bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Structure of a 2,4‐Unsubstituted cis/trans‐1,3‐Disilacyclobutane by Dehydrofluorination of a Highly Hindered Fluorosilane
Authors: Pietschnig Rudolf , Spirk Stefan , Belaj Ferdinand , Merz Klaus 
Published: June 2005

AbstractThe preparation, molecular structure, and metalation behavior of a sterically highly congested fluorosilane (tBuTipMeSiF) are described. This silane is subjected to dehydrofluorination under thermally mild conditions. A C‐unsubstituted transient intermediate — either the silene or the corresponding silenoid — is generated in a metalation/elimination sequence at low temperatures, and this intermediate dimerizes to give the corresponding 1,3‐disilacyclobutane exclusively, even in the presence of a trapping agent. The significant steric hindrance in the starting fluorosilane and the final 1,3‐disilacyclobutane is corroborated by their crystal structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Four Novel 3D Copper(II) Coordination Polymers with Different Topologies
Authors: Yang Jin , Ma Jian‐Fang , Liu Ying‐Ying , Li Shun‐Li , Zheng Guo‐Li 
Published: June 2005

AbstractA series of CuII coordination polymers with different topologies, namely [CuL(L1)]·2 H2O (1), [CuL1.5(L2)]·3 H2O (2), [CuL(L3)]·3 H2O (3) and [Cu2L2.5(L4)(H2O)]·10 H2O (4) [L = 1,1'‐(1,4‐butanediyl)bis(imidazole), H2L1 = fumaric acid, H2L2 = 1,1'‐ferrocenedicarboxylic acid, H2L3 = succinic acid, and H4L4 = pyromellitic acid], are presented. Different polymeric frameworks are obtained by varying the polycarboxylate anions. These include the threefold interpenetrated diamond structure of 1, the rare twofold interpenetrated 4664 network of 2, and two planar four‐connected networks of 3 and 4, which display an unusual Archimedean‐type (658)(6482) net containing two different types of nodes and a (5648)(526282)2(68 410)(5462) net containing four different types of nodes, respectively. Thermogravimetric analysis (TGA) curves of 1, 2, 3, and 4 exhibit three similar weight‐loss stages. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation and Crystal Structures of Benzoylhydrazido‐ and‐diazenidorhenium Complexes with N,O‐Ligands and Their Catalytic Activity Towards Peroxidative Oxidation of Cycloalkanes
Authors: Kirillov Alexander M. , Haukka Matti , Guedes da Silva M. Fátima C. , Pombeiro Armando J. L. 
Published: June 2005

AbstractThe η2‐(benzoylhydrazido)rhenium(V) complex [Re{(OCH2CH2)2N(CH2CH2OH)}{N=NC(O)Ph}(PPh3)] (2) and the η1‐(benzoyldiazenido)rhenium(III) compounds [ReCl{N(CH2COO)(CH2CH2OH)(CH2CH2OH)}{N=NC(O)Ph}(PPh3)] (3) and [ReCl(O,N‐L){N=NC(O)Ph}(PPh3)2] [O,N‐L = N(=O)CH2COO (4), HN=C(Me)COO (5), C5H4N(COO) (6)], withchelating N,O‐ligands (amino alkoxides, amino‐, oxyamino‐,imino‐ and pyridinocarboxylates) have been prepared by treatment of [ReCl2{N=NC(O)Ph}(PPh3)2] (1) with triethanolamine [N(CH2CH2OH)3],N,N‐bis(2‐hydroxyethyl)glycine [N(CH2CH2OH)2(CH2COOH)],N‐hydroxyiminodiacetic acid [HON(CH2COOH)2],N‐hydroxy‐2,2'‐iminodipropionic acid [HON{CH(Me)COOH}2] and picolinic acid (NC5H4COOH‐2), respectively. The N,O‐ligands in4and5result from fragmentation of theN‐hydroxyiminodicarboxylic acids. All the complexes have been characterized by IR,1H and13C NMR spectroscopy, FAB+‐MS, elemental analysis and X‐ray diffraction structural analysis, which indicate a π‐delocalized chelated benzoylhydrazidorhenium ring in1and2, and, in the other complexes, an essentially linear η1‐diazenido ligand that is alwaystransto the O‐coordinated carboxylate moiety of the N,O‐ligand. The complexes act as catalysts (TON values up to about 45) for peroxidative oxidation, by radical mechanisms, of cyclohexane and cyclopentane to the corresponding alcohols and ketones, under mild conditions (room temperature, use of aqueous H2O2and without added acid). This is an unprecedented use of inorganic Re coordination compounds as catalysts in alkane functionalization. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Trigonal‐Prismatic vs. Octahedral Geometry for MnII Complexes with Innocent Didentate Ligands: A Subtle Difference as Shown by XRD and DFT on [Mn(acac)2(bpy)]
Authors: van Gorkum Remy , Buda Francesco , Kooijman Huub , Spek Anthony L. , Bouwman Elisabeth , Reedijk Jan 
Published: June 2005

