bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface electrochemistry and electrocatalytic activity of ion pairs formed from oppositely-charged phthalocyanine and porphyrin species
Authors: Chen Junsheng , Lever A. B. P.
Published: July 2009

Self-assembled ion pairs are deposited onto a graphite electrode surface by dipping the electrode sequentially into phthalocyanine cations and anions, or a phthalocyanine cation and porphyrin anion. The electrochemical properties of these surface-bound ion pairs are compared with the properties of the individual surface-bound components. The order of deposition is shown to be crucial, implying that these species lie flat on the surface. A detailed study of the electrocatalytic oxidation of oxalate anion is used to explore their reactivity as a function of deposition order.
Through space singlet-singlet and triplet-triplet energy transfers in cofacial bisporphyrins held by the carbazoyl spacer
Authors: Gros Claude P. , Mohammed Aly Shawkat , El Ojaimi Maya , Barbe Jean-Michel , Brisach Frédéric , Abd-El-Aziz Alaa S. , Guilard Roger , Harvey Pierre D.
Published: July 2009

The through space singlet-singlet and triplet-triplet energy transfers in cofacial bis(etio-porphyrins) rigidly held by the carbazoyl spacer were investigated. The studies on singlet-singlet transfer, which operates via a Förster mechanism, were performed using the zinc porphyrin and free base chromophores as energy donor and acceptor, respectively, while the investigation on triplet-triplet processes was performed using the palladium porphyrin, and the zinc porphyrin and free base chromophores as donor and acceptors, respectively. The rate for singlet-singlet transfer ( k ET ( singlet )) is unexpectedly slower than that reported for other similar, rigidly held bisporphyrins such as H 2( DPO ) Zn ( DPO = 4,6- bis [5-(2,8,13,17- tetraethyl -3,7,12,18- tetramethylporphyrinyl )] dibenzofuran ) and H 2( DPS ) Zn ( DPS = 4,6- bis [5-(2,8,13,17- tetraethyl -3,7,12,18- tetramethyl - porphyrinyl )] dibenzothiophene )). This slower rate is interpreted by the presence of the H -atom exactly located between the two meso-carbons in the dyads. The rates for triplet-triplet transfer are also slow but not too different from that recently reported for H 2( DPX ) Pd ( DPX = 4,5- bis [5-(2,8,13,17- tetraethyl -3,7,12,18- tetramethylporphyrinyl )]-9,9- dimethylxanthene ) and H 2( DPB ) Pd ( DPB = 1,8- bis [5-(2,8,13,17- tetraethyl -3,7,12,18- tetramethylporphyrinyl )] biphenylene ) at 77 K. In such cases, the slow rate is interpreted by a through space energy transfer pathway which operates according to a (small range) Dexter mechanism (since the Förster mechanism is inoperative for triplet-triplet processes). The k ET (triplet) increases at 298 K which is tentatively interpreted by favorable excited state distortions in the triplet state and fluxion processes which ease intramolecular transfers for these dyads in fluid solution in comparison with former glassy matrices.
Extending the self-organization algorithm of chlorosomal bacteriochlorophylls to synthetic pigments
Authors: Balaban Mihaela Carmen , Balaban Teodor Silviu
Published: July 2009

Two new zinc porphyrins having two meso-undecyl solubilizing groups and two meso-formyl groups or two meso-cyano groups have been prepared in good yields and were shown by stationary absorption and fluorescence spectroscopies to self-organize in nonpolar solvents such as n-heptane. The diformyl and dicyano recognition groups can thus successfully replace the hydroxy and carbonyl recognition groups encountered in the natural self-organizing bacteriochlorophylls and which were, up to now, the only recognition groups used in synthetic or semisynthetic bacteriochlorophyll mimics.
The progress on design and synthesis of photoactive porphyrins-based dyads, triads and polymers
Authors: Jiang Li , Li Yuliang
Published: July 2009

Porphyrins are the most frequently employed building blocks as electron donors and sensitizers in artificial photosynthetic models for solar energy conversion. Recently, we have reported a series of covalently linked, donor-acceptor dyads, triads and copolymers containing porphyrin analogs aiming to improve light-harvesting capacity and charge-separation efficiency with a potential application in solar cells. In this review, we would like to summarize our recent studies on these photoactive, porphyrin-containing composite systems focusing on the designs and properties of these systems based on intermolecular electro- and energy transfer.
Supramolecular photocurrent-generating systems using porphyrin composite materials
Authors: Konishi Toshifumi , Horie Masaki , Wada Tatsuo , Ogasawara Shin , Kikuchi Jun-ichi , Ikeda Atsushi
Published: July 2009

Supramolecular design principles for a porphyrin-sensitized, wet-type solar cell are described. To construct efficient organic photocurrent-generating systems, the following two important targets exist: (i) kinetic control of photoinduced electron-transfer processes by spatial, three-dimensional alignment of photo-functional molecules (sensitizers, electron donors, acceptors, and mediators) and (ii) highly dense deposition of composites of the photo-functional molecules on an electrode. These objectives can be achieved by tailoring a photoactive multilayer using supramolecular interactions, such as molecular adsorption, inclusion, coordination, and recognition. Using these interactions, it is expected that the reduction of the costs of synthesis and the combinational fabrication of a simplified-molecular device will become possible. In addition, recent approaches toward the construction of supramolecular porphyrin-sensitized photovoltaic cells are introduced.
Pyren-1-ylmethyl N-substituted oxoporphyrinogens
Authors: Hill Jonathan P. , Ariga Katsuhiko , Schumacher Amy Lea , Karr Paul A. , D'Souza Francis
Published: July 2009

