochemistry of a p-SWNTs/FePP cast film on a glassy carbon electrode. Transmission electron and atomic force microscopies, as well as UV-visible-near IR spectroscopy, revealed that the protoporphyrin IX derivatives individually dissolved the p-SWNTs in polar solvents under mild conditions of sonication using a bath-type sonicator, followed by centrifugation at 1000 g. The raw-SWNTs were more easily dissolved than the p-SWNTs with protoporphyrin IX zinc(II) ( ZnPP ), whereas the amount of the solubilized/dispersed p-SWNTs did not depend on the concentration of the solubilizer and sonication time. The absorption and fluorescence spectral measurements of the octaalkylporphyrins in dimethylformamide containing 1 vol% tetrahydrofuran with various amounts of the s-SWNTs showed that the absorption maxima of the octaalkylporphyrins decreased with an increase in the concentration of the s-SWNTs without wavelength shift and the fluorescence of the porphyrins was quenched by the addition of the s-SWNTs. These spectral behaviors are direct evidence for the interaction between the nanotube sidewall and the porphyrins in the solutions. The cyclic voltammograms of the p-SWNTs/hemin ( FePP ) and free hemin ( FePP ) suggest that the nanotubes act as a conduction passage for electrons between hemin ( FePP ) and the glassy carbon electrode.
Synthetic hydroxymethyl-porphyrins for protection of carboxy group
Authors: Tamiaki Hitoshi , Kumon Kouji , Shibata Reiko
Published: July 2009

Hydroxymethyl-porphyrins were prepared by modifying tetraarylporphyrin possessing a p-(methoxycarbonyl)phenyl group at the meso-position and octaethylporphyrin. The synthetic alcohols reacted with carboxylic acids by the use of coupling reagents, to give the corresponding esters quantitatively. Due to the porphyrin dye moiety, the esterification was easily monitored on thin layer chromatography, and the resulting esters were highly soluble in most organic solvents and easily handled. The esters were readily cleaved by the action of an acid to give the original carboxylic acid and hydroxymethyl-porphyrin. Separation of the two species was performed by simple filtration: the carboxylic acid was soluble (filtrate) and the porphyrins were precipitates in methanol. These protective groups for carboxy groups were useful for peptide synthesis in the liquid phase.
Protonation and deprotonation of nitrogens in tetrapyrazino-porphyrazine macrocycles
Authors: Petrik Pavel , Zimcik Petr , Kopecky Kamil , Musil Zbynek , Miletin Miroslav , Loukotova Veronika
Published: July 2009

Acid-base properties of zinc phthalocyanine (Pc) and zinc and metal-free tetrapyrazinoporphyrazine (TPPz) macrocycles with eight peripheral tert-butylsulfanyl or diethylamino substituents are investigated in this work by means of UV-vis spectroscopy. The Pc and TPPz are protonated on the azomethine nitrogens in acidic media. The monoprotonated form was found using trifluoroacetic acid and lower amounts of H 2 SO 4. The higher concentrations of sulfuric acid lead to the appearance of the diprotonated form, and possibly also the triprotonated form in the case of Pc. It was found that the pyrazine nitrogens in the TPPz macrocycle undergo protonation at approx. 20-30% of sulfuric acid in THF solution. TPPz with diethylamino peripheral substituents are protonated preferably on these peripheral tertiary amines. Metal-free TPPz can readily lose the hydrogens on central nitrogens in strong basic media (e.g. tetrabutylammonium hydroxide) to directly form a dianion, with no presence of important or detectable amounts of the monoanion species. A different form of deprotonated macrocycle was observed in pyridine suggesting the formation of only a proton transfer complex, not a true ionic form. The acidity of the central nitrogens is dependent on the strength of the electron-donating effect of peripheral substituents. TPPz with tert-butylsulfanyl substituents is a stronger acid than the one with diethylamino substituents.
Discotic liquid crystals of transition metal complexes 38†: peripheral chain substituent position effect on columnar mesophase and stacking structures of novel phthalocyanine-based liquid crystals
Authors: Ichihara Masahiro , Suzuki Ayumi , Hatsusaka Kazuaki , Ohta Kazuchika
Published: July 2009

