bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Properties of Electrophosphorescent Chelating Polymers with Iridium Complexes in the Conjugated Backbone
Authors: Zhen Hongyu , Jiang Changyun , Yang Wei , Jiang Jiaxing , Huang Fei , Cao Yong 
Published: June 2005

AbstractThe synthesis of electrophosphorescent chelating polymers by Suzuki polycondensation of A‐A‐ and B‐B‐type monomers is described, in which the fluorene‐alt‐carbazole (PFCz) segment is used as polymer backbone. By using alkyl‐substituted ligands of iridium complex monomers, chelating copolymers with higher contents of iridium complex can be synthesized. Chemical and photophysical characterization confirm that the Ir complex is incorporated into the polymer backbone as one of the monomer repeat units by means of two 5‐bromotolylpyridine ligands. Chelating polymers with Ir complexes in the conjugated polymer backbone show highly efficient energy transfer of excitons from the PFCz host segment to the Ir complex by an intramolecular trapping mechanism. The external quantum and luminous efficiencies of a device made with PFCzMppyIrhm4 copolymer reach 4.1 % ph/el (photons/electron) and 5.4 cd A−1, respectively, at a current density of 32.2 mA cm−2, an emission peak of 577 nm, and a luminance of 1730 cd cm−2. Most important, the devices made from the chelating copolymers show no notable efficiency decay with increasing current density due to reduced concentration quenching and triplet–triplet (T–T) annihilation. This indicates that incorporation of the phosphorescent complex into the rigid conjugated polymer main chain is a new way to simultaneously realize high efficiency, long‐term stability, and simple processing of phosphorescent polymer light‐emitting diodes.
Nonlinear Optical Properties in Calix[n]arenes: Orientation Effects of Monomers
Authors: Datta Ayan , Pati Swapan K. 
Published: June 2005

AbstractWe investigate the nonlinear optical (NLO) polarizations for various geometric arrangements of the dipolar chromophores in a calix[n]arene geometry. The interactions were studied by using (HF)3as model compounds both in parallel and frustrated orientations. The interdipolar angle between the monomer molecules is varied so that many different arrangements of the dipoles can be realized which is associated with the opening up of the calix[n]arene rings. Quantum‐chemical calculations at both ab initio and semiempirical levels, show that the all‐parallel arrangement of the dipoles exhibit the maximum magnitude for the nonlinear optical coefficients at small interdipolar angles for all interdipolar distances. In the frustrated orientations however, the NLO response is maximum at large interdipolar angles corresponding to the flattened calix[n]arene rings. The role of hydrogen bonding in stabilizing these assemblies in various conformations has been investigated. Crystallographic database analysis for calix[3]arenes shows that optical properties in real molecular systems can be modeled based on our simple interaction theory.
IPy2BF4‐Mediated Rearrangements of 1,2‐Difunctionalized Compounds and Olefins
Authors: Fañanás Francisco J. , Álvarez‐Pérez Mónica , Rodríguez Félix 
Published: June 2005

AbstractAcetal derivatives are easily obtained from 1,2‐difunctionalized compounds by a new reaction mediated by IPy2BF4 with a mechanism based on a 1,2‐migration of aryl or alkyl groups. A new oxidative rearrangement reaction of olefins is also described. Moreover, when this metal‐free protocol is applied to cyclic olefins, interesting ring‐contraction reactions are observed. The new methodologies described here are a clean and efficient alternative to known strategies that make use of potentially toxic metallic complexes.
Intramolecular Hydrogen‐Bond‐Assisted Planarization of Asymmetrically Functionalized Alternating Phenylene–Pyridinylene Copolymers
Authors: Vetrichelvan Muthalagu , Valiyaveettil Suresh 
Published: June 2005

