bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitrophotosensitizing efficacy of cationic phthalocyanine derivatives againstC.albicans: effect of serum albumins
Authors: Chiti Giacomo , Dei Donata , Fantetti Lia , Roncucci Gabrio
Published: July 2009

The effect of serum albumins (as Fetal Calf Serum) on in vitro photosensing efficacy against C.albicans of three cationic Zn ( II ) phthalocyanine derivatives was evaluated. A clearly structure-dependent reduction in the antifungine activity was observed. For this reason the binding of the photosensitizers with albumins (as bovine serum albumin, BSA) at pH 7.4 was studied. Because of aggregation phenomena, the phthalocyanine derivatives showed little fluorescence in aqueous solutions and fluorescence intensity increased as a function of protein concentration. Titration plots were built and binding constant were determined. The obtained binding parameters and the hydrolipophilic properties of the studied molecules (octanol/water partition coefficient PO / W, number of cationic charges, amphipilicity) were correlated with the observed biological effect.
Synthesis, spectroscopic and electrochemical investigations of supramolecular nickel(II)tetraazaporphyrin complexes
Authors: Prasad Rajendra , Kumar Ajay
Published: July 2009

The ( bpy )2RuIIand ( phen )2RuIImoieties were linked to [ Ni ( OBTTAP )]1, periphery through coordinate bonds in order to synthesize cationic di- and pentanuclear complexes 2-5 that were obtained as PF6−salts. They were characterized by IR,1H NMR, UV-vis, and mass spectral data. The electronic absorption, emission and redox data of these bichromophoric systems indicate the presence of a high degree of intercomponent electronic interaction. The position and relative intensities of the Soret and Q bands in these complexes is altered due to peripheral binding of the metal units. The compounds were non-emissive for the Q band excitation but, Soret excitation led to a strong S2emission, observed between 400-450 nm. In cyclic voltammetry, the compounds exhibited one Ru centered oxidation together with one or two OBTTAP centered oxidations. The RuII/ RuIIIoxidations were observed at significantly lower potentials as compared to the corresponding simple maleonitrile-benzylthioether complexes and has been interpretted in terms of weaker d π( S )– d π( Ru ) interactions.
First evidence of formation of stable DBU Zn-phthalocyanine complexes: synthesis and characterization
Authors: Del Sole Roberta , De Luca Agnese , Mele Giuseppe , Vasapollo Giuseppe
Published: July 2009

Novel Zn (II) phthalocyanine and naphthalocyanine DBU complexes have been prepared in a one-pot synthesis reacting phthalonitrile precursors with an excess of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). For the first time, it has been well evidenced that DBU played the role of coordinating axial ligand together with the well known role of strong base. Also, DBU complexes showed better solubility in organic solvents due to the coordination of the bulky axial DBU ligand, compared to the Zn (II) phthalocyanines and naphthalocyanines without coordinated DBU. The coordinating properties of DBU toward ZnPcs (DBU free) complexes have also been investigated along with the ZnPc (pyridine) complex. Thermal analysis results reflecting the stability of the synthesized complexes under air are also presented.
Rapid synthesis of phthalocyanine-based discotic liquid crystals by using a novel hand-made microwave-heating apparatus
Authors: Ooi Keisuke , Maeda Fumihiro , Ohta Kazuchika , Takizawa Tokihiro , Matsuse Takehiko
Published: July 2009

Phthalocyanine ( Pc )-based discotic liquid crystals could be prepared very rapidly by using our developed novel microwave-heating apparatus. It took only 10-20 min to synthesize these Pc metal complexes and metal-free Pc derivatives in an organic solvent (glycerin) by microwave irradiation, whereas it took 24-48 h to synthesize them by the conventional oil bath method. To our knowledge, it is the first example of metal-free Pc derivatives synthesized by microwave methods in an organic solvent. In the vast examples of Pc syntheses by conventional oil bath methods, the Pc metal complexes can be obtained in higher yields by “Template Effect” of the metal than the corresponding metal-free Pc derivatives. Therefore, we expected that the present Pc metal complexes ( C n S )8 PcCu (2) could be also prepared by microwave methods in higher yields than the metal-free Pc derivatives ( C n S )8 PcH 2 (1). Contrary to our expectation, the yields of the metal complexes ( C n S )8 PcCu (2) were lower than those of the metal-free derivatives ( C n S )8 PcH 2 (1). It is very interesting that this result by the microwave method is quite opposite to the results by conventional oil bath method. Hence, in this work we have focused our interest on the “Template Effect” in the syntheses of Pc derivatives by the microwave method in order to investigate the relationship between microwave heating and template effect. It is the first attempt in Pc syntheses by the microwave method.
Imine-substituted dipyrromethanes in the synthesis of porphyrins bearing one or two meso substituents
Authors: Taniguchi Masahiko , Balakumar Arumugham , Fan Dazhong , McDowell Brian E. , Lindsey Jonathan S.
Published: July 2009

5,15-substituted porphyrins are valuable compounds in bioorganic and materials chemistry. A new synthesis has been developed that employs 1,9-diformylation of a dipyrromethane, conversion of the diformyldipyrromethane to the bis(imino) derivative, and reaction of the bis(imino)dipyrromethane + a dipyrromethane to give the zinc-porphyrin bearing trans-AB-substituents. 1,9-diformylation was achieved via Vilsmeier reaction. Imination was achieved by treatment of the 1,9-diformyldipyrromethane with excess amine under neat conditions at room temperature. The porphyrin-forming reaction was carried out over 2 h in refluxing ethanol containing zinc acetate exposed to air. Oxidation of the intermediate porphyrinogen occurs aerobically. A complex composed of two bis(imino)dipyrromethanes and two zinc atoms was observed to form reversibly during the course of the reaction. A set of zinc-porphyrins with trans-AB-, A 2-, or A-substituents has been prepared in yields of ~30% (without detectable scrambling) with straightforward purification. The reaction is applicable to A/B substituent combinations of aryl/aryl, aryl/alkyl, and aryl/H.
Influences of experimental parameters on the stability of a benzoporphyrin drug in water/ethanol mixtures: a statistical approach investigation
Authors: Tessaro André Luiz , Fernandes Daniela Martins , Terezo Ailton José , de Souza Vagner Roberto , Hioka Noboru
Published: July 2009