In order to clarify the peripheral chain substitution position effect on columnar mesophase and stacking structures, we have synthesized three novel series of discotic liquid crystals (1-3) having octakis(phenoxy)phthalocyaninato copper(II) as a central core and one peripheral chain at the para position (1), meta position (2) or ortho position (3) of each phenoxy group, and three more novel series of discotic liquid crystals (4-6) having the same central core and two peripheral chains at para and meta positions (4), meta and meta positions (5) or ortho and meta positions (6) of each phenoxy group. Their columnar mesophase and stacking structures were investigated with a polarizing optical microscope, a differential scanning calorimeter and a temperature-dependent X-ray diffractometer. According to the results, their columnar mesophase and stacking structures strongly depended on the peripheral chain substitution positions and the number of peripheral chains. Derivatives 3 and 5 are viscous isotropic liquid at room temperature. Derivatives 1, 2, 4 and 6 exhibit various kinds of columnar mesophases: 1 Colhd; 2 Colhd and Colho; 4 Colhd, Colrd(P21/a), Coltet.d and Cub ( Pn [ three bar ] m ); 6 Colhd, Colrd(P21/a) and Colrd(X). Moreover, derivatives 1, 4 and 6 exhibit disordered columnar mesophases. However, derivative 2 only exhibits an ordered columnar mesophase and its X-ray diffraction pattern shows a sharp reflection corresponding to a very short intracolumnar stacking distance of 3.33 Å. Thus, we can drastically change the mesophase and stacking structures by the peripheral chain substitution positions and the number of peripheral chains at each phenoxy group. This is a new way of controlling mesomorphic structure.
Tetranuclear supramolecular structures containing phthalocyanine cores
Authors: Özçesmeci Ibrahim , Güner Sadik , Okur Ali Ihsan , Gül Ahmet
Published: July 2009

A metal-free phthalocyanine with four pyridyl donor groups, bound through ethylthio ester bridges on the periphery, have been prepared. The pyridine donors were quaternized with iodomethane to a water-soluble tetracationic phthalocyanine. The tetranuclear supramolecular phthalocyanine was prepared by the coordination of peripheral pyridine donors with VO(acac)2. The paramagnetic tetranuclear structure was studied in powder and solution forms by the electron paramagnetic resonance (EPR) technique. Electron paramagnetic resonance studies, together with the other spectral data confirmed the presence of identical pyridine-coordinated VO(acac)2paramagnetic centers attached to the peripheral positions of the phthalocyanine core. The X-band EPR signals recorded from powder and solution forms of supramolecules have a characteristic line shape that proves the presence of axial symmetry around the paramagnetic vanadium ions. The anisotropic Lande splitting factors were calculated as g∥< g⊥< ge= 2.0023. Orbital energy levels for magnetic electrons were determined from theoretically fitted Spin Hamiltonian parameters.
Synthesis and radiosensitizing properties of brominated tetrapyridine porphyrins
Authors: Lemay Rosalie , Tremblay-Morin Jean-Philippe , Ali Hasrat , Hunting Darel , van Lier Johan E. , Paquette Benoit
Published: July 2009

Brominated derivatives of tetrapyridinium copper porphyrin were prepared via bromination of the β-positions (pyrrole rings) and/or the peripheral alkyl side-chains attached to the pyridine moieties. The radiosensitizing properties of these new cationic, brominated porphyrins were tested on MDA-MB-231 breast cancer cells in vitro using a 60 Co source or an X-ray irradiator. The non-brominated porphyrin and the porphyrin containing bromines at β-positions only were devoid of any radiosensitizing activity. However, a pronounced radiosensitizing effect was observed with the porphyrin containing bromo atoms at both β-positions and the peripheral side-chains. A similar radiosensitizing effect was detected for different radiation energies, suggesting that high energy photons could be used to treat tumors in conjunction with this novel brominated, porphyrin-based radiosensitizer.
Thermodynamics investigation of a series of metalloporphyrazine-bovine serum albumin complexes
Authors: Bordbar A-Khalegh , Dezhampanah Hamid , Asadi Mozaffar , Safaei Elham , Sohrabi Nasrin , Khodadost Yadollah
Published: July 2009

