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Showing papers in "European Journal of Inorganic Chemistry in 2005"


Journal ArticleDOI
TL;DR: In this article, the most important aspects to take into consideration to improve the properties of γ-Al2O3 as a support for catalytic applications are discussed, and the usefulness of the latter during supported catalyst preparation and for stability evaluation after calcination.
Abstract: The present review discusses the most important aspects to take into consideration to improve the properties of γ-Al2O3 as a support for catalytic applications. We show that the synthetic route to γ-Al2O3 is the starting point that determines the micro- and macrostructure of the oxide and, consequently, allows control of the support characteristics. The relevance of the adequate structural characterization of the oxide as well as of its surface sorption behavior through the proton-affinity distributions, are considered. The usefulness of the latter during supported catalyst preparation, for catalytic active sites characterization, and for stability evaluation after calcination are discussed for the Co/γ-Al2O3 system in particular. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

614 citations


Journal ArticleDOI
TL;DR: In this article, the stabilization of various coordinatively unsaturated metal centers through the incorporation of N-heterocyclic carbene (NHC) ligands is described, and various thermochemical and infrared studies of metal carbene species are discussed.
Abstract: This review describes the stabilization of various coordinatively unsaturated metal centers through the incorporation of N-heterocyclic carbene (NHC) ligands. Such species are more thermally stable compared to the more ubiquitous tertiary phosphane systems. Although NHCs can be considered as phosphane mimics it has become apparent that there are substantial differences between the two ligand families. In general, NHC ligands are much more electron-donating and sterically demanding than bulky phosphane ligands. We also discuss the various thermochemical and infrared studies of metal carbene species that have provided insight into NHC ligands properties, and at last allowed meaningful comparison to tertiary phosphane ligands. While NHCs are generally viewed as strong binding low reactive ligands, in some instances they have been found to be not so innocent and can undergo facile intramolecular C–H activation as well as abnormal ligand binding [C-5(4) vs. C-2]. Here we highlight such reactions with late-transition metal centers that have allowed the isolation of various unsaturated LTM species. These have so far eluded isolation in analogous phosphane-based systems. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

418 citations


Journal ArticleDOI
TL;DR: Valence tautomeric complexes combine redox-active ligands and transition metal ions with two or more accessible oxidation states, exhibiting two nearly degenerated electronic states with localized electronic structures as mentioned in this paper.
Abstract: Valence tautomeric complexes combine redox-active ligands and transition metal ions with two or more accessible oxidation states, exhibiting two nearly degenerated electronic states with localized electronic structures Charge distribution in such electronic isomers has an appreciable sensitivity to the environment so an external perturbation, like photons, temperature and/or pressure, may lead to an intramolecular electron transfer between both redox active units and therefore to a reversible interconversion between the two degenerated electronic states Moreover, since each electronic isomer exhibits different optical, electronic and/or magnetic properties, these complexes are being proposed as candidates for future use in molecular electronic devices and switches Most of the valence tautomeric complexes reported thus far are based on quinone or quinone-type ligands with a series of transition metal ions such as Co, Cu, Ni and Mn Nevertheless, in the last few years, the number of electroactive ligands identified to be active in valence tautomeric complexes is being expanded by including new radical ligands such as polychlorotriphenylmethyl, phenoxyl or tetraphenylporphyrin radicals (© Wiley-VCH Verlag GmbH & Co KGaA, 69451 Weinheim, Germany, 2005)

275 citations


Journal ArticleDOI
TL;DR: In this paper, a series of disubstituted diiron complexes were characterized by X-ray crystallography and cyclic voltammetry to evaluate the effects of different tertiary phosphane ligands on the redox properties of the iron atoms of model complexes.
Abstract: A series of mono- and disubstituted diiron complexes [(μ-pdt)Fe2(CO)5L] [pdt = 1,3-propanedithiolato; L = PMe3 (2), PMe2Ph (3PPh3 (4), P(OEt)3 (5)] and [(μ-pdt)Fe2(CO)4L2] [L = PMe2Ph (6), PPh3 (7), P(OEt)3 (8)] were prepared as Fe-only hydrogenase-active-site models by controllable CO displacement of [(μ-pdt)Fe2(CO)6] by tertiary phosphanes. The coordination configurations of 3–6 were characterized by X-ray crystallography. Disubstituted diiron complex 6 features an apical/apical coordination mode, instead of the typical transoid basal/basal configuration. The electrochemistry of 2–6 and 8 was studied by cyclic voltammetry to evaluate the effects of different tertiary phosphane ligands on the redox properties of the iron atoms of model complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

