bluuebunny/crossref_metadata_2025 huggingface dataset:
MoRe-BASED AND NbN-BASED TUNNEL JUNCTIONS AND THEIR CHARACTERISTICS
Authors: SHATERNIK VOLODYMYR , LARKIN SERGIY , BELOGOLOVSKII MIKHAIL
Published: July 2009

Perspective for qubits Josephson Mo - Re alloy-oxide– Pb , Mo - Re alloy-normal metal–oxide– MoRe alloy, and NbN -normal metal–oxide– Pb junctions have been fabricated and investigated.
DEVELOPMENT OF MULTILAYER COATED CONDUCTORS WITH SIMPLIFIED BUFFER STRUCTURE
Authors: PYSARENKO S. V. , PAN A. V. , DOWNING S. , DOU S. X.
Published: July 2009

The quality superconducting YBa 2 Cu 3 O 7 films and YBa 2 Cu 3 O 7/ NdBa 2 Cu 3 O 7 multilayered film structures have been grown by pulsed laser deposition on metallic templates with magnesium oxide (MgO) buffer layer grown by incline substrate deposition. Different supplementary buffer layers have been deposited between the superconductor and MgO buffer layer. This additional buffer layer reduces the crystal structure misalignment of the superconducting layers. The critical current density has been observed to be higher in the multilayered structures in comparison with the same thickness of monolayer YBa 2 Cu 3 O 7 films. The origin of this enhancement is the improved microstructure of the multilayered systems obtained.
INTERFACIAL STRUCTURE OF Fe3Si/FeSi2 LAYERED FILMS DEPOSITED ON Si(111) AT ELEVATED SUBSTRATE-TEMPERATURES
Authors: TAKEDA KAORU , YOSHITAKE TSUYOSHI , SAKAMOTO YOSHIKI , HARA DAISUKE , ITAKURA MASARU , KUWANO NORIYUKI , NAGAYAMA KUNIHITO
Published: July 2009

Influence of substrate-temperature on the interfacial structure of Fe 3 Si / FeSi 2 layered films deposited on a Si (111) substrate were studied. Fe 3 Si / FeSi 2 films with sharp interfaces were grown at room substrate-temperature. At a substrate-temperature of 300 °C, interfaces between the Fe 3 Si and FeSi 2 layers were obviously unsharpened, while the crystallinity of Fe 3 Si was enhanced. The compositional periodic structure was barely unsharpened and it was nearly the same as that of the films deposited at room substrate-temperature. Epitaxial growth of Fe 3 Si layers across FeSi 2 layers was carried out. This substrate-temperature is the upper limit at which the heterostructure formation takes place. At 400 °C, ε- FeSi was formed due to activated interdiffusion, and the structure of Fe 3 Si changed partially from B2-type to DO3-type.
STUDY THE POLYOL PROCESS OF PREPARING THE Ru DOPED FePt NANOPARTICLES
Authors: LEE CHIH-HAO , HSU JEN-HO , SU HUI-CHIA , HUANG TZU WEN
Published: July 2009

The structure of Ru doped FePt nanoparticles using polyol process was studied. The particle size grown is around 5 nm, and a shell structure might be formed. By selecting the time and temperature of adding the Ru precursors into solution, three different processes to synthesize the FePtRu particles were studied resulting in different growing mechanics. The possible models during the reaction process are also discussed. The phase transition temperature for the as-grown FCC FePt nanoparticle to transform into L 10 FePt nanoparticle is about 823 K which is about the same as the one without doping Ru atoms. From the XAS study of each element, the possible scenario is that: although Ru atoms with the size close to the Pt , they do not totally replace the Pt sites in the FePt alloy. Instead, most of Ru formed a shell outside the FePt nanoparticles and Fe atoms are replaced.
STRUCTURAL AND MAGNETIC FIELD DEPENDENT TRANSPORT PROPERTIES OF p-MnxGe1-x/n-Ge HETEROJUNCTION
Authors: MAJUMDAR SANDIP , DAS AMAL KUMAR , RAY SAMIT KUMAR
Published: July 2009

We report the study of a promising Ge -based magnetic heterojunction diode composed of a Mn -doped p - Ge film grown on lightly doped n - Ge film. Magnetic field dependent current rectification of the diode occurs at a low temperature. The measurements of resistivity and magnetoresistance in plane at low temperatures reveal the presence of impurity band in Ge due to Mn doping.
TEMPERATURE DEPENDENT MAGNETO-TRANSPORT STUDIES IN FERROMAGNETIC GE1-XMNXTE WITH HIGH MN COMPOSITION
Authors: LIM S. T. , SIM C. H. , CHEN W. Q. , BI J. F. , TEO K. L. , LIEW T. , CHONG T. C.
Published: July 2009

We investigate the magneto-transport behaviour of Ge 1- x Mn x Te ( x = 0.98) grown by solid-source molecular-beam epitaxy. The magnetization curves measured in different field orientations show that part of the magnetic moments lies out-of-plane, and becomes enhanced as temperature increases. A transition from negative to positive magnetoresistance (MR) was observed at T ≥ 95 K in the MR measurements with field applied perpendicular to sample plane. This transition temperature corresponds to our measured Curie temperature T C ~ 95 K .
HYDROTHERMAL SYNTHESIS OF NANOCRYSTAL MNO2 UNDER PULSED MAGNETIC FIELD
Authors: ZHU ZHENZHEN , LI YING , ZHU MINGYUAN , JIN HONGMING , DENG XIAOLONG , WANG ZHUN , LIU HUAKUN
Published: July 2009

Nanocrystal MnO 2 was successful synthesized by hydrothermal method under pulsed magnetic field. The effect of pulsed magnetic field on the nucleation and growth of MnO 2 was studied by XRD and SEM analysis. It was found that the morphology of MnO 2 has been changed comparing without magnetic field. However, there were no different phases presented when pulsed magnetic field was applied.
MAGNETORHEOLOGICAL CHARACTERIZATION OF HOLLOW POLYMER/MAGNETITE MICROSPHERICAL COMPOSITE
Authors: FANG FEI FEI , KIM JI HYE , CHOI HYOUNG JIN
Published: July 2009

