bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutral Trinuclear Palladium(II) Metallocycles with Mixed Phosphane/Pyridine‐4‐thiolato Ligands and Their Catalytic Tests in Suzuki–Miyaura Coupling Reactions
Authors: Wang Hui , Zhong Rui , Guo Xu‐Qing , Feng Xiao‐Yan , Hou Xiu‐Feng 
Published: November 2009

AbstractThree neutral trinuclear palladium(II) complexes [Ph3PPdCl(μ‐4‐PyS)]3 (1), [Cy3PPdCl(μ‐4‐PyS)]3 (2) and [(PhO)3PPdCl(μ‐4‐PyS)]3 (3) (4‐PyS = pyridine‐4‐thiolate) were self‐assembled from corresponding metal fragments [R3PPdCl2]2 with lithium pyridine‐4‐thiolate (PySLi). The crystal structure reveals that complex 1 possesses a triangular macrocyclic structure in which the distances of Pd(1)···Pd(2), Pd(2)···Pd(3) and Pd(3)···Pd(1) are 7.764, 7.684 and 7.944 Å, respectively. An equilibrium between trinuclear complex 1 and mononuclear complex (Ph3P)2PdCl(4‐PyS) (4) in solution through coordination and de‐coordination of the PPh3 ligand is confirmed by 31P NMR spectroscopy. A comparative study on the Suzuki–Miyaura coupling reaction showed that complexes 1 and 2 are more active precatalysts than [R3PPdCl2]2 complexes without a PyS group.
Dye‐Sensitized Solar Cells Based on a Novel Fluorescent Dye with a Pyridine Ring and a Pyridinium Dye with the Pyridinium Ring Forming Strong Interactions with Nanocrystalline TiO2 Films
Authors: Ooyama Yousuke , Inoue Shogo , Asada Risa , Ito Genta , Kushimoto Kohei , Komaguchi Kenji , Imae Ichiro , Harima Yutaka 
Published: November 2009

AbstractAs new‐type donor–acceptor π‐conjugated dyes capable of forming a strong interaction between the electron‐acceptor moiety of the sensitizers and a TiO2 surface, fluorescent dye OH11 and pyridinum dye OH12 with a pyridine and pyridinium ring as the electron‐accepting group, respectively, have been designed and synthesized as photosensitizers for use in dye‐sensitized solar cells (DSSCs). The fluorescent dye OH11 exhibits an absorption band at around 410 nm and a fluorescence band at around 530 nm. On the other hand, the pyridinum dye OH12 shows an absorption maximum at around 560 nm, assigned to a strong intramolecular charge‐transfer excitation from the dibutylamino group to the pyridinium ring. The short‐circuit photocurrent densities of the DSSCs prepared by using OH11 and OH12 are 4.33 and 1.74mA cm–2, and the solar energy‐to‐electricity conversion yields are 1.33 and 0.51 %, respectively, under simulated solar light [AM (air mass) 1.5, 100 mW cm–2]. The open‐circuit photovoltage for OH11 (525 mV) is higher than that of OH12 (444 mV). The effects of the configuration of the dyes on the TiO2 surface and of their chemical structures on the photovoltaic performances are discussed on the basis of semi‐empirical molecular orbital calculations (AM1 and INDO/S), spectral analyses and cyclic voltammetry.
Spectroscopic Investigation of the Europium(3+) Ion in a New ZnY4W3O16 Matrix
Authors: Tomaszewicz Elżbieta , Guzik Malgorzata , Cybińska Joanna , Legendziewicz Janina 
Published: November 2009