AbstractWe report on the synthesis and characterization of a series of asymmetrically functionalized amphiphilic polymers with alternating π‐donor units (e.g., substituted benzene) and π‐acceptor units (e.g., pyridine) along the polymer backbone. The purpose of our present work involves incorporation of functional groups along the main chain to form intrachain hydrogen bonds, which promote planarization of the polymer backbone, and to fine‐tune the optical properties. The structure–property relationship of polymers P 1–P 6 was investigated by means of analytical methods, such as FTIR spectroscopy, 1H and 13C NMR spectroscopy, UV/Vis spectroscopy, fluorescence spectroscopy, gel permeation chromatography, thermogravimetric analysis, cyclic voltammetry, and X‐ray powder diffraction. All polymers were soluble in common organic solvents, and the optical and fluorescence spectra of the polymers showed significant changes according to the formation (P 4, P 5) or absence (P 6) of intramolecular hydrogen bonding along the polymer backbone. Moreover, the 2,6‐ or 3,5‐linkage of the pyridine rings in P 5 and P 6, respectively, reduced the conjugation along the polymer backbone and this is reflected in their optical properties. The optical properties of the polymers were influenced by the addition of acid (P 1–P 6), base (P 4–P 6), and metal ions (e.g., Cu2+, Fe3+, Ag+, Ni2+, Pd2+, Mn2+, Zn2+, Mg2+, and Pr3+). Such polymers could be used in various applications, including sensors and stimuli‐responsive displays.
Synthesis, Crystal Structures, and Properties of Oxovanadium(IV)–Lanthanide(III) Heteronuclear Complexes
Authors: Shi Wei , Chen Xiao‐Yan , Zhao Yan‐Nan , Zhao Bin , Cheng Peng , Yu Ao , Song Hai‐Bin , Wang Hong‐Gen , Liao Dai‐Zheng , Yan Shi‐Ping , Jiang Zong‐Hui 
Published: June 2005

AbstractA new series of oxovanadium(IV)–lanthanide(III) heteronuclear complexes [Yb(H2O)8]2[(VO)2(TTHA)]3⋅21 H2O (1), {[Ho(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5}⋅ 8.5 H2O (2), {[Gd(H2O)7(VO)2(TTHA)][(VO)2(TTHA)]0.5}⋅8.5 H2O (3), {[Eu(H2O)7][(VO)2(TTHA)]1.5}⋅ 10.5 H2O (4), and [Pr2(H2O)6(SO4)2][(VO)2(TTHA)] (5) (H6TTHA=triethylenetetraaminehexaacetic acid) were prepared by using the bulky flexible organic acid H6TTHA as structure‐directing agent. X‐ray crystallographic studies reveal that they contain the same [(VO)2(TTHA)]2− unit as building block, but the Ln3+ ion lies in different coordination environments. Although the lanthanide ions always exhibit similar chemical behavior, the structures of the complexes are not homologous. Compound 1 is composed of a [Yb(H2O)8]3+ ion and a [(VO)2(TTHA)]2− ion. Compounds 2 and 3 are isomorphous; both contain a trinuclear [Ln(H2O)7(VO)2(TTHA)]+ (Ln=Ho for 2 and Gd for 3) ion and a [(VO)2(TTHA)]2− ion. Compound 4 is an extended one‐dimensional chain, in which each Eu3+ ion links two [(VO)2(TTHA)]2− ions. For 5, the structure is further assembled into a three‐dimensional network with an interesting framework topology comprising V2Pr2 and V4Pr2 heterometallic lattices. Moreover, 4 and 5 are the first oxovanadium(IV)–lanthanide(III) coordination polymers and thus enlarge the realm of 3d–4f complexes. The IR, UV/Vis, and EPR spectra and the magnetic properties of the heterometallic complexes were studied. Notably, 2 shows unusual ferromagnetic interactions between the VO2+ and Ho3+ ions.
Deformed Phthalocyanines: Synthesis and Characterization of Zinc Phthalocyanines Bearing Phenyl Substituents at the 1‐, 4‐, 8‐, 11‐, 15‐, 18‐, 22‐, and/or 25‐Positions
Authors: Fukuda Takamitsu , Homma Shigetsugu , Kobayashi Nagao 
Published: June 2005