The equilibrium binding of the tetra-cationic complexes ( N , N ′, N ″, N ‴-tetra-methyltetra-2,3-pyridinoporphyrazinato)copper(II), ([ Cu (2,3- TMTPPA )]4+), ( N , N ′, N ″, N ‴-tetra-methyltetra-3,4-pyridinoporphyrazinato)copper(II), ([ Cu (3,4- TMTPPA )]4+), (( N , N ′, N ″, N ‴-tetra-methyltetra-3,4-pyridinoporphyrazinato)cobalt(II), ([ Co (3,4- TMTPPA )]4+) and (( N , N ′, N ″, N ‴-tetra-methyltetra-3,4-pyridinoporphyrazinato)zinc(II), ([ Zn (3,4- TMTPPA )]4+) with bovine serum albumin (BSA) has been studied in phosphate buffer pH = 7.0 and at various temperatures using multi-spectroscopy techniques. The results of resonance light scattering (RLS) studies represent no aggregate formation of porphyrazine in the surface of BSA and low tendency of these porphyrazine for aggregate formation. The binding constants and binding stoichiometries were determined by analyzing of optical absorption spectra of porphyrazine complexes at various concentration of BSA using SQUAD software. The results show that the best fitting corresponds to a 1:1 complex model between BSA and porphyrazines. The thermodynamic parameters were calculated by van't Hoff equation at various temperatures. The data indicate that the process is entropy driven suggesting that hydrophobic interactions play a considerable role in the complex formation. The binding of porphyrazine complexes to BSA quenches fluorescence emission of BSA via a dynamic mechanism and the quenching process obeys a linear Stern-Volmer relationship. The average aggregation number of BSA, which has been calculated from the analysis of fluorescence quenching data, indicates the absence of any porphyrazine induced aggregation of BSA due to its interaction with porphyrazine complexes. Fluorescence studies also indicate that porphyrazine is bound to site I of BSA placed in sub-domain IIA, where tryptophan 214 is located.
Cationic Zn and Al phthalocyanines: synthesis, spectroscopy and photosensitizing properties
Authors: Makarov Dmitry A. , Yuzhakova Olga A. , Slivka Ludmila K. , Kuznetsova Nina A. , Negrimovsky Vladimir M. , Kaliya Oleg L. , Lukyanets Evgeny A.
Published: July 2009

Several Zn (II) and Al (III) phthalocyanines bearing eight or sixteen positive charges on substituents of different structure have been prepared. Synthesized polycationic phthalocyanines have been studied in aqueous and alcoholic media by UV-vis spectroscopy and tested for their efficacy in singlet oxygen photosensitization. It has been found that a minor structural modification at the periphery of the photosensitizer allows control over its key features such as singlet oxygen generation due to specific intermolecular interactions in solution. The efficacy of polycationic phthalocyanines to sensitize tryptophan photobleaching in aqueous media and inactivation of bacteria in sewage water is also structure-dependent. Among the complexes studied, two dyes - zinc octakis(pyridiniomethyl)- and octakis[ N -(2-hydroxyethyl)- N , N -dimethylammoniomethyl]substituted phthalocyanines - are the best sensitizers and have high potential for photodynamic applications.
Efficient synthesis of porphycene
Authors: Urbańska Natalia , Pietraszkiewicz Marek , Waluk Jacek
Published: July 2009

Unsubstituted porphycene was prepared in 65% yield from 2,7,12,17-tetra-tert-butylporphycene. Taking into account the yield of the substrate, this represents more than a five-fold improvement compared to the methodology used to date. Enhanced availability of the parent porphycene may be exploited in synthetic procedures based on derivatization of the unsubstituted compound.
Syntheses and optoelectronic properties of amino/carboxyphenylporphyrins for potential use in dye-sensitizedTiO2solar cells
Authors: Walter Michael G. , Wamser Carl C. , Ruwitch Joseph , Zhao Yinping , Braden Dale , Stevens Matt , Denman Al , Pi Rick , Rudine Alexander , Pessiki Peter J.
Published: July 2009