The benzoporphyrin derivative, named B3B, is a promising new drug for application in photodynamic therapy. In aqueous organic solvent mixtures, B3B, can be used in topical application for superficial diseases, like for skin cancer. In this paper, the self-aggregation phenomena of porphyrin molecules in aqueous media was investigated using a chemometric tool to evaluate the effects of experimental variables on the stability of the B3B monomer in water/ethanol mixtures. A 23factorial design was employed which permitted determination of the magnitude of experimental parameters which influence aggregation of the drug at different pHs using the minimum number of experiments. At first, the pKavalues of the B3B in water/ethanol mixtures were determined by spectrophotometric measurements, resulting in pKa1= 3.3 and pKa2= 5.7, corresponding to the imino nitrogens and carboxylic groups, respectively. The experimental variables (B3B concentration, time and water/ethanol composition) were evaluated in three protonation states of the drug, at pH 7.0, 4.1 and 2.6. The two levels (low and high) were set up at: time 5 (-) and 360 minutes (+); [B3B] 4.4 × 10-6(-) and 26.5 × 10-6M (+); and water content in ethanol 40 (-) and 60% (+). The main parameter that determines the magnitude of the effects seems to be the charge component of B3B, which can be modulated by the pH. The results from the 23fractional design indicated that the main variable inducing B3B aggregation is the water percentage in ethanol at each pH selected. The magnitude of this effect was pronounced at pH 4.1 where the carboxylic and nitrogen free base forms of B3B are maintained. The factors of time and [B3B], despite being small, are not insignificant. Finally, the effect of water content was investigated in a wide range of water percentage in these three pHs.
Mono-crowned substituded iron porphyrin: synthesis, analytical properties and catalytic activity
Authors: Filho Juvenal C. S. , Ferreira Antonio G. , Gotardo Maria Carolina A. F. , das Dores Assis Marilda
Published: July 2009

A substituted porphyrin bearing a crown ether unit, H 2( M 18 C 6 P ), was synthesized from the reaction between (5-mono(o-aminophenyl)10,15,20-triphenylporphyrin) and the acyl derivative of the ether (4-carboxy-18-crown-6). The corresponding iron porphyrin, Fe ( M 18 C 6 P ) Cl , was obtained through iron insertion into H 2( M 18 C 6 P ). The new free-base porphyrin was analyzed by C , N , and H elemental analysis, UV-vis and IR spectroscopies, electrospray mass spectrometry (MS) and 1 H NMR. It selectively extracts 18% of the K + ions present in aqueous medium to the organic phase (chloroform). UV-vis spectroscopy studies showed that H 2( M 18 C 6 P ) is also capable of forming aggregates with K +, probably the 1:1 complex, in methanol. This happens because the ionic radius of the potassium ion is appropriate for its accommodation inside the cavity of the crown ether, and also because of the associative effect between the porphyrin and the crown ether unit. The iron porphyrin Fe ( M 18 C 6 P ) Cl was used as catalyst for the epoxidation of cyclooctene by iodosylbenzene or sodium hypochlorite, in methanol or biphasic water/dichloroethane system, respectively. The results obtained with sodium hypochlorite show that Fe ( M 18 C 6 P ) Cl is a potential catalyst for selective oxidations, because the crown ether unit can select or orient substrates. This iron porphyrin can also be employed as a catalyst in a biphasic water/organic solvent system, with no need of a phase transfer agent.
X-ray structural and DFT computational studies of a self-assembled via axial coordination magnesium porphyrin-fullerene conjugate
Authors: Gadde Suresh , Powell Douglas R. , Zandler Melvin E. , D'Souza Francis
Published: July 2009

Slow evaporation of a mixture of organic solvents containing meso-tetraphenylporphyrinato-magnesium(II), MgTPP and N -methyl-2-(4'- N -imidazolylphenyl)-fulleropyrrolidine, C 60 Im yielded, air stable, dark purple crystals. Determination of the structure by single crystal X-ray diffraction revealed two forms of slightly varying self-assembled via axial coordination MgTPP : C 60 Im dyad. The Mg - N distance of the newly formed coordinate bond was found to be 2.131 Å which was close to the porphyrin ring Mg - N bond distances. The edge-to-edge distances were found to be 9.024 and 9.269 Å, respectively, for the two structure forms. The center-to-center distance between the magnesium and fullerene was 13.296 Å irrespective of the structural forms. Additional intermolecular type interactions between the magnesium porphyrin and fullerene entities that are not axially coordinated were also observed. DFT calculations performed at the B3LYP/3-21G(*) level on the fullerene and porphyrin segments suggested that the charge transfer type π–π interactions are primarily responsible for the intermolecular association of the presently studied donor-acceptor dyad.
Photoinduced electron and energy transfer processes in rotaxanes containing zinc porphyrin as pendant and [60]fullerene and ferrocene as axle ends
Authors: Maes Mio , Sasabe Hisahiro , Kihara Nobuhiro , Araki Yasuyuki , Furusho Yoshio , Mizuno Kazuhiko , Takata Toshikazu , Ito Osamu
Published: July 2009