Magnetorheological (MR) suspensions, composed of colloidal particles dispersed in a carrier liquid, possess tunable rheological characteristics by applying an external magnetic field, showing dramatic changes of yield stress and shear viscosity caused by transformation between solid-like to liquid-like state. As a new MR material, we synthesized hollow polystyrene/magnetite (PS/Fe3O4) microspherical composite. Morphology of the PS obtained and the loaded magnetite were examined via SEM, and TGA spectra confirmed the composition. Magnetic property was tested by VSM data. MR characteristics of MR suspension based on PS / Fe 3 O 4 composites were studied via both steady shear and oscillatory tests using a rotational rheometer equipped with a magnetic field generator.
POTASSIUM-SODIUM-RUBIDIUM NIOBATE SINGLE CRYSTALS AND ELECTRIC PROPERTIES
Authors: KIMURA H. , TANAHASHI R. , MAIWA K. , BABA H. , CHENG Z. X. , WANG X. L.
Published: July 2009

Potassium-sodium-rubidium niobate single crystals are grown using an original pulling down method, to improve their composition change during a crystal growth, by means of co-doping of small ionic size sodium and large ionic size rubidium into potassium niobate. Even by the co-doping, single crystals can be grown with orthorhombic single-phase at room temperature, as well as pure potassium niobate. Their electric properties, such as the dielectric constant and the impedance, are changed depending on the doping ions.
GROWTH MODE OF GRAPHENE LAYERS DEPOSITED ON SiO2 SUBSTRATE
Authors: AO Z. M. , LIU T. , JIANG Q. , LI S.
Published: July 2009

Despite the intense interest in peculiar electronic structure of graphene layers for potential application, especially in the microelectronics, the growth mechanism of graphene on substrates is still unclear. Understanding the quantitative correlation between layer number n and the critical radius R c of the graphene cylinder will provide new insight in the fundamental science for the potential applications of graphene. In this work, the R c (n) function of graphene layers deposited on SiO 2 substrate is established with nanothermodynamics. The finding in which R c increases linearly as n increases agrees with the experimental results. This reveals the actual mechanism of the graphene growth behavior. In addition, the atomic structure of the graphene/ SiO 2 interface was optimized by density functional theory.
HYDROTHERMAL SYNTHESIS OF ZnO NANOSTRUCTURES UNDER HIGH PULSED MAGNETIC FIELD
Authors: WANG ZHUN , ZHU MINGYUAN , LI YING , JIN HONGMING , ZHU ZHENZHEN , DENG XIAOLONG , LI WENXIAN , ZENG RONG
Published: July 2009

Crystalline zinc oxide (ZnO) particles with different morphologies have been synthesized by the hydrothermal method under the magnetic field. It is found that the magnetic field influences the nucleation and growth of ZnO crystals. ZnO crystals obtained under high pulsed magnetic field were more uniform and well integrated.
NONLINEAR OPTICAL PROPERTIES OF QUANTUM DOTS: EXCITONS IN NANOSTRUCTURES
Authors: FU Y. , HELLSTRÖM S. , ÅGREN H.
Published: July 2009

We review the concepts of excitons and excitonic polaritons, their nonlinear optical properties in nanostructures and their applications within integrated electronics and optoelectronics. Various theoretical aspects of excitons and excitonic polaritons are introduced, followed by a summary of their experimental and application-specific development in nanostructures at the electronic and photonic engineering levels. A number of technical applications are highlighted.
ONLINE TRANSFER OF HUMAN MOTION TO HUMANOIDS
Authors: DARIUSH BEHZAD , GIENGER MICHAEL , ARUMBAKKAM ARJUN , ZHU YOUDING , JIAN BING , FUJIMURA KIKUO , GOERICK CHRISTIAN
Published: July 2009

Transferring motion from a human demonstrator to a humanoid robot is an important step toward developing robots that are easily programmable and that can replicate or learn from observed human motion. The so called motion retargeting problem has been well studied and several off-line solutions exist based on optimization approaches that rely on pre-recorded human motion data collected from a marker-based motion capture system. From the perspective of human robot interaction, there is a growing interest in online motion transfer, particularly without using markers. Such requirements have placed stringent demands on retargeting algorithms and limited the potential use of off-line and pre-recorded methods. To address these limitations, we present an online task space control theoretic retargeting formulation to generate robot joint motions that adhere to the robot's joint limit constraints, joint velocity constraints and self-collision constraints. The inputs to the proposed method include low dimensional normalized human motion descriptors, detected and tracked using a vision based key-point detection and tracking algorithm. The proposed vision algorithm does not rely on markers placed on anatomical landmarks, nor does it require special instrumentation or calibration. The current implementation requires a depth image sequence, which is collected from a single time of flight imaging device. The feasibility of the proposed approach is shown by means of online experimental results on the Honda humanoid robot — ASIMO.
REAL-TIME SPOKEN-LANGUAGE PROGRAMMING FOR COOPERATIVE INTERACTION WITH A HUMANOID APPRENTICE
Authors: DOMINEY PETER FORD , MALLET ANTHONY , YOSHIDA EIICHI
Published: July 2009

