bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel crowned porphyrin derived from meso-tetrakis(penta-fluorophenyl)porphyrin
Authors: Gotardo Maria Carolina A. F. , Sacco Hérica C. , Filho Juvenal C. S. , Ferreira Antônio G. , Tedesco Antônio Claudio , Assis Marilda D.
Published: July 2009

The porphyrin 5,10,15,20-tetrakis[4-(1,4,7,10,13-pentaoxacyclopentadecane-2-aminomethyl)2,3,5,6-tetrafluorophenyl]porphyrin,T15C5P, was synthesized by the reaction of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin with the crown ether 2-aminomethyl-(15-crown-5). The crowned porphyrin showed a distinct spectroscopic behavior in the presence of sodium and potassium ions. Dimerization studies based on absorption measurements clearly indicate that T15C5P aggregates in the presence of potassium ions in chloroform/methanol medium (1.0 × 10−5 mol.L −1 or 1.0 × 10−4 mol.L −1), with a dimerization constant ( K D ) of 2.14 × 10−5 and 2.23 × 10−5, respectively. The same formalism applied to the T15C5P in the presence of sodium ions indicated absence of the aggregation process. The ionic radius of Na + is suitable to fit well into the cavity of 15-crown-5 moieties, leading to intramolecular complexes only. Potassium ion is too large to lie in the hole of the crown ether entities and is probably located between two porphyrin molecules, promoting 2:1 aggregated complexes through it's sandwiching, as is observed for phthalocyanines.
A novel low symmetry sulfur containing porphyrazine: synthesis and its interaction with serum albumin
Authors: Yang Lifen , Ji Zhenping , Peng Zhenghe , Cheng Gongzhen
Published: July 2009

A novel low symmetry sulfur-containing porphyrazine, 5,23,28,32-octabutoxy-10,11,17,18-tetrahydro-[9,12,16,19]-tetrathiino-33H, 35H-dinaphtho-porphyrazine (OTTDP), was synthesized by mixed condensation and characterized by NMR, FAB-MS and UV-visible spectra; this complex was found to be low aggregation in organic solvents and can interact with the serum albumin at several binding sites.
Bifunctional HPPH-N2S2-99mTc conjugates as tumor imaging agents: synthesis and biodistribution studies
Authors: Ma Bing , Li Guolin , Kanter Peter , Lamonica Dominick , Grossman Zachary , Pandey Ravindra K.
Published: July 2009

Pyropheophorbide-a and the corresponding 3-(1'-hexyloxyethyl)-3-devinyl derivative ( HPPH ), the tumor-avid photosensitizers were conjugated with mono- or di-bisaminoethanethiols ( N 2 S 2 ligand). The in vivo biodistribution study of the related 99m Tc complexes was performed in F-344 rats bearing Ward colon tumors at 4 h and 24 h post injection. These data show that the complexes are stable and among four tracers, HPPH di-99 m Tc N 2 S 2 conjugate reaches the highest tumor uptake (%ID/g). The larger tumors reach higher concentrations of the tracer. However, the short 6 h half life of 99 m Tc is incompatible with the 24 h imaging time, suggesting that the use of a longer-lived isotope such as 111 In could still provide a useful scanning agent, or that further structure-activity screening could yield an HPPH analog with more appropriate pharmacokinetics for tumor imaging with 99 m Tc .
Properties and reactions of μ-(dihydroxo)dipalladium(II) bisporphyrin complexes
Authors: Takao Yuko , Takeda Tokuji , Tanikawa Sachiko , Setsune Jun-ichiro
Published: July 2009

μ-(dihydroxo)dipalladium(II) bisporphyrin was obtained by the reaction of dicationic bis(aqua)Pd(II) complexes of N21, N22-bridged porphyrin with NaOH or triethylamine. The reaction gives a mixture of two isomers and caused deprotonation from the active methylene compounds to give organopalladium(II) porphyrin complexes under neutral conditions.
Electroreduction of nitrite catalyzed by a dinuclear ruthenium phthalocyanine modified graphite electrode
Authors: Ebadi Mehrdad , Lever A. B. P.
Published: July 2009

The electrocatalytic reduction of nitrite on a dinuclear ruthenium phthalocyanine ( RuPc )2modified electrode is studied, using cyclic voltammetry (cyclic voltammogram), rotating disc electrode (RDE) and ring-disc electrode (RRDE) techniques. The products of nitrite reduction are ammonia, nitrous oxide, and hydroxylamine. Depending on the experimental conditions, ammonia or nitrous oxide is formed as the main product. The initial step in the electroreduction of nitrite catalyzed by ( RuPc )2is a one electron RuII/ RuIprocess, followed by coordination of NO2−to the metal center. Formation of a nitrosyl complex prior to the electroreduction does not occur. A suitable mechanism is proposed by analyzing the rate equation and the Tafel slope.
Synthesis of soluble functional dye phthalocyanines and perylene tetracarboxylic derivatives by microwave irradiation and their photoelectric performances
Authors: Liu Lung-chang , Hu Andrew Teh
Published: July 2009

Soluble phthalocyanines, including organo-soluble tetrakis(2,9,16,23-tert-butylphthalocyanines) ( M ( TBPc ), M = H 2, Cu , Mg ; M ( TBPc )2, M = Tb , Dy ) as well as the water-soluble sodium salt of sulfonated phthalocyanines (( MPc ( SO 3 Na )4), M = Cu , Zn , Mg ), and perylene tetracarboxylic derivatives (N,N'-bis(1,5-dimethylhexyl)-3,4: 9,10-perylenebis(dicarboximide)) have been prepared by microwave irradiation. Their photoelectric performances have also been investigated. Among lab-made cells, the SnO 2glass / MgPc ( SO 3 Na )4 / PDHEP / Al photoelectric cell exhibits the best photoelectricity conversion effect with a short-circuit photocurrent (116.0 μA / cm 2) under illumination of white light 1.201 mW/cm2.
Synthesis and structure of amorphous phaseCr(II) hemiporphyrazine using energy dispersive X-ray diffraction
Authors: Matassa Roberto , Cervone Elena , Sadun Claudia
Published: July 2009