AbstractIn this paper the first example of a mixed‐ligand MnII complex, having a trigonal‐prismatic coordination geometry with simple, innocent, didentate ligands is presented. The solution and solid‐state structures of [Mn(acac)2(bpy)] as studied by EPR spectroscopy, magnetic susceptibility measurements and XRD are presented: single crystals are hexagonal, space group P61 with unit cell dimensions a = 8.0482(9) Å, c = 51.602(10) Å, V = 2894.6(7) Å3 and Z = 6. The complex has the trigonal‐prismatic geometry only in the solid state. Density functional theory (DFT) calculations were performed to address the question of the preference for a specific coordination geometry in the related MnII complexes [Mn(acac)2(bpy)] (trigonal prismatic) and [Mn(acac)2(phen)] (distorted octahedral). Based on the very small energy differences for the calculated trigonal‐prismatic and octahedral structures it has been concluded that crystal packing effects must contribute largely in determining the trigonal‐prismatic structure for [Mn(acac)2(bpy)]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Preparation and Characterization of CoII, NiII, and ZnII Complexes of Sterically Demanding Hexaazamacrocyclic Dithiophenolates
Authors: Gressenbuch Mathias , Lozan Vasile , Steinfeld Gunther , Kersting Berthold 
Published: June 2005

AbstractN‐Alkylated variants of a Robson‐type 24‐membered hexaazamacrocyclic dinucleating dithiophenolate ligand bearing ethyl and propyl groups have been prepared and their ligating properties towards the 3d elements Ni, Co and Zn have been examined. The new ligands support the formation of dinuclear complexes of the type [(LR)MII2(L')]+, i.e. [(LEt)Ni2(Cl)]+ (7), [(LPr)Ni2(Cl)]+ (8), [(LEt)Ni2(OAc)]+ (9), [(LPr)Ni2(OAc)]+ (10), [(LEt)Ni2(O2COMe)]+ (11), [(LEt)Ni2(O2COEt)]+ (12), [(LEt)Zn2(OAc)]+ (14), [(LEt)Co2(Cl)]+ (17), and [(LEt)Co2(OAc)]+ (18), the overall structures of which are very similar to the corresponding complexes of the parent permethylated ligand system. The use of the longer alkyl chains expands the binding pocket of the complexes to a more conical, “calixarene”‐like cavity and has allowed for the isolation of the trication [(HLEt)Ni2]3+ (13), which is an intermediate in the substitution reactions of 7. Complex 13 reveals a new coordination mode of the supporting ligand with adjacent four‐ and five‐coordinate nickel atoms. Its higher stability is presumably a consequence of the increased steric crowding imposed by the longer alkyl chains of (LEt)2–. These results have thus demonstrated that these highly functionalized ligand systems allow for the stabilization of reactive intermediates. This information can now be used as a guide to further modulate the chemical reactivity of these compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Complex Formation of ICL670 and Related Ligands with FeIII and FeII
Authors: Steinhauser Stefan , Heinz Uwe , Bartholomä Mark , Weyhermüller Thomas , Nick Hanspeter , Hegetschweiler Kaspar 
Published: June 2005