169 citations


Journal ArticleDOI
Li Yang1, Ji-Kang Feng1, Ai-Min Ren1, Ming Zhang1, Yuguang Ma1, Xiaodong Liu1 
TL;DR: A series of new mixed-ligand copper(I) complexes [Cu(NN)POP]BF4, where NN = 1,10-phenanthroline (phen; 1a), 2,9dimethyl-phen (DMphen, 1b), 4,7-diphenylphen (DPpehn; 1c) and 2,2-bipyridine (bpy; 2a), have been synthesized as discussed by the authors.
Abstract: A series of new mixed-ligand copper(I) complexes [Cu(NN)POP]BF4, where NN = 1,10-phenanthroline (phen; 1a), 2,9dimethyl-phen (DMphen; 1b), 4,7-diphenyl-phen (DPpehn; 1c) and 2,2-bipyridine (bpy; 2a), have been synthesized. Density functional theory (DFT) was applied to study the ground- and excited-state properties of these copper(I) complexes. The electronic structure variation is obtained by changing the substituted positions on the phenanthroline ligand. A time-dependent-DFT approach (TDDFT) was used to interpret the absorption and emission spectra in this system based on the optimized geometries at the B3LYP/ LANL2DZ and CIS/LANL2DZ levels of theory, respectively. The results show that the lowest-energy excitations of all

165 citations


Journal ArticleDOI
TL;DR: An overview of recent work dealing with luminescence properties in solution of complexes of the lanthanide(3+) ions Nd3+, Eu3+, Tb3+, Er3+ and Yb3+ in which an organic chromophore is attached to the metal centre as a sensitizer is given as mentioned in this paper.
Abstract: An overview of recent work dealing with luminescence properties in solution of complexes of the lanthanide(3+) ions Nd3+, Eu3+, Tb3+, Er3+ and Yb3+ in which an organic chromophore is attached to the metal centre as a sensitizer is given. The various factors that influence the metal-centred luminescence lifetime and intensity are discussed and illustrated with own results and recent literature examples. The VIS emitting metal ions Eu3+ and Tb3+ require sensitizers that absorb light in the UV or near UV range whereas VIS absorbing sensitizers can be used for the NIR emitting ions Nd3+, Er3+ and Yb3+. The latter type of complexes is currently of great interest because of potential applications as luminescent markers in biological systems. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

162 citations


Journal ArticleDOI
TL;DR: A critical review of the principles guiding the synthesis of meso-and macroporous metal oxides on multiple length scales in the presence of surfactant mesophases and colloidal arrays of monodisperse spheres is provided in this paper.
Abstract: A critical review is provided of the principles guiding the synthesis of meso- and macroporous metal oxides on multiple length scales in the presence of surfactant mesophases and colloidal arrays of monodisperse spheres, and correlations between the synthesis conditions and the properties of the resulting meso- and macroporous oxides, such as thermal stability, pore structure, elemental and nanophase compositions of the inorganic wall, etc. The thermal stability of mesostructured metal-oxide phases, in particular, is discussed in terms of charge-matching at the organic–inorganic interface, the strength of interactions between inorganic species and surfactant headgroups, the flexibility of the M–O–M bond angles in the constituent metal oxides, the Tammann temperature of the metal oxide, and the occurrence of redox reactions in the metal-oxide wall. The ordered meso- and

161 citations


Journal ArticleDOI
TL;DR: In this article, the kinetic inertness of copper(II) complexes of carboxymethyl-armed cyclams and cyclens in 5 M HCl was determined confirming that the complex derived from cross-bridged cyclam (Cu-CB-TE2A) is by far the most resistant to acid decomplexation.
Abstract: The kinetic inertness of copper(II) complexes of several carboxymethyl-armed cyclams and cyclens in 5 M HCl have been determined confirming that the complex derived from cross-bridged cyclam (Cu-CB-TE2A) is by far the most resistant to acid decomplexation. FT-IR studies in D2O solution revealed its unique resistance to full carboxylate protonation and its retention of coordination by both pendant arms even in 1 M DCl. The X-ray structure of its monoprotonated form, [Cu-CB-TE2AH]+, also established full coordination by both COO– and COOH pendant arms in the solid state. Cyclic voltammograms of four carboxymethyl pendant-armed cyclam and cyclen complexes in aqueous solution were obtained with only Cu-CB-TE2A displaying a quasi-reversible CuII/CuI reduction wave. These indicators correlate with the superior in vivo behavior of this complex and its bifunctional conjugate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

158 citations


Journal ArticleDOI
TL;DR: The iron(II)- and α-ketoglutarate-dependent dioxygenases comprise enzymes that catalyze a variety of important reactions in biology, including steps in the biosynthesis of collagen and antibiotics, the degradation of xenobiotics, the repair of alkylated DNA, and the sensing of oxygen and response to hypoxia.
Abstract: The iron(II)- and α-ketoglutarate-dependent dioxygenases comprise enzymes that catalyze a variety of important reactions in biology, including steps in the biosynthesis of collagen and antibiotics, the degradation of xenobiotics, the repair of alkylated DNA, and the sensing of oxygen and response to hypoxia. In these reactions, the reductive activation of oxygen is coupled to hydroxylation of the substrate and decarboxylation of the co-substrate, α-ketoglutarate. It is believed that a single, conserved mechanistic pathway for formation of a high-valent iron intermediate that attacks the substrate is operant in all members of this family. Application

155 citations


Journal ArticleDOI
Jin Yang1, Jian-Fang Ma1, Ying-Ying Liu1, Shun-Li Li1, Guo-Li Zheng1 
TL;DR: In this paper, a series of CuII coordination polymers with different topologies, namely [CuL(L1)]·2 H2O (1), [cuL1.5(L2)]·3
Abstract: A 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)