A metal complex of general formula Cr (II)- C26H14N8has been obtained as an amorphous compound and studied by means of IR and Energy Dispersive X-ray Diffraction (EDXD). The chemical composition and the IR signals of the sample suggest that the hemiporphyrazine is bound to the metal atom via nitrogen atoms. EDXD data confirm this finding and show that the compound structure is composed of two parallel stacks of seven planar macro-molecules. The second stack is rotated by 5° around the z axis originating in its center of mass and the molecules are lying on parallel planes to xy plane.
Synthesis and electrochemical investigation of covalently linked porphyrin dimers containing a β-brominated subunit.
Authors: Ou Zhongping , Tagliatesta Pietro , Senge Mathias O. , Shao Jianguo , Kadish Karl M.
Published: July 2009

Ten meso-tetraphenylporphyrin-type heterodimers containing a partly or completely β-brominated subunit were synthesized and characterized by UV-visible spectroscopy, cyclic voltammetry and spectroelectrochemistry, showing the presence of low electronic interactions between the two subunits. The investigated compounds are represented as M [( tripp - tpp ( Br 4)] M and M [ tripp - tpp ( Br 8)] M ( M = 2 H , Zn , Ni , Co and Cu ) where tripp - tpp ( Br 4) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,12,13-tetrabromoporphyrinyl)]-benzene and tripp - tpp ( Br 8) is the tetraanion of 1-[5-(10,15,20-triphenylporphyrinyl)]-4-[10-(2,3,7,8,12,13,17,18-octabromoporphyrinyl)]-benzene. One of the synthesized dimers, H 2[ tripp - tpp ( Br 8)] H 2, was characterized by a single-crystal X-ray investigation.
Efficient synthesis of highly soluble doubly-bridged porphyrin-fullerene dyad
Authors: Efimov Alexander , Vainiotalo Pirjo , Tkachenko Nikolai V. , Lemmetyinen Helge
Published: July 2009

The double-linked porphyrin-fullerene dyad has been prepared in high yield. The title compound is soluble in a wide range of solvents with different polarity, such as n-pentane or benzonitrile.
Effects of pH and organic co-solvents on the oxidation of naphthalene with peroxosulfate catalyzed by iron(III) tetrakis(p-sulfonatophenyl)porphyrin
Authors: Kawasaki Mikio , Kuriss Anabel , Fukushima Masami , Sawada Akira , Tatsumi Kenji
Published: July 2009

The oxidation of naphthalene was investigated in a biomimetic catalytic system using KHSO 5 and iron(III) tetrakis(p-sulfonatophenyl)porphyrin ( FeTPPS ) in order to elucidate the influence of solution forms, such as buffer pH and co-solvent types, on the reaction. 1,4-naphthoquinone was the main byproduct and the efficiency of oxidation, particularly 1,4-naphthoquinone formation, was influenced by pH and the type of co-solvent used. The most efficient conversion of 1,4-naphthoquinone was observed at an acidic pH (= 3). At higher pH , the formation of μ-oxo species ( OFe 2( TPPS )2) leads to a decrease of the percentage of naphthalene oxidized. In addition, the organic co-solvents (methanol, ethanol, 2-propanol and acetonitrile) influenced the amounts of naphthalene conversion. The amounts of 1,4-naphthoquinone formed were related to the electron donating character of the organic co-solvents.
Highly brominated porphyrins: synthesis, structure and their properties
Authors: Bhyrappa Puttaiah , Purushothaman Bhavana , Vittal Jagadese J.
Published: July 2009

This article reports the first perbromination of β-pyrrole and meso-phenyl groups of the 5,10,15,20-tetrakis(3',5'-dimethoxyphenyl)porphinato copper(II) to generate highly brominated porphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2',6'-dibromo-3',5'-dimethoxyphenyl)-porphinato copper(II), CuT (3',5'- DMP ) PBr 16 complex. Its crystal structure exhibited unusual five-coordination geometry with saddle shaped conformation of the porphyrin core. H2T(3',5'- DMP ) PBr 16 and its metal complexes exhibited large anodic shift of oxidation potentials with marginal changes in reduction potentials relative to their corresponding octabromotetraphenylporphyrin, MTPPBr 8 derivatives. The enhanced electron deficiency of the ZnT (3',5'-DMP)PBr16 complex was probed by axial ligation of various Lewis bases with differing pK a values. The ZnT (3',5'-DMP)PBr16 complex exhibited decrease in equilibrium constants for the ligation of bases relative to sterically unhindered ZnTPPBr 8. This has been ascribed to the sterics induced by the bulky ortho-bromo phenyl substituents that prevents the facile binding of Lewis bases to the Zn (II)-center.
New aspects of porphyrin coordination chemistry in Russia and former Soviet Union countries
Authors: Berezin Boris D.
Published: July 2009

This paper summarizes what was discussed in a lecture at the IXth International Conference on Porphyrin Chemistry held in Suzdal (Russia) in September 2003. The development of porphyrin chemistry in former Soviet Union countries and over the world are discussed. Some ideas which were cultivated during three conditional porphyrin periods (1930-1960, 1960-1980 and 1980-2000) are also discussed.
Oleic acid peroxidation in the presence of metallo-porphyrins
Authors: Milaeva Elena R. , Gracheva Yulia A. , Shpakovsky Dmitry B. , Gerasimova Olga A. , Tyurin Vladimir Yu. , Petrosyan Valery S.
Published: July 2009