AbstractThe pFe values of the two ligands H3Lx and H3Ly in section 2.3 on page 4183 of the original article[1] are incorrect; the corresponding sentence with the correct values should read as follows: In general, the iron binding properties of H3Lx and H3Ly are indeed closely related: the pFe values[30] for H3Lx and H3Ly (total [L] = 10 μM, total [Fe] = 1 μM, pH = 7.4, H2O, I = 0.1 M) are 23.5 and 22.6, respectively.
Electrogenerated Chemiluminescence of Tris(2,2′‐bipyridyl)ruthenium(II) Immobilized in Humic Acid‐Silica‐Poly(vinyl alcohol) Composite Films
Authors: Ding Shou‐Nian , Xu Jing‐Juan , Chen Hong‐Yuan 
Published: June 2005

AbstractIn this paper, we report the first attempt to use humic acid (HA) as modifiers to prepare the organic‐inorganic hybrid modified glassy carbon electrodes based on HA‐silica‐PVA (poly(vinyl alcohol)) sol‐gel composite. Electroactive species of tris(2,2′‐bipyridyl)ruthenium(II) (Ru(bpy)$\rm{ {_{3}^{2+}}}$) can easily incorporate into the HA‐silica‐PVA films to form Ru(bpy)$\rm{ {_{3}^{2+}}}$ modified electrodes. The amount of Ru(bpy)$\rm{ {_{3}^{2+}}}$ incorporated in the composite films strongly depends on the amount of HA in the hybrid sol. Electrochemical and electrogenerated chemiluminescence (ECL) of Ru(bpy)$\rm{ {_{3}^{2+}}}$ immobilized in HA‐silica composite films coated on a glassy carbon electrode have been studied with tripropylamine (TPA) as the coreactant. The analytical performance of this modified electrode was evaluated in a flow injection analysis (FIA) system with a homemade flow cell. The as‐prepared electrode showed good stability and high sensitivity. The detection limits (S/N=3) were 0.050 μmol L−1 for TPA and 0.20 μmol L−1 for oxalate, and the linear ranges were from 0.10 μmol L−1 to 1.0 mmol L−1 for TPA and from 1.0 μmol L−1 to 1.0 mmol L−1 for oxalate, respectively. The resulting electrodes were stable over two months.
Novel Ytterbium(III) Selective Membrane Sensor Based on N‐(2‐Pyridyl)‐N′‐(2‐Methoxyphenyl)‐Thiourea as an Excellent Carrier and Its Application to Determination of Fluoride in Mouth Wash Preparation Samples
Authors: Ganjali Mohammad Reza , Rasoolipour Solmaz , Rezapour Morteza , Norouzi Parviz , Tajarodi Azadeh , Hanifehpour Yousef 
Published: June 2005

AbstractThe construction, performance, and applications of a novel ytterbium(III) sensor based on N‐(2‐pyridyl)‐N′‐(2‐methoxyphenyl)‐thiourea (PMT), as an excellent carrier, in plasticized poly(vinyl chloride) PVC matrix, is described. The influences of membrane composition and pH on the potentiometric response of the sensor were investigated. The sensor exhibits a nice Nernstian response for Yb(III) ion over a wide concentration range of 4 decades of concentration (1.0×10−6–1.0×10−2 M), and a detection limit of 5.0×10−7 M. The response time of the electrodes is between 8 and 10 s, depending on the concentration of ytterbium(III) ions. The proposed sensor can be used for about 8 weeks without any considerable divergence in potential. The sensor revealed very good selectivity for Yb(III) in the presence of several metal ions. The best performance was observed for the membrane containing; 30% PVC, 59% o‐nitrophenyloctyl ether (NPOE) as solvent mediator, 7% PMT, and 4% sodium tetraphenyl borate (NaTPB). It was successfully applied as indicator electrodes in the potentiometric titration of Yb(III) with EDTA and for the determination of fluoride ion in two mouth wash formulations. The proposed La(III) sensor was found to work well under laboratory conditions. It was also used as an indicator electrode in titration of a 1.0×10−4 M of Yb(III) with a standard EDTA solution (1.0×10−2 M). It was also used for determination of Yb(III) ion in Xenotime .
Diagnostic Implications of Uric Acid in Electroanalytical Measurements
Authors: Dutt Jodi S. N. , Cardosi Marco F. , Livingstone Callum , Davis James 
Published: June 2005