An apprentice is an able-bodied individual that will interactively assist an expert, and through this interaction, acquire knowledge and skill in the given task domain. A humanoid apprentice should have a useful repertoire of sensory-motor acts that the human can command with spoken language, along with a real-time behavioral sequence acquisition ability. The learned sequences should function as executable procedures that can operate in a flexible manner that are not rigidly sensitive to initial conditions. Our study integrates these capabilities in a real-time system on the HRP-2 humanoid, for learning a cooperative assembly task. We previously defined a system for Spoken Language Programming (SLP) that allowed the user to guide the robot through an arbitrary, task relevant, motor sequence via spoken commands, and to store this sequence as re-usable macro. Here, we significantly extend the SPL system: It integrates vision and motion planning into the SLP framework, providing a new level of flexibility in the actions that can be created, and it allows the user to create "generic" functions with arguments (e.g. Give me X), and it allows multiple functions to be created.
RUNNING PATTERN GENERATION WITH A FIXED POINT IN A 2D PLANAR BIPED
Authors: CHO BAEK-KYU , OH JUN-HO
Published: July 2009

This paper discusses the generation of a running pattern for a biped and verifies the validity of the proposed method of running pattern generation via experiments. When a running pattern is created with resolved momentum control, the angular momentum of the robot at the Center of Mass (COM) is set to zero, as the angular momentum causes the robot to rotate. However, this also induces unnatural motion of the upper body of the robot. To resolve this problem, the biped was set to a virtual under-actuated robot with a free joint at its support ankle, and a fixed point for a virtual system was determined. Following this, a new periodic running pattern was formulated using the fixed point. The fixed point is easily determined using a numerical approach. In an experiment, the planar biped ran forward using the proposed pattern generation method for running. Its maximum velocity was 2.88 km/h. In the future, faster running of the biped will be realized in a planar plane and the biped will run in an actual environment.
Synthesis, photophysical and photochemical studies of germanium and tin phthalocyanine complexes
Authors: Maree Suzanne , Phillips David , Nyokong Tebello
Published: July 2009

This work reports on the synthesis of tin and germanium phthalocyanine complexes containing phenoxy and substituted phenoxy groups as phthalocyanine ring substituents. The compounds studied are: dichlorogermanium phthalocyanine complexes containing eight phenoxy (4a), o-methyl phenoxy (4b) or estrone (4c) groups on the ring. The corresponding dichlorotin complexes (5a, 5b and 5c) and diiodotin complex (6a) were also investigated, as well as diestrone phthalocyaninato tin (7). Germanium octaphenoxy phthalocyanine complexes undergo phototransformation rather than direct photobleaching, whereas tin octaphenoxy phthalocyanine complexes undergo a photobleaching process, which is mediated by photoreduction of the phthalocyanine ring. Tin octaphenoxy phthalocyanine complexes gave higher ΦΔ values than the corresponding germanium complexes. Also tin phthalocyanine complexes containing an unsubstituted ring gave higher ΦΔ values than the corresponding octaphenoxy substituted complexes. The triplet quantum yields increased with the increase in electron-donating power of the ring substituents.
First synthesis of 5[helicene] fused phthalocyanines: exceptional solubilities and long Q-band absorptions
Authors: Mandal Braja K. , Sooksimuang Thanasat
Published: July 2009

A new class of phthalocyanine derivatives containing fused [5]helicene moieties has been synthesized. These derivatives, named as helicenocyanines, are soluble in common organic solvents and exhibit significant red shift of Q-band absorptions. Electrochemical, thermal and fluorescence characteristics of these helicenocyanines are presented.
Straightforward route to trans-A2B-corroles bearing substituents with basic nitrogen atoms
Authors: Gryko Daniel T. , Piechota Katarzyna E.
Published: July 2009

We have developed a comprehensive methodology that affords regioisomerically pure trans- A 2 B -corroles bearing substituents with basic nitrogen atoms at meso positions. The corrole formation reaction involves the acid-catalyzed condensation of a dipyrromethane (DPM) and an aldehyde followed by oxidation with DDQ. The optimal conditions for this process were identified by extensive modifications of the previously developed conditions for the synthesis of trans-A2B-corroles with aromatic substituents. In particular three distinct sets of conditions were identified for various specific cases. Pyridine, quinoline and quinoxaline derived aldehydes as well as other aromatic aldehydes with tertiary amine groups in different positions were succesfully used in the condensation involving sterically hindered dipyrromethanes under the following conditions: (First step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 50 mM, 1h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1.5 or 1.3 eqs. of DDQ versus DPM). A different set of conditions was developed for the condesation involving sterically unhindered dipyrromethanes: (first step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 17 mM, 5h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1 eq of DDQ versus DPM). In this case only aldehydes with the formyl group directly adjacent to the heterocylic ring are efficient substrates; for the remaining aldehydes an extensive scrambling was observed. The condensation of pyridyldipyrromethanes with aldehydes bearing electron-withdrawing substituents (first step: CH 2 Cl 2, [DPM] = 33 mM, [aldehyde] = 17 mM, [TFA] = 67 mM, 1h, room temperature, second step: neutralization with Et 3 N , CH 2 Cl 2, dilution 26 times, 1 eq of DDQ versus DPM) leads to corroles in 2-11 % yield depending on the position of the nitrogen atom. Finally, 10-(4-formylphenyl)-5,15-dimesitylcorrole was obtained and reacted with mesityldipyrromethane, giving the symmetrical corrole dyad in 14% yield. A total of 21 new corroles of type trans- A 2 B were prepared.
Synthesis and spectroscopic characterization of Ni, Zn, Pd and Pt tetra(pentafluorophenyl)porpholactone with comparisons to Mg, Zn, Y, Pd and Pt metal complexes of tetra(pentafluorophenyl)porphine
Authors: Khalil Gamal , Gouterman Martin , Ching Stephen , Costin Colin , Coyle Lisa , Gouin Sebastien , Green Edmond , Sadilek Martin , Wan River , Yearyean Jeff , Zelelow Biniam
Published: July 2009

