bluuebunny/crossref_metadata_2025_split huggingface dataset:
Luminescent Cyclometalated Iridium(III) Polypyridine Complexes Containing a Thiourea Moiety: Synthesis, Characterization, Photophysics, Electrochemistry and Anion‐Binding Properties
Authors: Lo Kenneth Kam‐Wing , Lau Jason Shing‐Yip , Lo David Ka‐Kit , Lo Larry Tso‐Lun 
Published: August 2006

AbstractA series of new luminescent cyclometalated iridium(III) polypyridine thiourea complexes [Ir(N‐C)2(N‐N)](PF6) [HN‐C =2‐phenylpyridine (Hppy), N‐N = N‐ethyl‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐Et) (1a), N‐phenyl‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐Ph) (1b), N‐(1‐adamantanemethyl)‐N′‐1,10‐phenanthrolin‐5‐yl thiourea (phen‐TU‐MeA) (1c); HN‐C = 7,8‐benzoquinoline (Hbzq), N‐N = phen‐TU‐Et (2a), phen‐TU‐Ph (2b), phen‐TU‐MeA (2c); HN‐C = 2‐phenylquinoline (Hpq), N‐N = phen‐TU‐Et (3a), phen‐TU‐Ph (3b), phen‐TU‐MeA (3c)] have been synthesized and characterized. The photophysical and electrochemical properties of these complexes have been investigated. On the basis of the photophysical and electrochemical data, the nature of the emissive states has been assigned. The thiourea moieties of the complexes allow them to act as receptors for anions; the binding of OAc–, F–, and H2PO4– to the complexes has been investigated by emission titrations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis and Reactivity of New Mono‐ and Dinuclear Hydridoirida‐β‐diketones – The Formation and Characterization of a Dinuclear Tris‐μ‐acyliridium(III) Complex
Authors: Acha Francisco , Garralda María A. , Hernández Ricardo , Ibarlucea Lourdes , Pinilla Elena , Torres M. Rosario , Zarandona Malkoa 
Published: August 2006

AbstractThe hydridoirida‐β‐diketone [IrH{[PPh2(o‐C6H4CO)]2H}Cl] (1) reacts with silver salts of potentially coordinating anions such as tosylate (–OTs) or triflate (–OTf) to afford the mononuclear neutral derivatives [IrH{[PPh2(o‐C6H4CO)]2H}(X)] [X = OTs (2), OTf (3)]. In acetone solution the triflate anion in 3 is displaced by the solvent to afford the cationic complex [IrH{[PPh2(o‐C6H4CO)]2H}(acetone)]OTf (4), which is stable only in acetone solution. The reaction of 1 with halide scavengers containing less coordinating anions such as PF6– or BF4– results in the formation of cationic compounds [{IrH[{PPh2(o‐C6H4CO)}2H]}2(μ‐Cl)]A [A = BF4 (5), PF6 (6)] containing a dinuclear species with a single chlorine atom bridging two hydridoirida‐β‐diketone fragments. Both fragments are magnetically non‐equivalent and the acylphosphane groups in each hydridoirida‐β‐diketone fragment are chemically equivalent. This species undergoes a fluxional process in solution, with ΔH‡ = 7.8 ± 0.4 kcal mol–1 and ΔS‡ = –10.9 ± 0.5 eu. A combination of rotation around the Ir–Cl bonds and variation of the Ir–Cl–Ir angle is suggested to be responsible for the fluxionality. Complex 5 reacts further with AgBF4 to undergo chloride abstraction along with hydrogen loss and deprotonation to give the cationic dinuclear complex [Ir2H{PPh2(o‐C6H4CO)}{μ‐PPh2(o‐C6H4CO)}3]BF4 (7), which contains an acylphosphane chelate along with three acylphosphane bridging ligands and a single hydrido ligand. Bubbling of HCl through an MeOH solution of 7 gives 1, thus making the loss of hydride, enolic protons and chloride from complex 1 a reversible process. All the complexes were fully characterized spectroscopically. Single‐crystal X‐ray diffraction analysis was performed on complexes 5 and 7. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Identification of the Dinuclear and Tetranuclear Air‐Oxidized Products Derived from Labile Phenolate‐Bridged Dimanganese(II) Pyridyl‐Chelate Compounds
Authors: Larsen Frank Bartnik , Boisen Astrid , Berry Kevin J. , Moubaraki Boujemaa , Murray Keith S. , McKee Vickie , Scarrow Robert C. , McKenzie Christine J. 
Published: August 2006