Photoinduced electron-transfer processes of a newly synthesized rotaxane containing porphyrinatozinc ( ZnP ), [60]fullerene ( C 60), and ferrocene ( Fc ) have been studied in terms of the time-resolved fluorescence and transient absorption measurements in polar and nonpolar solvents. In this rotaxane, ( ZnP ; C 60- Fc ) rotax , ZnP was chosen as a pendant of a crown-ether necklace, through which an axle with C 60 and Fc at both termini was penetrated. By the selective excitation of the ZnP moiety in a nonpolar solvent, energy transfer predominantly takes place to the C 60 moiety of ( ZnP ; C 60- Fc ) rotax . In polar solvents, charge-separation process takes place via the excited singlet state of the ZnP moiety in addition to the energy-transfer process. From the nanosecond transient absorption spectra, a clear absorption band of the C 60•− moiety was observed at 1000 nm as well as a broad absorption in the 600-800 nm region due to ZnP •+, suggesting the generation of ( ZnP •+; C 60•−- Fc ) rotax in the first step. Afterward, the hole-transferring process from ZnP •+ to Fc is thermodynamically possible, although this process is not fast because of its through-space process character. The final lifetimes of the C 60•− moiety were evaluated to be 290 and 370 ns in benzonitrile and DMF, respectively. The ratios of the charge-separation rates to charge-recombination rates were ca. 1000, indicating that ( ZnP ; C 60- Fc ) rotax affords an efficient photosynthetic model.
Substituent effect on two-photon absorption properties of conjugated porphyrins
Authors: Ogawa Kazuya , Dy Joanne , Kobuke Yoshiaki
Published: July 2009

Two-photon absorption (2PA) cross section values of bisacetylene-connected bisporphyrins were measured by using a nanosecond open aperture Z-scan method. The maximum effective cross section values of alkyl and aryl meso-substituted bisporphyrins were 14,000 GM at 890 nm and 7,700 GM at 860 nm, respectively, and the value of alkyl-substituted bisporphyrin was almost twice of that of aryl-substituted one. In one-photon absorption spectra, Q-bands of alkyl-substituted bisporphyrin were red-shifted at 635 nm and 685 nm, and intensified compared with those of aryl-substituted one at 625 nm and 678 nm, respectively, indicating higher π-electron density of the former compound compared to that of the later. The large enhancement observed for alkyl-substituted bisporphyrin is attributed to the increase in π- electron density compared with aryl-substituted one. It was found that the alkyl group is better to obtain large 2PA cross section values than the aryl group as the meso-substituent of the porphyrin.
Self-assembly of a C60 derivative bearing an ammonium unit with porphyrin-crown ether conjugates
Authors: Nierengarten Jean-François , Solladié Nathalie
Published: July 2009

Our recent progresses in the synthesis and the study of supramolecular porphyrin-fullerene conjugates are reported. In particular, we show that π-stacking of the two chromophores can have a dramatic effect on recognition interactions in non-covalent C 60-porphyrin ensembles. Specifically, a supramolecular complex has been obtained from a porphyrin-crown ether conjugate and a methanofullerene derivative bearing an ammonium function. In addition to the ammonium-crown ether interaction, intramolecular stacking of the fullerene moiety and the porphyrin subunit has been evidenced in the supramolecular system. Due to this additional recognition element, the association constant ( K a ) for the complex is increased by two orders of magnitude when compared to K a values previously found for complexation of the fullerene-ammonium derivative with other crown ethers. Finally, non-covalent systems resulting from the association of the fullerene-ammonium derivative with porphyrins bearing two crown-ether subunits have been investigated. Intramolecular C 60-porphyrin interactions have also been observed within these supramolecular arrays. As a result, the 2:1 complexes are very stable.
Porphyrins with β,β'-fused five-membered rings
Authors: Smith Kevin M. , Lee Sang Hee , Vicente M. Graça H.
Published: July 2009

Recent studies involving porphyrin systems bearing fused five-membered rings are reviewed, these including pyrrolo[3,4-b]porphyrins and fused metallocenoporphyrins. Diels-Alder cycloadditions between pyrroloporphyrins, to give benzoporphyrins, are discussed. The syntheses of mono-, and the two regioisomers (adj- and opp-) of bis-sulfolenoporphyrins are then discussed and their reactions with dienophiles such as dimethyl acetylenedicarboxylate are outlined.
[2,2]paracyclophane-bisphthalocyanines: non-classical push-pull systems for second harmonic generation
Authors: de la Escosura Andrés , Claessens Christian G. , Ledoux-Rak Isabelle , Zyss Joseph , Martínez-Díaz M. Victoria , Torres Tomás
Published: July 2009

The EFISH and HRS responses of a push-pull bisphthalocyanine-[2,2]paracyclophane compound have been measured at 1.9 and 1.06 μm, respectively, obtaining a remarkably high hyperpolarizability β HRS value. Since the two electronically different phthalocyanine chromophores are connected through a non π-conjugated and rigid [2,2]paracyclophane spacer, this result implies an efficient through-space intramolecular charge transfer between them. The results have been compared to that of structurally related, unsymmetrically substituted phthalocyanines 2-5, bearing either [2,2]paracyclophane or phenyl substituents. In these cases, the [2,2]paracycloplane does not play a significant role in the NLO response, being that the nature of the peripheral sustituents on the phthalocyanine is the most influent structural feature.
Porphyrinic assemblies of pyridine-containing macrocycles
Authors: Campbell Katie , McDonald Robert , Tykwinski Rik R.
Published: July 2009

Using a combination of palladium-catalyzed cross-coupling and copper-catalyzed homocoupling reactions, two pyridine-containing macrocycles with varying pendant substitution were constructed. Their synthesis and subsequent coordination to a ruthenium porphyrin is described. In addition to synthetic details and characterization, an examination of their electronic properties is provided.
Electronic effects on carbon monoxide dissociation from iron(II) tetraphenylporhyrins
Authors: Lopez Marco A. , De La Rosa Martha A.
Published: July 2009