New mixed-substituent amino/carboxyphenylporphyrins for a dye-sensitized TiO2solar cell were prepared using several synthetic routes. The reaction of 4-carbomethoxy- and 4-acetamidobenzaldehydes with pyrrole in propionic acid under aerobic conditions afforded mixtures of mixed amide/ester substituted tetraphenylporphyrins which were separated using centrifugal chromatography then deprotected to give the target compounds. Condensation of p-nitrophenyldipyrromethane with 4-carbomethoxybenzaldehyde in CH2Cl2catalyzed by trifluoroacetic acid, followed by oxidation with dichlorodicyanoquinone gives trans-dicarbomethoxy/dinitrophenylporphyrin, which when treated with SnCl2and HCl affords the trans-diamino/dicarboxy derivative, trans- TA2C2PP . Commercially available tetrakis-5,10,15,20-(4-carboxyphenyl)porphyrin (TCPP) was converted to mixtures of mixed amino/carbomethoxyphenylporphyrins using hydroxylamine hydrochloride in polyphosphoric acid with methanol workup. Relative yields and product distributions from each route are discussed and the optoelectronic characteristics of the synthesized porphyrins were studied using UV-visible spectroscopy and cyclic voltammetry.
Synthesis, characterization, and electrochemical and electrical properties of a novel ball-type hexanuclear metallophthalo-cyanine, bridged by calix[4]arenes substituted with four hexyl-thiometallophthalocyanines through nitro coupling
Authors: Ceyhan Tanju , Altindal Ahmet , Özkaya Ali Riza , Salih Bekir , Erbil Mehmet K. , Bekaroğlu Özer
Published: July 2009

In this study, the synthesis of a supramolecular hexaphthalocyaninato hexazinc(II) with hexylthio substituents is reported. Starting from 5,11,17,23-tetra-tert-butyl-25,27-dihydroxy-26,28-dimethoxycalix[4]arene, mononitro derivative of calix[4]arene 1 was obtained. Compound 1 was converted to phthalodinitrile derivative 2 by the reaction with 4-nitrophthalonitrile in dry dimethylsulfoxide by the method of nucleophilic substitution of an activated nitro group in an aromatic ring. The tetramerization of compound 2 with Zn ( OAc )2·2 H 2 O in 1-pentanol gave the novel ball-type binuclear zinc (II) phthalocyanine 3 which was reacted with unsymmetric zinc(II) phthalocyanine 4 to furnish a supramolecular assembly of a zinc(II) phthalocyanine of a ball type with four zinc(II) phthalocyanines through azo bridges, 5. Newly synthesized compounds were characterized by elemental analysis, UV-vis, IR, MALDI-TOF MS and 1 H NMR spectra. The electrochemical and spectroelectrochemical properties of 5 were also examined in nonaqueous media. The measurements showed the formation of various mixed-valence oxidation and reduction species, due to the strong intramolecular interactions between the Pc rings. Both DC and AC conductivity data were analyzed by the existing theory.
Isolation and characterization of new heme analogues with weakly coordinating anions: Formation of monoimidazole complex, OEPFe(Im)(SbF6)
Authors: Khorasani-Motlagh Mozhgan , Noroozifar Meissam , Moodi Asieh
Published: July 2009

The effects of weakly coordinating anions, BF 4, AsF 6 and SbF 6, as axial ligands on the formation and coordination chemistry of heme analogues have been examined. Three new five-coordinate and stable iron(III) heme analogues, OEPFeX , where OEP is the dianion of octaethylporphyrin and X = BF 4, AsF 6 and SbF 6, have been isolated. The compounds have been characterized by different spectroscopic methods as well as elemental analysis. 1 H NMR spectroscopy and magnetic moment measurements show that the OEPFeX are paramagnetic and iron is five-coordinate. In addition, monoimidazole ferric-porphyrin complex, OEPFe ( Im )( SbF 6) has been prepared in solution, by starting with OEPFe ( SbF 6). The electrochemical properties of OEPFeX ( X = BF 4, AsF 6, SbF 6) have been studied by cyclic voltammetry and differential pulse polarography.
Synthesis of porphyrins for metal deposition studies in molecular information storage applications
Authors: Kulikov Oleg V. , Schmidt Izabela , Muresan Ana Z. , Lee Marcia A.-P. , Bocian David F. , Lindsey Jonathan S.
Published: July 2009