AbstractThe synthesis of a series of zinc phthalocyanines partially phenyl‐substituted at the 1‐, 4‐, 8‐, 11‐, 15‐, 18‐, 22‐, and/or 25‐positions (the so‐called α‐positions) is reported. Macrocycle formation based on 3,6‐diphenylphthalonitrile, o‐phthalonitrile, and zinc acetate predominantly yielded the near‐planar disubstituted complex and opposite tetrasubstituted isomer, while the lithium method yielded the sterically hindered hexasubstituted complex and adjacent tetrasubstituted isomer. All compounds have been characterized by 1H NMR, MALDI‐TOF‐MS, and elemental analysis methods. In addition, crystal structures have been solved for the di‐, hexa‐, and octasubstituted complexes and the adjacent tetrasubstituted isomer. DFT geometry optimization calculations predict more highly deformed structures than those observed in the crystals. The packing force of the crystals cannot therefore be ignored, particularly for the less phenyl‐substituted derivatives. The crystal structures have revealed that overlap of the phenyl groups causes substantial deformation of the phthalocyanine (Pc) ligands within the crystals, while strong π–π stacking in the remainder of the Pc moiety lacking phenyl substituents can suppress the impact of the deformation. Absorption spectra show sizable red shifts of the Q‐band with increasing number of phenyl groups. Analysis of the results of absorption spectra and electrochemical measurements reveals that a substantial portion of the red shift is attributable to the ring deformations. Molecular orbital calculations lend further support to this conclusion. A moderately intense absorption band emerging at around 430 nm for highly deformed octaphenyl‐substituted zinc Pc can be assigned to the HOMO→LUMO+3 transition, which is parity‐forbidden for planar Pcs, but becomes allowed since the ring deformations remove the center of symmetry.
Efficient CF and CC Activation by a Novel N‐Heterocyclic Carbene–Nickel(0) Complex
Authors: Schaub Thomas , Radius Udo 
Published: June 2005

AbstractThe NHC‐stabilized complex [Ni2(iPr2Im)4(cod)] (1) was isolated in good yield from the reaction of [Ni(cod)2] with 1,3‐diisopropylimidazole‐2‐ylidene (iPr2Im). Compound1is a source of the [Ni(iPr2Im)2] complex fragment in stoichiometric and catalytic transformations. The reactions of1with ethylene and CO under atmospheric pressure or with equimolar amounts of diphenylacetylene lead to the compounds [Ni(iPr2Im)2(η2‐C2H4)] (2), [Ni(iPr2Im)2(η2‐C2Ph2)] (3), and [Ni(iPr2Im)2(CO)2] (4) in good yields. In all cases the [Ni(iPr2Im)2] complex fragment is readily transferred without decomposition or fragmentation. In the infrared spectrum of carbonyl complex4, the CO stretching frequencies are observed at 1847 and 1921 cm−1, and are significantly shifted to lower wavenumbers compared with other nickel(0) carbonyl complexes of the type [NiL2(CO)2]. Complex1activates the CF bond of hexafluorobenzene very efficiently to give [Ni(iPr2Im)2(F)(C6F5)] (5). Furthermore, [Ni2(iPr2Im)4(cod)] (1) is also an excellent catalyst for the catalytic insertion of diphenylacetylene into the 2,2′ bond of biphenylene. The reaction of1with equimolar amounts of biphenylene at low temperature leads to [Ni(iPr2Im)2(2,2′‐biphenyl)] (6), which is formed by insertion into the strained 2,2′ bond. The reaction of diphenylacetylene and biphenylene at 80 °C in the presence of 2 mol % of1as catalyst yields diphenylphenanthrene quantitatively and is complete within 30 minutes.
Synthesis and Optical Resolution of a Series of Inherently Chiral Calix[4]crowns with Cone and Partial Cone Conformations
Authors: Luo Jun , Zheng Qi‐Yu , Chen Chuan‐Feng , Huang Zhi‐Tang 
Published: June 2005