The influence of free bases of meso-tetrakis(3,5-di-tert-butyl-4-hydroxy-phenyl)porphyrins and meso-tetraphenylporphyrins and their complexes of Co , Ni , Cu , Pt upon the radical chain oxidation of oleic acid as model substrates for lipid peroxidation has been studied. It was shown that the introduction of the antioxidative phenolic fragment into the porphyrin ring leads to the dual activity of phenolic porphyrins when compared with their tetraphenyl substituted analogues in substrate oxidation. Free base phenolic porphyrins and their nickel, copper, platinum complexes demonstrate acute inhibitory effect upon oleic acid peroxidation due to the key role of 2,6-di-tert-butylphenol moities, whereas cobalt porphyrin exhibits dual activity associated with the presence of both the redox active metal center and phenolic group.
New bacteriochlorin derivatives with a fused N-aminoimide ring
Authors: Mironov Andrey F. , Grin Michael A. , Tsiprovskiy Alexander G. , Kachala Vadim V. , Karmakova Tatyana A. , Plyutinskaya Anna D. , Yakubovskaya Raisa I.
Published: July 2009

Upon interaction of hydrazine hydrate with bacteriopurpurin, the initially formed monohydrazide in an acidic medium readily reacts with the second carboxyl group to give a six-membered N-aminocycloimide of bacteriochlorin p6. The free amino group at the fused imide ring makes it easy to obtain N-alkyl and N-acyl derivatives. The compounds thus obtained exhibit high light-induced cytotoxicity on A549 human adenocarcinoma cells.
Structure and excited state properties of multiporphyrin arrays formed by supramolecular design
Authors: Zenkevich Eduard I. , von Borczyskowski Christian , Shulga Alexander M.
Published: July 2009

Structurally defined nanoscale self-assembled multiporphyrin arrays of variable geo-metry and composition (up to eight tetrapyrrole macrocycles) have been formed via two-fold extra-ligation in solutions at 77-293 K. The array formation is based on non-covalent binding interactions of the phenyl bridged Zn octaethylporphyrin chemical dimers or trimers, ( ZnOEP )2Ph or ( ZnOEP )3Ph2, with di- and tetrapyridyl substituted tetrapyrrole extra-ligands (porphyrin, pentafluorophenyl substituted porphyrin, Cu porphyrin, tetrahydroporphyrin). Using steady-state and time-resolved measurements, spectral properties as well as pathways and dynamics of non-radiative relaxation processes (energy migration, photoinduced electron transfer, exchange d-π effects, realized in nano-femtosecond time scale) have been studied in these complexes upon variation of the composition, mutual geometry, redox and photophysical properties of interacting subunits as well as on the tempera-ture and polarity of surrounding.
Primary photoprocesses in cationic 5,10,15,20-meso-tetrakis(4-N-methylpyridiniumyl)porphyrin and its transition metal complexes bound with nucleic acids
Authors: Chirvony Vladimir S.
Published: July 2009

Photophysical properties of meso-tetrakis(4-N-methylpyridiniumyl)porphyrin ( TMpyP 4) and its metallocomplexes M (II) TMpy P4 ( M = Zn , Cu , Ni , Co ) bound to natural DNA and synthetic poly-, oligo- and mononucleotides are considered with a primary emphasis placed upon intermolecular interaction of the photoexcited porphyrins with the nearest environment. Quenching of the fluorescent S 1 (but not triplet T 1) state due to guanine to porphyrin electron transfer is observed for TMpyP 4 intercalated between GC base pairs of the double-strand helixes, whereas in the case of TMpyP 4 complexed with guanosine monophosphate (GMP) both S 1 and T 1 states of the porphyrin are quenched. Furthermore, a dependence of the efficiency of TMpyP 4 triplet state quenching by the dissolved molecular oxygen from air on the porphyrin localization enables one to readily distinguish porphyrin groove binding mode from intercalation. Excited states of the TMpyP 4 complexes with transition metals, in spite of their very short lifetimes, also interact with nucleic acid components by means of an axial ligand binding/release to/from the metal. A possible structure of the five-coordinate excited complex (“exciplex”) formed in case of CuTMpyP 4 groove binding to some single- and double-strand polynucleotides is discussed.
Fullerene complexes with cobalt(II) tetraphenylporphyrin: from molecular to ionic crystals
Authors: Konarev Dmitri V. , Khasanov Salavat S. , Saito Gunzi , Lyubovskaya Rimma N.
Published: July 2009

The complexes of cobalt(II) tetraphenylporphyrin ( Co II TPP ) with fullerenes C 60, C 70 and C 60( CN )2 are presented. It is shown that Co II TPP forms complexes with fullerenes in different solvents: [ Co II TPP •fullerene•solvent] ( solvent = C 6 H 6, C 6 H 5 Me , C 6 H 4 Cl 2, CS 2, CHCl 3). The use of additional donors ( Cp 2 Fe , Cr 0( C 6 H 6)2, and TDAE ) in the synthesis of Co II TPP /fullerene complexes allows one to obtain multi-component complexes ranging from neutral [( Co II TPP • Py )2• Cp 2 Fe • fullerene • solvent ] to ionic [ Co II TPP •( D 2•+)•( fullerene •−)• solvent ] ( D 2 = Cr I( C 6 H 6)2, TDAE ). The interaction of Co II TPP with neutral and negatively charged fullerenes is considered. The neutral Co II TPP /fullerene complexes are characterized by a secondary M…C(fullerene) bonding with the shortest Co … C contacts in the 2.69-2.82 Å range and noticeable changes in the electronic structure of the parent components. At the same time, σ-bonding is observed in ionic complexes between Co II TPP and fullerene radical anions with the shortened Co … C contacts being in the 2.28-2.32 Å range. The resulting ( Co II TPP •fullerene−) anions are diamagnetic. The σ-bonding is relatively weak and the ( Co II TPP •fullerene−) anions begin to dissociate above 200 K.
Stability of octaphenyltetraazaporphyrin complexes with rare earth metals in proton-donor media
Authors: Khelevina Ol'ga G.
Published: July 2009

The acid-base interactions and solvoprotolytic dissociation of octaphenyltetraaza-porphyrin complexes with rare earth metals are discussed. The thermodynamic and kinetic stability of the acid forms of the complexes are compared.
Porphyrins with fused exocyclic rings
Authors: Vicente M. Graça H. , Smith Kevin M.
Published: July 2009