Porphyrins may serve as the active charge-storage medium in memory chips. A series of 14 porphyrins (trans-A2B2, trans-AB2C, or A4 type; free base, copper or zinc chelate) has been synthesized for investigation of metal deposition on porphyrin monolayers. Each trans-AB2C porphyrin is equipped with a surface attachment group and a distal functional group (or flanking functional groups). The surface attachment groups include S-acetylthiomethyl, hydroxymethyl, TMS-ethynyl, allyl, and triallylmethyl; the functional groups include amino, cyano, dipyrrin-5-yl, formyl, and nitro; all of which are attached to the p-position of a porphyrin meso-phenyl group. Two non-redox-active triallylmethyl-substituted arenes were also prepared for use as control compounds.
A new fluorescence molecular switch incorporating TTF and tetraphenylporphyrin units
Authors: Liu Yibo , Wang Chengyun , Li Meijiang , Lv Sufang , Lai Guoqiao , Shen Yongjia
Published: July 2009

A donor-σ-acceptor compound incorporating tetrathiafulvalene and tetraphenylporphyrin units was synthesized. The structures of the target compound and its intermediates have been characterized by 1 H NMR, ESI MS, UV-vis, IR and mp. The results of UV-vis and cyclic voltammetry of the compound indicated negligible intramolecular charge transfer interaction in its ground state. The fluorescence and fluorescence lifetime of the compound were reduced, compared to tetraphenylporphyrin, which evidently indicated that photoinduced electron transfer occurred from the tetrathiafulvalene (TTF) unit to the tetraphenylporphyrin unit in the excited state. The fluorescence intensity of the compound could be reversibly modulated by sequential oxidation and reduction of the TTF unit using electrochemical and chemical methods. Therefore, a new fluorescence molecular switch based on TTF and porphyrin units was established.
Synthesis of meso-thienyl- and meso-furyl N2S3 sapphyrins and N2S4 rubyrins
Authors: Rai Smita , Mangalampalli Ravikanth
Published: July 2009

Sapphyrins with N 2 S 3 core and rubyrins with N 2 S 4 core containing five-membered thienyl- and furyl groups at meso positions have been synthesized and characterized. The spectral studies indicate that the meso-thienyl and meso-furyl groups alter the electronic properties of the sapphyrin and rubyrin compared to meso-tolyl groups and maximum effects were observed for meso-furyl sapphyrins and rubyrins.
Synthesis of a boronic ester-appended bismuth(III) porphyrin as a potential alpha-particle bi-emitter
Authors: Balieu Sébastien , Bouraiou Abdel Malek , Carboni Bertrand , Boitrel Bernard
Published: July 2009

As 213 Bi , a spontaneous alpha-emitting radioisotope, and 10 B , a neutron-activated source of alpha particles, have been found to be potential tools in the treatment of cancer patients, a novel bismuth porphyrin, bearing both boron atoms and a strap with a hanging carboxylic group, was synthesized.
Robust carbene ruthenium-porphyrin catalysts for cyclopropanation reaction of a wide variety of alkenes
Authors: Wada Satoko , Shimomura Masanobu , Kikuchi Tomofumi , Yuge Hidetaka , Miyamoto T. Ken
Published: July 2009