5,10,15,20-tetrakis(3,5-di-tert-butyl-4-oxocyclohexadien-2,5-yl)porphyrinogen was alkylated at its macrocyclic nitrogen atoms with pyren-1-ylmethyl groups and the effect of increasing N-substitution on the spectroscopic and electrochemical properties was investigated. Both pyrene and oxoporphyrinogen chromophores exhibit fluorescence and there is little interaction between them except in the higher N-substituted compounds. Intra- or intermolecular excimer formation by pyrene is precluded by attachment to the bulky oxoporphyrinogen. Electrochemical measurements revealed reversible redox behavior.
Intramolecular photoinduced electron-transfer processes in buta-1,3-diynyl-benzene-linked porphyrin-fullerene dyad
Authors: Yamanaka Ken-ichi , Fujitsuka Mamoru , Araki Yasuyuki , Tashiro Kentaro , Sato Azumi , Yuzawa Tetsuro , Aida Takuzo
Published: July 2009

Intramolecular electron-transfer process of porphyrin-fullerene dyad linked by phenyl buta-1,3-diynyl-phenyl unit ( ZnP - sp - C 60) was studied by laser flash photolysis. Picosecond fluorescence lifetime and transient absorption measurements revealed that photoinduced charge-separation takes place via the excited singlet state (1 ZnP *) with the rate constant of (1-2) × 1010 s −1. For the charge recombination, about a half of the radical-ion pair decayed quickly with 2.9 × 109 s −1 as evaluated from picosecond transient absorption measurements, whereas the remaining half was long-lived with slow decay (1.6 × 106 s −1) as estimated from nanosecond transient absorption measurements. The lifetime of the radical-ion pair of ZnP - sp - C 60 was longer than those of directly connected dyads with a buta-1,3-diynyl bridge and buta-1,3-diynyl-phenyl bridge by the insertion of an extra phenyl group in addition to the pyrrodino ring.
Charge separation in a conformationally-flexible porphyrin-fullerene dyad synthesised using cross-metathesis
Authors: Bell Toby D. M. , Ghiggino Kenneth P. , Haynes Andrew , Langford Steven J. , Woodward Clint P.
Published: July 2009

The synthesis of a Zn (II) porphyrin-fullerene dyad in which the two chromophore units are tethered by a conformationally-flexible linker, is described. The synthesis is highlighted by the use of a cross metathesis strategy to prepare the linker between the chromophores. Photoexcitation of the Zn (II) porphyrin unit of the dyad in tetrahydrofuran leads to substantial (77%) quenching of porphyrin fluorescence. The multiple exponentials fluorescence decay kinetics observed are attributed to different rates of electron transfer from photoexcited porphyrin to fullerene in the various conformers present. A charge-separated state with a 330 ns lifetime is observed by transient spectroscopy.
Complexes of bovine serum albumin with water-soluble Cu and Co containing cationic meso-tetra(4-N-oxyethylpyridyl)-porphyrins
Authors: Karapetyan Nelli H. , Aloyan Lusine R. , Ghazaryan Robert K. , Mamasakhlisov Yevgeni
Published: July 2009

Bovine serum albumin complexes with water-soluble cationic porphyrins, Cu - and Co-meso-tetra(4- N -hydroxyethylpyridyl)porphyrins ( CuT4OEPyP , CoT4OEPyP ), and their 3- N -analogs, meso-tetra(3- N -hydroxyethylpyridyl)porphyrins ( CuT3OEPyP , CoT3OEPyP ), have been investigated. The porphyrin-bovine serum albumin binding was monitored by the absorption in the visible region at 400-460 nm. The stoichiometry of binding and the binding constants of the porphyrins to bovine serum albumin were determined using binding isotherms and Scatchard plots. The K b values obtained for these porphyrin- bovine serum albumin complexes are 1.7 × 105 M −1, 3.2 × 105 M −1, 1.4 × 105 M −1 and 3 × 105 M −1 respectively. Binding constants are sensitive to pH and ionic strength of the solution.
Titration syntheses of polyaminosubstituted phthalocyanines via nucleophilic aromatic substitutions on zinc(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluorophthalocyanine
Authors: Leznoff Clifford C. , Hiebert Annette , Ok Sibel
Published: July 2009

Primary amines, secondary amines and tertiary butyl esters of amino acids are used as nucleophiles with zinc(II) hexadecafluorophthalocyanine to provide mixtures of mono and disubstituted fluorinated phthalocyanines under mild conditions, or polyaminosubstituted phthalocyanines when using the amines as solvents. Diamines give cyclic substituted phthalocyanines, binuclear or trinuclear phthalocyanines or mixtures of both types, depending on the chain length or structure of the diamine.
Oxidation of chlorophyll a with selenium dioxide
Authors: Hynninen Paavo H. , Juhani Pitkänen K.
Published: July 2009

The SeO 2 oxidation of chlorophyll ( Chl ) a in deaerated pyridine solution under argon, produced, after 4 hours of refluxing, work-up and chromatographic purifications on a sucrose column, 132(S/R)-hydroxy- Chl a (20%), 132(S/R), P 4(S/R)-dihydroxy- Chl a (19%) and P 4(S/R)-hydroxy-132-demethoxycarbonyl-132-oxo- Chl a (10%). The major products were characterized by 1 H and 13 C NMR spectra, electronic absorption spectra (UV-vis) and FAB-MS. The C -132 oxidation of the enolizable isocyclic ring was found to be faster than the allylic C - P 4 oxidation of the phytyl chain. Essential features of the mechanisms proposed for the C - P 4 allylic oxidation and the C -132 oxidation of Chl a are the ene-reaction and the [2,3]-sigmatropic rearrangement. In the C -132 oxidation, the ene-reaction affords the selenite ester of the Chl enol as the first intermediate, which is then converted by [2,3]-sigmatropic rearrangement to the hydrolyzable Chl selenoxylate ester intermediate. However, in pyridine, we regard the attack of the nucleophilic oxygen atom of the Chl enol or enolate to the electrophilic Se -atom of SeO 2 as a likely alternative for the ene-reaction of the Chl isocyclic ring. The C - P 4 hydroxylation of the phytyl chain exhibited very little diastereoselectivity, whereas the C -132 hydroxylation reaction showed moderate diastereoselectivity, producing 80% of 132( R )- HO - Chl a ( de = 60%) and 20% of 132( S )- HO - Chl a. Kinetic or thermodynamic control of the [2,3]-sigmatropic rearrangement was considered as a possible factor underlying the diastereoselectivity observed for the C -132 hydroxylation.
Structure-function relationship in antimony corrole photosensitizers: Time-resolved electron paramagnetic resonance and optical study
Authors: Wagnert Linn , Berg Alexander , Stavitski Eli , Luobeznova Inna , Gross Zeev , Levanon Haim
Published: July 2009