136 citations


Journal ArticleDOI
TL;DR: In this article, four new metal-organic polymers with short anion bridges and flexible long spacers were synthesized and characterized by single-crystal X-ray diffraction studies and their magnetic properties were investigated.
Abstract: Four new metal-organic polymers with SCN–/N3– anion bridges and flexible long spacers L {L = bim [1,2-bis(imidazol-1-yl)ethane] and bte [1,2-bis(1,2,4-triazol-1-yl)ethane]}, [Co(SCN)2(bim)] (1-Co), [Co(SCN)2(bte)] (2-Co), [Mn(N3)2(bte)] (3-Mn), and [Mn(N3)2(bim)] (4-Mn), were synthesized and characterized by single-crystal X-ray diffraction studies and their magnetic properties were investigated. Complex 1-Co is a triple-bridging chain complex with double end-to-end SCN– anions and single gauche-bim spacers as bridges. Complexes 2-Co and 3-Mn both contain 1D chains bridged by double end-to-end SCN– or N3– anions and these chains are further extended to 2D (4,4) layers by the anti-bte spacers. Complex 4-Mn has a topological 3D diamond structure constructed through 1D double end-on azide-bridged MnII chains and extended through the anti-bim spacers. Magnetic measurements reveal that 1-Co and 3-Mn remain paramagnetic; the dominant magnetic coupling between CoII is weak ferromagnetic and that between MnII is strong antiferromagnetic. As for 2-Co and 4-Mn, they show metamagnetic behavior below TN = 2.9 and 3.0 K, respectively. Our results show that a combination of the short anion bridges (SCN–/N3–) and flexible bidentate long spacers can be used to construct coordination polymers with novel topologies and interesting magnetic properties. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, the solid-state structures of the Schiff-base copper complexes have been determined by X-ray crystallography, showing that the Cu I I centers have distorted square-pyramidal geometry.
Abstract: The copper(II) complexes of the Schiff-base ligands H 2 Sams and H 2 Saes and the reduced Schiff-base ligands H 2 Sam and H 2 Sae formed between salicylaldehyde and aminomethanesulfonic acid or 2-aminoethanesulfonic acid (taurine) have been synthesized in moderate yields. The solid-state structures of the five dinuclear complexes, [Cu 2 (Sams) 2 (H 2 O 2 ] (1), [Cu 2 (Sam) 2 (H 2 O) 2 ].H 2 O (2), [Cu 2 (Saes) 2 (H 2 O) 2 ].2H 2 O (3), [Cu 2 (Sae) 2 ].2H 2 O (4), and [Cu 2 (Sae) 2 (DMF) 2 ].2DMF (5), have been determined by X-ray crystallography, showing that the Cu I I centers have distorted square-pyramidal geometry. The Schiff-base copper complexes 1 and 3 have hydrogen-bonded 2D sheet structures while the reduced Schiff-base complexes 4 and 5 display a 2D coordination network and a hydrogen-bonded 2D structure respectively. All these complexes have been investigated for their catecholase activity and activity measurements have been compared with those of dinuclear copper(II) complexes of similar ligands obtained with carboxylate analogues of the corresponding sulfonic acids; these studies show that 4 has significantly higher activity. Further, a strong antiferromagnetic interaction between Cu I I ions in dimeric complexes 1 [J = -9.04(2) cm - 1 ], 3 [J = -272(4) cm - 1 ), and 4 [J = -237(4) cm - 1 ] has been observed.

Journal ArticleDOI
Abstract: The reaction of hetrocyclic dicarboxylic acids, such as pyridine-2,5-dicarboxylic acid and imidazole-4,5-dicarboxylic acid,under hydrothermal conditions in the presence of an appropriate zinc salt yields three new zinc coordination polymers $^{0} _{\infty} [{Zn_{2}(H_{2}O)_{4}}{C_{5}H_{3}N(COO)_{2}}_{2}](1), ^{1} _{\infty} [{Zn(C_{12}H_{8}N_{2})}{C_{5}H_{3}N(COO)_{2}} . 0.5H_{2}O] (2)$, and $^{1} _{\infty} [{Zn(C_{12}H_{8}N_{2})}{C_{3}HN_{2}(COO)_{2}}] (3)$. While 1 forms with a zero-dimensional molecular rectangular box structure, 2 and 3 have zig-zag one-dimensional chain structures. The $Zn^{2+}$ ions are coordinated by both the carboxylate oxygen atoms and also by the nitrogen atoms of the heterocycles. The 1,10-phenanthroline molecules in 2 and 3 act as a secondary ligands and occupy the inter-chain spaces. The moderate hydrogen-bond interaction energy in 1 and the \pi...\pi interactions in 2 and 3 appear to play an important role for the structural stability. The structures of 2 and 3 appear to be related, even though they are formed with different carboxylic acids. All three compounds exhibit photoluminescence at room temperature.