Ni , Zn , Pd and Pt tetra(pentafluorophenyl)porpholactone (TFPL) were synthesized and identified by their optical and mass spectra. The lactone ring was produced from the parent free-base porphyrin using silver nitrate and oxalic acid with a yield of 73%, and the metals were inserted by standard procedures from metal salts. The compounds show intense Soret Bands in the region 390-420 nm. The longest wavelength visible absorbance peaks, in the region 572-608 nm, are weaker than the Soret peaks by a factor of only ~3 for the Ni , Pd , and Pt complexes but a factor of ~10 for the free-base and Zn complexes. As found with other metalloporphyrins the Ni complex is dark, Zn shows fluorescence and Pd and Pt complexes show strong phosphorescence. The Pd complex also shows a weak fluorescence not quenched by oxygen. The phosphorescence lifetimes of Pd and Pt complexes of TFPL in 3-methylpentane at 77 K are, respectively, ~1 ms and ~70 μs, about 60% that of the TFPP complexes. The wavelengths of phosphorescence emission, 733 nm and 758 nm for PtTFPL and PdTFPL, respectively, are sufficiently red-shifted so that these pressure sensitive luminophors can be included in the same pressure sensitive paint (PSP) as Eu complexes, whose emission at ~615 nm can serve as a temperature sensor. The fluorescences of Mg , Zn , and Y(TFPP) show weak origin bands, making them suitable as unquenched references for PSP.
Overview of optical sensors using porphyrins
Authors: Okura Ichiro
Published: July 2009

To meet recent requirement of sensors, new optical sensor technology by molecules of functional chemical compounds as nano-scale sensor probes is developing. In this overview, the background and the concept of optical sensor technology are briefly introduced and a new optical sensing system by triplet-triplet absorption is discussed as an example.
Mechanisms of porphyrinoid localization in tumors
Authors: Osterloh Jens , Vicente M. Graça H.
Published: July 2009

The photosensitizing and pharmacokinetic properties of porphyrin-type compounds have been investigated for nearly a century. In the last decade, two porphyrin derivatives were approved in the U.S.A. and in several other countries for the photodynamic treatment of various lesions. An overview of the different mechanisms for preferential porphyrinoid localization in malignant tumors is presented herein. Several uptake pathways are possible for each photosensitizer, which are determined by its structure, mode of delivery and tumor type. Comparisons of the different mechanisms and correlations with the structure of the sensitizer are presented. Current delivery systems for porphyrin sensitizers are described, as well as recent strategies for enhancing their tumor-specificity, including conjugation to a carrier system that selectively targets a tumor-associated receptor or antigen.
Synthesis of the first N-hydroxycycloimide in the bacteriochlorophyll a series
Authors: Mironov Andrei F. , Grin Michael A. , Tsyprovskiy Alexander G.
Published: July 2009

The first N-hydroxycycloimide of bacteriochlorin p6has been synthesized and chemical modification at the hydroxyl group demonstrated. The relative reactivities of the acetyl substituent and the anhydride ring in reaction with hydroxylamine were studied.
Effects of axial ligands on the photophysical properties of silicon octaphenoxyphthalocyanine
Authors: Maree M. David , Nyokong Tebello , Suhling Klaus , Phillips David
Published: July 2009

The photochemistry and photophysics of six axially substituted silicon phthalocyanines are reported and show the importance of the axial groups in the photochemistry of these compounds. The fluorescence quantum yields are especially affected by the axial ligand. A very good correlation was found for the experimentally determined fluorescence lifetimes and the theoretically determined lifetimes using the Strickler-Berg equation for the unaggregated molecules.
Preparation, mass spectrometry and electrochemical studies of metal connected porphyrin oligomers
Authors: Richeter Sébastien , Jeandon Christophe , Sauber Christian , Gisselbrecht Jean-Paul , Ruppert Romain , Callot Henry J.
Published: July 2009

Oligomers built from metal ions and porphyrins bearing enaminoketones at the ring periphery were prepared. These dimers or trimers, where all porphyrinic rings are coplanar, show large interactions in the ground state between the individual porphyrin cores, as shown by their optical properties and electrochemical studies. In particular, a spectacular decrease of the HOMO-LUMO gap (with values as low as 1.32 eV) was observed for monomeric porphyrins metalated on the external sites. Along with standard analytical methods, APPI (Atmospheric Pressure PhotoIonization) mass spectrometry was found to be a very powerful tool to characterize these metal connected porphyrin oligomers.
Synthesis and characterization of di-n-hexylamino-substituted phthalocyanines
Authors: Gümüş Gülay , Ahsen Vefa
Published: July 2009

Metal-free- and metallophthalocyanines ( M = Ni , Zn and Co ) carrying four di-n-hexylamino and four chloro groups in peripheral positions have been synthesized from the corresponding dichlorophthalonitrile derivative in the presence of the anhydrous metal salts [ NiCl 2, Zn ( O 2 CMe )2, CoCl 2] or a strong organic base. The new compounds have been characterized by elemental analyses, IR, NMR and electronic spectroscopy and mass spectra.
Host-guest complexes of anionic porphyrin sensitizers with cyclodextrins
Authors: Mosinger Jiří , Kliment Viktor , Sejbal Jan , Kubát Pavel , Lang Kamil
Published: July 2009