AbstractA new Zn and Eu tungstate was characterized by spectroscopic techniques. This tungstate, of the formula ZnEu4W3O16, crystallized in the orthorhombic system and was synthesized by a solid‐state reaction. It melts incongruently at 1330°. The luminescent properties, including excitation and emission processes, luminescent dynamics, and local environments of the Eu3+ ions in ZnEu4W3O16 and ZnY4W3O16 : Eu3+ diluted phases (1, 5, and 10 mol‐% of Eu3+ ion) were studied basing on the f6‐intraconfigurational transitions in the 250–720 nm spectral range. The excitation spectra of this system (λem 615 and 470 nm) show broad bands with maxima at 265 and 315 nm related to the ligand‐to‐metal charge‐transfer (LMCT) states. The emission spectra under excitation at the O→W (265 nm) and O→Eu3+ (315 nm) LMCT states present the blue‐green emission bands. The emission of tungstate groups mainly originate from the charge‐transfer state of excited 2p orbitals of O2− to the empty orbitals of the central W6+ ions. On the other hand, in the emission of the Eu3+ ions, both the charge transfer from O2− to Eu3+ and the energy transfer from W6+ ions to Eu3+ are involved. The emission spectra under excitation at the 7F0→5L6 transition of the Eu3+ ion (394 nm) of ZnY4W3O16 : Eu3+ diluted samples show narrow emission lines from the 5D3, 5D2, and 5D1 emitting states. The effect of the active‐ion (Eu3+) concentration on the colorimetric characteristic of the emissions of the compound under investigation are presented.
The Photochemical Behavior of the Uranyl Ion (UO$\rm{{_{2}^{2+}}}$): a Dimer Perspective and Outlook
Authors: Görller‐Walrand Christiane , Servaes Kelly 
Published: November 2009

AbstractThe complex formation of uranyl (UO$\rm{ {_{2}^{2+}}}$) with oxalic acid (HOOCCOOH) in acetone is studied by UV/VIS, absorption, luminescence, and excitation spectroscopy. Based on solid‐state crystallographic data, we propose a dimer structure with D2h symmetry for the complex in solution. This symmetry is vibrationally distorted to D2 by the out‐of‐plane equatorial‐ligand vibration. From the spectroscopic point of view, this vibration induces intensity in the transitions Πg←Σ$\rm{{_{g}^{+}}}$ and one component of Δg←Σ$\rm{ {_{g}^{+}}}$. From the photochemical point of view, this vibration induces a twisting mechanism that destroys the complex. From the theoretical point of view, it is worthwhile to notice that the symmetry of the odd out‐of‐plane vibration is the same as the symmetry of the odd LUMO (fxyz). By vibrating accordingly to the LUMO symmetry, the complex is self‐destroying by absorption of light, and the uranyl is regenerated. A small comment is devoted to a possible δ–δ interaction and the quintuple U2 bond distance proposed by Gagliardi and Ross [29].
NMR Characterization of Lanthanide(3+) Complexes of Tetraazatetrakisphosphinato and Tetraazatetra­kisphosphonato Ligands
Authors: Pereira Giovannia A. , Ball Laura , Sherry A. Dean , Peters Joop A. , Geraldes Carlos F. G. C. 
Published: November 2009

AbstractThe three‐dimensional structures in aqueous solution of the entire series of the Ln3+ complexes [Ln(DOTP*‐Et)]− (formed from the free ligand P,P′,P″,P′′′‐[1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayltetrakis(methylene)]tetrakis[P‐ethylphosphinic acid] (H4DOTP*‐Et) were studied by NMR techniques to rationalize the parameters governing the relaxivity of the Gd3+ complex and evaluate its potential as MRI contrast agent. From the 1H‐ and 31P‐NMR lanthanide‐induced‐shift (LIS) values, especially of the [Yb(DOTP*‐Et)]− complex, it was concluded that the [Ln(DOTP*‐Et)]− complexes adopt in solution twisted square antiprismatic coordination geometries which change gradually their coordination‐cage structure along the lanthanide series. These complexes have no inner‐sphere‐H2O coordination, and preferentially have the (R,R,R,R) configuration of the P‐atoms in the pendant arms. Self‐association was observed in aqueous solution for the tetraazatetrakisphosphonic acid ester complexes [Ln(DOTP*‐OEt)]− (=[Ln(DOTP‐Et)]−) and [Ln(DOTP*‐OBu)]− (=[Ln(DOTP‐Bu)]−) at and above 5 mM concentration, through analysis of 31P‐NMR, EPR, vapor‐pressure‐osmometry, and luminescence‐spectroscopic data. The presence of the cationic detergent cetylpyridinium chloride (CPC; but not of neutral surfactants) shifts the isomer equilibrium of [Eu(DOTP*‐OBu)]− to the (S,S,S,S) form which selectively binds to the cationic micelle surface.
A [Cyclentetrakis(methylene)]tetrakis[2‐hydroxybenzamide] Ligand That Complexes and Sensitizes Lanthanide(III) Ions
Authors: D'Aléo Anthony , Xu Jide , Do King , Muller Gilles , Raymond Kenneth N. 
Published: November 2009