Journal ArticleDOI
TL;DR: In this article, the half-sandwich R-II-[9]aneS(3) complexes were characterized both in solution and in the solid state by X-ray crystallography and the results suggest that the aromatic fragment of the piano-stool Ru-II compounds is not an essential feature for the in vitro anticancer activity, and it might be effectively replaced by another face-capping ligand with a low steric demand, such as [9]ANES (3).
Abstract: New half-sandwich R-II-[9]aneS(3) complexes ([9]aneS(3) = 1,4,7-trithiacyclononane), namely [RuCl2(PTA)([9]aneS(3))] (4), [RuCl(PTA)(2)([9]aneS(3))][OTf] (5), [RuCl(en)([9]aneS(3))][OTf] (6), [RuCl(enac)([9]aneS(3))][OTf] (7), [RuCl(bipy)([9]ane-S-3)][OTf] (8), and [Ru(dmso-S)(bipy)([9]aneS(3))][OTf](2) (9) [PTA = 1,3,5-triaza-7-phosphaadamantane; enac = 1,2-bis-(isopropyleneimino)ethane; OTf = CF3SO3-] were prepared from Ru-[9]aneS(3)-dmso precursors and structurally characterized, both in solution and in the solid state by X-ray crystallography. Some of them are analogs of known cytotoxic organometallic Ru-II-(eta(6)-arene) and Ru-II-(eta(5)-cyclopentadienyl) compounds, in which the aromatic fragment is replaced by the sulfur macrocycle 1,4,7-trithiacyclononane, while the rest of the coordination sphere is left unchanged. Similarly to the aromatic analogs for which data are available, in aqueous solution the Ru-[9]aneS(3) complexes (with the exception of 5) hydrolyze a chloride (or a dmso in the case of 9) to give the corresponding aquo species. This process is rapidly reversed in the presence of free chloride, and coordination of phosphate is likely to occur to the aquo species in phosphate buffered solutions at physiological pH. Preliminary in vitro tests performed on complexes 4-6 against the mouse adenocarcinoma cancer cell line (TS/A) and the human mammary normal cell line (HBL-100) showed that, in general, the Ru-[9]aneS(3) compounds have a cytotoxicity comparable to that of the corresponding organometallic analogs. These results suggest that the aromatic fragment of the piano-stool Ru-II compounds is not an essential feature for the in vitro anticancer activity, and it might be effectively replaced by another face-capping ligand with a low steric demand, such as [9]aneS(3). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, the principles of DNA-based assembly of metal nanoparticles in one, two and three dimensions are described, with selected examples to illustrate the properties of these assemblies as well as emerging applications.
Abstract: In this microreview we describe the principles of DNA-based assembly of metal nanoparticles in one, two and three dimensions. Different methods of liquid-phase synthesis of metal nanoparticles as well as their functionalisation with DNA are introduced. The concepts developed up to now for the assembly are explained, with selected examples to illustrate the properties of these assemblies as well as emerging applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: The enantiopure complexes 1-9 have been employed as catalysts for the transfer hydrogenation of acetophenone in aqueous solution using sodium formate and water as a hydrogen source as discussed by the authors.
Abstract: The cationic chloro complexes [(arene)Ru(H 2 N∩NH 2 )Cl] + (1: arene = C 6 H 6 ; 2: arene = p-MeC 6 H 4 iPr; 3: arene = C 6 Me 6 ) have been synthesised from the corresponding arene ruthenium dichloride dimers and enantiopure (R,R or S,S) trans-1,2-diaminocyclohexane (H 2 N∩NH 2 ) and isolated as the chloride salts. The compounds are all water-soluble and, in the case of the hexamethylbenzene derivative 3, the aqua complex formed upon hydrolysis [(C 6 Me 6 )Ru(H 2 N∩NH 2 )-OH 2 ] 2 + (4) could be isolated as the tetrafluoroborate salt. The molecular structures of 3 and 4 have been determined by single-crystal X-ray diffraction analyses of [(C 6 Me 6 )Ru-(H 2 N∩NH 2 )Cl]Cl and [(C 6 Me 6 )Ru(H 2 N∩NH 2 )OH 2 ][BF 4 ] 2 . Treatment of [Ru 2 (arene) 2 Cl 4 ] with the monotosylated trans-1,2-diaminocyclohexane derivative (TsHN∩NH 2 ) does not yield the expected cationic complexes, analogous to 1-3 but the neutral deprotonated complexes [(arene)Ru(TsN∩NH 2 )-Cl] (5: arene = C 6 H 6 ; 6: arene = p-MeC 6 H 4 iPr; 7: arene = C 6 Me 6 ; 8: arene = C 6 H 5 COOMe). Hydrolysis of the chloro complex 7 in aqueous solution gave, upon precipitation of silver chloride, the corresponding monocationic aqua complex [(C 6 Me 6 )Ru)(TsHN∩NH 2 )(OH 2 )] 2 + (9) which was isolated and characterised as its tetrafluoroborate salt. The enantiopure complexes 1-9 have been employed as catalysts for the transfer hydrogenation of acetophenone in aqueous solution using sodium formate and water as a hydrogen source. The best results were obtained (60 °C) with 7, giving a catalytic turnover frequency of 43 h - 1 and an enantiomeric excess of 93 %.