AbstractUrate has a long history in clinical analysis and has served as an important diagnostic in a number of contexts. The increasing interest in metabolic syndrome has led to urate being used in combination with a number of other biomarkers in the assessment of cardiovascular risk. The traditional view of urate as principally an interferent in electrochemical measurement is now gradually being replaced with the realization that its measurement could serve as an invaluable secondary (if not primary) marker when monitoring conditions such as diabetes and heart disease. Rather than attempting to wholly exclude urate electrochemistry, many strategies are being developed that can integrate the urate signal within the device architecture such that a range of biomarkers can be sequentially assessed. The present review has sought to rationalize the clinical importance that urate measurements could hold in future diagnostic applications – particularly within near patient testing contexts. The technologies harnessed for its detection and also those previously employed for its removal are reviewed with the aim of highlighting how the seemingly contrasting approaches are evolving to aid the development of new sensing devices for clinical analysis.
Stripping Analysis at Bismuth Electrodes: A Review
Authors: Wang Joseph 
Published: June 2005

AbstractFor many years mercury electrodes were the transducer of choice in stripping voltammetry of trace metals owing to their high sensitivity, reproducibility, and renewability. However, because of the toxicity of mercury, alternative (‘environmentally friendly’) electrode materials are highly desired for both centralized and field applications. Recently introduced bismuth electrodes offer a very attractive alternative to commonly used mercury electrodes. Such electrodes display well‐defined, undistorted and highly reproducible response, favorable resolution of neighboring peaks, high hydrogen evolution, with good signal‐to‐background characteristics comparable to those of common mercury electrodes. The attractive stripping behavior of bismuth electrodes reflects the ability of bismuth to form ‘fused’ multicomponent alloys with heavy metals. Bismuth stripping electrodes thus hold great promise for decentralized metal testing, with applications ranging from continuous remote sensing to single‐use measurements. Fundamental studies aimed at understanding the behavior of bismuth film electrodes should lead to rational preparation and operation of reliable alternative (‘non–mercury’) stripping electrodes that would have a major impact upon electroanalysis of trace metals. This article reviews the development, behavior, scope and prospects of bismuth electrodes for stripping‐based electrochemical measurements of trace metals.
Characterization and Application of Bismuth‐Film Modified Carbon Film Electrodes
Authors: Pauliukaitė Rasa , Brett Christopher M. A. 
Published: June 2005

AbstractBismuth film electrodes, formed by electrochemical deposition on carbon film resistor electrode substrates at constant applied potential, by potential cycling or at constant applied current have been investigated for the first time. The electrochemical behaviour of the films was characterised by cyclic voltammetry and electrochemical impedance spectroscopy and they were applied to the determination of Zn, Cd, and Pb by square‐wave anodic stripping voltammetry. The highest sensitivities coupled with nanomolar detection limits were achieved at bismuth films formed at constant potential; however, in situ deposited bismuth films exhibited better reproducibility. Future application as small, short‐term‐use sensors is indicated.
Low Frequency Square‐Wave Voltammetry of Weak Acids at Platinum Microelectrodes
Authors: Bragato Carlo , Daniele Salvatore , Baldo M. Antonietta 
Published: June 2005