The photodynamic sensitizers zinc(II)- and palladium(II)-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrins and 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin form 1:1 and/or 1:2 supramolecular complexes with native cyclodextrins (CD) and 2-hydroxypropyl cyclodextrins (hpCD) in aqueous neutral solutions. The formation of these assemblies causes a bathochromic shift of the porphyrin Soret band in the UV-vis spectra and a red shift of the fluorescence emission bands. The binding constants span over three orders of magnitude, from 8.1 × 102M−1to 5.4 × 105M−1(or 1.1 × 106M−2) depending on the size of the CD cavity and on the functionalization by adding 2-hydroxypropyl groups. The highest binding constants were obtained for hpβCD and hpγCD. The Nuclear Overhauser spectroscopy signals (ROESY) revealed three binding modes: i) inclusion of the porphyrin 4-sulfonatophenyl or 4-carboxyphenyl groups via the secondary face of βCD and hpβCD with sulfonic or carboxylic groups oriented towards the primary hydroxyl groups. ii) inclusion of the porphyrin groups via the primary face of γCD and hpγCD. iii) non-specific binding of the porphyrin monomers or aggregates on the cyclodextrin exterior. The inclusion host-guest complexation via i) or ii) does not influence the inherent photophysical properties of the monomeric porphyrins such as the quantum yields of fluorescence, the triplet states, and the singlet oxygen formation. Due to the deaggregation effect of cyclodextrins, the inclusion complexes remain efficient supramolecular sensitizers of singlet oxygen even under conditions of extensive aggregation in aqueous solutions.
Synthesis and characterization of unsymmetrically substituted dienophilic nickel phthalocyanines for Diels-Alder reactions
Authors: Youssef Tamer E. , Hanack Michael
Published: July 2009

A general synthesis of unsymmetrically substituted dienophilic nickel phthalocyanines is described. The desired nickel phthalocyanine complexes [3,4,10,11,17,18-hexakis(2-ethyl-hexyloxy)tribenzo(b,g,i]-24,27-di-hydro-24,27-epoxynaphthalo[q]porphyrazinato]nickel(II) (4) and dodeca alkoxy-substituted PcNi (5) were synthesized using a statistical approach by the condensation of 1,2-dicyano-4,5-bis(2-ethylhexyloxy)benzene (1) or 1,2-dicyano-3,4,5,6-tetrakis(2-ethylhexyloxy)benzene (2) and 6,7-dicyano-1,4-dihydro-1,4-epoxy-1,4-dimethylnaphthalene (3) in the presence of nickel(II) acetate. Reaction of 4 or 5 with tetraphenyl-cyclopentadieneone (9) lead to the phthalocyanine-tetracyclone adducts 10 and 11, respectively, which are precursors for intermediate adducts 12 and 13 containing isobenzofuran moiety as diene subunits. The dimer 14 was synthesized from 4 and the isobenzofuran intermediate 12. Dehydrogenation of the Diels-Alder product 14 to the fully conjugated derivative 15 was carried out successfully with p-toluenesulfonic acid.
Energy transfer and structure determination of porphyrin dimers linked via a phenylenebisvinylene bridge: A time-resolved triplet electron paramagnetic resonance study
Authors: Stavitski Eli , Galili Tamar , Levanon Haim , Burrell Anthony K. , Officer David L. , Scott Sonya
Published: July 2009

The photoexcited triplet state in a series of homo and hetero dimers was examined by time resolved electron paramagnetic resonance (TREPR) spectroscopy. The systems studied here consist of free-base tetraxylylporphyrin ( H 2 TXP ) and Zn (II) tetraxylylporphyrin ( ZnTXP ) and held together covalently by phenylenebisvinylene bridge at different positions. Experiments were carried out on the dimers, dissolved in an isotropic matrix (toluene), and in an anisotropic matrix of a liquid crystal (LC). Analysis of the results demonstrates that the dimers exhibit different geometries, depending on the linkage. Specifically, the triplet line shape analysis indicates that the para-dimers have a planar structure, the meta-dimers reveal the existence of two structural conformers, i.e. planar and slightly bent, while the ortho-dimers are characterized by the strongly bent molecular structure. The dimers exhibit efficient intramolecular singlet energy transfer (EnT) from ZnTXP to H 2 TXP subunit. On the other hand, EnT in all hetero dimers studied here is incomplete and some contribution from ZnTXP subunit is present in all triplet spectra. Thus, the efficiency of the EnT in the present systems is determined by properties of the connecting spacer, and does not depend on specific conformation and geometry of the molecule.
Synthesis, characterization and aggregation behavior ofNi(II)andZn(II)phthalocyanines with peripheral monoazacrown ethers
Authors: Atilla Devrim , Ahsen Vefa
Published: July 2009

The synthesis of metallo derivatives ( Ni , Zn ) of phthalocyanines (pcs) obtained from 4,5-dicyanobenzomonoazacrown ether substituted with long alkyl chains (5a-d) are described. The new compounds have been characterized by elemental analysis,1H ,13C NMR, MS, IR and UV-vis spectroscopy techniques. The aggregation properties and alkali metal interaction of the pcs (6a-d and 7a-d) were investigated.
Syntheses and some chemistry of stable isoporphyrin systems
Authors: Xie Hong , Leung Sam H. , Smith Kevin M.
Published: July 2009

Isoporphyrin zinc(II) complexes can be synthesized using the MacDonald ["2+2"] approach, with suitably substituted dipyrromethanes and 5,5-dialkyldipyrromethanes. The zinc(II) complexes are stable, show characteristic optical and1H NMR spectra, and have been characterized as perchlorate salts by X-ray diffraction. Attempts to prepare other metal salts of isoporphyrins ( Ni , Cu , Fe ), either by metalation during ring synthesis or by subsequent metalation of metal-free isoporphyrins, were unsuccessful. Evidence shows that a metal-free isoporphyrins can synthesized by demetalating the corresponding zinc(II) complexes with TFA. However, workup with base after the reaction must be avoided. The optical spectra of relatively unstable metal-free isoporphyrins (λmax( CH2Cl2) 430, 700 nm) are blue shifted relative to their zinc(II) complexes (λmax( CH2Cl2) 416, 731, 797 nm), and can be remetalated with zinc(II) acetate, to generate the fully characterized zinc(II) salts.
Perhalogenated porphyrins as a sink of excitation energy in porphyrin heterodimers
Authors: Venanzi Mariano , Tagliatesta Pietro , Pastorini Alessandra , Mari Patrizia , Elisei Fausto , Latterini Loredana , Kadish Karl M.
Published: July 2009