A review is presented of the authors’ work, and directly relevant work of others, on the synthesis, structure and chemistry of porphyrin systems bearing fused aliphatic and π-conjugated rings. This includes a number of oligomeric porphyrin arrays.
Contributions to the chemistry of anionic water-soluble tetraarylporphyrins and their metal complexes
Authors: Buchler Johann W.
Published: July 2009

Recent contributions to the coordination chemistry of tetraanionic water-soluble tetraarylporphyrins, namely 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin, [1]4−, 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin, [2]4−, and 5,10,15,20-tetrakis(4-hydroxidophosphorylmethylphenyl)porphyrin, [ H 43]4−, are reported. Problems with the isolation of sodium and potassium salts of [2]4− are discussed. The tetraphosphonoporphyrin H 8[3] is precipitated as a dihydrochloride H 8[3]·2 HCl , its metal complexes H 8[3-M] as such. The synthesis of salts containing Ce and Os complexes of [1]4−, Al , Ga , In , Ge , Sn , As , Sb , Mn , Mo , W , Re , Os , and Pt complexes of [2]4−, and Ni , Cu , Zn , Pt and Os complexes of [ H 43]4− as documented in publications and doctoral theses from the Darmstadt laboratory are reviewed. Some properties of the new complex salts are reported. The results of crystal structure determinations of the potassium salt of tetrakis(4-sulfonatophenyl)porphyrinatoplatinate(II), K 8[2-Pt]2·10 DMSO ·6 H 2O· C 7 H 8, and the mixed sodium-potassium salt of tetrakis(4-sulfonatophenyl)porphyrinatoaluminate, K 2 Na [ Al ( DMSO )2( tpps 4)]·8( DMSO )·2 H 2 O , are shown.
N-confused porphyrins as new scaffolds for supramolecular architecture
Authors: Maeda Hiromitsu , Furuta Hiroyuki
Published: July 2009

The peripheral nitrogen of N -confused porphyrins ( NCP ) can serve as a hydrogen bonding donor and acceptor, and a metal coordination site as well. NCP forms versatile dimers with the assistance of metal ions such as Pd II, Pt II, Zn II, Cd II, Hg II, Mn II and Fe II. The square-planar divalent metal complexes of C 6 F 5-substituted NCP with Cu II, Ni II and Pd II act as efficient anion binding receptors. The doubly N -confused porphyrins ( N 2 CP ), possessing both N and NH at the periphery, form self-assembled 1-D hydrogen bonding networks, whose orientations differ in cis (zigzag) and trans (straight) isomers.
Recent developments in robust microporous porphyrin solids
Authors: Smithenry Dennis W. , Suslick Kenneth S.
Published: July 2009

A review of the recent literature is presented which assesses the development of robust microporous porphyrin framework solids and their potential to perform selective sorption or heterogeneous shape- or size-selective catalysis. The review focuses only on those porphyrin solids whose porosity is robust, i.e. whose framework remains after the removal of solvates, as determined by thermal gravimetric analysis (TGA), X-ray powder diffraction (XRD), or gas adsorption studies. Eleven such robust porphyrin framework solids are presented.
β-Pyrrole brominated meso-tetraphenylporphyrins: synthesis, spectral and electrochemical properties
Authors: Ou Zhongping , Shao Jianguo , D'Souza Francis , Tagliatesta Pietro , Kadish Karl M.
Published: July 2009

The synthesis, catalytic properties, UV-visible spectra and electrochemistry of β-pyrrole brominated porphyrins are summarized in this brief review. The effect of the Br substituents of the porphyrin ring on the redox behavior, and on axial CO or pyridine binding to the porphyrins is also discussed.
Linear tetrapyrroles as functional pigments in chemistry and biology
Authors: Mizutani Tadashi , Yagi Shigeyuki
Published: July 2009

1,19,21,24-tetrahydro-1,19-bilindione is the framework of pigments frequently found in nature, which includes biliverdin IX α, phytochromobilin and phycocyanobilin. 1,19-bilindiones have unique features such as (1) photochemical and thermal cis-trans isomerization, (2) excited energy transfer, (3) chiroptical properties due to the cyclic helical conformation, (4) redox activity, (5) coordination to various metals, and (6) reconstitution to proteins. 1,19-bilindione can adopt a number of conformations since it has exocyclic three double bonds and three single bonds that are rotatable thermally and photochemically. In solution, biliverdin and phycocyanobilin adopt a cyclic helical ZZZ, syn, syn, syn conformation, but other conformations are stabilized depending on the experimental conditions and substituents on the bilin framework. The conformational changes in 1,19-bilindiones are related to the biological functions of a photoreceptor protein, phytochrome. Structural and conformational studies of bilindiones are summarized both in solution and in protein. The conformational changes of bilins can be used for other functions such as a chirality sensor. The bilindiones and the zinc complexes of bilindiones can be employed as a chirality sensor due to the helically chiral structure and the dynamics of racemization of enantiomers. In this paper, we discuss the conformational equilibria and dynamics of bilindiones and its implications in photobiology and materials science.
Enhancement of enzymatic activity for myoglobins by modification of heme-propionate side chains
Authors: Hayashi Takashi , Sato Hideaki , Matsuo Takashi , Matsuda Takaaki , Hitomi Yutaka , Hisaeda Yoshio
Published: July 2009