Three photosensitizers based on tris-(pentafluorophenyl)antimony corroles that differ in oxidation state and axial ligands, namely, (pyridine) Sb (III)-, (oxo) Sb (V)- and (difluoro) Sb (V) complexes, were studied by time-resolved electron paramagnetic resonance spectroscopy and laser flash photolysis. The magnetic and orientational parameters of the corroles oriented in a nematic liquid crystal as well as their triplet lifetimes in liquid toluene were determined and interpreted in terms of their structure and geometry. The negative zero-field splitting parameter D assigned to all studied corroles is explained by the asymmetric π-electron withdrawal effect caused by perfluorinated peripheral aryl groups, which force the triplet electron spins to align in head-to-tail configuration. The effect of the axial ligands on the photoexcited triplet state properties of the corroles is correlated with their different efficiency to perform photoassisted aerobic oxygenation of some organic molecules. This is explained by the dependence of the main parameters of the photoexcited complexes on the interaction between the central ion and corrole π-system. This interaction is strongly influenced by axial ligands coordination, affecting the macrocycle symmetry, planarity, and rigidity.
Benzo-9-crown-3 substituted phenyl porphyrin
Authors: Moghimi Abolghasem , Ghandi Mehdi , Naeemi Sedigheh Sadat , Safari Nasser , Bahadoran Farzad
Published: July 2009

The synthesis and spectroscopic characterization of two new substituted tetraphenyl-porphyrins with one or two benzo-9-crown-3 appended units are described.
Synthesis of one-dimensional structured metal phthalocyanine in an ionic liquid
Authors: Jacob David S. , Mallenahalli Somashekarappa , Gedanken Aharon , Solovyov Leonid A. , Xenogiannopoulou Evangelia , Iliopoulos Konstantinos , Couris Stelios
Published: July 2009

Nickel phthalocyanine is synthesized in an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate) giving a high yield of one-dimensional structures. The morphology of the synthesized material is detected by a high-resolution scanning electron microscope, a high-resolution transmission electron microscope, characterized by powder X-ray diffraction, and a CHN analyzer. The nonlinear optical properties of the synthesized phthalocyanine are also investigated.
The influence of oxygen on the radiosensitizing activity of Photofrin II and hypericin
Authors: Schaffer Pamela , Kulka Ulrike , Ertl-Wagner Birgit , Hell Roswita , Balandin Alina , Hofstetter Alfons , Jori Giulio , Schaffer Moshe
Published: July 2009

Several clinical studies, as well as investigations performed on tissue cultures and murine tumor models, have demonstrated the in vitro and in vivo efficacy of Photofrin II and hypericin as radiosensitizing agents. The mechanisms involved in the radiosensitizing action of Photofrin II and hypericin are partially understood; the recognition of the major role performed by oxygen regarding the modulation of cellular radiosensitivity has prompted the present investigations on the relevance of oxygenation for the success of Photofrin II or hypericin-based radiation therapy of tumors. RT4 human bladder carcinoma cell lines were seeded and incubated with various concentrations of Photofrin II or hypericin under ambient and 5% oxygen levels. The cells were irradiated with ionizing radiation between 1 and 6 Gy. The same experiments were repeated with Photofrin II and hypericin alone, without radiation. The cell survival was evaluated. The results demonstrated an increase of radiation-induced cell damage in the presence of Photofrin II and hypericin, respectively, when sufficient oxygen was available. Low levels of oxygen reduced the activity of Photofrin II as well as of hypericin as a radiosensitizer, with minimal tumor damage ( p < 0.05 in a Student t-test). The mechanism of action of Photofrin II and hypericin as radiosensitizers requires the presence of sufficiently high oxygen concentrations.
Synthesis of 1:2 molecular complexes between free base meso-tetraarylporphyrins and sulfur trioxide
Authors: Dehghani Hossein , Fathi Fereshteh
Published: July 2009

The interaction of meso-tetraarylporphyrins, H 2 T (4- X ) PP , with sulfur trioxide pyridine complex ( SO 3. py ) in chloroform only produced 1:2 molecular complexes, [ H 2 T (4- X ) PP ( SO 3)2]. UV-vis, 1 H NMR, and FT-IR spectra, as well as elemental analysis, suggested pseudo tetrahedrally distorted porphyrin core structures with σ-bonding from two pyrrolenine nitrogen donors to the d orbital of sulfur in two SO 3 s and the occurrence of two hydrogen bonds between two pyrrolic NH and oxygens of sulfur trioxides from above and below the mean plane of the porphyrins.
Electrochemical and photophysical characterization of non-peripherally-octaalkyl substituted dichlorotin(IV) phthalocyanine and tetrabenzotriazaporphyrin compounds
Authors: Khene Samson , Cammidge Andrew N. , Cook Michael J. , Nyokong Tebello
Published: July 2009