Journal ArticleDOI
TL;DR: This paper showed that pyrochlore does not form at chemical compositions predicted by the traditional formula for this crystal structure, A2B2O6O', where A denotes large (8-coordinated, e.g. Bi3+) and B small (6coordinated), e. g. Zn2+, Nb5+) cation sites.
Abstract: Phase equilibrium studies of the Bi–Zn–Nb–O system show that pyrochlore does not form at chemical compositions predicted by the traditional formula for this crystal structure, A2B2O6O', where A denotes large (8-coordinated, e.g. Bi3+) and B small (6-coordinated, e.g. Zn2+, Nb5+) cation sites. Instead, pyrochlore forms only at compositions with excess B cations which, surprisingly, occupy the large A-cation sites. Reports of similar behavior in other pyrochlores suggest a previously unrecognized inherent structural feature (displacive disorder) which allows the formation of a large family of cubic pyrochlores with small B cations occupying up to ca. 25 % of the large A-cation sites. Many pyrochlores can now be synthesized by deliberately combining large and small metal ions on the A sites. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: A dinuclear Ni-II complex, [Ni-2(L)(2)(H2O)(NCS)(2)]center dot 3H(2)O (1), was synthesized and characterized by IR and UV/Vis spectroscopy, cyclic voltammetry and single-crystal X-ray diffraction studies.
Abstract: A dinuclear Ni-II complex, [Ni-2(L)(2)(H2O)(NCS)(2)]center dot 3H(2)O (1) in which the metal atoms are bridged by one water molecule and two mu(2)-phenolate ions, and a thiocyanato-bridged dimeric Cull complex, [Cu(L)NCS](2) (2) [L = tridentate Schiff-base ligand, N-(3-aminopropyl)salicylaldimine, derived from 1:1 condensation of salicylaldehyde and 1,3-diaminopropane], have been synthesized and characterized by IR and UV/Vis spectroscopy, cyclic voltammetry and single-crystal X-ray diffraction studies. The structure of 1 consists of dinuclear units with crystallographic C-2 symmetry in which each Ni-II atom is in a distorted octahedral environment. The Ni-O distance and the Ni-O-Ni angle, through the bridged water molecule, are 2.240(11) angstrom and 82.5(5)degrees, respectively. The structure of 2 consists of dinuclear units bridged asymmetrically by di-mu(1,3)-NCS ions; each Cull ion is in a square-pyramidal environment with tau = 0.25. Variable-temperature magnetic susceptibility studies indicate the presence of dominant ferromagnetic exchange coupling in complex 1 with J = 3.1 cm(-1), whereas complex 2 exhibits weak antiferromagnetic coupling between the Cu-II centers with J = -1.7 cm(-1). ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, the inner cavity of the nanocluster 5b was analyzed by X-ray crystallographic results, showing that the formation of polymeric product was hindered, and exclusive formation of the spherical cage compound was achieved.
Abstract: Reaction of [CpxFe(5-P5)] {Cpx = 5-C5Me5 (1a), 5-C5Me4Et (1b)} with CuBr leads to the fullerene-like nanoballs [{CpxFe(5:1:1:1:1:1-P5)}12{CuBr}10{Cu2Br3}5{Cu(CH3CN)2}5] {Cpx = 5-C5Me5 (5a), 5-C5Me4Et (5b)} comprising a cluster core of 90 non-carbon atoms. In contrast to previous results by variation of stoichiometry and concentration conditions, the formation of polymeric product was hindered, and exclusive formation of the spherical cage compound was achieved. The cluster 5b possesses an inside diameter of 1.29 nm and an outside diameter of 2.37 nm. Definitive evidence for encapsulation of a [CpxFe(5-P5)] unit (1b) within the inner cavity of the nanocluster 5b is shown by X-ray crystallographic results.

Journal ArticleDOI
TL;DR: Several sal 2 en-type reduced Schiff bases have been prepared from the reaction of 2 equiv. of salicylaldehyde derivatives with ethylenediamine followed by reduction with NaBH 4 and subsequently characterised by X-ray diffraction as mentioned in this paper.
Abstract: Several sal 2 en-type reduced Schiff bases have been prepared from the reaction of 2 equiv. of salicylaldehyde (or derivatives) with ethylenediamine followed by reduction with NaBH 4 and subsequently characterised. The water-soluble ligands (SO 3 -sal) 2 en and R(SO 3 -sal) 2 en (SO 3 -sal = salicylaldehyde-5-sulphonate) have been studied by pH potentiometry and 1 H NMR spectroscopy and the protonation constants of R(SO 2 -sal) 2 en have been determined. The Schiff bases are more susceptible to hydrolysis than the corresponding reduced Schiff bases. The crystal structures of H 2 (o-van) 2 en and KH(o-van) 2 en (o-van = o-vanillin) have been determined by X-ray diffraction. The vanadium(IV) complexes have been prepared and characterised by magnetic measurements and IR, UV/Vis and EPR spectroscopy. The colours, magnetic susceptibilities and IR spectra of the new vanadium(IV) complexes of the reduced Schiff bases now obtained suggest oligomeric/polymeric structures for the compounds while the corresponding V I V O-Schiff-base complexes are monomeric. The complexation of (V I V O] 2 + and (V V O 2 ] + with R(SO 3 -sal) 2 en in aqueous solution has been studied by pH potentiometry, UV/Vis as well as by EPR spectroscopy for the V I V O system and 1 H and 5 1 V NMR spectroscopy for the V V O 2 system. Complex formation constants have been determined and binding modes have been proposed. N,N'-ethylenebis(pyridoxylaminato) (Rpyr 2 en) has also been obtained and the structure of Na(V V O 2 (Rpyr 2 en)].CH 3 OH.3H 2 O determined by X-ray diffraction. The Rpyr 2 en 2 - ligand coordinates through both the N-amine and O-phenolate moieties in a symmetrical α-cis type coordination mode, i.e. with both O-phenolato donors cis to the O-oxo atoms and trans to each other.