The modification of myoglobin is an attractive process not only for understanding its molecular mechanism but also for engineering the protein function. The strategy of myoglobin functionalization can be divided into at least two approaches: site-directed mutagenesis and reconstitution with a non-natural prosthetic group. The former method enables us to mainly modulate the physiological function, while the latter has the advantage of introducing a new function on the protein. Particularly, replacement of the native hemin with an artificially created hemin having hydrophobic moieties at the terminal of the heme-propionate side chains serves as an appropriate substrate-binding site near the heme pocket, and consequently enhances the peroxidase and peroxygenase activities for the reconstituted myoglobin. In addition, the incorporation of the synthetic hemin bearing modified heme-propionates into an appropriate apomyoglobin mutant drastically enhances the peroxidase activity. In contrast, to convert myoglobin into a cytochrome P450 enzyme, a flavin moiety as an electron transfer mediator was introduced at the terminal of the heme-propionate side chain. The flavomyoglobin catalyzes the deformylation of 2-phenylpropanal in the presence of NADH under aerobic conditions through the peroxoanion formation from the oxygenated species. In addition, modification of the heme-propionate side chains has an significant influence on regulating the reactivity of the horseradish peroxidase. Furthermore, the heme-propionate side chain can form a metal binding site with a carboxylate residue in the heme pocket. These studies indicate that modification of the heme-propionate side chains can be a new and effective way to engineer functions for the hemoproteins.
CoenzymeB12-dependent enzymatic dehydration of 1,2-diols: simple reaction, complex mechanism!
Authors: Speranza Giovanna , Buckel Wolfgang , Golding Bernard T.
Published: July 2009

The conversion of glycerol to acrolein is an undesirable event in whisky production, caused by infection of the broth with Klebsiella pneumoniae. This organism uses glycerol dehydratase to transform glycerol into 3-hydroxypropanal, which affords acrolein on distillation. The enzyme requires adenosylcobalamin (coenzyme B12) as cofactor and a monovalent cation (e.g. K+). Diol dehydratase is a similar enzyme that converts 1,2-diols ( C2- C4) including glycerol into an aldehyde and water. The subtle stereochemical features of these enzymes are exemplified by propane-1,2-diol: both enantiomers are substrates but different hydrogen and oxygen atoms are abstracted. The mechanism of action of the dehydratases has been elucidated by protein crystallography and ab initio molecular orbital calculations, aided by stereochemical and model studies. The 5'-deoxyadenosyl (adenosyl) radical from homolysis of the coenzyme's Co - C σ-bond abstracts a specific hydrogen atom from C -1 of diol substrate giving a substrate radical that rearranges to a product radical by 1,2-shift of hydroxyl from C -2 to C -1. The rearrangement mechanism involves an acid-base 'push-pull' in which migration of OH is facilitated by partial protonation by Hisα143, synergistically assisted by partial deprotonation of the non-migrating ( C -1) OH by the carboxylate of Gluα170. The active site K+ion holds the two hydroxyl groups in the correct conformation, whilst not significantly contributing to catalysis. Recently, diol dehydratases not dependent on coenzyme B12have been discovered. These enzymes utilize the same kind of diol radical chemistry as the coenzyme B12-dependent enzymes and they also use the adenosyl radical as initiator, but this is generated from S-adenosylmethionine.
Supramolecular assemblies for electron transfer
Authors: Guldi Dirk M. , Imahori Hiroshi
Published: July 2009

Recent advances in electron transfer chemistry of supramolecular electron donor-acceptor assemblies – containing porphyrins and metalloporphyrins – in connection with ICPP-3 are reviewed briefly by focusing on aspects of electron and energy transfer reactions.
Synthesis and properties of water-soluble porphyrins bearing multidentate ligands
Authors: Uemori Yoshio , Sakurai Masato , Osada Atsuko , Munakata Hiroki , Imai Hiroyasu , Nakagawa Shigeo
Published: July 2009

Water-soluble porphyrins bearing multidentate ligands were prepared by covalent binding of nitrilotriacetic acid to 5,10,15,20-tetrakis(4-aminophenyl)porphyrin or three atropisomers of 5,10,15,20-tetrakis(2-aminophenyl)porphyrin. The acid-base properties and monomer-dimer behavior of the porphyrins were affected by the positions of the multidentate ligands with respect to the porphyrin plane. Among the porphyrins, the porphyrin bearing multidentate ligands at the para position of the phenyl groups dimerized in an aqueous solution. The association constants of the porphyrins with various aromatic compounds were studied in water at pH 7.4 containing 10 mM HEPES at 25°C. These values varied with the structure and charges of both the porphyrins and the aromatic compounds. The association constants of the porphyrin bearing multidentate ligands at the 2-position of the phenyl groups were small compared to those of the porphyrin bearing multidentate ligands at the 4-position.
First highly distorted π-extended Fe(II) porphyrin – a unique model to elucidate factors affecting the electrochemical potentials
Authors: Kadish Karl M. , Finikova Olga S. , Espinosa Enrique , Gros Claude P. , Stefano Guido De , Cheprakov Andrei V. , Beletskaya Irina P. , Guilard Roger
Published: July 2009

The preparation, X-ray crystal structure and electrochemistry of a new poly-substituted air-stable tetrabenzoporphyrin iron(II) bis-pyridine complex (1) is reported.
Contrast-enhanced near-infrared (NIR) optical imaging for subsurface cancer detection
Authors: Zheng Gang , Chen Yu , Intes Xavier , Chance Britton , Glickson Jerry D.
Published: July 2009

Synergistic efforts in the developments of molecular specific imaging probes and advancements of optical imaging technologies (including the novel instrumentation and imaging algorithms) that lead to a new tool for early disease diagnosis and drug discovery are described.
New porphyrin architectures and host-guest chemistry
Authors: Maiya Bhaskar G.
Published: July 2009

This article reviews recent developments that have taken place in research related to new porphyrin architectures and their host-guest chemistry, as described in a microsymposium bearing the same name held during the 3rd International Conference on Porphyrins and Phthalocyanines (ICPP-3). The usefulness of representative arrays, aggregates, donor-acceptor systems, and receptor motifs based on porphyrin architectures is highlighted as it applies to the fabrication of molecular devices, understanding the biomimetic electron transfer processes, and recognition of bioorganic substrates.
Synthesis and photochemical studies of substituted adjacent binaphthalophthalocyanines
Authors: Seotsanyana-Mokhosi Itumeleng , Nyokong Tebello
Published: July 2009