Three non-peripherally substituted tin(IV) macrocylic compounds, octahexylphthalocyaninato dichlorotin(IV) (3a), octahexyltetrabenzo-5,10,15- triazaporphyrinato dichlorotin(IV) (3b) and octadecylphthalocyaninato dichlorotin(IV) (3c) were synthesized and their photophysical and electrochemical behavior studied. Complex 3b, containing a CH group in place of one of the aza nitrogen atoms of the phthalocyanine core, shows a split Q-band due to its lower symmetry. The triplet state quantum yields were found to be lower than would be expected on the basis of the heavy atom effect of tin as the central metal for phthalocyanine derivatives (3a and 3c). In contrast, 3b shows a triplet quantum yield Φ T = 0.78. The triplet state lifetimes were solvent dependent, and were higher in tetrahydrofuran than in toluene. Cyclic voltammetry and spectroelectrochemistry of the complexes revealed only ring-based redox processes.
Influence of steric hindrance on the solvent-dependent absorption spectral behavior of highly brominated free base porphyrin and its Zn(II) complex
Authors: Bhyrappa Puttaiah , Arunkumar Chellaiah , Varghese Babu
Published: July 2009

Electronic absorption spectra of highly brominated free base porphyrin, 2,3,7,8,12,13,17,18-octabromo-tetrakis(2′,6′-dibromo-3′,5′-dimethoxyphenyl)porphyrin, H 2 T (3′,5′-DMP) PBr 16 and its Zn (II) complex were examined in various solvents. These derivatives exhibit red-shifted absorption spectral features in polar solvents relative to that observed in less polar or nonpolar solvents. The extent of red shifts observed in highly brominated porphyrins is less than those reported for the corresponding 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin, H 2 TPPBr 8 and its Zn (II) complex. The crystal structure of the H 2T(3′,5′-DMP) PBr 16 showed saddle-shaped geometry with steric hindrance of the bromo groups on the opposite phenyl rings which provide limited open access to the core. The decreased red shift of the absorption spectral bands of MT (3′,5′-DMP) PBr 16 ( M = 2 H , Zn (II)) derivatives when compared to unhindered MTPPBr 8 is possibly due to the steric hindrance offered by the ortho-bromo groups rather than the electronic effects of the porphyrin π-system.
Inclusion complex of iron meso-tetrakis(p-sulfonatophenyl)porphyrin and 2-hydroxypropyl-β-cyclodextrin as a functional model of cytochrome P-450: study on a supramolecular formation and its application in aqueous oxidation of styrene
Authors: Khavasi Hamid Reza , Sasan Koroush , Safari Nasser
Published: July 2009

In this report, the interaction of iron(III) meso-tetrakis(p-sulfonatophenyl)porphyrin, TPPS 4 FeCl , and 2-hydroxypropyl-β-cyclodextrin, HP-β-CD as a model of cytochrome P -450 enzyme, has been investigated by UV-vis and 1 H NMR spectroscopy, in different pHs. The formation of a 1:1 inclusion complex has been confirmed by spectroscopic methods. Equilibrium constants ( K 1) for the formation of the inclusion complexes have been estimated from the absorbance changes in neutral, basic and acidic phosphate buffer solutions. The K 1 values show that the inclusion behavior of HP-β-CD depends upon pH. The inclusion ability of the inclusion complex for the TPPS 4 FeCl /HP-β-CD system is strongest ( K 1 = 678.4 m−1) in a neutral solution. In the second part, these inclusion complexes have been examined for the aqueous-catalytic oxidation of styrene under different reaction conditions. The effect of imidazole as an axial ligand and the effect of pH on the catalytic behavior of TPPS 4 FeCl / HP -β- CD were also investigated. This data suggests that the addition of HP-β-CD to the porphyrin solution increases catalytic activity and selectivity of the system.
Solvent and acidity effects on the UV-visible spectra and protonation-deprotonation of free-base octaethylcorrole
Authors: Ou Zhongping , Sun Hongxia , Zhu Weihua , Da Zulin , Kadish Karl M.
Published: July 2009

The UV-visible spectrum of free-base octaethylcorrole, (OECor) H 3, was recorded in thirteen different nonaqueous solvents as well as in a mixed acetonitrile/acid solvent containing one of seven different acids. Spectra were also measured in seven different solutions of neat concentrated acid and in CH 3 CN containing piperidine or tetrabutylammonium hydroxide as an added base. The overall data was analyzed as a function of solvent acidity or basicity parameters and the number of protons on the central nitrogens of the macrocycle, the predominant form of the corrole in these solutions being respresented as (OECor)H 3, [ (OECor)H 4]+, [ (OECor)H 2]− or [ (OECor)H ]2− where OECor = trianion of octaethylcorrole. The mono-protonated corrole, [ (OECor)H 4]+, is formed in concentrated acetic acid or in CH 3 CN containing 0.10 M trifluoroacetic acid, H 2 SO 4, HCl , H 3 PO 4 or HClO 4. The mono-deprotonated corrole, [ (OECor)H 2]−, is generated in piperidine while doubly deprotonated [ (OECor)H ]2− exists in solutions of tetrabutylammonium hydroxide. An addition of protons to the macrocycle of [ (OECor)H 4]+ also occurs in the presence of concentrated strong acids and this results in a loss of the characteristic Soret band of the corrole leading presumably to [ (OECor)H 5]2+ where the second proton has been added to a meso-position of the macrocycle. The UV-visible spectral changes upon formation of [ (OECor)H 4]+, [ (OECor)H 2]− or [ (OECor)H ]2− in CH 3 CN were monitored during a titration with the relevent acid or base and equilibrium constants for protonation or deprotonation of (OECor)H 3 were determined using standard equations. The measured logK values are compared to protonation and deprotonation constants obtained for two related corroles and two related porphyrins under the same experimental conditions.
Demetalation of corrole complexes: an old dream turning into reality
Authors: Mandoj Federica , Nardis Sara , Pomarico Giuseppe , Paolesse Roberto
Published: July 2009