AbstractA series of inherently chiral calix[4]arenes with cone and partial cone conformations and with crown ether moieties of variable size have been readily synthesized. By taking advantage of the carboxy appendage on the lower rim, these were condensed with the chiral auxiliary (S)‐BINOL to form diastereomers which, in most cases, could be separated by preparative TLC, or more desirably, by column chromatography on silica gel (diastereomeric excess >99 % based on HPLC analysis). Seven enantiopure antipodes of inherently chiral calix[4]crowns were obtained after hydrolysis. It has been found that both the size of the crown moiety and alkylation of the last phenolic hydroxy group (accompanied with or without a change in the conformation) affect the separation of the diastereomers.
Selective Guest Encapsulation by a Cobalt‐Assembled Cage Molecule
Authors: Harrison Roger G. , Burrows Jessica L. , Hansen Lee D. 
Published: June 2005

AbstractMetal‐assembled resorcinarene‐based cages enclose space and entrap organic molecules from water. Addition of cobalt(II) ions to a neutral, aqueous solution of a resorcinarene that has iminodiacetic acids attached to its upper rim results in the formation of cages. These cages not only entrap organic molecules, but they do so in a selective manner. Guests with optimum size, shape, and polarity are preferentially entrapped. For example, selection of p‐xylene is twenty thousand times more favorable than that of m‐xylene. The enthalpy of resorcinarene deprotonation and cage formation was calculated by performing calorimetry studies and ranged from −305 to −348 kJ mol−1. The change in enthalpy of guest encapsulation varied by as much as 43 kJ mol−1. The differences in change in free energy of guest encapsulation varied by −16 kJ mol−1. The changes in enthalpy and free energy of guest encapsulation were used to calculate the changes in entropy, which ranged from −97 to +37 J mol−1 K−1. An enthalpy–entropy compensation of guest encapsulation was observed.
Rigid Nanoscopic Containers for Highly Dispersed, Stable Metal and Bimetal Nanoparticles with Both Size and Site Control
Authors: Wang Chunlei , Zhu Guangshan , Li Jian , Cai Xiaohui , Wei Yuhong , Zhang Daliang , Qiu Shilun 
Published: June 2005

AbstractWe demonstrate a novel strategy for the preparation of mesoporous silica‐supported, highly dispersed, stable metal and bimetal nanoparticles with both size and site control. The supporting mesoporous silica, functionalized by polyaminoamine (PAMAM) dendrimers, is prepared by repeated Michael addition with methyl acrylates (MA) and amidation reaction with ethylenediamine (EDA), by using aminopropyl‐functionalized mesoporous silica as the starting material. The encapsulation of metal nanoparticles within the dendrimer‐propagated mesoporous silica is achieved by the chemical reduction of metal‐salt‐impregnated dendrimer–mesoporous silica by using aqueous hydrazine. The site control of the metal or bimetal nanoparticles is accomplished by the localization of inter‐ or intradendrimeric nanoparticles within the mesoporous silica tunnels. The size of the encapsulated nanoparticles is controlled by their confinement to the nanocavity of the dendrimer and the mesopore. For Cu and Pd, particles locate at the lining of mesoporous tunnels, and have diameters of less than 2.0 nm. For Pd/Pt, particles locate at the middle of mesoporous tunnels and have diameters in the range of 2.0–4.2 nm. The Pd and Pd/Pt nanoparticles are very stable in air, whereas the Cu nanoparticles are stable only in an inert atmosphere.
Wiederaufladbare Batterien
Authors: Winter Martin , Besenhard Jürgen O. 
Published: June 2005