We report the kinetics of CO binding to a series of substituted ferrous tetra(4-X-phenyl)porphyrins ( X = CF 3, Cl , H , CH 3, OCH 3) in DMSO solvent using a mixture of 1,2-DMI/1-MeIm as proximal base. The CO dissociation rate constant increases with electron donation of the substituent X; the aggregate Hammett ρ value is -0.38. Using a Swain-Lupton analysis we determine the electronic effects to be transmitted 67% by through-bond or field effect and 33% by resonance. These results indicate that there is significant conjugation between the phenyl rings and the porphyrin core of iron tetraphenylporphyrin systems.
Substituted tetrapyrazolylporphyrins: application in organic light-emitting diodes
Authors: Guo Can-Cheng , Ren Tie-Gang , Song Jian-Xin , Liu Qiang , Luo Kai , Lin Wei-Ying , Jiang Guo-Fang
Published: July 2009

Six substituted tetrapyrazolylporphyrins ( TAPyPH 2), meso-tetrakis(1-phenylpyrazol-4-yl)porphyrin ( TPPyPH 2), meso-tetrakis[1-(p-tolyl)pyrazol-4-yl] porphyrin ((p- CH 3) TPPyPH 2), meso-tetrakis[1-(p-methoxyphenyl)pyrazol-4-yl]porphyrin ((p- CH 3 O ) TPPyPH 2), meso-tetrakis[1-(p-chlorophenyl) pyrazol-4-yl]porphyrin ((p- Cl ) TPPyPH 2), meso-tetrakis[1-(p-bromophenyl)pyrazol-4-yl]porphyrin ((p- Br ) TPPyPH 2) and meso-tetrakis[1-(m-tolyl)pyrazol-4-yl]porphyrin ((m- CH 3) TPPyPH 2), were synthesized by the condensation of pyrrole with the corresponding substituted formylpyrazole and used as the doping materials in the Organic Light-Emitting Diodes (OLEDs) with hole-transport materials of N , N '-diphenyl- N , N '-bis (4-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine (TPD) within a tris(8-hydroxyquinoline) aluminum ( Alq 3) host layer. Both the electroluminescence properties of these OLEDs and effects of the peripheral substituents of the tetrapyrazolylporphyrins on EL properties of the OLEDs were studied. The tests found that the OLEDs using substituted tetrapyrazolylporphyrins ( TAPyPH 2) as the dopants had the saturated red emission at a concentration of 1.5 wt.%. The electron-donating groups of tetrapyrazolylporphyrins (for example, p- CH 3 and p- CH 3 O ) increased the luminance of OLEDs, while the electron-drawing groups (for example, p- Cl and p- Br ) decreased the luminance. The OLEDs using meso-tetrakis(1-phenylpyrazol-4-yl)porphyrin ( TPPyPH 2) as a dopant showed saturated red emission at 680 nm (CIE coordinates of x = 0.65, y = 0.31) with a luminance of 305 cd/m2 at a driving voltage of 25 V at concentration of 1.5 wt.%. Compared with OLEDs doped by the free-base tetraphenylporphyrin (TPPH2), the OLEDs doped by the tetrapyrazolylporphyrins had better luminance and higher emission efficiency. An explanation for these results was given based on the molecular structure and spectral properties of the porphyrin compounds.
Molecular structure and spectroscopic properties of octaethylbenzochloracene, the porphycene analog of a benzochlorin
Authors: Barkigia Kathleen M. , Robinson Byron C. , Renner Mark W.
Published: July 2009

The X-ray structure, electrochemistry, and optical spectroscopy of the porphycene analog of a benzochlorin, octaethylbenzochloracene (OEBzC) are reported. The OEBzC macrocycle is easier to oxidize and harder to reduce than octaethylporphycene (OEPc). The optical spectra of OEBzC and of the diacid salt are also reported. The optical spectrum for the one-electron oxidation of OEBzC is indicative of π-cation radical formation. In porphyrins, saturation of one pyrrole ring and addition of an exocyclic benzene ring progressively red-shifts the first absorption band. For porphycenes, saturation of one pyrrole ring results in a 35 nm blue shift in the first absorption relative to OEPc. Compared to 2,3-dihydroporphycene (DHPc), the first absorption band in OEBzC is red-shifted 24 nm. These studies further illustrate how the fused exocyclic benzene ring influences the macrocycle conformation, chemical and physical properties of porphycenes.
Diverse porphyrin dimers as candidates for high-density charge-storage molecules
Authors: Lysenko Andrey B. , Thamyongkit Patchanita , Schmidt Izabela , Diers James R. , Bocian David F. , Lindsey Jonathan S.
Published: July 2009

Porphyrinic molecules have been shown to be viable candidates for a molecular-based information storage medium on the basis of redox activity. An optimal redox-based information storage medium requires a large charge density in the molecular footprint on the anchoring substrate. The use of dimeric versus monomeric architectures affords one route to achieving increased charge density without sacrificing surface cross sectional area. Towards this goal, a series of zinc and cobalt containing porphyrin dimers has been prepared and characterized. The interporphyrin linkages in the dimers include p-phenylene, ethynyl, 1,4-butadiynyl, and ethynylphenylethynyl joining porphyrin meso-positions; Crossley-type fusion bridging porphyrin β-positions, and Osuka-type triple fusions bridging one meso- and two β-positions. The electrochemical features of each dimer have been evaluated.
Tautomerism in N-confused porphyrins as the basis of a novel fiber-optic humidity sensor
Authors: Zilbermann Israel , Meron Eli , Maimon Eric , Soifer Leonid , Elbaz Lior , Korin Eli , Bettelheim Armand
Published: July 2009

It is shown that N -confused porphyrins exhibit tautomerism not only in organic solvents, as already reported, but also after incorporation in dry/humid Nafion films. This allows the development of a new fiber-optic humidity sensor which exhibits long-term stability and a linear response over the humidity range 0 to at least 4000 ppm.
Synthesis of new phthalocyanines substituted with four 1H-benzoimidazol-2-ylsulfanyl and 2-(1H-benzo[d]imidazol-2-ylthioetoxy) groups
Authors: Ağırtaş M. Salih , Yıldıko Ümit , Yılan Ayfer
Published: July 2009