Different strategies for the demetalation of corrole complexes have been developed, using copper complexes of corrole as model compounds. Best results were obtained using the acidic mixture CHCl 3/ H 2 SO 4, which allowed the almost complete removal of copper ions from both meso-triaryl-, β-octaalkyl- and fully substituted corroles. This route reduced both the decomposition of the starting complex and the formation of isocorrole species produced by oxidation of the corrole ring in the acidic conditions necessary for the demetalation reaction. To investigate the scope of the reaction, the same approach was later extended to other metal complexes of corrole, such as cobalt, manganese, iron and germanium derivatives. Although not always successful, this approach demonstrated that in the case of corrole it is also possible to obtain a reversible coordination of metal ions, a route of synthetic interest for further functionalization of the corrole ring.
Synthesis and characterizations of peripheral octa-amino and octa-amidophthalocyanines
Authors: Yuksel Fatma , Tuncel Sinem , Ahsen Vefa
Published: July 2009

Novel 2,3,9,10,16,17,23,24-octaamino substituted Ni(II) phthalocyanine (2) was synthesized from tosylamido (tosyl: toluene-p-sulphonyl) derivative by the cleavage of tosyl groups in the presence of 90% sulfuric acid. Octa-hexanoylamido Ni(II) phthalocyanine (3a) and octa-lauroylamido Ni(II) phthalocyanine (3b) were obtained by reacting of octa-amino Ni(II) phthalocyanine (2) with hexanoyl chloride and lauroyl chloride, respectively. The new compounds have been characterized by elemental analysis, FT-IR, NMR and UV-vis spectroscopy and mass spectrometry. The aggregation behaviors of new compounds were investigated by UV-vis spectroscopy.
Porphyrin-based catenanes and rotaxanes
Authors: Sauvage Jean-Pierre , Collin Jean-Paul , Faiz Jonathan A. , Frey Julien , Heitz Valérie , Tock Christian
Published: July 2009

Catenanes and rotaxanes containing porphyrin subunits have become popular synthetic targets because of the large variety of available synthetic strategies including the coordination chemistry of metalated porphyrins, coupled with the many attractive physical properties of porphyrins. The present review article outlines various synthetic approaches and templating strategies that have been used to prepare a range of mechanically interlocked architectures that incorporate porphyrins as fundamental subunits either grafted onto macrocycles or as stoppers. These species are of interest in relation to recreating natural processes such as the photosynthetic apparatus or enzyme binding sites. In recent years, "molecular machines" have also experienced a spectacular development. Porphyrin-based rotaxanes are particularly promising in relation to this research field, this is shown by the elaboration of a "molecular press" whose properties will be briefly discussed in this review.
Adventures in the synthesis of meso-substituted corroles
Authors: Gryko Daniel T.
Published: July 2009

This personal account describes how methodology for the synthesis of meso-substituted corroles reached the mature state within just a few years. Both latest developments and many dead-end attempts are described. The comprehensive comparison of conditions of the reaction of aldehydes with dipyrromethanes leading to trans-A2B-corroles is presented.
Electrocatalytic and photosensitizing behavior of metallophthalocyanine complexes
Authors: Nyokong Tebello
Published: July 2009

Electrocatalytic or photosensitizing (photocatalytic) properties of metallophthalocyanine (MPc) complexes are dependent on the central metal. Electrocatalytic behavior is observed for electroactive central metals such as Co , Mn and Fe , whereas photosensitizing behavior is observed for diamagnetic metals such as Al , Zn and Si . In the presence of nanoparticles such as quantum dots, the photosensitizing behavior of MPc complexes is improved. Carbon nanotubes enhance the electrocatalytic behavior of MPc complexes.
Unexpected isolation and characterization of a chloroiron complex with a 10-acetylcorrole ligand
Authors: Bröring Martin , Köhler Silke
Published: July 2009

The chloroiron complex of 10-acetyl-2,3,7,8,12,13,17,18-octaethylcorrole was isolated as an unexpected product from an attempted preparation of chloroiron-2,2'-bidipyrrin when acetone was used in the solvent mixture. In the molecular structure derived from X-ray crystallographic analysis the orthogonal arrangement of the acetyl group with the corrole macrocycle is clearly apparent, and the UV-vis spectrum of the compound indicates only a small electronic influence of the acetyl group on the corrole π-system. The paramagnetic 1 H NMR spectrum taken at ambient temperature shows two signal sets in a ratio of 2.2:1, indicating two stable orientations of the acetyl group in solution. Attempts to prepare the species from chloroiron-2,2'-bidipyrrin with iron(III)chloride in acetone were successful but gave inconsistent and generally low yields. A rationale for the formation of the new corrole is proposed.
Ionic complex of fullerene C602− dianions with (MDABCO+)2·MnIITPP coordination assemblies: synthesis, crystal structure and magnetic properties
Authors: Konarev Dmitri V. , Khasanov Salavat S. , Saito Gunzi , Lyubovskaya Rimma N.
Published: July 2009