AbstractThe synthesis of the cyclen derivative H4L1⋅2 HBr containing four 2‐hydroxybenzamide groups is described. The spectroscopic properties of the LnIII conplexes of L1 (Ln=Gd, Tb, Yb, and Eu) reveal changes of the UV/VIS‐absorption, circular‐dichroism‐absorption, luminescence, and circularly polarized luminescence spectra. It is shown that at least two metal‐complex species are present in solution, whose relative amounts are pH dependent. At pH>8.0, an intense long‐lived emission is observed (for [TbL1] and [YbL1]), while at pH<8.0, a weaker, shorter‐lived species predominates. Unconventional LnIII emitters (Pr, Nd, Sm, Dy, and Tm) were sensitized in basic solution, both in the VIS and in the near‐IR, to measure the emission of these ions.
Solution Chemistry of Europium(III) Aqua Ion at Micromolar Concentrations as Probed by Direct Excitation Luminescence Spectroscopy
Authors: Andolina Christopher M. , Mathews Ryan A. , Morrow Janet R. 
Published: November 2009

AbstractDirect excitation europium(III) luminescence spectroscopy is used to study the speciation of aqueous europium(III) ions at micromolar concentrations and near neutral pH. The pH and concentration dependence of the europium(III) 7F0→5D0 excitation peak is consistent with the formation of both mononuclear and dinuclear europium(III) hydroxide complexes at pH 6.5. Luminescence intensity and lifetime quenching studies in the presence of NdIII at pH 5.0 and 6.5 support the formation of a dinuclear complex at pH 6.5. Steady state excitation and time‐resolved luminescence spectroscopy are consistent with the formation of innersphere nitrate and fluoride complexes, but outersphere perchlorate and chloride complexes at pH 6.5 and 5.0.
The Heterometallic Clusters of Trivalent Rare Earth Metals of [Ln(OPh)6{Li(dme)}3], with Ln=Eu and Sm
Authors: Maudez William , Fromm Katharina M. 
Published: November 2009

AbstractTwo new heterobimetallic phenoxide LnIII–Li complexes of formula [Ln(μ2‐OPh)6{Li(dme)}3] (Ln=Sm, Eu) have been synthesized and characterized using single‐crystal X‐ray diffraction. These two compounds are isostructural.
Lanthanide(III) Complexes of 2‐[4,7,10‐Tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic Acid (H7DOA3P): Multinuclear‐NMR and Kinetic Studies
Authors: Campello Maria Paula , Balbina Marina , Santos Isabel , Lubal Přemysl , Ševčík Radek , Ševčíková Romana 
Published: November 2009

AbstractThe protonation constants of 2‐[4,7,10‐tris(phosphonomethyl)‐1,4,7,10‐tetraazacyclododecan‐1‐yl]acetic acid (H7DOA3P) and of the complexes [Ln(DOA3P)]4− (Ln=Ce, Pr, Sm, Eu, and Yb) have been determined by multinuclear NMR spectroscopy in the range pD 2–13.8, without control of ionic strength. Seven out of eleven protonation steps were detected (pK$\rm{{_{i}^{H}}}$=13.66, 12.11, 7.19, 6.15, 5.77, 2.99, and 1.99), and the values found compare well with the ones recently determined by potentiometry for H7DOA3P, and for other related ligands. The overall basicity of H7DOA3P is higher than that of H4DOTA and trans‐H6DO2A2P but lower than that of H8DOTP. Based on multinuclear‐NMR spectroscopy, the protonation sequence for H7DOA3P was also tentatively assigned. Three protonation constants (pKMHL, pKMH2L, and pKMH3L) were determined for the lanthanide complexes, and the values found are relatively high, although lower than the protonation constants of the related ligand (pK$\rm{{_{3}^{H}}}$, pK$\rm{{_{4}^{H}}}$, and pK$\rm{{_{5}^{H}}}$), indicating that the coordinated phosphonate groups in these complexes are protonated. The acid‐assisted dissociation of [Ln(DOA3P)]4− (Ln=Ce, Eu), in the region cH+=0.05–3.00 mol dm−3 and at different temperatures (25–60°), indicated that they have slightly the same kinetic inertness, being the [Eu(H2O)9]3+ aqua ion the final product for europium. The rates of complex formation for [Ln(DOA3P)]4− (Ln=Ce, Eu) were studied by UV/VIS spectroscopy in the pH range 5.6–6.8. The reaction intermediate [Eu(DOA3P)]* as ‘out‐of‐cage’ complex contains four H2O molecules, while the final product, [Eu(DOA3P)]4−, does not contain any H2O molecule, as proved by steady‐state/time‐resolved luminescence spectroscopy.
Self‐Assembly of Spheroidal Structures: The Coordination Chemistry of Pentacyanocyclopentadienide
Authors: da Silva Carlos , Bergamo Mirka , Černý Radovan , Williams Alan F. 
Published: November 2009