The photophysics of a new family of free-base and zinc derivatives of meso- tetraphenylporphyrin heterodimers have been studied by UV-vis absorption, fluorescence and nanosecond flash photolysis techniques. An almost complete (≈99%) and directionally controlled transfer of excitation energy from a donor porphyrin moiety was obtained by multiple bromination (four and eight Br substituents in the two series of compounds investigated) on the β-pyrrole positions of the acceptor porphyrin molecule. The covalently linked porphyrin dimers populate almost exclusively low energy triplet states because of the extremely efficient intramolecular singlet-to-triplet inter system crossing (ISC) process which is enhanced by the multiple heavy atoms substitutions. The nature of the electronic interactions determining the actual relaxation pathway followed by the porphyrin donor-acceptor pair is discussed.
Porphyrin building blocks: using a modified Barton-Zard approach to construct annulated pyrroles
Authors: Johnstone Ken D. , Pearce Wayne A. , Pyke Simon M.
Published: July 2009

A modification of the Barton-Zard pyrrole synthesis involving condensation of isocyanoacetate esters with cyclic unsaturated sulfones using sodium hydride as base is demonstrated for the construction of annulated pyrroles.
Peripherally-metallated porphyrins: meso-η1-porphyrinyl-platinum(II) complexes of 5,15-diaryl- and 5,10,15-triarylporphyrins
Authors: Hartnell Regan D. , Edwards Alison J. , Arnold Dennis P.
Published: July 2009

Attempted metathesis reactions of peripherally-metallated meso-η1-porphyrinylplatinum(II) complexes such as trans-[ PtBr ( NiDPP )( PPh 3)2]( H 2 DPP = 5,15- diphenylporphyrin ) with organolithium reagents fail due to competitive addition at the porphyrin ring carbon opposite to the metal substituent. This reaction can be prevented by using 5,10,15-triarylporphyrins, e.g. 5,10,15-triphenylporphyrin ( H 2 TrPP ) and 5-phenyl-10,20-bis(3′,5′-di-t-butylphenyl)porphyrin ( H 2 DAPP ) as substrates. These triarylporphyrins are readily prepared using the method of Senge and co-workers by addition of phenyllithium to the appropriate 5,15-diarylporphyrins, followed by aqueous protolysis and oxidation. They are convenient, soluble building blocks for selective substitutions and subsequent transformations at the remaining free meso carbon. The sequence of bromination, optional central metallation and oxidative addition of Pt (0) tris(phosphine) complexes generates the organoplatinum porphyrins in high overall yields. The bromo ligand on the Pt (II) centre can be substituted by alkynyl nucleophiles, including 5-ethynyl NiDPP , to form the first examples of meso-η1-porphyrinylplatinum(II) complexes with a second Pt - C bond. The range of porphyrinylplatinum(II) bis(tertiary phosphine) complexes was extended to the triethylphosphine analogues, by oxidative addition of H 2 TrPPBr to Pt ( PEt 3)3, and the initially-formed cis adduct is only slowly thermally transformed to trans-[ PtBr ( H 2 TrPP )( PEt 3)2]16. The molecular structures of NiDAPP 9b, trans-[ Pt ( NiDPP )( C 2 NiDPP )( PPh 3)2]14 and 16 were determined by X-ray crystallography.
Efficient synthesis of free-base 2-formyl-5,10,15,20-tetraarylporphyrins, their reduction and conversion to [(porphyrin-2-yl)methyl]phosphonium salts
Authors: Bonfantini Edia E. , Burrell Anthony K. , Campbell Wayne M. , Crossley Maxwell J. , Gosper Jeffrey J. , Harding Margaret M. , Officer David L. , Reid David C. W.
Published: July 2009

A highly efficient synthesis of 2-formyl-5,10,15,20-tetraarylporphyrins, 1 and 2, that can be carried out on multi-gram scales is reported. The key steps in the sequence involve use of copper(II) chelation to ensure very efficient electrophilic substitution, and the demetalation of the intermediate iminium salt that results from Vilsmeier-Haack formylation of the copper(II) porphyrins prior to base-catalyzed hydrolysis of the salt to the corresponding free-base 2-formylporphyrin. This sequence avoids the formation of by-products that inevitably result when the formyl group is subjected to acidic conditions. Borohydride reduction of (metallo)-2-formylporphyrins give the corresponding 2-hydroxymethyl-porphyrins in quantitative yield. Catalytic reduction of copper(II) 2-hydroxymethyl-5,10,15,20-tetraphenylporphyrin 15 with hydrogen under acidic conditions affords 2-methyl-5,10,15,20-tetraphenylporphyrin 20 in 60% yield. Treatment of 2-hydroxymethyl-porphyrins with thionyl chloride in dry pyridine yields the corresponding 2-chloromethyl-porphyrins in good yields. The 2-chloromethyl-porphyrins give the corresponding triphenyl[(porphyrin-2-yl)methyl]phosphonium chlorides in 90% yield on treatment with PPh 3 in boiling chloroform. These salts are useful building blocks for the synthesis of conjugated porphyrin dimers and higher oligomers.
Novel phthalocyanines containing cardanol derivatives
Authors: Attanasi Orazio A. , Ciccarella Giuseppe , Filippone Paolino , Mele Giuseppe , Spadavecchia Jolanda , Vasapollo Giuseppe
Published: July 2009

The synthesis and characterization of metal-free and metallo derivatives ( Cu , Zn , Ni , Pd ) of tetra-substituted phthalocyanines are described. The new compounds contain as a peripheral substituent 3-n-pentadecylphenol, a component of cardanol, which is a renewable organic source.
Parallel synthesis of meso-substituted corroles and meso-substituted [22]pentaphyrins(1.1.1.0.0) from diacyl-dipyrromethanes
Authors: Gryko Daniel T. , Tasior Mariusz , Koszarna Beata
Published: July 2009