AbstractThe reduction process of monoprotic weak acids (lactic and acetic acid, and dihydrogen phosphate ion) and mixtures of a strong and a weak acid (perchloric and one of the above weak acids) have been investigated by square‐wave voltammetry (SWV) at a platinum microelectrode 12.5 μm radius. The SW measurements have been performed at low frequencies (i.e., 3 Hz), where the heterogeneous electron transfer process, involving hydrogen evolution (2H++2e=H2), is essentially reversible, and non‐planar diffusion conditions prevail in the mass transport. Under these conditions, the forward and the reverse current‐potential profiles are sigmoidal, whereas the net current‐potential profile is peak shaped. The influence of dissociation constant and analytical concentration of the weak acid on the features of the square‐wave voltammograms has been examined in detail. In general, both these characteristics of the weak acids affect the square‐wave parameters peak potential (Ep), width at half height (W1/2) and net peak current (ip) in a complex manner. Their dependence on concentration is due to the 2 : 1 stoichiometry of the heterogeneous electron transfer, while the dissociation constant contribution arises because of the CE mechanism involved in the overall electrode process. The kinetic of the homogeneous reaction has been investigated by the use of the forward current plateau (achieved by the end of the sweep) along with a theoretical equation. Mixtures of a strong and a weak acid can provide one or two waves, depending on the acid strength and on the analytical concentration of each acid. Peak potential differences of about 80 mV are needed to discern two peaks. Calibration plots, examined for all the weak acids, have shown that linearity may exist only over relatively small concentration ranges.
Gallium(III)‐Schiff Base Complexes as Novel Ionophores for Fluoride Selective Polymeric Membrane Electrodes
Authors: Mitchell‐Koch Jeremy T. , Malinowska Elzbieta , Meyerhoff Mark E. 
Published: June 2005

AbstractGallium(III)‐Schiff base complexes are examined as potential ionophores for the development of fluoride ion‐selective polymeric membrane electrodes. To probe the effect of ionophore structure, several different salen and salophen compounds have been synthesized and tested in plasticized poly(vinyl chloride) membranes (H21–5). A salophen ligand structure highly substituted with t‐butyl groups (H21) was found to be optimal with respect to membrane compatibility, and its corresponding Ga(III) complex yields membrane electrodes with greatly enhanced potentiometric selectivity for fluoride ion over a host of other anions. Addition of lipophilic anionic sites into the membrane phase provides optimized response and selectivity, indicating that the Ga1 ionophore functions as a charge carrier. The use of dioctylsebacate as the membrane plasticizer helps reduce any dimer‐monomer equilibria in the membrane phase, yielding sensors with rapid and fully reversible EMF response. Optimal potentiometric detection of fluoride is achieved in solutions buffered to relatively low pH values (pH 3.0), to reduce anionic response to hydroxide. The use of gallium(III)‐Schiff base complexes is shown to offer a promising research direction to ultimately achieve polymeric membrane fluoride sensors that exhibit potentiometric response equivalent to the classical lanthanum fluoride‐based solid state type membrane electrode.
Thermoresponsive Poly‐N‐isopropylacrylamide Gels Modified with Colloidal Gold Nanoparticles for Electroanalytical Applications. 1. Preparation and Characterization
Authors: Kazimierska Ewa A. , Ciszkowska Malgorzata 
Published: June 2005

AbstractPreparation and spectroscopic and electrochemical characterization of thermoresponsive poly‐N‐isopropylacrylamide (NIPA) hydrogels modified with gold colloidal nanoparticles is described. Gold nanoparticles of various sizes in the range from 2.7 to 18 nanometers in diameter were synthesized and introduced to NIPA polymeric gels during the polymerization process. Dry, ground polymers were reswelled by solutions of well‐known and well‐controlled composition. Such polymeric gels undergo discontinuous reversible volume phase transition in response to temperature increase; this results in a release of up to 90% of solvent from the polymeric matrix. The potential window was determined in NIPA gels modified with gold nanoparticles and compared to that in pure NIPA gels. Diffusion coefficients of electroactive probes in NIPA gels modified with gold and in expelled solutions were determined. It was found that diffusion coefficients of Fc(MeOH)2 in swollen neat NIPA and NIPA‐gel modified with gold nanoparticles are identical within experimental error and they are approximately 10–30% smaller than those in aqueous solutions. Concentration of Fc(MeOH)2 in expelled solutions was up to 30% smaller than in swollen gel. Mole fractions of electroactive probes in collapsed gels and expelled solutions were also determined.
Modulation of the genotoxicity of pesticides reacted with redox‐modified smectite clay
Authors: Sorensen Kara C. , Stucki Joseph W. , Warner Richard E. , Wagner Elizabeth D. , Plewa Michael J. 
Published: May 2005