AbstractModelling studies show that the anion pentacyanocyclopentadienide, 1, can complex linearly coordinating cations such as silver(I) and copper(I) to form a spheroidal complex [M30(1)12]18+ with minimum distortion. The anion 1 complexes transition metal ions to give species which appear to be polymers in the solid state. The structure of Ag(1) was determined by powder diffraction and shows a one‐dimensional polymeric structure with three coordinate AgI and two CN functions of the ligand 1 non‐coordinated. No evidence for the formation of the spheroidal complex was found.
(Tetracycline)europium(III) Complex as Luminescent Probe for Hydrogen Peroxide Detection
Authors: Dehaen Geert , Absillis Gregory , Driesen Kris , Binnemans Koen , Parac‐Vogt Tatjana N. 
Published: November 2009

AbstractLuminescence spectra of aqueous solutions containing a fixed concentration of tetracycline (TC) and increasing concentrations of Eu3+ were recorded both in the absence and presence of hydrogen peroxide (H2O2). In H2O2‐free solutions in which the Eu/TC molar ratio was varied from 1 : 1 to 8 : 1, the 5D0→7F0 transition consisted of only one peak at 580 nm. In the presence of H2O2, an extra peak appeared in the spectrum at 578 nm when the Eu/TC molar ratios were above 2.5. A detailed analysis of this spectral region revealed that at lower Eu/TC molar ratios (up to 2 : 1), the 5D0→7F0 transition experienced a slight blue shift. This indicates that at low Eu/TC molar ratios, the presence of H2O2 leads to two different environments of the trivalent europium ions, which most likely form bridged peroxide complexes with hydrogen peroxide (μ‐H2O2 ligand). Luminescence spectra measured in the presence of molybdate ions, which catalytically decompose H2O2, led to the disappearance of the extra europium(III) site that was formed in the presence of H2O2. The intensity of the hypersensitive 5D0→7F2 transition did not linearly depend on the H2O2/TC molar ratio. For H2O2/TC ratios up to 10, a sharp linear increase of the peak intensity was observed, but with further increase of the H2O2 concentration, the intensity remained nearly constant. For H2O2/TC ratios above 100, the intensity of this transition even started to decrease, which limits the use of the (tetracycline)europium(III) system to quantify hydrogen peroxide in solution.
Formation of Novel Dinuclear Lanthanide Luminescent Samarium(III), Europium(III), and Terbium(III) Triple‐Stranded Helicates from a C2‐Symmetrical Pyridine‐2,6‐dicarboxamide‐Based 1,3‐Xylenediyl‐Linked Ligand in MeCN
Authors: Comby Steve , Stomeo Floriana , McCoy Colin P. , Gunnlaugsson Thorfinnur 
Published: November 2009