AbstractDioxygen‐sensitive dinuclear manganese complexes of the phenoxo‐hinged dinucleating ligand 2,6‐bis{[N,N′‐bis(2‐picolyl)amino]methyl}‐4‐tert‐butylphenolato (bpbp–) containing exogenous labile THF, water and perchlorato ligands are described. The manganese(II) complexes [Mn2(bpbp)(ClO4)2(THF)]+ (1) and [Mn2(bpbp)(ClO4)(H2O)2]2+ (2) have been isolated as the salts 1·ClO4·THF·3H2O, 1·B(C6H5)4·4THF and 2·(ClO4)2·H2O. Complexes 1 and 2 are spontaneously oxidised in air in solution and the solid state. The reaction products of the air oxidation in THF, water and methanol solutions are labile dinuclear MnII–MnIII, MnIII2 and MnIII–MnIV complexes containing water‐ and methanol‐derived exogenous ligands. In addition, a Mn4 complex has been isolated. Magnetic susceptibility data confirm the MnII–MnIII oxidation state assignment with an S = 2/S = 5/2 model with weak antiferromagnetic coupling (J = –3.7 cm–1) in [Mn2(bpbp)(CH3O)2(H2O)2](ClO4)2 [3·(ClO4)2]. A tetranuclear complex, [Mn4(O)4–n(OH)n(bpbp)2](ClO4)4 [n = 1 or 2; 7·(ClO4)4], recovered from THF shows a Mn4O6 adamantane‐type core with the O bridges furnished by the two phenolato groups and four hydroxide/oxide bridges. We have arrived at two feasible formulations for the core metal oxidation states and oxo‐bridge protonation states, namely [MnIII4(O)2(OH)2(bpbp)2]4+ and [MnIII3MnIV(O)3(OH)(bpbp)2]4+, for 7, on the basis of a bond valence sum analysis of the crystal structure, elemental analysis and XANES. Thus, complex 7 is at least two oxidation state levels lower than known complexes with the Mn4O6 adamantane core structure. The magnetism of 7 was fitted well to an MnIII4 three‐J model. Complex cations related to 3 by homology, and to 7 by hydration/solvation, have been identified by ESI mass spectrometry. The [Mn2(bpbp)(OH)2(H2O)2]2+ ion (4) present in aqueous solutions on dissolution of 1·ClO4·THF·3H2O in air or by simple dissolution of 3 in water‐containing solvent is isoelectronic to 3. In the presence of significant amounts of water the MnII–MnIII complexes 3 and 4 are susceptible to further metal oxidation and concomitant aquo ligand deprotonation to give ions assignable to [MnIII/IV2(bpbp)O(OCH3)2(H2O)]2+ (5) and [MnIII2(bpbp)(OH)3(H2O)]2+ (6). ESI mass spectra of water or methanol solutions of 1, 2, 3 and 7 show predominantly an ion assignable to the oxide [Mn2(bpbp)(O)]2+ (8). Cation 8 is most likely not present in solution. Using mild source conditions and MS‐MS techniques, the gas‐phase fragmentation pathways to generate 8 have been mapped. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Pressure Effect Investigations on the Spin Crossover Systems{Fe[H2B(pz)2]2(bipy)} and {Fe[H2B(pz)2]2(phen)}
Authors: Galet Ana , Gaspar Ana Belén , Agusti Gloria , Muñoz M. Carmen , Levchenko Georgii , Real José Antonio 
Published: August 2006