The crystals of the ionic complex containing fullerene C 602− dianions and positively charged ( MDABCO +)2· Mn II TPP assemblies: {( MDABCO +)2·MnII TPP }·( C 602−)·( C 6 H 4 Cl 2)4·( CH 3 CN )2 (1) were obtained for the first time ( MDABCO +: the cation of N-methyldiazabicyclooctane; TPP: tetraphenylporphyrin). The C 602− dianions are isolated in the complex with the shortest center-to-center distance of 13.228 Å. The Mn II atoms are six-coordinated in the ( MDABCO +)2· Mn II TPP units. The length of the Mn-N(TPP) equatorial bonds of 2.093-2.098(1) Å corresponds to the high-spin state of the Mn II atoms (S = 5/2) which was confirmed by the magnetic measurements (µ eff = 5.61 µ B at 300 K). The Mn II atoms are located exactly in the porphyrin plane and this results in the radial expansion of the porphyrin core. The long (2.537(1)−2.545(1) Å) Mn - N ( MDABCO +) axial bonds indicate essential destabilization of the six-coordinated ( MDABCO +)2· Mn II TPP units due to the population of the d ( z 2) orbital in high-spin state. The contribution from the C 602− dianions was not found in magnetic measurements on the basis of the contribution from high-spin Mn II TPP and most probably they are diamagnetic in the 2-300 K range.
Synthesis of chlorin and bacteriochlorin conjugates for photodynamic and boron neutron capture therapy
Authors: Mironov Andrey F. , Grin Mikhail A.
Published: July 2009

The review summarizes the synthesis and study of properties of the bioconjugates of chlorophyll a and bacteriochlorophyll a with carbohydrates, carboranes and other moieties, focusing on the synthetic methods of obtaining conjugates and preliminary biological testing thereof. Boronated chlorins and bacteriochlorins can be used in both photodynamic and boron neutron capture therapy.
Photovoltaic properties of Schottky-barrier cells utilizing sub-phthalocyanine layer
Authors: Pakhomov Georgij L. , Travkin Vlad V. , Bogdanova Alexandra Yu. , Guo Tzung-Fang
Published: July 2009

We have fabricated and tested Schottky-type photovoltaic cells based on chloro(sub-phthalocyaninato)boron(III) complex, SubPcBCl. The vacuum-deposited SubPcBCl layer was sandwiched between standard glass/ITO substrate and evaporated Au , Ag or Al top metallic electrode. Performance of such cells depends on the work function of the cathode material. Power conversion efficiency of the non-optimized cells with Al cathode approaches ~0.01% under 1 sun illumination. The photovoltaic effect takes place even if gold is used as top electrode.
Temperature-dependent phosphorescence spectra of Pd- and Pt-porphins and their applications
Authors: Kruk Mikalai M. , Starukhin Aleksander S. , Czerwieniec Rafal
Published: July 2009

In this paper the temperature dependence of radiative deactivation of Pd - and Pt -porphin triplet states in Shpol'skii matrices has been studied in the temperature range of 4.2-210 K. Dramatic changes in the phosphorescence spectra, with increasing temperature, were observed. It has been proposed that this is due to the inclusion of thermally activated states of the studied molecules in the processes of radiative deactivation of triplet states. For Pd -porphin the T 1 → S 0 emission is merely observed at liquid helium temperature. An increase in temperature leads to the activation of several radiative T i → S 0 transitions, so additional bands appear in the phosphorescence spectrum. In the case of Pt -porphin, temperature activation takes place as early as at liquid helium temperature. The degeneracy lifting of lowest T 1,2 states due to crystal field splitting was observed for both Pd - and Pt -porphins. The splitting value δ = ΔE( T 2 − T 1) has been measured in different matrices and the dependencies on both the metal ion in the given matrix and the matrix type for the given metal ion, have been revealed. The possibility of designing the luminescent molecular thermometers for cryogenic temperatures based on the high temperature sensitivity of the Pd - and Pt -porphin phosphorescence in n-alkane matrices, has been discussed. The workability of the dependence of Pd - and Pt -porphin phosphorescent properties on temperature in the design of the molecular thermometer family for the temperature range from a few K up to temperatures close to the melting point of n-alkane matrix (150-200 K) is demonstrated.
pH-dependent porphyrin based receptor for bromide-ions selective binding
Authors: Sheinin Vladimir B. , Ratkova Ekaterina L. , Mamardashvili Nugzar Zh.
Published: July 2009

It was determined that the diprotonated form of 2,8,12,18-tetramethyl-3,7,13,17-tetrabutyl- H21, H23-porphine ( H4III2+) acts as a bromide selective receptor. It forms stable complexes H4III2+( CH3CN )( Br−) ( log Kd1= 5.50 ± 0.03), H4III2+( Br−)2( log Kd2= 3.25 ± 0.03) in the system H2III-( Et )4NBr - HClO4-acetonitrile at 25°C. Spectrophotometric method allows to determine the bromide ions' concentration 3 × 10−8M−1.
Preclinical photodynamic therapy research in Spain 4: Cytoskeleton and adhesion complexes of cultured tumor cells as targets of photosensitizers
Authors: Sanz-Rodríguez Francisco , Casas Adriana , González Salvador , Espada Jesús , Jaén Pedro , Regadera Javier , Blázquez-Castro Alfonso , Zamarrón Alicia , Bagazgoitia Lorea , Iglesias de la Cruz Carmen , Juarranz Ángeles
Published: July 2009

Tumor cell death induced by photodynamic therapy (PDT) with different photosensitizers (PSs) is due to the selective damage of several membranous organelles including mitochondria, lysosomes and Golgi apparatus. Other cell structures such as the cytoskeleton (CSK) (microtubules, actin microfilaments and cytokeratin intermediate filaments) and the cell adhesion components (cadherins and integrins) are also implicated in cell death induced by PSs. CSK and adhesion components are responsible for many cellular functions such as the maintenance of morphology, motility, division and adhesion, all of them of fundamental importance for growth and dissemination of tumors. Therefore, they are considered very important targets for anticancer therapies, including PDT. In addition, similarly to the rest of the anticancer therapies, PDT often leaves a significant number of surviving tumor cells. The reorganization of CSK as well as the adhesion proteins in the PDT resistant cells affect their invasive migratory capabilities. Taking into account all these features, both CSK and adhesion proteins are crucial targets of PDT.
Electrospray mass spectrometry for the study of the non-covalent interactions of porphyrins and duplex desoxyribonucleotides
Authors: Ramos Catarina I.V. , Graça Santana-Marques M.
Published: July 2009