AbstractAs a matter of fact, most of our technical electrochemical energy storage systems operate outside the limitations of thermodynamics. As in the case of rechargeable batteries with aqueous electrolytes (part I of this article), kinetics control the operation and safety also in batteries with nonaqueous electrolytes (this second and final part).A striking example is the lithium ion battery which possesses an operating voltage of >3,5 V and a very high energy density. From a thermodynamic viewpoint such a cell is impossible because the used organic electrolyte is in contact with two lithium insertion electrodes that operate at extreme reducing and oxidizing potentials, respectively. However, a unique mechanism kinetically prevents the decomposition of the electrolyte due to the formation of electronically insulating interphases between electrode and electrolyte that are still permeable to the electrochemically active Li+ cations. Lithium ion batteries have already made their breakthrough into the market as small format systems for portable electronics. The only „kinetically shielded”︁ high energy density, however, might be a safety complication for large format batteries, which are assembled for electric vehicle (EV) propulsion. Safety concerns are also valid for high temperature (300°C) batteries such as the sodium‐sulfur and sodium‐nickel chloride systems. These systems are still in the stage of „experimental batteries”︁, which may find future application in large units for EV's or uninterruptible power systems. The paper is concluded by a performance comparison of various rechargeable battery systems with aqueous and nonaqueous electrolytes. (Possible) applications in consumer electronics and EV's are discussed in more detail.
Kupfer — Die biochemische Bedeutung eines Metalls
Authors: Pascaly Matthis , Jolk Ingo , Krebs Bernt 
Published: June 2005

AbstractThe essential trace element copper plays a key role in living systems. Its metalloproteins are involved in various reactions. The IT ononuclear blue copper type‐1 proteins take, part in electron transfer processes. Type‐2 proteins can either act as oxidases, oxygenases, dioxygenases, or superoxide dismutases, containing one copper core. Dinuclear copper centers of Type‐3 proteins are the oxygen transport system hemocyanin, oxidases and oxygenases. Due to this variety of functions copper deficiency and also abundance can cause severe damage of any life form.
Sandwich‐artige Cyclopentadienylkomplexe von Hauptgruppenelementen
Authors: Jutzi Peter 
Published: June 2005

AbstractCyclopentadienyl (Cp) complexes of maingroup elements are classified and compared in terms of structural types, bonding features, and characteristic reactions. Halfsandwich, sandwich and multidecker sandwich arrangements of different type are observed including cluster species with weak or strong metal‐metal bonds. The Cp‐El bonding ranges from mainly covalent to purely ionic with important structure‐determining intermolecular contacts in the latter. π‐Complexation allows the stabilisation of compounds with low‐valent elements such as AI(I), Ga(I), and Si(I1). Important reaction principles and applications are shortly described.
Chemische Biologie
Authors: Splittgerber Ute 
Published: June 2005

AbstractChemische Biologie ist eine junge Forschungsrichtung im Grenzgebiet zwischen Organischer Cherme und Zellbiologie, welche aus einem Bedarf nach neuen Techniken zur Untersuchung zellbiologischer Mechanismen entstanden ist. Chemische Methoden werden mit biochemischen und molekularbiologischen Methoden kombiniert, um neuartige Möglichkeiten für die biologische Grundlagenforschung zu schaffen. So werden synthetische Oligosaccharide kovalent an die Oberfläche lebender Zellen gebunden, die Konzentration von Calciumionen im Zytosol künstlich reguliert und Rezeptoren künstlich aktiviert.
Fritz Haber, Carl Bosch und Friedrich Bergius — Protagonisten der Hochdrucksynthese
Authors: Stoltzenberg Dietrich 
Published: June 2005

AbstractIt is tried to fix the limits between the notions high pressure synthesis and high temperature chemistry. The work of Fritz Haber to apply high pressure to synthetise ammonia and of Friedrich Bergius to liquify coal to synthetise petrol is described. Special attention is given to the merits of Carl Bosch and his coworkers at BASF for applying the high pressure synthesis into industrial scale. The consequences of thc work of Haber, Bergius und Bosch on chemistry, social and political life and their importance for the present are considered.
Elektrosynthesen. Strom doppelt genutzt: Erste technische „Paired Electrosynthesis”︁
Authors: Hannebaum Heinz , Pütter Hermann 
Published: June 2005