AbstractPressure effect studies on the spin crossover behaviour of the mononuclear compounds {Fe[H2B(pz)2]2(bipy)}(1) and {Fe[H2B(pz)2]2(phen)}(2) have been performed in the range of 105 Pa–1.02 GPa at variable temperatures (100–310 K). Continuous spin transitions and displacement of its characteristic temperature has been observed for 1 with increasing pressure. Meanwhile the response of 2 under applied pressures is quite unexpected, and can only be understood in terms of a crystallographic phase transition or change in the bulk modulus of the compound. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Studies on the Interaction of Vanadia with Modified Silica Supports and Catalytic Activity for Oxidative Dehydrogenation of Propane: Effect of Support Modification by Al3+, Zr4+ or Y3+
Authors: Sasikala Rajamma , Sudarsan Vasanth , Kulshreshtha Shailendra K. 
Published: August 2006

AbstractDetailed structural studies of vanadia supported on SiO2 and modified SiO2 (Si0.8M0.2O2±δ where M = Al3+, Zr4+ and Y3+) were carried out using different techniques such as powder XRD, IR spectroscopy and 29Si, 27Al and 51V MAS NMR spectroscopy. All samples except vanadia impregnated on Zr4+ or Y3+ modified SiO2 existed as amorphous phases. A crystalline phase of ZrO2 was seen in Zr4+ modified SiO2 and YVO4 was seen in Y3+ modified SiO2 after vanadia impregnation. Based on 29Si MAS NMR and IR spectroscopic studies it was concluded that substitution of Si4+ by M results in the breakage of the Si–O–Si network and formation of silicon structural units with Si–O–M type linkages. Unlike all other modified SiO2, the silicon structural units remained unaffected in Al3+ modified SiO2 before and after vanadia impregnation. A profound change in the interaction of vanadia with the support was observed when the SiO2 support was modified with different cations and in all cases the V5+ preferentially interacted with the substituted cations. Two types of vanadia species, viz. the octahedral and tetrahedral V5+, were present in vanadia impregnated silica and Al3+ modified silica but the amount of tetrahedral V5+ was more in the latter. In Zr4+ modified silica, V5+ was present in a crystalline environment which is the V5+ dissolved in the ZrO2 phase. Vanadia impregnated on Y3+ modified silica exhibited very little chemical shift anisotropy indicating a symmetric environment around V5+ in YVO4. The catalytic activity for the selective oxidation of propane to propene was tested on these supported catalysts. Vanadia supported on Zr4+ modified silica showed maximum selectivity whereas vanadia on silica and Al3+ modified silica showed comparable selectivity for propene formation. Vanadia on Y3+ modified silica did not show the formation of propene at all. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Testing Phosphanes in the Palladium Catalysed Allylation of Secondary and Primary Amines
Authors: Thoumazet Claire , Grützmacher Hansjörg , Deschamps Bernard , Ricard Louis , le Floch Pascal 
Published: August 2006

AbstractThe electronic nature of the ligand plays a crucial role in the palladium‐catalysed allylation of amines with allylic alcohols. The better the ligand is as a π acceptor, the more active the catalyst. Experiments with a series with mono‐ and bidentate ligands featuring phosphanes and phospholes applied in the catalytic allylation of aniline clearly demonstrate this. Bolstered by DFT calculations, we have devised a new efficient catalyst for this process which carries the strong π acceptor 1,2,5‐triphenylphosphole as a ligand. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Claisen Rearrangement of Carbohydrate‐Derived Precursors Towards Highly Functionalized Cyclooctenones with L‐xylo, D‐arabino and L‐lyxo Configuration and Their Diastereoselective Transformations
Authors: Jürs Stefan , Werschkun Barbara , Thiem Joachim 
Published: August 2006