The synthesis of new two phthalonitrile derivatives is described. Using these starting materials, metallophthalocyanines substituted with four 1 H -benzoimidazol-2-ylsulfanyl and 2-(1 H -benzo[d]imidazol-2-ylthioetoxy) have been synthesized, respectively. The newly synthesized compounds have been characterized by elemental analyses, UV-visible, IR and 1 H NMR spectra.
Two-photon absorption properties of substituted porphyrins
Authors: Shen Liang , Wang Xiaomei , Li Bo , Jiang Wanli , Yang Ping , Qian Shixiong , Tao Xutang , Jiang Minhua
Published: July 2009

The two-photon absorption (TPA) properties of two newly synthesized substituted porphyrins: 5,10,15,20-tetra-(4-pyrrolidinylphenyl)porphyrin (1) and 5,10,15,20-tetra-(4-diphenylamino-benzoic acid phenyl) porphyrin ester (3) were measured by the femtosecond Z-scan technique at 800 nm Ti : sapphire laser and by direct nonlinear optical transmission (NLT) using nanosecond Nd : YAG laser. The substituent effects, pumped wavelength and the environment upon the molecular TPA cross-section were investigated. It is found that the TPA cross-section for 3 is enhanced under excitation of 800 nm, relative to its precursor, 5,10,15,20-tetra(4-hydroxyphenyl) porphyrin (2), due to the former possessing extension conjugation of "D-A-core-A-D" molecular architecture. Also sample 3 obtained an increased TPA cross-section in rigid film relative to that in solution, suggesting that the enhancement is facilitated by the quasi-planar structure which allows direct interbranch conjugation throughout the molecule.
Aerobic oxidative cleavage of C=C double bond of styrene catalyzed by simple manganese porphyrin
Authors: Li Yong-Fei , Guo Can-Cheng , Yan Xu-Hui , Liu Qiang
Published: July 2009

The aerobic oxidative cleavage of styrene C=C double bonds catalyzed by simple manganese porphyrin is reported. Under the catalysis of chloro(tetraphenylporphinato)manganese, the oxidative cleavage of the carbon-carbon double bond of the styrene with air yields benzaldehyde. Our results show that the oxidative cleavage and the epoxidation of the styrene double bond are the competition reactions in the styrene-manganese porphyrin-air system. The reaction temperature decided the product distribution. Under the conditions of 0.4 MPa air and 30 ppm of chloro(tetraphenylporphinato)manganese, the styrene conversion was 20.0% and the selectivity of benzaldehyde and styrene oxide was 81.7% and 12.7% respectively when the reaction temperature was 110°C. Styrene conversion was 92.5% and the selectivity of benzaldehyde and styrene oxide was 48.1% and 41.2% respectively when the reaction temperature was 120°C.
Catalysis of μ-oxo-bis[porphyriniron(III)] for toluene oxidation with molecular oxygen
Authors: Hu Hai-Yang , Jiang Quan , Liu Qiang , Song Jian-Xin , Lin Wei-Ying , Guo Can-Cheng
Published: July 2009

Toluene oxidation with molecular oxygen as the sole oxidant, and μ-oxo-bis[tetraphenylporphinatoiron(III)] as the catalyst, are reported. Under the reaction conditions of 438 K and 0.8 MPa, the molar total yields for the products benzaldehyde and benzyl alcohol and the turnover number of the catalyst are 4.35% and 21,830 (based on the metal ion), respectively. Compared with the reaction catalyzed by the corresponding monometalloporphyrin TPPFe III Cl , the total yields of the oxidation products and the catalyst turnover number by the dimeric iron porphyrin were almost twice those by the former. A possible reaction mechanism of the toluene oxidation by μ-oxo-bis[tetraphenylporphinatoiron(III)] is proposed.
Spectral study of the nitrogen monoxide interaction with sublimed layers of meso-mono-4-pyridyl-tri-phenyl- and meso-mono-3-pyridyl-tri-phenyl-porphyrinatocobalt(II)
Authors: Kurtikyan Tigran S. , Harutyunyan Hayk A. , Ghazaryan Robert K. , Goodwin John A.
Published: July 2009

The low-temperature interaction of NO(15NO ) with sublimed layers of meso-mono-4-pyridyl-tri-phenyl- and meso-mono-3-pyridyl-tri-phenyl-porphyrinatocobalt(II) ( CoM4PyTPP (I) and CoM3PyTPP (II), respectively) has been investigated by means of FTIR and UV-visible spectroscopy. In addition to the stable five-coordinate nitrosyl complexes that are similar to the closely-related meso-tetraphenylporphyrinatocobalt(II)-nitrosyl Co(TPP)(NO) complex, a new type of complex with coordinated NO (15 NO ) has been found for the layers that were maintained at room temperature overnight before addition of nitric oxide at low temperature. The ν{ NO (15 NO )} in this species are more than 20 cm−1 lower than in five-coordinate compounds. These adducts are assigned to six-coordinate nitrosyl complexes, in which the fifth coordination site is occupied by the pyridyl group of the adjacent I (II) molecules. Warming the layers containing six-coordinate nitrosyl complexes of I almost completely transforms them to stable five-coordinate nitrosyl species indicating oligomers' disruption rather than loss of nitric oxide. In the case of II, however, a noticeable fraction of the six-coordinate species is left upon warming. Introducing new portions of NO to these layers at low temperature leads to formation of additional quantities of the six-coordinate species. Hence, part of six-coordinate complexes in II decomposed upon warming by releasing NO instead of by breaking Co -pyridyl bonds, therefore leaving free the sixth coordination sites in these layers. This result suggests a good possibility for creating solid state NO storage devices in which nitrogen monoxide can be kept and easily released by warming of the system.
Functional alcohol-soluble double-decker phthalocyanines: synthesis, characterization, electrochemistry and peripheral metal ion binding
Authors: Yaraşır Meryem N. , Kandaz Mehmet , Koca Atıf , Salih Bekir
Published: July 2009