A series of carbene ruthenium-porphyrins [ Ru ( por )(: CR 1 R 2)] ( por = TPP ; R 1 = R 2 = p- C 6 H 4 Cl 2, p- C 6 H 4 Me 3, p- C 6 H 4 Ph 4; R 1 = Ph , R 2 = p- C 6 H 4 Ph 6; R 1 = Ph , R 2 = COPh 7; R 1 = p- C 6 H 4 Me , R 2 = CO (p- C 6 H 4 Me ) 8; R 1 = COMe, R 2 = COPh 9; por = TTP ; R 1 = R2 = Ph 1', COPh 5') were synthesized and characterized. The starting material [ Ru ( por )( CO )] was treated with corresponding diazo compounds N 2 CR 1 R 2 in CH 2 Cl 2 or octane for the diaryl carbene complexes 1', 2-4 and 6, while it was subjected to photolysis in THF , followed by reflux with the diazo compounds for the acyl carbene complexes 5' and 7-9. The compounds were robust in octane under reflux and were able to catalyze cyclopropanation reactions with methyl diazoacetate (MDA) toward a wide variety of alkenes. Monocyclopropanation of 25 alkenes was demonstrated with catalyst 3 in octane under reflux. By reaction with more than equimolar amounts of MDA in the presence of catalyst 9, the first porphyrin-catalyzed biscyclopropanation was attained toward nonconjugated α, ω-dienes, viz. 1,5-hexadiene and 1,7-octadiene.
A new facile electrochemical method for functionalization of porphyrin
Authors: Jamaat Parisa Rajabali , Davarani Saied Saeed Hosseiny , Fumani Neda Sheijooni , Masoumi Leila , Safari Nasser
Published: July 2009

Different meso-functionalized porphyrins were conveniently synthesized by direct reactions of meso-porphyrincatechols with 2-phenyl-1,3-indandione and 2-mercaptobenzothiazole as nucleophiles in relatively high yields via practical and efficient electrooxidation in aqueous solution, using cyclic voltammetry and controlled-potential coulometry. The results indicate that O-benzoquinone generated by electrochemically driven oxidation of the meso-porphyrincatechols is scavenged by nucleophiles to give related products via an EEEECCCC electrochemical pathway. Spectroscopic and molecular modeling studies show that there is no indication of atropoisomers in our isolated products.
Spectroscopic studies of aggregation behavior of meso-tetra(4-hydroxyphenyl)porphyrin in aqueous AOT solution
Authors: Ma Hongmin , Sun Shuting , Chen Xin , Wu Dan , Zhu Peihua , Du Bin , Wei Qin
Published: July 2009

The interactions of two amphiphilic porphyrins with anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in aqueous solutions were studied by UV-vis absorption spectroscopy, fluorescence spectroscopy, resonance light scattering technique, fluorescence anisotropy and surface tension measurements. The two porphyrins, meso-tetra(4-hydroxyphenyl)porphyrin (THPP) and meso-tetra(3,5-dibromo-4-hydroxylphenyl)porphyrin (T(DBHP)P), exist as irregular aggregates in aqueous solutions with a broad and low absorption peak near the maximum of monomer peak. The interaction of THPP with AOT leads to the formation of a fluorescent aggregate of porphyrin which was assigned as J-type aggregate according to exciton theory. A long red-shifted Soret band together with a new strong Q-band, a broad emission peak and a sharply peaked resonance light scattering signal are observed for this J-aggregate. The formation of J-aggregate is independent of the initial THPP concentration and can be influenced greatly by ionic strength. The aggregation kinetics has been investigated by UV-vis absorption spectroscopy and fluorescence anisotropy. Conversion of the porphyrin monomers to J-aggregate is observed. The addition of THPP increases the surface tension of solution and changes the critical micelle concentration of AOT. J-aggregate was not observed for T(DBHP)P in AOT solutions which only shows solubilization. The mechanism of aggregation was discussed.
Pyrroles, dipyrrins and prodigiosenes: one, two and three
Authors: Thompson Alison , Bennett Sarah , Gillis H. Martin , Wood Tabitha E.
Published: July 2009

The Thompson group aims to further the chemistry of pyrroles, dipyrrins and prodigiosenes. This micro-review discusses each of these research areas in turn, focussing on our achievements thus far.
Probing the heme-thiolate oxygenase domain of inducible nitric oxide synthase withRu(II) andRe(I) electron tunneling wires
Authors: Whited Charlotte A. , Belliston-Bittner Wendy , Dunn Alexander R. , Winkler Jay R. , Gray Harry B.
Published: July 2009