AbstractD‐Glucose and D‐mannose have been transformed into precursors incorporating allyl vinyl ether substructures. Both thermally and catalytically, these cyclic allyl vinyl ethers could be converted into the corresponding Claisen rearrangement products. The conformations of these enantiopure 5‐cyclooctenones were studied by NMR spectroscopy and X‐ray crystallography. They proved to be versatile substrates for highly stereo‐ and regioselective modifications. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of Conformationally Locked Carbocyclic Nucleosides Built on a Thiabicyclo[3.1.0]hexane System as a Pseudosugar Surrogate
Authors: Elhalem Eleonora , Comin María J. , Rodriguez Juan B. 
Published: August 2006

AbstractThe synthesis of prototype models of purine and pyrimidine carbanucleosides built on a 6‐thiabicyclo[3.1.0]hexane system as pseudosugar moiety has been investigated. These pyrimidine carbanucleosides proved to be very stable compounds, in contrast to the parent epoxy analogs, which experienced epoxide ring‐opening due to intramolecular enol base attack. In addition, as the synthesis of a thiirane moiety fused to a five‐membered ring is not a trivial synthetic task, validation and optimization of the existing methods for episulfide preparation were required to access the committed synthetic precursor of the title compounds: (±)‐(1RS,2RS,5SR)‐6‐thiabicyclo[3.1.0]hexan‐2‐ol, compound 28. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
On extrinsic information of good binary codes operating over Gaussian channels
Authors: Peleg M. , Sanderovich A. , Shamai (Shitz) S. 
Published: August 2006

AbstractWe show that the extrinsic information about the coded bits of any good (capacity achieving) binary code operating over a Gaussian channel is zero when the channel capacity is lower than the code rate and unity when capacity exceeds the code rate, that is, the extrinsic information transfer (EXIT) chart is a step function of the signal to noise ratio and independent of the code. It follows that, for a common class of iterative receivers where the error correcting decoder must operate at first iteration at rate above capacity (such as in turbo equalization, iterative channel estimation, parallel and serial concatenated coding and the like), classical good codes which achieve capacity over the Additive White Gaussian Noise Channel are not effective and should be replaced by different new ones. Copyright © 2006 AEIT.
Performance of collaborative codes in CSMA/CD environment
Authors: Gebali F. , Al‐Sammak A. J. 
Published: August 2006

AbstractA new medium access control scheme is proposed for implementing collaborative codes in a system using carrier sense multiple access with collision detection protocol (CC‐CSMA/CD). We also propose a new backoff algorithm which is simple to implement and to analyse. A discrete‐time Markov chain analytical model is developed for CC‐CSMA/CD. The resulting model describes the regular CSMA/CD as a special case. Protocol performance measures were studied such as throughput, packet acceptance probability, average packet delay and channel utilisation. It is found that CC‐CSMA/CD offers improvements over a system that uses CSMA/CD in terms of throughput, packet acceptance probability, delay and channel utilisation. Copyright © 2006 AEIT.
Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives
Authors: Zhonghe Zhou 
Published: August 2006

AbstractThe Jehol Biota, preserved in the lacustrine sediments of Liaoning Province, northeast China, has provided a new window for understanding Early Cretaceous terrestrial ecosystems. Based on recent geochronological and biostratigraphic studies of the fossil‐bearing deposits, a preliminary temporal framework has been established and suggests that the Jehol Biota had lasted for at least 11 Ma during the late Early Cretaceous (131–120 Ma). The development of the Jehol Biota can be divided into three major phases, with the most significant biological radiations occurring in the second phase between the Barremian and Aptian (approximately 125 Ma). Thanks to a diverse forest environment, major vertebrate groups, i.e. pterosaurs, dinosaurs, birds and mammals, in the Jehol Biota are characterized by a remarkably high percentage of arboreal and herbivorous forms. In addition to strong phylogenetic and morphological differentiation and high taxonomic diversity, the Jehol Biota is also characterized by significant dietary differentiation and biological interactions, i.e. competition and co‐evolution between various animal groups, in an environment shaped by tectonic activities and palaeoclimatic changes both at a global and local scale. Copyright © 2006 John Wiley & Sons, Ltd.
Distinguishing anomalocaridids from arthropods and priapulids
Authors: Xianguang Hou , Bergström Jan , Jie Yang 
Published: August 2006