In this study we report the preparation, physical characterization and electrochemistry of peripherally functionalized substituted ionophore double-decker lanthanide phthalocyanines, lanthanide bis-[(4,4″,4″,4‴)-tetrakis-(6-hydroxyhexylthio)phthalocyaninates], { M [ Pc ( S - C 6 H 13 OH )4]2} ( M = Pr III, Yb III, and Lu III). All benzenes on the double-decker phthalocyanines are functionalized with hydroxyhexylsulfanyl moieties for potential use as metal ion binding and surface anchors. The double-decker phthalocyanines synthesized from the anhydrous metal salts { Ln ( acac )3} and the corresponding 4-(6-hydroxyhexylthio)-1,2-dicyanobenzene exhibit ion-specific optical changes in the presence of Ag + and Pd 2+. Thio donors of the complexes coordinate to Ag + and Pd 2+ to give 4:1 metal-phthalocyanine complexes. Newly synthesized lanthanide double-decker phthalocyanines are soluble in methanol ( MeOH ), ethanol ( EtOH ), tetrahydrofuran ( THF ), dimethylformamide ( DMF ), dimethylsulfoxide ( DMSO ), chloronapthalene, quinoline and less soluble in i- PrOH and acetonitrile. Electrochemical studies reveal that all lanthanide-base complexes undergo ligand-based redox processes. The smaller HOMO-LUMO gaps of the complexes indicate the existence of strong π-orbital interactions between the rings of the sandwich. The newly synthesized compounds have been characterized by elemental analysis, FTIR, 1H and 13 C NMR, MS (ESI and Maldi-TOF), UV-vis and EPR spectral data.
Synthesis of a new substituted zinc phthalocyanine as functional monomer in the preparation of MIPs
Authors: Longo Luigia , Vasapollo Giuseppe , Scardino Anna , Picca Rosaria Anna , Malitesta Cosimino
Published: July 2009

A new zinc phthalocyanine peripherally substituted with methacrylic groups was synthesized to be employed as a functional monomer in the formation of molecularly imprinted polymers as nucleoside receptors. The binding affinity and selectivity of the synthesized phthalocyanine towards nucleosides were evaluated by UV-vis titration experiments in CH 2 Cl 2 at 298 K. The binding constant ( K a) and Gibbs free energy changes (-Δ G 0) were calculated according to the modified Benesi-Hildebrand equation. Binding experiments showed that K a of phthalocyanine with tri-O-acetyladenosine ( TOAA ) is 1.35 × 104, 500 times that of phthalocyanine with tri-O-acetyluridine ( TOAU ), indicating a high selectivity of the synthesized phthalocyanine derivative.
Alkynyl-substituted phthalocyanines: versatile building blocks for molecular materials synthesis
Authors: Bottari Giovanni , Díaz David D. , Torres Tomás
Published: July 2009

Phthalocyanines are an interesting class of aromatic macrocycles which possess unique physical and chemical properties that make them excellent building blocks for the construction of molecular materials. Among the different functional groups that can be incorporated into the phthalocyanine's skeleton, the alkynyl group is one of the most interesting; this is confirmed by the large number of organic synthetic materials constructed from acetylene-based scaffolds due its rigidity and linearity, allowing high exciton and electron coupling between chromophore units. Additionally, these systems are particularly important, considering the wide range of functional group interconversions that the triple bond may permit. This account represents a concise overview of the most important contributions on the synthesis and applications of mono- and poly-alkynyl-substituted phthalocyanine-based molecular systems, towards the development of new functional molecular materials.
Self-assembled monolayers and electropolymerized thin films of phthalocyanines as molecular materials for electroanalysis
Authors: Nyokong Tebello , Bedioui Fethi
Published: July 2009

In this review, we report on the newly developed area of research devoted to the formation of self-assembled monolayers of metallophthalocyanines by focusing on some significant examples dedicated to electroanalytical applications. We also summarize recent examples on the use of electropolymerized metallophthalocyanine films in electroanalysis. In both cases, activation and detection of thiols are the main targeted applications.
A new spectroelectrochemical cell with a long optical path length for redox studies of phthalocyanines
Authors: Isago Hiroaki
Published: July 2009

A new spectroelectrochemical cell with a long optical path length has been fabricated for redox studies of phthalocyanines, where the propagation axis of the optical beam is parallel to the electrode/solution interface. It is composed of a homemade Teflon block that fits inside a standard 1 cm quartz optical-cell, equipped with a platinum-foil working electrode, a platinum-wire auxiliary electrode, and a AgCl -coated silver-wire reference electrode. This new cell makes it much easier to acquire spectral data for dilute solutions containing species, like phthalocyanines, that have limited solubility in common organic solvents or that strongly aggregate in solution. As examples, electrolyses of the [tetra(tert-butyl)phthalocyaninato]zinc(II) complex and its cobalt(II) analogue were performed to monitor spectral changes ascribable to phthalocyanine-ligand-centered oxidation and metal-centered reduction, respectively. Spectra of unaggregated electrogenerated species were successfully observed.
Synthesis and characterization of novel azo-bridged Zn(II) and Co(II) bisphthalocyanines
Authors: Yazıcı Ayşegül , Ateş Davut , Bekaroğlu Özer , Kobayashi Nagao
Published: July 2009

Metal phthalocyanines containing an unsymmetrically substituted nitro group were synthesized from 4-nitrophthalonitrile and the corresponding anhydrous metal salts ( Co ( OAc )2, Zn ( OAc )2) by the method of statistically mixed condensation reactions. The new type of metallo-bisphthalocyanine compounds connected by a N = N bridge was prepared from the reactions of respective nitro compounds with sodium hydroxide ( NaOH ) and activated zinc powder in a mixture of methanol ( MeOH ) and tetrahydrofuran (THF). The structures of these compounds were characterized by using 1 H NMR, IR, elemental analyses, UV-vis and magnetic circular dichroism spectroscopies.
Analysis of the nonlinear transmission properties of some naphthalocyanines
Authors: Dini Danilo , Calvete Mario , Vagin Sergej , Hanack Michael , Eriksson Anders , Lopes Cesar
Published: July 2009