A new method was devised for the synthesis of 1,9-diacyldipyrromethanes - crucial intermediates in the synthesis of meso-substituted corroles and porphyrins with different substituents. The diacylodipyrromethanes formation involves acylation of dipyrromethanes with salts made in situ from POCl 3 and tertiary amides. This modified Vilsmeier approach gives higher yields and no concomitant formation of monoacyldipyrromethanes as compared with the Grignard route. Moreover, compounds possessing groups previously inaccessible ( CN , NO 2 etc.) can be synthesized. During optimization of the transformation of diacyldipyrromethanes into meso-substituted corroles it was found that if macrocyclization reaction mediated by DDQ is performed in the presence of large excess of pyrrole, meso-substituted [22]pentaphyrins(1.1.1.0.0) can be obtained in moderate yield. The currently described procedure constitutes a new method for the synthesis of these valuable porphyrinoids. Corroles possessing interesting, easy to transform, functional groups were obtained in 3-40% yield.
Oxidative direct coupling of metalloporphyrins
Authors: Nakamura Yasuyuki , Aratani Naoki , Tsuda Akihiko , Osuka Atsuhiro , Furukawa Ko , Kato Tatsuhisa
Published: July 2009

A variety of directly-linked diporphyrins can be prepared by an oxidative coupling reaction of 5,15-diaryl metalloporphyrins. Regioselectivity of the coupling reaction depends on the metal in the porphyrin core; Zn II -porphyrins favor meso-meso coupling and Pd II -porphyrins favor meso-β coupling. β-β Linked diporphyrins were isolated for the first time from the oxidation of 5,15-diaryl Pd II -porphyrin with DDQ and Sc ( OTf )3.
Photochromic porphyrins
Authors: Gorodetsky Brian , Sud David , Norsten Tyler B. , Myles Andrew J. , Branda Neil R.
Published: July 2009

This paper presents an overview of several examples of molecular systems in which the electronic changes that result from the photoinduced isomerization of photochromic phenoxynaphthacenequinone (PNQ) and dithienylethene (DTE) derivatives significantly influence the luminescence behavior of attached porphyrins.
Recent developments in the formation of carbon-carbon bond reactions catalyzed by metalloporphyrins
Authors: Tagliatesta Pietro , Floris Barbara , Galloni Pierluca
Published: July 2009

Recent advances in the catalytic formation of carbon-carbon bonds by metalloporphyrins are surveyed. New studies on cyclopropanation and olefination reactions are discussed and a new application of metalloporphyrin catalysis, the cyclotrimerization of phenylethynes, is presented.
NMR spectroscopic evidence for the self-association of some asymmetrically substituted phthalocyanines in solution
Authors: Chambrier Isabelle , Cook Michael J. , Mayes Denise A. , MacDonald Colin
Published: July 2009

1 H NMR data obtained for two series of asymmetrically octasubstituted metal-free and zinc phthalocyanines, bearing one or two hydroxyalkyl groups, indicate a degree of solution phase aggregation particular to the systems. The metal-free derivatives appear to stack cofacially through the interaction of their π systems and give rise to unusually well resolved, solvent, temperature and concentration dependent 1 H NMR spectra. Structural features for the aggregates, in which the phthalocyanine rings are cofacial but offset in a particular way, are proposed based on the NMR data. The zinc derivatives appear to form dynamic aggregates in solution in which the oxygen borne by one of the substituents coordinates to the zinc at the centre of the core through an inter- and/or intramolecular interaction leading to the temperature dependent 1 H NMR spectra that are observed.
Influence of cyclodextrins on the fluorescence, photostability and singlet oxygen quantum yields of zinc phthalocyanine and naphthalocyanine complexes
Authors: Tau Prudence , Ogunsipe Abimbola O. , Maree Suzanne , Maree M. David , Nyokong Tebello
Published: July 2009

The effects of formation of cyclodextrin inclusion complexes on the photochemical and photophysical properties of zinc phthalocyanine ( ZnPc ) and various peripherally substituted zinc phthalocyanines as well as zinc naphthalocyanine ( ZnNPc ) are investigated. The cyclodextrins employed were the hydroxypropyl-γ-cyclodextrin and unsubstituted β-cyclodextrin. Job's plots were employed to confirm the stoichiometry of the inclusion complexes and showed 2:1 and 4:1 (cyclodextrin:phthalocyanine) inclusion behavior. The phthalocyanine inclusion complexes showed larger singlet oxygen quantum yield (ϕΔ) values when compared to the free phthalocyanines before inclusion, for complexes 1 (zinc naphthalocyanine), 2 (zinc tetranitrophthalocyanine) and 4 (zinc tetra-tert-butylphenoxyphthalocyanine). The fluorescence quantum yields generally remained unchanged following inclusion.
Electrochemical and resonance Raman studies of nitridomanganese(V) porphyrins in nonaqueous solution
Authors: Jou Jeng-Yi , Chang Chih-Hao , Lee Gene-Hsiang , Wang Yu , Su Y. Oliver , Yeh Wei-Lun , Cheng Shu-Hua
Published: July 2009

The UV-vis spectral, electrochemical and resonance Raman data of [meso-tetrakis(4-pyridyl)porphyrinato]nitridomanganese(V), MnN(TPyP) , were investigated. MnN(TTP) (where ( TTP )2− = dianion of meso-tetrakis(p-tolyl)porphyrin) and MnN(OEP) (where ( OEP )2− = dianion of 2,3,7,8,12,13,17,18-octaethylporphyrin) were also examined in comparison. Cyclic voltammetry of MnN ( TPyP ) showed an irreversible oxidation wave at +1.22 V and two redox couples at −1.05 and −1.40 V vs. Ag / AgCl , respectively. According to spectroelectrochemical studies, the first and the second reductions involved formation of the porphyrin anion and dianion, respectively, the latter leading to a phlorin. The electron-withdrawing 4-pyridyl substituent shifted the redox potential of the porphyrin ring to a more positive value. However, the bond strength of the Mn - N triple bond was not affected. Resonance Raman studies indicated that the Mn≡N stretching frequencies (νMnN) occurring within 1050 ± 1 cm−1 in various solvents did not change significantly. The hydrogen-bonding between methanol and MnN ( TPyP ) lowered νMnN to 1040 cm−1. A further lowering of νMnN was found in the presence of nitrogeneous bases such as imidazole (ImH), piperidine (Pip) and pyridine (Py) and may be due to coordination to the manganese center. νMnN is correlated with the pKa's of a series of pyridines.
Spectral properties of cationic water-soluble metallo-porphyrins immobilized in a perfluorosulfonated ion-exchange membrane
Authors: Vasil'ev Victor V. , Borisov Sergey M. , Maldotti Andrea , Molinari Alessandra
Published: July 2009