An overview of the use of electrospray mass spectrometry for the study of non-covalent interactions of cationic porphyrins and small DNA duplexes, highlighting the work developed in the Mass Spectrometry Laboratory of the University of Aveiro, is presented here.
Molecular modeling of porphyrin-based conjugates and subphthalocyanine aggregates
Authors: Ferro Víctor R. , Poveda Luis A. , Lopez Rafael , García de la Vega José M.
Published: July 2009

A theoretical study was carried out on both porphyrin-based conjugates (with interest in the so-called artificial photosynthesis) and subphthalocyanine aggregates (with potential applications as new materials for optoelectronics, solar energy and other uses). A simple molecular orbital model for studying the role of the spacer groups in the electron transfer in porphyrin-quinone conjugates was developed. The influence of the π-π interaction, hydrogen association and covalent linkage on the stability and structural features in porphyrin-porphyrin complexes as well as the charge separation in donor-acceptor porphyrin dimers, were reproduced. Theoretical models suggest the potential feasibility of SubPc's aggregative processes leading to nanometer-sized fully aromatic fullerene-like molecular architectures.
Recent advances in the functionalization of meso-triarylcorroles via cycloaddition reactions
Authors: Barata Joana F.B. , Neves Maria G.P.M.S. , Tomé Augusto C. , Cavaleiro José A.S.
Published: July 2009

With reference to the Portugal-Spain Special Issue of the Journal of Porphyrins and Phthalocyanines, this highlight is mainly concerned with the contribution by the University of Aveiro group on the functionalization of the β-pyrrolic positions of triarylcorroles via cycloaddition reactions.
Metal-mediated multiporphyrin functional assemblies
Authors: Hernández Laura P. , González-Álvarez Almudena , Oliva Ana I. , Ballester Pablo
Published: July 2009

During the last ten years, our research group has been applying metal-mediated self-assembly processes to the construction of multiporphyrin functional assemblies. The construction of well-defined and discrete supramolecular structures resulting from self-assembly requires the use of multiple and separated connections operating in one or more closed loops. Consequently, the great majority of the multiporphyrin assemblies that we have prepared are of cyclic nature. We have placed special emphasis not only on the characterization in solution of the formed assemblies but also on the thermodynamic characterization of the assembly process and in the assessment of cooperativity. Finally, we also present examples in which functionality has been derived from the three-dimensional structures of multicomponent assemblies.
Metalloporphyrins in the biomimetic oxidative valorization of natural and other organic substrates
Authors: Simões Mário M.Q. , De Paula Rodrigo , Neves M. Graça P.M.S. , Cavaleiro José A.S.
Published: July 2009

Cheap and abundant natural products can be transformed into products of higher commercial value. One of the approaches for the functionalization of organic compounds is their oxidation in the presence of an oxygen atom donor, under the influence of a suitable catalyst. Metalloporphyrins, with structures based on the well known meso-tetraphenylporphyrin (TPPH2), are amongst the catalysts commonly studied and have demonstrated to be efficient in the oxygenation of organic compounds. These transformations have been studied in the presence of different oxygen atom donors. However, our biomimetic oxidative approach is based on the use of clean and environmentally benign hydrogen peroxide in the presence of metalloporphyrins. This approach will be outlined in this review.
Subphthalocyanines: synthesis, self-organization, properties and applications
Authors: Medina Anaïs , Claessens Christian G.
Published: July 2009

Subphthalocyanines, lower homologs of phthalocyanines, show great promise for applications in many fields of contemporary research such as non-linear optics, donor-acceptor systems for photovoltaics, photodynamic therapy and anion sensing. This short review gives a brief overview of the latest developments in the chemistry, characterization, self-organization, properties and applications of this fascinating molecule.
Extended π-aromatic systems for energy conversion: phthalocyanines and porphyrins in molecular solar cells
Authors: Rio Yannick , Vázquez Purificación , Palomares Emilio
Published: July 2009

Phthalocyanines, porphyrins and analogs are highly versatile and stable molecules with an extended π-aromatic system and high extinction coefficients, making them suitable for integration in solar cells as photoactive components and/or as light-harvesting materials. The most significant results by Spanish groups in the field are collected in this report.
An ICT research agenda, HPC and innovation, and why only the developed world lacks women in computing
Authors: Wing Jeannette M. , Reed Daniel , Guzdial Mark
Published: July 2009

The
Communications
Web site, http://cacm.acm.org, features 13 bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish excerpts from selected posts, plus readers' comments.
IT drives policy---and vice versa
Authors: Geller Tom
Published: July 2009

Technologists discuss government policies affecting broadband, patent reform, privacy---and President Obama's effect on it all.
Economic and business dimensionsEntrepreneurship during a slump
Authors: Draper Tim
Published: July 2009

A contrarian's perspective on how entrepreneurial opportunities and innovation can thrive during an economic crisis.
PuzzledProbability and intuition
Authors: Winkler Peter
Published: July 2009

Welcome to three new puzzles. Solutions to the first two will be published next month; the third is (as yet) unsolved. In each puzzle, the issue is how your intuition matches up with the mathematics.
Technical opinionWhat drives the adoption of antiphishing measures by Hong Kong banks?
Authors: Bose Indranil , Leung Alvin Chung Man
Published: July 2009

Introduction

Phishing mongers and posers have taken the world by a storm and it is estimated that the annual financial loss due to phishing scams is at least US $320 million. Hong Kong has been a hotspot of phishing attacks and since majority of phishing incidences occurring in the world are related to the financial services industry, banks in Hong Kong have been frequent targets. We conducted a study of Hong Kong banks in 2005 and 2007 to assess their phishing readiness and to understand the driving forces that shaped their adoption of anti-phishing measures (AM) over time. We searched the security related information available on the Web sites of the Hong Kong banks to determine AM adopted by them. We scored the banks based on the adoption of AM and related it to characteristics of banks and other plausible external factors.
In the virtual extension
Authors: CACM Staff
Published: July 2009

Communications'
Virtual Extension brings more quality articles to ACM members. These articles are now available in the ACM Digital Library.
A model of message flow control
Authors: Kille S. E. , Brink D. H.
Published: July 2009

Substantial experience has now been gained in the use of store and forward message systems. At present, most significant systems currently fall into one of the following categories:

- Closed corporate systems, such as the DEC Engineering network.