In our search for the definition of new molecular compounds combining low linear absorption with high nonlinear optical absorption in the same wavelength range, we have prepared a series of vanadyl, chloroindium and lead naphthalocyaninato complexes with a relatively low linear optical absorption within the visible range when compared to phthalocyanines, but with similar chemical stability. The transmission properties of these complexes for nanosecond pulses at 532 nm have been evaluated and confronted in both linear and nonlinear regimes. Halogenated naphthalocyanines displayed the best optical-limiting performances. It was also found that an increase in concentration generally results in a reduction of the limiting efficiency of the systems, due to the phenomena of intermolecular aggregation and consequent excited-state quenching.
A new synthesis of tetra(quinoxalino)tetraazaporphyrin by the retro Diels-Alder reaction of a soluble precursor
Authors: Okujima Tetsuo , Kikuchi Makoto , Yamada Hiroko , Uno Hidemitsu , Ono Noboru
Published: July 2009

Soluble tetra(pyrazino)tetraazaporphyrin was synthesized by the reaction of bicyclo[2.2.2]octadiene-fused dicyanopyrazine. The retro Diels-Alder reaction of the soluble tetra(pyrazino)tetraazaporphyrin gave a tetra(quinoxalino)tetraazaporphyrin in quantitative yield.
meso-substituted corroles bearing peripheral donor sites
Authors: Gryko Daniel T. , Tasior Mariusz , Peterle Torsten , Bröring Martin
Published: July 2009

Various pathways towards corroles bearing additional donor sites especially those with diazacrown units have been evaluated. Macrocyclic diamidation based on the reaction of diamines with diesters was found to be the key step in the overall synthetic scheme. This strategy was applied successfully to the synthesis of three compounds possessing macrocyclic diamide or diamine moieties. In addition, a meso-picolyl derivatized corrole was prepared. The new ligands were investigated with respect to the regioselectivity of transition metal insertion. Mononuclear corrolates of copper and cobalt are formed as the only isolable products, if simple copper and cobalt precursors and standard metalation protocols are applied. The results prove, that corroles can be used as selectively coordinating building blocks in multi-compartment ligand systems with peripheral crown ether and pyridyl functionalization.
Synthesis and properties of dimeric porphyrin based on the hydroxyphenylporphyrin scaffold
Authors: Li Di , Shi Yingyan , Fa Huanbao , Zheng Wenqi , Shan Ning , Yang Min , Wang Dejun , Cheng Xiuli , Wang Xingqiao
Published: July 2009

A porphyrin dimer was prepared by coupling H2MHTPP and 1,4-dichloro-2,5-dinitrobenzene in a one-step synthesis. Its structure was established by a MALDI-TOF mass spectrum and its electrochemical and photochemical properties were investigated. Surface photovoltage spectroscopy (SPS) revealed that the porphyrin dimer is a p-type semiconductor.
The role of radical derivatives of high reactivity in the radiosensitizing action of Photofrin II
Authors: Schaffer Moshe , Kulka Ulrike , Schaffer Pamela , Ertl-Wagner Birgit , Corti Luigi , Hell Roswitha , Hofstetter Alfons , Jori Giulio
Published: July 2009

The in vitro and in vivo efficacy of Photofrin II as a selective radiosensitizing agent has recently been demonstrated, the mechanism of action still being unknown. We aimed to investigate the mechanism of action of Photofrin II and the role played by radiolytically generated cytotoxic species. RT4 human bladder carcinoma cell lines were seeded and incubated with Photofrin II and mannitol, with Photofrin II alone, and with no added agent. The cells were treated with ionizing radiation (6 Gy). The numbers of colonies in the respective groups were compared. In addition, the influence of mannitol and histidine on cell survival after Photofrin-incubation and irradiation (0-1-2-4-6 Gy) was evaluated by a tetrazolium-based colorimetric assay in an ELISA reader. RT4 cells, which were exposed to 6 Gy radiation after incubation with Photofrin II, showed a significantly lower survival rate compared to cells exposed to the same radiation dose in the absence of Photofrin II ( p < 0.05 in a Student t-test). The addition of mannitol as a scavenger for OH radicals exerted a protective effect especially against the radiosensitizing action of Photofrin. Increased cell survival was observed when mannitol and histidine were present in addition to Photofrin II. The mechanism of radio sensitization by Photofrin II appears to involve the formation of radical derivatives of high reactivity, such as OH radicals.
Synthesis, spectral data, and crystal structure of two novel substitution patterns in dithiaporphyrins
Authors: You Youngjae , Daniels Thalia S. , Dominiak Paulina M. , Detty Michael R.
Published: July 2009

The syntheses, characterizations and crystal structures of 5-(4-tert-butylphenyl)-15,20-diphenyl-10-(4-methoxy)phenyl-21,23-dithiaporphyrin (1b) and 2,3-dimethoxy-10,15-diphenyl-21,23-dithiaporphyrin (2) are described. The cyclization of 2-[1-(4-methoxyphenyl)-1-pyrrolomethyl]-5-(1-phenyl-1-pyrrolomethyl)thiophene and 2-[1-(4-t-butylphenyl)-1-hydroxymethyl]-5-(1-phenyl-1-hydroxymethyl)thiophene gave predominantly the cis-regioisomer, which was characterized by X-ray crystallography.
Porphyrins bearing quaternary azaaromatic moieties
Authors: Śliwa Wanda , Herman Barbara , Girek Tomasz
Published: July 2009

In this review, porphyrins bearing quaternary azaaromatic moieties are described as follows: firstly those with useful physicochemical properties, then, species showing biological activities and finally, porphyrins bound with fullerenes and with cyclodextrins.
Synthesis and characterization of novel phthalocyanines with nitrone substituents
Authors: Achar B. Narayana , Kumar T. M. Mohan
Published: July 2009