Adjacent phthalocyanines with a binaphthalo backbone and phenoxy substituents were synthesized and their photochemical properties were investigated. The adjacent phthalocyanines are the binaphthalophthalocyanines, with the phenoxy, 4-tert-butylphenoxy and the sulfophenoxy substituents, respectively and bis-binaphthalophthalocyanine which has an extended π conjugation system and larger singlet oxygen quantum yield compared to the other compounds. The presence of the phenoxy substituents as well as the binaphthalo bridge does not cause a marked difference on the fluorescing properties of these complexes when compared to zinc phthalocyanine. The binaphthalo backbone allowed the molecules to photoswitch during photolysis affording them very high photostability.
Characterization of sulfonated phthalocyanines by mass spectrometry and capillary electrophoresis
Authors: Dixon Dabney W. , Gill Anila F. , Sook Brian R.
Published: July 2009

We report the characterization of sulfonated phthalocyanines using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. In general, sulfonated phthalocyanines were found as aggregates in capillary electrophoresis separations, even at low concentration. Separations were much better at pH 9.0 than at pH 2.5. The addition of β-cyclodextrin did not alter the electropherograms significantly. The electropherograms of commercially available copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid and 4,4',4″,4‴-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. In general, MALDI gave better results than ESI. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Sulfonated tetraphenylporphyrin derivatives were used as standards for mass spectrometry and to estimate the effect of net charge on the capillary electrophoresis migration time for sulfonated tetrapyrroles. Clean separation of the sulfonated tetraphenylporphyrin derivatives [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3) and 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2a)] was observed by capillary electrophoresis.
Unusual solvent dependent electronic absorption spectral properties of nickel(II) and copper(II) perhaloporphyrins
Authors: Sankar Muniappan , Arunkumar Chellaiah , Bhyrappa Puttaiah
Published: July 2009

Electronic absorption spectra of divalent metal ( Ni (II) and Cu (II)) complexes of 2,3,7,8,12,13,17,18-octa(bromo/chloro)-5,10,15,20-tetraphenylporphyrins (MOXTPP; X = Br , Cl ) were examined in various solvents. M (II) perhaloporphyrins exhibited dramatic shifts in their optical absorption spectral features relative to the corresponding metallotetraphenylporphyrins, MTPPs. Copper(II) perhaloporphyrins show significant red-shifts of the absorption bands in coordinating solvents relative to that observed for nickel(II) perhaloporphyrins. The large red-shift of the electronic absorption bands and the gain in intensity of the longest wavelength band (Q(0,0)), of Cu (II) perhaloporphyrins in certain coordinating solvents is comparable to that found in meso-tetraphenylporphinatozinc(II), ZnTPP. The solvent dependent spectral features of M (II) perhaloporphyrins are attributed to a coordinative interaction of the solvent with the core metal ion induced by the electron deficient porphyrin macrocycle.
Hybrid thin films of ZnO with porphyrins and phthalocyanines prepared by one-step electrodeposition
Authors: Michaelis Esther , Nonomura Kazuteru , Schlettwein Derck , Yoshida Tsukasa , Minoura Hideki , Wöhrle Dieter
Published: July 2009

Hybrid thin films of crystalline zinc oxide and the zinc complex of 5,10,15,20-tetrakis-(4-sulfonatophenyl)porphyrin (ZnTPPS) have been prepared by cathodic electrodeposition from different aqueous zinc salt solutions. Films from a solution containing zinc nitrate and the porphyrin derivate show a rough surface and porosity, whereas films prepared from an oxygen-saturated zinc chloride solution were very smooth. The presence of the porphyrin derivative in the deposition solution has a clear influence on the morphology of the hybrid films compared with pure zinc oxide films. In aqueous zinc nitrate solution the addition of the porphyrin derivative hinders the growth of zinc oxide. In contrast, the addition of the dye to the oxygen-saturated zinc chloride solution leads to an increase of the growth rate of ZnO /porphyrin hybrid films. An increased spectral absorbance was reached when two dyes (zinc complex of tetrasulfonated phthalocyanine and porphyrin) were added to the zinc nitrate solution since the electrodeposited hybrid thin films contained both dyes. UV-vis spectra revealed the presence of both macrocyclic metal complexes in the ZnO films.
Synthesis, characterization and EPR spectroscopy of novel s-triazines bearing three oxygen-linked phthalocyanines
Authors: Ceyhan Tanju , Korkmaz Mustafa , Kutluay Türker , Bekaroğlu Özer
Published: July 2009

Compound 1 (2,4,6-tris(2-oxaphthalonitrile)- s -triazine) has been prepared by the reaction of 4-nitrophthalonitrile and cyanuric acid in dry DMF as the solvent in the presence of K 2 CO 3 as the base. An interesting s -triazine, containing three oxa metal phthalocyanines ( M = Zn , Co or Cu ) has been synthesized from compound 1, 4,5-bis(hexylthio)phthalonitrile and the corresponding anhydrous metal salts ( Zn ( OAc )2, CoCl 2 or CuCl ) by the method of statistically mixed condensation. The new compounds and phthalocyanines were obtained in sufficient purity after successive washings with different solvents and were characterized by elemental analysis, UV-vis, IR, NMR and EPR spectroscopy.
Phthalocyanine coatings on silica and zinc oxide: Synthesis and their activities in the oxidation of sulfide
Authors: Wöhrle Dieter , Baziakina Natascha , Suvorova Olga , Makarov Sergey , Kutureva Valentina , Schupak Elena , Schnurpfeil Günter
Published: July 2009

The reactivity of phthalonitrile, tetrafluorophthalonitrile and 4,5-dibutoxyphthalonitrile with unmodified surfaces of ZnO and SiO 2 and with the modified systems SiO 2/ Cp 2 Co , ZnO / Cp 2 Co , SiO 2/ Zn ( AcAc )2 prepared by deposition of cobaltocene ( Cp 2 Co ) and zinc acetylacetonate Zn ( AcAc )2, was studied ("in-situ-synthesis") in processes of phthalocyanine coatings. The formation of structural uniform phthalocyanines on carriers were established by UV-vis and mass spectra. The compounds were used then to compare their catalytic and photocatalytic activities in the oxidation of sulfide as a test reaction.
Spectroscopic, electrochemical, and microgravimetric studies on palladium phthalocyanine films
Authors: Gaffo Luciana , Gonçalves Débora , Faria Ronaldo C. , Moreira Wania C. , Oliveira Osvaldo N.
Published: July 2009