The behavior of palladium(II), platinum(II) and rhodium(III) complexes with two cationic water-soluble porphyrins: meso-tetrakis(4-N-methylpyridyl)porphyrin and meso-tetrakis(4-N,N,N-trimethylaminophenyl)porphyrin in Nafion® membrane and in Nafion® solution have been studied by UV-visible absorption and emission spectroscopy. All metalloporphyrins are localized in the interfacial region of Nafion®. The six-coordinate Rh(III) complexes are monomeric inside Nafion®, but immobilized four-coordinate Pd(II) and Pt(II) complexes form face-to-face dimers with a characteristic blue shifted Soret band. All immobilized complexes exhibit a strong red phosphorescence at room temperature in the absence of oxygen. Phosphorescence decays for all metalloporphyrins were found to be a single exponential but phosphorescence lifetimes noticeably increased in the Nafion® membrane as compared to lifetimes in aqueous solution.
Schiff-base porphyrin and expanded porphyrin analogs
Authors: Callaway Wyeth B. , Veauthier Jacqueline M. , Sessler Jonathan L.
Published: July 2009

In recent years, the field of porphyrin chemistry has expanded to include several new analogs of the original four pyrrole, carbon-bridged systems. This review traces the development of one such class of new macrocycles, namely Schiff-base porphyrin analogs. The review's focus is on the synthesis and properties of these new Schiff-base macrocycles that for ease of division have been divided into four classes: systems with two pyrrole rings, systems with three pyrrole or heterocyclic rings, systems with four pyrrole or heterocyclic rings, and systems with five or more pyrrole or heterocyclic rings. In addition to the role of metal ions as templating agents in the synthesis of these complexes, the rich coordination chemistry of several of the macrocycles is also discussed. X-ray crystallography has played an important role in determining the structures of many of these Schiff-base porphyrin analogs and many of the available structures have been incorporated into this review. Aromaticity of the macrocycles is discussed and has been evaluated from available electronic and NMR spectra. Finally, several potential applications of these molecules are discussed, briefly.
Synthesis of one-dimensional bis-porphyrinic compounds with a transition metal complex as bridging unit
Authors: Chambron Jean-Claude , Collin Jean-Paul , Dixon Isabelle , Heitz Valérie , Salom-Roig Xavier J. , Sauvage Jean-Pierre
Published: July 2009

Linear multicomponent systems, consisting of two porphyrins attached to a central transition metal center, have been prepared and some of their electron- or energy transfer properties have been studied. Each porphyrin is covalently bound to a bidentate or a terdentate ligand, these coordinating molecules being gathered around the metal to afford the desired structure. The spatial arrangement is such that the porphyrinic components are located at both ends of an axis, the transition metal occupying its center. The edge-to-edge distance between the porphyrins is relatively large (~ 20 to 25 Å) and, due to the rigidity of the connectors, it is very well controlled. Three different strategies have been used to construct such assemblies. In the first approach, the porphyrinic fragments are attached at the back of 2,2′,6′,2″-terpyridine ligands (terpy), on the central position (4′). After reaction with an appropriate metal center (ruthenium(II) or iridium(III)), an octahedral complex is obtained which constitutes the central part of the assembly, whereas the porphyrins are at the periphery of the central complex. The second strategy involves the preparation of a 5,5′-disubstituted 2,2′-bipyridine (bipy) ligand followed by its coordination to ruthenium(II). Subsequently, the porphyrinic nuclei are constructed at both ends of the substituents, leading to a linear geometry with a central complex and two laterally-disposed porphyrins. Finally, a very special ligand has been designed and synthesized, which incorporates two 1,10-phenanthroline nuclei (phen). This ligand can wrap itself around an octahedral center (ruthenium(II)) so as to generate a helical arrangement. Both ends of the single-stranded helix can subsequently be attached to porphyrins.
Palladium chemistry in recent porphyrin research
Authors: Setsune Jun-ichiro
Published: July 2009

Palladium-catalyzed reactions such as Sonogashira coupling, Suzuki coupling, Stille coupling, Heck reactions, and Glaser-Hey oxidation were used to construct porphyrin modules of nano-scale molecular size in recent years. Recent developments in the supramolecular assembly of porphyrins and Pd (II) and in the organopalladium complexes of various porphyrins are also summarized.
Protein surface recognition by porphyrin-based receptors
Authors: Tsou Lun K. , Jain Rishi K. , Hamilton Andrew D.
Published: July 2009

Protein surface recognition is largely unexplored owing to the large solvent exposed surface and lack of proper molecular scaffolds to match the binding residues. This review describes the design, synthesis, and fluorescence binding studies of functionalized porphyrins aimed at targeting surface residues of proteins through complementary recognition. The pattern of lysine residues surrounding the heme-edge of horse heart cytochrome c has been targeted by tetraphenylporphyrin and tetrabiphenylporphyrin receptors that bind with nano- and sub-nanomolar affinity. Other designed porphyrin-based receptors also recognize potassium channel as a target. The strategies for protein surface recognition offer a new use for porphyrins as molecular scaffolds.