A novel series of nitrone-substituted, metal phthalocyanine complexes (the central metal ion being Co , Ni and Cu , respectively) were synthesized for the first time in pure state with quantitative yield. These complexes were characterized using elemental analysis, UV-visible, IR-spectroscopy, magnetic susceptibility, X-ray crystallography, and thermogravimetry. All three complexes had a monoclinic structure with different crystal lattice constants. Horowitz-Metzger, Coats-Redfern and Broido's relations were employed to calculate the kinetic and activation parameters associated with the thermal decomposition of the above complexes. Electrical conductivity studies were undertaken for all three complexes using a two-probe technique in the temperature range 30-200°C. They showed an improvement of 103-105 times the electrical conductivity at room temperature, compared to the corresponding unsubstituted metal phthalocyanines.
Microwave-assisted synthesis of porphyrins and metalloporphyrins: a rapid and efficient synthetic method
Authors: Nascimento Bruno F. O. , Pineiro Marta , Rocha Gonsalves António M. d'A. , Ramos Silva Manuela , Matos Beja Ana , Paixão José A.
Published: July 2009

The effective 'one-pot' microwave-assisted synthesis of several substituted 5,10,15,20-tetraarylporphyrins is reported. The microwave-assisted insertion of five different transition metals into the 5,10,15,20-tetraphenylporphyrin, 5,10,15,20-tetrakis(4-chlorophenyl)porphyrin and 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin core was also achieved with high yields. In addition to their simplicity, both these straightforward, experimental protocols were also characterized by extremely short reaction times and quite small quantities of solvents employed.
Synthesis and liquid crystal behavior of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes
Authors: Zhang Ying , Jiang Weili , Jiang Jianzhuang , Xue Qingbin
Published: July 2009

A series of tris[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth(III) complexes M 2[ Pc ( OC 8 H 17)8]3 [ M = Eu , Gd , Y , Lu ] has been prepared by the reaction of corresponding bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth complexes with M ( acac )3·n H 2 O in refluxing 1,2,4-trichlorobenzene. These liquid crystalline sandwich, triple-decker complexes were characterized by elemental analysis and various spectroscopic methods including 1 H NMR, UV-vis, IR and mass spectroscopies. Their liquid crystal phase transition behavior was studied by Polarized Optical Microscope, Differential Scanning Calorimeter and X-ray diffraction. The complexes, with octyloxy attached as side chains, showed rectangular columnar liquid crystal phases in a liquid crystal temperature range between 83 and 305°C. In addition to the rare earth contraction, both the transition temperature and the wide temperature range of the mesophase show a slight but obvious trend to decrease, respectively, in the same order. In contrast, the molecular packing of these complexes as revealed by X-ray diffraction was found to be almost independent of the ionic size of the central rare earth.
Microwave synthesis and photophysics of new tetrasulfonated tin(II) macrocycles
Authors: Khene Samson , Ogunsipe Abimbola , Antunes Edith , Nyokong Tebello
Published: July 2009

This work reports on the microwave synthesis of tetrasulfonated tin phthalocyanine and tetrasulfonated tin α,β,γ-tetrabenzcorrole. The latter was only formed at low ratios (<1:8) of 4-sulfophthalic acid to urea. Both complexes are aggregated in aqueous media, but can be partly or fully disaggregated by the addition of Triton X-100. The α,β,γ-tetrabenzcorrole complex has lower triplet life times and yields, while the binding constant and quenching (of bovine serum albumin) constant are lower for α,β,γ-tetrabenzcorrole compared to tetrasulfonated tin phthalocyanine.
Microwave-assisted immobilization of metallophthalocyanines in mesoporous channels of MCM-41
Authors: Pirouzmand Mahtab , Amini Mostafa M. , Safari Nasser
Published: July 2009

Metallophthalocyanines have been assembled in MCM-41 channels by microwave irradiation of a mixture of ion-exchanged MCM-41, and 1,2-dicyanobenzene under solvent-free conditions in a considerably short period of time. The prepared materials have been characterized by diffuse reflectance UV-vis spectroscopy, X-ray powder diffraction XRD, differential scanning calorimetry DSC, and Brunauer-Emmett-Teller BET nitrogen adsorption desorption techniques. The X-ray diffraction and Brunauer-Emmett-Teller results showed that the textural properties of MCM-41 were preserved during microwave irradiation.
Azaphthalocyanines with extended conjugation through heteroaryl and aryl substituents: Photochemical and photophysical properties
Authors: Mørkved Eva H. , Afseth Nils Kr. , Zimcik Petr
Published: July 2009

Magnesium and zinc complexes of azaphthalocyanines (AzaPc) with eight peripheral aromatic (phenyl) or heteroaromatic (pyridyl, thienyl, furyl) substituents are studied from the point of view of their singlet oxygen (ΦΔ) and fluorescence (ΦF) quantum yields, and UV-vis absorption spectra. Zn complexes have higher ΦΔthan Mg complexes by a factor of two, whereas the Mg complexes have higher ΦFthan Zn complexes, also by a factor of two. Thienyl AzaPc have the highest ΦΔamong all studied substances (0.635 for Zn complex) followed by phenyl and pyridyl derivatives. The order of ΦFvalues is then reversed - the highest values were reached for pyridyl and phenyl derivatives followed by thienyl AzaPc. Both furyl AzaPc were unstable towards light and decomposed giving very low ΦΔand ΦF. The Q-bands of the furyl and thienyl AzaPc were red-shifted for approx. 20 nm compared to phenyl and pyridyl derivatives indicating lower sterical hindrance between five-membered rings and thus allowing better conjugation of π-systems. Pyridyl-, thienyl- and furyl-substituted pyrazino[2,3-b]pyrazine-2,3-dicarbonitriles were also prepared but decomposed during attempted cyclotetramerizations.