The optical properties of palladium phthalocyanine in dimethylformamide, toluene, acetonitrile, and dichloromethane solutions were studied in the visible range of energy. Palladium phthalocyanine in organic medium presented itself as a mixture of monomeric and dimeric species in equilibrium, and it was only in dichloromethane that the monomeric, non-aggregated form predominated. Palladium phthalocyanine films were prepared by casting, and studied by cyclic voltammetry and spectroelectrochemistry. The films showed an electrochromic response from blue to purple, and stability that depended on the applied potential. Electrochemical quartz crystal microbalance experiments indicated that the film exfoliates into solution after applying high values of final potentials. Raman spectroscopy was used to structurally characterize the palladium phthalocyanine film, which showed a central metal with +2 oxidation state that is not affected even when the film is oxidized.
Tuning the maximum absorption wavelengths of phthalocyanine derivatives
Authors: Jin Shan , Cheng Gongzhen , Chen George Z. , Ji Zhenping
Published: July 2009

A new series of low-symmetry octasubstituted metal-free phthalocyanines with the general formula H 2 N x P β4− x ( OBu )8 ( x = 0-4) were synthesized by mixed condensation of two different substituted precursors (4,5-dibutoxy- phthalonitrile and 1,4-dibutoxy-2,3-dicyanonaphthalene). Their electronic absorption spectra and MALDI-TOF-MS were investigated. The regiospecific, nonlinear and linear substituent effects of alkoxyl groups on the positions of the Q-bands of phthalocyanines with different substituent groups at different peripheral positions were systematically investigated. The results could provide a guide to the tuning of Q-band absorptions of phthalocyanine derivatives.
Electrochemistry of homoleptic bis[3(4),12(13),21(22),30(31)-tetra(tert-butyl)-naphthalocyaninato] rare earth(III) complexes
Authors: Li Renjie , Zhang Xianxi , Pan Na , Zhu Peihua , Kobayashi Nagao , Jiang Jianzhuang
Published: July 2009

The electrochemistry of homoleptic bis(naphthalocyaninato) double-decker complexes for the whole series of tervalent rare earths M ( TBNc )2 ( M = Y , La … Lu except Ce and Pm ; H 2 TBNc = 3(4),12(13),21(22),30(31)-tetra(tert-butyl)naphthalocyanine) has been systematically studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Up to three quasi-reversible one-electron oxidations and four quasi-reversible one-electron reductions have been revealed for these double-deckers.The half-wave potentials of all oxidations and the first reduction for double-decker complexes are dependent on the size of the metal center. The difference between the redox potentials of the first and second reductions for M III( TBNc )2, which represents the potential difference between the first oxidation and first reduction of [ M III( TBNc )2]−, lies in the range 1.09-0.95 V and gradually diminishes along with the lanthanide contraction, indicating increased π-π interaction in the double-deckers in the same order. Comparison of electrochemical characteristics between M ( TBNc )2 and M ( TBPc )2 ( H 2 TBPc = 2(3),9(10),16(17),24(25)-tetra(tert-butyl)-phthalocyanine) reveals that extension of the ligand conjugated system upon going from phthalocyanine to naphthalocyanine attenuates the ring-to-ring separation effect on the redox potentials of the double-deckers of the whole series of tervalent lanthanides.
Synthesis and electrochemical properties of bis(octacyanophthalocyaninato)neodymium(III) complex
Authors: Yonekura Tatsuya , Ohsaka Takeo , Kitamura Fusao , Tokuda Koichi
Published: July 2009

The bis(octacyanophthalocyaninato)neodymium(III) was synthesized and its electrochemical behavior in N,N-dimethylformamide ( DMF ) was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). Multiple redox reactions were observed on the cyclic voltammogram, although the voltammetric feature was complicated due to aggregation. With the aid of SWV, it was concluded that the redox potentials of the complex positively shifted by about 700 mV compared with potentials of the unsubstituted complex, which was ascribed to the strong electron-withdrawn effect of the substituted cyano group.
Further synthetic and structural investigations of new pre-organized picket porphyrins
Authors: Didier Amandine , Ruzié Christian , Baveux-Chambenoît Valérie , Richard Philippe , Boitrel Bernard
Published: July 2009

The straightforward synthesis of three new picket porphyrins with a restrained conformation is described. These porphyrins have an unusual behavior due to the conjugated but still flexible nature of their pickets. The crystal structure of their common precusor is also reported and confirms the presumed geometry of this type of picket. Indeed, the latter one is formally obtained by the conjugation of two aromatic rings through an amide bond. Although the specific shape of the picket is expected to overcrowd the center of the porphyrin, it is shown that different types of nucleophilic reagents can add easily on these pickets.
Synthesis, characterization and photochemistry of 5,10,15,20-tetrakis(4-N-pentylpyridyl)porphyrins, [(TPePyP)H2]4+ and [(TPePyP)ZnII]4+
Authors: Ajith Herath H. M. , Karunaratne Veranja , Gamini Rajapakse R. M. , Wickramasinghe Anura
Published: July 2009