AbstractThe Chengjiang fossil lagerstätte has yielded four described species of dinocaridids. These have been interpreted either as arthropods or as arthropod progenitors, occasionally with the anomalocaridid Parapeytoia yunnanensis serving as a link. This view is rejected both because anomalocaridids have a number of derived characters absent from early arthropods, and also because a shared origin gives a more parsimonious picture. Sclerites thought to belong to the mouth of P. yunnanensis differ fundamentally from those of its holotype and from those of other dinocaridids. It appears that they belong to a new large priapulid, described here as Omnidens amplus gen. et sp. nov. Copyright © 2006 John Wiley & Sons, Ltd.
Use of tight belts and risk of esophageal adenocarcinoma
Authors: Lagergren Jesper , Jansson Catarina 
Published: August 2006

AbstractIt has recently been hypothesized that the general shift in use from suspenders to belts among men might be a factor that could promote reflux, particularly among overweight men, and thereby contribute to the alarmingly increasing incidence of esophageal and cardia adenocarcinoma. We addressed this hypothesis in a nationwide Swedish population‐based case–control study, conducted in 1995–1997. Included were 189 patients with esophageal adenocarcinoma and 262 patients with cardia adenocarcinoma, who were compared with 167 patients with esophageal squamous cell carcinoma and 820 population‐based control participants. Data were collected at structured face‐to‐face interviews with all study participants. Tumor classification was uniform and thorough. Odds ratios (OR) with 95% confidence intervals (CI), adjusted for potential confounders, were estimated in multivariable logistic regression models. Daily use of tight belts 20 years earlier did not entail an increased risk of adenocarcinoma of the esophagus (OR 1.1, 95% CI 0.7–1.8) or cardia (OR 0.8, 95% CI 0.5–1.3) compared to never use. Adjustment for reflux symptoms, body mass and other potentially relevant covariates did not influence the results. Similarly, in analyses restricted to overweight men, no associations were identified. No association with esophageal squamous cell carcinoma was found. In conclusion, this study provided no support for the hypothesis that use of tight belts is associated with an increased risk of developing esophageal or cardia adenocarcinoma. © 2006 Wiley‐Liss, Inc.
Prospective study of vegetable consumption and liver cancer in Japan
Authors: Pham Truong‐Minh , Fujino Yoshihisa , Ide Reiko , Kubo Tatsuhiko , Shirane Kiyoyumi , Tokui Noritaka , Mizoue Tetsuya , Ogimoto Itsuro , Matsuda Shinya , Yoshimura Takesumi 
Published: August 2006