- Academic / Research networks, such as the DARPA Internet, and the UK Joint Academic Network (JANET).

- Vendor provided services, without interaction with other vendor services (isolated Management Domains in X.400 terminology).

- Single system communities, such as the UUCP community.
Hox Genes and Segmentation of the Hindbrain and Axial Skeleton
Authors: Alexander Tara , Nolte Christof , Krumlauf Robb
Published: July 2009

Segmentation is an important process that is frequently used during development to segregate groups of cells with distinct features. Segmental compartments provide a mechanism for generating and organizing regional properties along an embryonic axis and within tissues. In vertebrates the development of two major systems, the hindbrain and the paraxial mesoderm, displays overt signs of compartmentalization and depends on the process of segmentation for their functional organization. The hindbrain plays a key role in regulating head development, and it is a complex coordination center for motor activity, breathing rhythms, and many unconscious functions. The paraxial mesoderm generates somites, which give rise to the axial skeleton. The cellular processes of segmentation in these two systems depend on ordered patterns of Hox gene expression as a mechanism for generating a combinatorial code that specifies unique identities of the segments and their derivatives. In this review, we compare and contrast the signaling inputs and transcriptional mechanisms by which Hox gene regulatory networks are established during segmentation in these two different systems.
Global Emergence ofBatrachochytrium dendrobatidisand Amphibian Chytridiomycosis in Space, Time, and Host
Authors: Fisher Matthew C. , Garner Trenton W.J. , Walker Susan F.
Published: July 2009

Batrachochytrium dendrobatidis (Bd) is a chytrid fungus that causes chytridiomycosis in amphibians. Only named in 1999, Bd is a proximate driver of declines in global amphibian biodiversity. The pathogen infects over 350 species of amphibians and is found on all continents except Antarctica. However, the processes that have led to the global distribution of Bd and the occurrence of chytridiomycosis remain unclear. This review explores the molecular, epidemiological, and ecological evidence that Bd evolved from an endemic ancestral lineage to achieve global prominence via anthropogenically mediated spread. We then consider the major host and pathogen factors that have led to the occurrence of chytridiomycosis in amphibian species, populations, and communities.
High‐Fidelity Aerothermal Engineering Analysis for Planetary Probes Using DOTNET Framework and OLAP Cubes Database
Authors: Subrahmanyam Prabhakar
Published: July 2009

This publication presents the architecture integration and implementation of various modules in Sparta framework. Sparta is a trajectory engine that is hooked to an Online Analytical Processing (OLAP) database for Multi‐dimensional analysis capability. OLAP is an Online Analytical Processing database that has a comprehensive list of atmospheric entry probes and their vehicle dimensions, trajectory data, aero‐thermal data and material properties like Carbon, Silicon and Carbon‐Phenolic based Ablators. An approach is presented for dynamic TPS design. OLAP has the capability to run in one simulation several different trajectory conditions and the output is stored back into the database and can be queried for appropriate trajectory type. An OLAP simulation can be setup by spawning individual threads to run for three types of trajectory: Nominal, Undershoot and Overshoot trajectory. Sparta graphical user interface provides capabilities to choose from a list of flight vehicles or enter trajectory and geometry information of a vehicle in design. DOTNET framework acts as a middleware layer between the trajectory engine and the user interface and also between the web user interface and the OLAP database. Trajectory output can be obtained in TecPlot format, Excel output or in a KML (Keyhole Markup Language) format. Framework employs an API (application programming interface) to convert trajectory data into a formatted KML file that is used by Google Earth for simulating Earth‐entry fly‐by visualizations.
Interfacing Sca‐1pos Mesenchymal Stem Cells with Biocompatible Scaffolds with Different Chemical Composition and Geometry
Authors: Forte G. , Franzese O. , Pagliari S. , Pagliari F. , Di Francesco A. M. , Cossa P. , Laudisi A. , Fiaccavento R. , Minieri M. , Bonmassar E. , Di Nardo P.
Published: July 2009

An immortalized murine mesenchymal stem cell line (mTERT‐MSC) enriched for Linneg/Sca‐1pos fraction has been obtained through the transfection of MSC with murine TERT and single‐cell isolation. Such cell line maintained the typical MSC self‐renewal capacity and continuously expressed MSC phenotype. Moreover, mTERT‐MSC retained the functional features of freshly isolated MSC in culture without evidence of senescence or spontaneous differentiation events. Thus, mTERT‐MSC have been cultured onto PLA films, 30 and 100 μm PLA microbeads, and onto unpressed and pressed HYAFF‐11 scaffolds. While the cells adhered preserving their morphology on PLA films, clusters of mTERT‐MSC were detected on PLA beads and unpressed fibrous scaffolds. Finally, mTERT‐MSC were not able to colonize the inner layers of pressed HYAFF‐11. Nevertheless, such cell line displayed the ability to preserve Sca‐1 expression and to retain multilineage potential when appropriately stimulated on all the scaffolds tested.