AbstractEine neue Elektrosynthese erfüllt erstmals den Traum der Elektrochemiker, gleichzeitig Anoden‐ und Kathodenreaktion für organische Synthesen technisch zu nutzen.
Vorbereitungen für die Jahrtausend‐Party
Authors: Magin Rudolf 
Published: June 2005

AbstractAround the world, BASF has been preparing for Y2K since 1996. The Information services and the Process Control Technology divisions, as well as embedded systems and logistics, not to mention the company's customers and suppliers have all been systenmatically tested for Y2K capability. In addition, special precautionary measures in particular, at large Verbund sites – will be in place during the switchover period.
Successful carboplatin desensitization in patients with proven carboplatin allergy
Authors: Confino‐Cohen Ronit , Fishman Amiram , Altaras Marco , Goldberg Arnon 
Published: June 2005

AbstractBACKGROUNDCarboplatin is one of the most useful and well tolerated cytotoxic drugs for gynecologic malignancies. Hypersensitivity to carboplatin is not rare among patients receiving multiple recurrent treatments with this drug. The aim of the current study was to offer a safe and convenient carboplatin desensitization strategy to patients with a proven allergic reaction to this drug.METHODSPatients with an immediate objective allergic reaction to carboplatin were skin tested with the drug. A 6‐hour carboplatin desensitization protocol was administered to the patients with a carboplatin‐positive skin test on each of the following treatment courses.RESULTSTwenty‐three patients with an allergic reaction to carboplatin and a positive skin test were included in the current study. Twenty patients (86.9%) were desensitized. One patient developed a mild urticarial rash. Nineteen patients tolerated 80 desensitization courses uneventfully.CONCLUSIONSThe data presented a successful desensitization protocol for individuals with a proven allergic reaction to carboplatin. The protocol was safe and convenient and offered an effective therapeutic strategy to patients who required this drug. Cancer 2005. © 2005 American Cancer Society.
2‐Chlorodeoxyadenosine and cytarabine combination therapy for idiopathic hypereosinophilic syndrome
Authors: Jabbour Elias , Verstovsek Srdan , Giles Francis , Gandhi Varsha , Cortes Jorge , O'Brien Susan , Plunkett William , Garcia‐Manero Guillermo , Ellen Jackson C. , Kantarjian Hagop , Andreeff Michael 
Published: June 2005

AbstractBACKGROUNDHypereosinophilic syndrome (HES) is a rare, disabling, and incurable disease. In this study, a combination of 2‐chlorodeoxyadenosine (2‐CdA) and cytosine arabinoside (ara‐C) chemotherapy was evaluated in patients with HES.METHODSNine patients with HES were treated with ara‐C (1 g/m2) given intravenously over 2 hours at 0 hours, 48 hours, 72 hours, 96 hours, and 120 hours; and 2‐CdA (12 mg/m2 per day) was given as a continuous intravenous infusion over 5 days starting at 24 hours. A second course of the same therapy was administered in patients who had a response.RESULTSAll patients had signs and symptoms of end‐organ involvement. The median time from diagnosis to therapy was 25 months. Seven patients had received prior therapies. Five patients (55%) achieved a complete remission (CR), 1 after receiving 2 courses of therapy. Elimination of eosinophilia was accompanied by the resolution of symptoms. The median disease‐free survival and overall survival after the diagnosis for patients who achieved CR was 26 months and 44 months, respectively. Treatment was tolerated well. Febrile neutropenia occurred in 28% of the 14 courses that were given. The median time to recovery from neutropenia and thrombocytopenia was 17 days and 39 days, respectively.CONCLUSIONSThe combined 2‐CdA and ara‐C chemotherapy regimen had activity in patients with HES. Cancer 2005. © 2005 American Cancer Society.