Nitric oxide synthase (NOS) catalyzes the production of nitric oxide from L-arginine and dioxygen at a thiolate-ligated heme active site. Although many of the reaction intermediates are as yet unidentified, it is well established that the catalytic cycle begins with substrate binding and rate-limiting electron transfer to the heme. Here, we show that Ru (II)-diimine and Re (I)-diimine electron tunneling wires trigger nanosecond photoreduction of the active-site heme in the enzyme. Very rapid generation of a reduced thiolate-ligated heme opens the way for direct observation of short-lived intermediates in the NOS reaction cycle.
Deprotonation induced dioxygen activation and ligand oxidation by dipyrromethane-palladium complexes
Authors: Katayev Evgeny A. , Lavrov Herman V. , Khrustalev Victor N.
Published: July 2009

Novel palladium(II) complexes with α,α'-bis(phenylimino)- and α,α'-bis(picolyl)-substituted meso- H -dipyrromethanes have been prepared. The complexes are able to react with dioxygen upon activation with potassium tert-butoxide. Reactions with dioxygen afford C - N or C - C self-bond cleavage producing α-pyrrole-carboxylate or α-hydroxypyrrole residues, respectively. According to DFT calculations the deprotonation of meso-hydrogen leads to the redistribution of electron density between ligand and metal, thus formally forming dipyrromethene-palladium(0) anionic complex. Possible reactive oxygen-containing intermediates have been suggested on the basis of calculations.
Redox-controlled multistability of double-decker cerium tetra-(15-crown-5)-phthalocyaninate ultrathin films
Authors: Selector Sofia L. , Arslanov Vladimir V. , Gorbunova Yulia G. , Raitman Oleg A. , Sheinina Larisa S. , Birin Kirill P. , Tsivadze Aslan Yu.
Published: July 2009

The optical and electrochemical properties of novel double-decker cerium bis-tetra-15-crown-5-phthalocyaninate [ Ce ( R 4 Pc 2−)2]0 (R4Pc2− = [4,5,4',5',4",5",4'",5'"-tetrakis-(1,4,7,10,13-pentaoxapentadecamethylene)-phthalocyaninate-anion]) Langmuir-Blodgett and cast films were investigated. The particular feature of cerium ion in complex with tetra-15-crown-5-phthalocyanine is the stability of oxidation state +4 unlike other lanthanide metal centers. Cyclic voltammetry curves exhibited three stable redox states in the Langmuir-Blodgett and cast films. Redox processes in Langmuir-Blodgett films are reversible and reproducible at multiple scan procedures. The mechanisms of redox transformations in Langmuir-Blodgett films are suggested. We demonstrated that the well-defined structure of Langmuir-Blodgett film is essential for fast electron transfer within the planar system, in which the charge is delocalized along the conjugated assembly of uniformly ordered stacks of discotic crown-phthalocyaninate. Fast charge relaxation was observed in highly ordered Langmuir-Blodgett film whereas the electrochemically written redox states remained unchanged in unordered cast film. The combination of electrochemistry with surface plasmon resonance spectroscopy allowed us to demonstrate that stepwise change of potential in the range 200-850 mV induced the respective optical response, which can be observed as the change in resonance angle value. High-speed response and reversibility of the switching process between stable states may be utilized as the basis for switchable optoelectronic devices. Electrochemical multistability of cerium crown-phthalocyaninate provided a basis for developing a simple strategy to fabricate nanoelectromechanical systems with high efficiency and fast response. Our approach relies on the modulation of the distance between decks in a complex stack via redox-controlled change of metal center size that results in change of linear dimensions of the stacks. The reported results are valuable, not only because of their potential applications, for instance, in OFET and MEMS fabrication, but also from a fundamental point of view since they illustrate the interplay between the orientation of stacks bearing discotic aromatic molecules and charge transfer within such a planar assembly.