Tetracationic 5,10,15,20-tetrakis(4- N -pentylpyridyl)porphyrins, [( TPePyP ) H 2]4+ and its zinc-porphyrin analogue [( TPePyP ) Zn II]4+ have been synthesized and characterized by 1 H NMR and UV-visible spectroscopic techniques. Photobleaching studies carried out in solutions of varying pH show that, in the presence of oxygen, [( TPePyP ) H 2]4+ undergoes fast photodegradation in aqueous medium when the solution is irradiated with 560 nm light. The steady-state singlet oxygen quantum yields (ΦΔ) for [( TPePyP ) H 2]4+ is 0.80 and that for its Zn analogue is 0.85. These quantities were measured using 1,3-diphenylisobenzofuran (DPBF) as a singlet oxygen scavenger, in N,N-dimethyl-formamide solution. These ΦΔ values are compared with those for other well known sensitizers such as protoporphyrindimethylester PPDME and hematoporphyrindihydrochloride HPDHC.
The reaction of μ-oxo-bis(phthalocyaninato)iron(III) with hydrogen sulphide in the presence of pyridine: Evidence for axial coordination of dichloromethane
Authors: Monacelli Fabrizio , Viola Elisa
Published: July 2009

The oxo-bridged complex ( py ) FePc - O - FePc ( py ) ( py = pyridine , Pc = phthalocyaninato dianion) reacts in dichloromethane with hydrogen sulphide giving elementary sulphur and the reduced ( py )2( FePc ) complex in the stoichiometric ratio 1:1. Under excess py and H2S , the reaction is first-order and the rate constant at a given py concentration is an increasing function of the reducing agent concentration, with asymptotic tendency to a limiting value. This latter depends on the pyridine concentration being higher the lower is the base concentration. When the reaction is carried out in pure pyridine, the rate constant is, instead, a strictly linear function of [ H2S ], with zero intercept. A reaction mechanism is proposed where the dichloromethane is directly involved in the axial coordination about the iron centers and H2S competes efficiently with both pyridine and solvent.
Alcohol oxidation with dioxygen mediated by oxotitanium porphyrin and related transition metal complexes
Authors: Du Guodong , Keith Woo L.
Published: July 2009

Oxotitanium porphyrin ( TTP ) Ti = O and related transition metal complexes were shown to catalyze the oxidation of alcohols using dioxygen as the oxidant. Vicinal diols were cleaved to carbonyl compounds in the presence of catalytic amounts of ( TTP ) Ti = O , ( TTP ) V = O or ( Saldach ) V = O . α-Hydroxy ketones were oxidized to α-diketones with ( TTP ) Ti = O . Benzyl alcohol was converted to benzaldehyde in modest to high yields by a number of high valent transition metal complexes. Reaction pathways for the transformations mediated by ( TTP ) Ti = O are discussed. Formation of diolato and enediolato complexes is believed to be the key step in the diol cleavage and α-hydroxy ketone oxidation, respectively.
Synthesis, spectroscopy, surface photovoltage, and electrochemical properties of porphyrin compound liquid crystals
Authors: Yu Miao , Liu Guo F. , Cui Xiao L.
Published: July 2009

Two series of porphyrin liquid crystalline compounds, meso-tetra-[(p-alkacyloxy-m-ethyloxy)phenyl]porphyrin ( TPAMEP ), and [5-(p-alkacyloxy) phenyl-10,15,20-tri-phenyl] porphyrin ( APTPP ) are synthesized and display a hexagonal columnar discotic columnar ( Col h ) phase. Their structure and properties were studied by elemental analysis, molar conductance, UV-visible and infrared spectra. Luminescence spectra of the compounds were discussed. Quantum yields of the Q band are in the region 0.007935-0.05847. The electrochemical studies show that the redox potentials do not change with the variation of the chain length. The surface photovoltage (SPV) response of the compounds was investigated by means of surface photovoltage spectroscopy (SPS) and field-induced surface photovoltage spectroscopy (FISPS), and the bands are analogous with the UV-visible absorption spectra.
Effect of molecular complex formation of metallophthalocyanines with pyridine on their aggregation
Authors: Lebedeva Natalia Sh. , Pavlycheva Natalia A. , Petrova Olga V. , Parfenyuk Elena V.
Published: July 2009

The results for aggregation equilibrium of metallophthalocyanines in buffer and buffer-pyridine solutions were obtained and generalized. The influence of specific interactions of the metallophthalocyanines with pyridine on their aggregation state in solution was estimated.
Rapid and efficient synthesis of metallophthalocyanines in ionic liquid
Authors: Safari Nasser , Jamaat Parisa R. , Shirvan Sadif A. , Shoghpour Samad , Ebadi Amin , Darvishi Maria , Shaabani Ahmad
Published: July 2009

Metallophthalocyanines have been synthesized in a very short time with excellent yields in the presence of tetrabutylammonium bromide ( TBAB ) as an ionic liquid at 185 °C. The ionic liquid can be recycled for subsequent reactions without any appreciable loss of efficiency.
Meso-meso linked hybrid porphyrin arrays from meso-formylated porphyrins
Authors: Hong Seung-Ki , Jeoung Eunhee , Lee Chang-Hee
Published: July 2009

Directly meso-meso linked, partially metallated porphyrin oligomers (dimer, trimer, bent trimer and tetramer) have been synthesized by condensation of meso-formylated porphyrins with pyrrole. The reaction could be useful in the construction of partially metallated, porphyrin arrays.
Synthesis, characterization and fluorescence properties study of meso-tetrakis(1-arylpyrazole-4-yl)porphyrins
Authors: Guo Can-Cheng , Ren Tie-Gang , Wang Jian , Li Chun-Yan , Song Jian-Xin
Published: July 2009

Five new meso-tetrakis(1-arylpyrazol-4-yl)porphyrins were synthesized to investigate their fluorescence properties. Preparation of these porphyrins was carried out by cyclization of tetramethoxypropane with substituted phenylhydrazine, followed by formylation to give the corresponding aldehydes, which reacted with pyrrole under the Adler reaction condition to get the target porphyrins (1a-1e). All the porphyrins were characterized by 1 H NMR, elemental analysis, UV-vis spectra and mass spectra. Red fluorescence emission of these porphyrins was observed in fluorescence spectra. Compared with meso-tetraphenylporphyrin (TPPH2), these meso-tetrakis(1-arylpyrazol-4-yl) porphyrins had a significant red shift in UV-vis and fluorescence spectra with increased fluorescence quantum yields.