AbstractThe synthesis of the C2‐symmetrical ligand 1 consisting of two naphthalene units connected to two pyridine‐2,6‐dicarboxamide moieties linked by a xylene spacer and the formation of LnIII‐based (Ln=Sm, Eu, Tb, and Lu) dimetallic helicates [Ln2⋅13] in MeCN by means of a metal‐directed synthesis is described. By analyzing the metal‐induced changes in the absorption and the fluorescence of 1, the formation of the helicates, and the presence of a second species [Ln2⋅12] was confirmed by nonlinear‐regression analysis. While significant changes were observed in the photophysical properties of 1, the most dramatic changes were observed in the metal‐centred lanthanide emissions, upon excitation of the naphthalene antennae. From the changes in the lanthanide emission, we were able to demonstrate that these helicates were formed in high yields (ca. 90% after the addition of 0.6 equiv. of LnIII), with high binding constants, which matched well with that determined from the changes in the absorption spectra. The formation of the LuIII helicate, [Lu2⋅13], was also investigated for comparison purposes, as we were unable to obtain accurate binding constants from the changes in the fluorescence emission upon formation of [Sm2⋅13], [Eu2⋅13], and [Tb2⋅13].
Up‐regulation of TRPM6 transcriptional activity by AP‐1 in renal epithelial cells
Authors: Ikari Akira , Sanada Ayumi , Okude Chiaki , Sawada Hayato , Yamazaki Yasuhiro , Sugatani Junko , Miwa Masao 
Published: November 2009

AbstractTransient receptor potential melastatin 6 (TRPM6) channel is involved in the reabsorption of magnesium in the kidney. We recently found that TRPM6 expression is up‐regulated by EGF, but the regulatory mechanism has not been clear. TRPM6 mRNA was endogenously expressed in HEK293 cells. TRPM6 mRNA expression was increased by EGF, which was inhibited by U0126, an MEK inhibitor. Promoter activity of human TRPM6 was observed in the TRPM6 5′‐flanking region from −1,214 to −718. This promoter activity was enhanced by EGF and inhibited by U0126. Three putative AP‐1 binding sites were identified within the region of −1,214/−718. The mutation of the putative AP‐1 binding site (−741/−736) completely inhibited the EGF‐induced promoter activity. EGF increased p‐ERK1/2, c‐Fos, c‐Jun, and p‐c‐Jun levels, which were inhibited by U0126. The introduction of c‐Fos or c‐Jun siRNA inhibited the EGF‐induced promoter activity. A chromatin immunoprecipitation assay revealed that c‐Fos and c‐Jun bind to the AP‐1 binding site within the region of −1,214/−718. These results suggest that EGF up‐regulates TRPM6 mRNA expression mediate via the activation of ERK/AP‐1‐dependent pathway. J. Cell. Physiol. 222: 481–487, 2010. © 2009 Wiley‐Liss, Inc.
Detection of CFTR transgene mRNA expression in respiratory epithelium isolated from the murine nasal cavity
Authors: Holder Emma , Stevenson Barbara , Farley Raymond , Hilliard Tom , Wodehouse Theresa , Somerton Lucinda , Larsen Mia , O'Donoghue Jean , Coles Rebecca L. , Scheule Ronald K. , Cheng Seng H. , Gill Deborah R. , Hyde Stephen C. , Griesenbach Uta , Alton Eric W. F. W. , Porteous David J. , Boyd A. Christopher 
Published: November 2009

AbstractBackgroundWhen assessing the efficacy of gene transfer agents (GTAs) for cystic fibrosis (CF) gene therapy, we routinely evaluate gene transfer in the mouse nose and measure transfection efficiency by assessing transgene‐specific mRNA using the real‐time (TaqMan) quantitative reverse transcriptase‐polymerase chain reaction. TaqMan is traditionally used to quantify expression in whole tissue homogenates, which in the nose would contain many cells types, including respiratory and olfactory epithelium. Only the respiratory epithelium is a satisfactory model for human airway epithelium and therefore CFTR gene transfer should be specifically assessed in respiratory epithelial cells (RECs).MethodsWe have compared laser microdissection, pronase digestion and nasal brushing for: (i) the ability to enrich RECs from the wild‐type mouse nose and (ii) the length of time to perform the procedure. Using TaqMan, we subsequently assessed gene transfer in enriched RECs after nasal perfusion of GL67A/pCF1‐CFTR complexes in a CF mouse model.ResultsLaser microdissection successfully isolated RECs; however, time‐consuming sample preparation made this technique unsuitable for high‐throughput studies. Pronase digestion was sufficiently rapid but only yielded 19% (range = 13%) RECs (n = 6). The nasal brushing method was superior, yielding 92% (range = 15%) RECs (n = 8) and was equally effective in CF knockout mice (91%, range = 14%, n = 10). Importantly, gene transfer was detectable in brushed RECs from 70% of perfused mice and the number of vector‐specific transcripts was comparable to 3.5% of endogenous wild‐type Cftr levels.ConclusionsIsolation of RECs by brushing allows accurate assessment of GTA transfection efficiency in an experimental system that is relevant for CF gene therapy. Copyright © 2009 John Wiley & Sons, Ltd.
Comparative gene transfer between cationic and thiourea lipoplexes
Authors: Breton Marie , Leblond Jeanne , Seguin Johanne , Midoux Patrick , Scherman Daniel , Herscovici Jean , Pichon Chantal , Mignet Nathalie 
Published: November 2009