AbstractPesticides are toxic agents intentionally released into the environment; their use raises public health and environmental concerns. In recent years there has been much attention to the biotic degradation of pesticides. Abiotic mechanisms in the soil can contribute to pesticide degradation yet the toxicological impact of such degradation is unclear. This study combines for the first time an investigation into abiotic mechanisms of degradation coupled with toxicological endpoints in mammalian cells. The genotoxicity of three commonly used agricultural pesticides was assessed before and after exposure to redox‐modified clay minerals. The objectives of the study were to determine the genotoxicity of 2,4‐dichlorophenoxy acetic acid (2,4‐D), dicamba, and oxamyl, using single cell gel electrophoresis with Chinese hamster ovary (CHO) cells, and to determine the effect of the iron oxidation state in clay minerals (ferruginous smectite SWa‐1) on the genotoxic potency of the pesticides. 2,4‐D alone or following reaction with redox‐modified clays did not induce DNA damage in CHO cells. Oxamyl alone induced a concentration‐dependent increase in genomic DNA damage; however, its genotoxicity declined after reaction with reduced clay minerals. Dicamba was not genotoxic when directly analyzed. When dicamba was reacted with reduced clay, a concentration‐dependent increase in genomic DNA damage was observed. This is the first reported case of a pesticide being converted into a genotoxin after exposure to redox‐modified smectites. These data introduce a new paradigm on the interaction between redox‐modified clays and pesticide‐related environmental genotoxicity. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
Altered centrosomes in ataxia‐telangiectasia cells and rapamycin‐treated Chinese hamster cells
Authors: Bonatti Stefania , Simili Marcella , Benedetti Pier Alberto , Morandi Fabio , Menichini Paola , Carratore Renata Del , Barale Roberto , Abbondandolo Angelo 
Published: May 2005

AbstractRapamycin induces chromosome malsegregation in mammalian cell lines and yeast. Previous studies indicate that the function impaired in ataxia‐telangiectasia (A‐T) patients is necessary for both the growth inhibition and the chromosome malsegregation induced by rapamycin, and that treating the non‐tumorigenic Chinese hamster cell line CHEF/18 with rapamycin results in supernumerary centrosomes and multipolar spindles. In this paper we report that lymphoblastoid cell lines established from A‐T patients as well as hamster A‐T‐like cells are more resistant to rapamycin than the respective normal cell lines. Two cell lines derived from Nijmegen Breakage Syndrome (NBS) patients, who have clinical symptoms similar to those of A‐T but a different molecular defect, were not resistant to rapamycin. Both A‐T lymphoblastoid cells and A‐T‐like fibroblasts had giant centrosomes formed by more than two areas of γ‐tubulin‐reacting material. Such giant centrosomes were also observed in CHEF/18 cells after prolonged treatment with rapamycin. Formation of giant centrosomes, possibly due to the coalescence of supernumerary centrosomes, was associated with increased aneuploidy in treated cells. Expression analysis of cell‐cycle regulatory genes in rapamycin‐treated human lymphoblastoid cells indicated that rapamycin decreased the expression of the tumor suppressor geneGADD45. The levels ofRB,p21andp53mRNA were also decreased, although to a lesser extent. As rapamycin is often used as an immunosuppressant in pediatric transplant patients, these data indicate that caution should be taken, especially when the drug is given for prolonged periods of time. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.