Journal ArticleDOI
TL;DR: The ionic liquid 1-dodecyl-3-methylimidazole chloride ([C12- mim]Cl) is doped with 1 mol-% of the lanthanide ternary complexes [Ln(tta)3(phen)] resulting in luminescent mesogenic phases at room temperature.
Abstract: The ionic liquid 1-dodecyl-3-methylimidazole chloride ([C12- mim]Cl) is doped with 1 mol-% of the lanthanide ternary complexes [Ln(tta)3(phen)] (tta = thenoyltrifluoroacetonate, phen = 1,10-phenanthroline, Ln = Nd, Eu, Er, Yb), resulting in luminescent mesogenic phases at room temperature. According to DSC and SAXS measurements, the temperature of the crystal liquid crystal transition is below 10 °C. Analysis of vibrational and luminescence data points to the inner co-ordination sphere of the EuIII ion being very similar in both the mesomorphic sample and the parent β-diketonate complex. The mesomorphic samples containing NdIII, ErIII, or YbIII display relatively intense near-infrared luminescence. This emission is enhanced in the liquid crystalline phases with respect to the initial compounds, as demonstrated for instance by the quantum yield of the [Yb(tta)3(phen)]-containing mesogenic sample which amounts to 2.1%, as compared to 1.6 and 1.1%for the powdered ternary complex and its solution in toluene, respectively. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: A review of the literature dealing with ionic liquids with fluorine-containing cations is presented in this paper, where a wide range of properties can be tuned, including viscosity, melting point, density, conductivity, solubility, liquid range, thermal and hydrolytic stability.
Abstract: Interest in ionic liquids with fluorine-containing cations has grown markedly in recent years. The syntheses, characterization and properties of quaternary fluoroalkyl-substituted ammonium, imidazolium, triazolium, pyridinium, pyrazinium, pyridazinium, pyrimidinium, piperazinium, pyrrolidinium, oxazolidinium, and morpholinium salts have been studied in detail. By modifying the anion or the fluorine-containing substituent on the cation, a wide range of properties of fluorine-containing ionic liquids can be tuned, including viscosity, melting point, density, conductivity, solubility, liquid range, thermal and hydrolytic stability. They are promising solvents for electrochemical, photovoltaic, surfactant and synthetic applications. In this Microreview, only the literature dealing with ionic liquids that involve fluorine-containing cations is presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, the structure of a monomeric Mn I I complex with the tridentate N-centered N 3 ligand tris[(1-methyl-2-imidazolyl)methyl]amine (TMIMA) was described.
Abstract: Two crystal structures are described in this article: (a) the structure of a monomeric Mn I I complex with the tridentate N-centered N 3 ligand tris[(1-methyl-2-imidazolyl)methyl]amine (TMIMA) ([Mn I I (TMIMA) 2 ] 2 + ); and(b) the structure of a monomeric Mn I I I complex with the tridentate N-centered N 2 O ligand 2-{[(1-methyl-2-imidazolyl)methyl]amino}phenolate (PI - ) [ 2 ] ([Mn I I I (PI) 2 ] + ) (5). The latter was isolated both in the Mn I I and in the Mn I I I state, although only Mn I I I crystals were successfully grown. They are part of a series of Mn complexes prepared as SOD mimics, namely [Mn(BMPG)(H 2 O)] + (2) {BMPG = N,N-bis[(6-methyl-.2-pyridyl)methyl]glycinate}, [Mn(IPG)(MeOH)] + (3) {IPG = N-[(1-methyl-2-imidazolyl) methyl]-N-(2-pyridylmethyl)glycinate), [Mn(BIG)(H 2 O) 2 ] + (4) {BIG = N,N-bis[(1-methyl-2-imidazolyl)methyl]glycinate}. The reactivity of Mn I I complexes 1 and 2 in an anhydrous medium is described and compared to that of complexes 3 and 4, the data for which was previously published. The cyclic voltammograms of the whole complex series were recorded in an aqueous medium (collidine buffer). Their SOD-like activities were estimated by the McCord-Fridovich test (IC50 with 22 μM cytc Fe I I I : 1.6′0.1 μMolL - 1 for 1, 1.2′0.5 μmolL - 1 for 2, 3.0′0.2 μmolL - 1 for 3, 3.7′0.6 μmolL - 1 for 4, 0.8′0.1 μmolL - 1 for 5). IC50 values were converted into the corresponding kinetic constant k M c C F values. A linear correlation between E a and log(k M c C F ) was obtained, indicating that in this series the conversion to Mn I I I is probably the rate-limiting step. This is of substantial importance for further Mn-SOD mimic design in this series.