AbstractBackgroundWe have previously developed lipopolythiourea lipids as neutral DNA condensing agents for systemic gene delivery. Optimization of the lipopolythiourea structure led to efficient transfecting agents. To further evaluate these lipids, we investigated the internalization process of the thiourea lipoplexes and their intracellular mechanism of transfection versus that of cationic lipoplexes.MethodsThe MTT test was used for cytotoxicity assessment. Transfection efficiency was determined by luciferase read‐out. Permeation to propidium iodide and enhanced green fluorescent protein was evaluated by flow cytometry. Kinetics of internalization and DNA release were monitored by confocal microscopy with labelled DNA. Endocytosis inhibitors were used to study the mechanisms of lipoplex internalization.ResultsAlthough thiourea/DNA complexes exhibit an almost similar level of transfection compared to that of cationic complexes, the thiourea lipoplexes were shown to be six‐fold less internalized. Complexes were able to permeabilize the cytoplasmic membrane to 30 kDa molecules. Finally, DNA was shown to be released in less than 10 min in the cellular cytoplasm versus 30 min for cationic lipoplexes.ConclusionsDespite a weaker internalization compared to cationic lipids, the thiourea lipoplexes were able to transfect cells at a similar level as a result of its greater ability to destabilize the cytoplasmic membrane and release DNA Copyright © 2009 John Wiley & Sons, Ltd.
Primer on gadolinium chemistry
Authors: Sherry A. Dean , Caravan Peter , Lenkinski Robert E. 
Published: November 2009

AbstractGadolinium is widely known by all practitioners of magnetic resonance imaging (MRI) but few appreciate the basic solution chemistry of this trivalent lanthanide ion. Given the recent linkage between gadolinium contrast agents and nephrogenic systemic fibrosis, some basic chemistry of this ion must be more widely understood. This short primer on gadolinium chemistry is intended to provide the reader the background principles necessary to understand the basics of chelation chemistry, water hydration numbers, and the differences between thermodynamic stability and kinetic stability or inertness. We illustrate the fundamental importance of kinetic dissociation rates in determining gadolinium toxicity in vivo by presenting new data for a novel europium DOTA‐tetraamide complex that is relatively unstable thermodynamically yet extraordinarily inert kinetically and also quite nontoxic. This, plus other literature evidence, forms the basis of the fundamental axiom that it is the kinetic stability of a gadolinium complex, not its thermodynamic stability, that determines its in vivo toxicity. J. Magn. Reson. Imaging 2009;30:1240–1248. © 2009 Wiley‐Liss, Inc.
Nephrogenic systemic fibrosis versus contrast‐induced nephropathy: Risks and benefits of contrast‐enhanced MR and CT in renally impaired patients
Authors: Martin Diego R. , Semelka Richard C. , Chapman Arlene , Peters Harm , Finn Paul J. , Kalb Bobby , Thomsen Henrik 
Published: November 2009

AbstractMagnetic resonance imaging (MRI) and computed tomography (CT) have become essential to diagnostic evaluation of many, or most, important medically and surgically treated diseases. It is important to consider comprehensively the implications in making decisions when choosing one or the other cross‐sectional imaging modality. Factors to consider include the relative risks of the contrast agent. Other factors include the relative procedural risks, including radiation risks and the relative expected diagnostic yield of the examination technique (1, 2). In this review we describe both nephrogenic systemic fibrosis and contrast‐induced nephropathy to compare the implications with regard to relative risks and benefits of contrast‐enhanced MRI or CT in patients with impaired renal function. J. Magn. Reson. Imaging 2009;30:1350–1356. © 2009 Wiley‐Liss, Inc.