AbstractWe examined the relationship between vegetable consumption and the risk of death from liver cancer in a cohort study in Japan. This analysis is based on data from 6,049 subjects aged 40 to 79 years enrolled in a cohort study conducted in Fukuoka Prefecture, Japan. The follow‐up period was from 1986 to 1999. All liver cancer deaths were recorded. The vegetable consumption was classified into 3 groups: “once per week or less,” “2–4 times per week” and “daily intake.” The Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence interval (95% CI). A total of 51 male and 22 female liver cancer deaths were recorded during 62,343 person‐years of follow‐up. The “once per week or less” group was considered the referent group. In males, the multivariate HRs of liver cancer deaths were 0.61 (95% CI: 0.33–1.14) and 0.25 (95% CI: 0.11–0.59) in the “2–4 times per week” and “daily intake” groups, respectively. In females, the multivariate HRs were 0.44 (95% CI: 0.13–1.51) and 0.51 (95% CI: 0.16–1.69), respectively. The multivariate HRs were also reported by history of hepatitis and cirrhosis. In those without a history of these conditions, the multivariate HRs were 0.54 (95% CI: 0.27–1.09) and 0.36 (95% CI: 0.16–0.83). In those with a history of these conditions, the multivariate HRs were 0.58 (95% CI: 0.22–1.56) and 0.37 (95% CI: 0.13–1.06), respectively. Our study reveals an inverse association between vegetable consumption and the risk of death from liver cancer. These results provide further evidence of the protective effect of vegetables against liver cancer. © 2006 Wiley‐Liss, Inc.
Physical activity and lung cancer risk in the European Prospective Investigation into Cancer and Nutrition Cohort
Authors: Steindorf Karen , Friedenreich Christine , Linseisen Jakob , Rohrmann Sabine , Rundle Andrew , Veglia Fabrizio , Vineis Paolo , Johnsen Nina Fønns , Tjønneland Anne , Overvad Kim , Raaschou‐Nielsen Ole , Clavel‐Chapelon Françoise , Boutron‐Ruault Marie‐Christine , Schulz Mandy , Boeing Heiner , Trichopoulou Antonia , Kalapothaki Victoria , Koliva Maria , Krogh Vittorio , Palli Domenico , Tumino Rosario , Panico Salvatore , Monninkhof Evelyn , Peeters Petra H. , Boshuizen Hendriek C. , Bueno‐de‐Mesquita H. Bas , Chirlaque Maria‐Dolores , Agudo Antonio , Larrañaga Nerea , Quirós José R. , Martínez Carmen , Barricarte Aurelio , Janzon Lars , Berglund Göran , Bingham Sheila , Khaw Kay‐Tee , Key Timothy J. , Norat Teresa , Jenab Mazda , Cust Anne , Riboli Elio 
Published: August 2006

AbstractResearch conducted predominantly in male populations on physical activity and lung cancer has yielded inconsistent results. We examined this relationship among 416,277 men and women from the European Prospective Investigation into Cancer and Nutrition (EPIC). Detailed information on recent recreational, household and occupational physical activity, smoking habits and diet was assessed at baseline between 1992 and 2000. Relative risks (RR) were estimated using Cox regression. During 6.3 years of follow‐up we identified 607 men and 476 women with incident lung cancer. We did not observe an inverse association between recent occupational, recreational or household physical activity and lung cancer risk in either males or females. However, we found some reduction in lung cancer risk associated with sports in males (adjusted RR = 0.71; 95% confidence interval 0.50–0.98; highest tertile vs. inactive group), cycling (RR = 0.73; 0.54–0.99) in females and non‐occupational vigorous physical activity. For occupational physical activity, lung cancer risk was increased for unemployed men (adjusted RR = 1.57; 1.20–2.05) and men with standing occupations (RR = 1.35; 1.02–1.79) compared with sitting professions. There was no evidence of heterogeneity of physical activity associations across countries, or across any of the considered cofactors. For some histologic subtypes suggestive sex‐specific reductions, limited by subgroup sizes, were observed, especially with vigorous physical activity. In total, our study shows no consistent protective associations of physical activity with lung cancer risk. It can be assumed that the elevated risks found for occupational physical activity are not produced mechanistically by physical activity itself but rather reflect exposure to occupation‐related lung cancer risk factors. © 2006 Wiley‐Liss, Inc.
Raf kinases: Oncogenesis and drug discovery
Authors: Schreck Ralf , Rapp Ulf R. 
Published: August 2006

AbstractRaf kinase signaling has been thoroughly investigated over the last 20 years. A‐Raf, B‐Raf and C‐Raf, the 3 mammalian members of the Raf family, are involved in a variety of cellular processes such as growth, proliferation, survival, differentiation and transformation. The detection of B‐RAF mutations in a wide variety of human cancers, the description of wildtype and mutant B‐RAF as tumor antigens in melanoma and the promising outcome of clinical trials evaluating the Raf inhibitor Nexavar® (Sorafenib, BAY 43‐9006) have sparked a broad interest in the scientific community. After a short historical detour and an introduction into Raf kinase signaling, we are going to discuss here recent outcomes of Raf kinase research with respect to tumor formation and give an overview on current efforts to develop anticancer therapies interfering with aberrant Raf kinase signaling. © 2006 Wiley‐Liss, Inc.