Journal ArticleDOI
TL;DR: In this article, the same 3D framework as 1D open channels is used for coordination polymers of InCl3 with pyromellitic dianhydride and pyridine derivatives.
Abstract: Hydrothermal reactions of InCl3 with pyromellitic dianhydride and pyridine derivatives produce three coordination polymers: {(HL)[In3(btec)2(OH)2]·L}n [btec = 1,2,4,5-benzenetetracarboxylate, L = 2-picoline (1), L = 4-picoline (2)] and {(Hdpea)[In3(btec)2(OH)2]}n [dpea = 1,2-bis(4-pyridyl)ethane] (3). Single crystal X-ray diffraction and powder X-ray diffraction analyses reveal that compounds 1–3 are isostructural and possess the same 3D framework as 1D open channels. Thermal gravimetric studies show that compounds 1–3 are stable up to 300 °C. The guests of the protonated pyridine derivatives located at the channels in 1 and 2 can be fully exchanged by Ca2+ and Ba2+ ions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, a biochemical characterization of the intracrystalline macromolecules associated to the vateritic and aragonitic phases of otoliths is presented.
Abstract: Calcium carbonate polymorphism is one of the most challenging problems in biomineralization. Calcium carbonate exists in three crystalline forms: calcite, aragonite and vaterite. Otoliths of teleost fishes are made of vaterite and aragonite, located in different sacs and never mixed together. This paper presents a biochemical characterization of the intracrystalline macromolecules associated to the vateritic and aragonitic phases of otoliths. Experimental evidences from cal

Journal ArticleDOI
TL;DR: In this article, two Schiff base compartmental ligands derived from the condensation of 3-ethoxysalicylaldehyde with 1,2-diaminocyclohexane and orthophenylenediamine, respectively, were used to isolate two diphenoxo-bridged discrete dinuclear Cu I I Gd I I I complexes.
Abstract: Two Schiff base compartmental ligands, H 2 L 1 and H 2 L 2 , derived from the condensation of 3-ethoxysalicylaldehyde with 1,2-diaminocyclohexane and orthophenylenediamine, respectively, have been utilized to isolate two diphenoxo-bridged discrete dinuclear Cu I I Gd I I I complexes, [Cu I I (H 2 O)-L 1 Gd I I I (NO 3 ) 3 ] (3) and [Cu I I L 2 Gd I I I (NO 3 ) 3 ] (4). This is the first report on the 3d-4f compounds derived from compartmental Schiff base ligands with cyclic diamines. The compounds 3 and 4 crystallize in the triclinic Pi and orthorhombic Pna2(1) space groups, respectively, with the following unit cell parameters - 3: a = 8.8713(2) A, b = 12.8399(3) A, c = 14.0067(3) A, a = 80.6649(5)°, β = 77.4059(5)°, γ = 76.8879(5)°, and Z = 2; 4: a = 9.2210(1) A, b = 16.5407(2) A, c = 19.9248(4) A, and Z = 4. Structural analysis reveals that both are discrete dinuclear complexes. In 3, one water molecule is coordinated to the copper(II) ion to result in a square-pyramidal coordination geometry, while the geometry of the coppe(II) center in 4 is square planar. In both complexes, the gadolinium(III) center has an O 1 0 coordination environment. In contrast to expectation, although the N 2 O 2 cavity affords a better planar environment for the copper(II) center in 4, the bridging moiety in complex 3 is more planar than that in 4 or in most of the previously reported examples (the dihedral angle between two CuO 2 Gd planes: 2.1° for 3 and 7.1° for 4). Variable-temperature and variable-field magnetic measurements reveal that the metal centers in both the complexes are ferromagnetically coupled (J values: 6.3 cm - 1 for 3 and 5.4 cm - 1 for 4; H = -2JS C u .S G d ). Interestingly, complex 3 exhibits strongest ferromagnetic interaction among the related compounds.

Journal ArticleDOI
TL;DR: In this paper, the crystal and molecular structures of ligand I and complex 3 have been solved by single-crystal X-ray diffraction, and the anion 3 is in a distorted tetragonal-pyramidal environment (τ = 0.23).
Abstract: [VO(acac)2] reacts with H2L [H2L are the hydrazones H2pydx-inh (I), H2pydx-nh (II), or H2pydx-bhz (III); pydx = pyridoxal, inh = isonicotinohydrazide, nh = nicotinohydrazide, bhz = benzohydrazide] in dry methanol to yield the oxovanadium(IV) complexes [VOL] (H2L = I: 1; H2L = II: 4) or [VO(pydx-bhz)]. These complexes, when exposed to air, convert into the corresponding dioxovanadium(V) complexes [VO2HL] (H2L = I: 2; H2L = II: 5; H2L = III: 7). Aqueous solutions of vanadate and the ligands at pH = 7.5 give rise to the formation of [K(H2O)3][VO2(pydx-inh)] (3), [K(H2O)2][VO2(pydx-nh)] (6) and [K(H2O)2][VO2(pydx-bhz)] (8). Treatment of 6 and 8 with H2O2 generates the oxo(peroxo)vanadium complexes [VO(O2)L] (H2L = II: 9; H2L = III: 10). Complexes 9 and 10 are capable of transferring an oxo group to PPh3. Acidification of 8 with HCl afforded a hydroxo(oxo) complex. The crystal and molecular structures of ligand I and complex 3 have been solved by single-crystal X-ray diffraction. In the anion 3, the vanadium atom is in a distorted tetragonal-pyramidal environment (τ = 0.23). The K+ ion is coordinated to four water molecules (two of which bridge to a neighbouring K+ ion), the pyridine nitrogen atom of an isonicotinic moiety, the equatorial oxo group of the VO2+ fragment, and the alcoholic group of the pyridoxal moiety, which links adjacent layers in the three-dimensional lattice network. In the presence of KBr/H2O2, the anionic complexes 3, 6 and 8 catalyse the oxidative bromination of salicylaldehyde in water to 5-bromosalicylaldehyde in ca. 40% yields with ca. 87% selectivity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this paper, the crystal structure of this phase has been determined by X-ray diffraction and reveals an open framework structure with formic acid molecules occupying channels in the lattice which is stable even after removal of the solvent molecules.
Abstract: Recrystallisation of iron(II) formate dihydrate from formic acid under solvothermal conditions results in single-crystals of the iron(II) formate, α-Fe(O2CH)2·1/3HCO2H. The crystal structure of this phase has been determined by X-ray diffraction and reveals an open framework structure with formic acid molecules occupying channels in the lattice which is stable even after removal of the solvent molecules. Magnetic susceptibility and Mossbauer measurements show that the compound undergoes 3D magnetic ordering below TC = 16 K. α-Fe(O2CH)2·1/3HCO2H and the corresponding magnesium, cobalt, nickel and zinc formates form an isomorphous series. In contrast to the iron compound, the magnetic behaviour of the cobalt analogue is dominated by antiferromagnetic interactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this article, a polypyridylruthenium(II) complex was synthesized and characterized by elemental analysis, UV/Vis, IR and 1H NMR spectroscopy, FAB-MS and cyclic voltammetry methods.
Abstract: 2-(9-Anthryl)-1H-imidazo[4,5-f][1,10]phenanthroline (aip) and [2-(1-pyrenyl)-1H-imidazo[4,5-f][1,10]phenanthroline (pyip) and their complexes [Ru(phen)2(aip)]2+ (1) and [Ru(phen)2(pyip)]2+ (2) (phen = 1,10-phenanthroline) have been synthesized and characterized by elemental analysis, UV/Vis, IR and 1H NMR spectroscopy, FAB-MS and cyclic voltammetry methods. Both 1 and 2 are redox-active and undergo oxidation at 1.43 and 1.47 V (vs. SCE), respectively. Both 1 and 2 show only the 3MLCT emission typical of any polypyridylruthenium(II) complex. These new complexes are seen to be excellent binders of calf-thymus (CT) DNA, as revealed by the results of absorption, luminescence, viscometric titrations, and thermal denaturation studies. These results also indicate that while ruthenium-bound aip and pyip intercalate within the base pairs of the duplex, the phen moieties act only as spectator ligands in each case. Steady-state emission studies carried out in aqueous media with and without DNA reveal that [Ru(phen)2(pyip)]2+ is a better “molecular light switch” for DNA than [Ru(phen)2(aip)]2+. Under an identical set of experimental conditions of light and drug dose, the DNA photocleavage ability of [Ru(phen)2(pyip)]2+ is also higher than that of [Ru(phen)2(aip)]2+. “Inhibitor studies” suggest that the oxygen species are mainly responsible for the DNA photocleavage by these complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Journal ArticleDOI
TL;DR: In this paper, thin films of NbS2 and TaS2 have been produced from [M(NMe2)(5)] (M = Nb, Ta) and tBuSH by aerosol assisted chemical vapor deposition on glass.
Abstract: Thin films of NbS2 and TaS2 have been produced from [M(NMe2)(5)] (M = Nb, Ta) and tBuSH by aerosol-assisted chemical vapor deposition on glass. Gold-colored, reflective films were obtained and deposition took place at 250-350 degrees C for NbS2 and 225-450 degrees C for TaS2 using dichloromethane or hexanes as solvent. The niobium and tantalum sulfide films were analyzed by Raman spectroscopy, scanning electron microscopy (SEM), X-ray powder diffraction, energy dispersive analysis of X-rays (EDAX) and X-ray photoelectron spectroscopy (XPS). In order to identify possible compounds present in the aerosol mist, the solution phase reaction of [M(NMe2)(5)] and five equivalents of tBuSH in toluene at room temperature was carried out. Yellow crystals of the partially substituted tantalum thiolate [Ta(S-tBU)(2)(NMe2)(3)] were isolated. The X-ray structure of [Ta(S-tBU)(2)(NMe2)(3)] has been determined. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).