Showing papers in "Inorganic Chemistry in 2004"
TL;DR: The study reveals the dominant role of the structure of the ligand over that of the d(10) metal-hydroxy cluster-based coordination polymers and the presence of the cluster significantly increasing the emission lifetime and the manifestation of photoluminescence.
Abstract: The free solvated ligand, H(2)bna.CH(3)OH.H(2)O (1), and its dimeric complex, [Cd(2)(bna)(2)(H(2)O)(6)] (2) (bna = 2,2'-dihydroxy-[1,1']-binaphthalene-3,3'-dicarboxylate), were obtained by evaporation of the solutions, while two new d(10) metal-hydroxy cluster-based coordination polymers, namely [Cd(8)(OH)(4)(H(2)O)(10)(bna)(6)].17H(2)O (3) and [Hpy](2)[Zn(4)(OH)(2)(H(2)O)(2)(bna)(4)].2H(2)O.2CH(3)CN (4), were obtained by a hydrothermal route. All the compounds have been characterized by X-ray crystallography and photoluminescence measurements. Compound 1 consists of a three-dimensional, hydrogen-bonded supramolecular array, 2 exhibits a dimeric molecule featuring a square motif organized by two Cd(II) atoms and two bna ligands each at the corner, and 3 contains unprecedented [Cd(8)(micro(3)-OH)(2)(micro-OH)(2)(micro-H(2)O)(2)](12+) octanuclear metallacrown cores which are interlinked through bna to afford a two-dimensional structure, while 4 features layers with butterfly-shaped [Zn(4)(micro(3)-OH)(2)](6+) clusters. All the complexes display photoluminescent properties in the blue/green range. The manifestation of photoluminescence, as probed by molecular orbital calculations performed on the complexes and also on hypothetical multinuclear complexes, is attributed to a ligand-to-metal charge-transfer mechanism. In addition to presenting a new approach for the study of the photoluminescent properties of metal-cluster-based coordination polymers by using simple model compounds, the study also reveals the dominant role of the structure of the ligand over that of the d(10) metal-hydroxy (or oxy) cluster and the presence of the cluster significantly increasing the emission lifetime.
667 citations
TL;DR: WO(3) hollow spheres have been synthesized in solution phase by the controlled hydrolysis of WCl(6) using novel carbon microspheres as the templates and these spheres had large diameters and thin shells composed of numerous small nanocrystals.
Abstract: In this paper, we describe how WO(3) hollow spheres have been synthesized in solution phase by the controlled hydrolysis of WCl(6) using novel carbon microspheres as the templates. All of the products were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized spheres had large diameters of about 400 nm and thin shells of about 30 nm composed of numerous small nanocrystals. Prompted by the porous structure and small crystal size of the shell wall, we constructed WO(3) hollow-sphere gas sensors and found that these sensors had good sensitivity to alcohol, acetone, CS(2), and other organic gases.
568 citations
TL;DR: (PO) has been isolated and structurally characterized and shown to be inert to the polymerization of PO and the compounds (Tp(tBu))CaX in THF are shows to be highly active and stereoselective.
Abstract: A series of monomeric amide or aryloxide complexes of the form LCaX, where L = CH[CMeNC(6)H(3)-2,6-](2), CH[CMeNC(6)H(4)-2-OMe](2), a bulky tris-pyrazolyl borate, Tp(iPr) or Tp(tBu) or 9-BBN-pz(2) and X = N(SiMe(3))(2) or OC(6)H(3)-2,6-, has been prepared and characterized and investigated in the ring-opening polymerizations of lactide. The compounds (Tp(tBu))CaX in THF are shown to be highly active and stereoselective. The propylene oxide complex (Tp(tBu))Ca(OC(6)H(3)-2,6-).(PO) has been isolated and structurally characterized (single-crystal X-ray) and shown to be inert to the polymerization of PO.
361 citations
TL;DR: Two novel d(10) metal coordination polymers have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction and show strong photoluminescence properties at room temperature.
Abstract: Two novel d10 metal coordination polymers [Zn(PDB)]n (1) and [Cd3(PDB)2(OH)2(H2O)2]n (2) (H2PDB = pyridine-3,4-dicarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction. Crystal data for 1: C7H3NO4Zn, orthorhombic Pna21, a = 8.423(17) A, b = 6.574(13) A, c = 12.899(3) A, Z = 4. Crystal data for 2: C14H12N2O12Cd3, monoclinic C2/c, a = 20.130(4) A, b = 6.692(13) A, c = 13.081(3) A, β = 102.78(3)°, Z = 4. Both compounds exhibit novel three-dimensional frameworks. Compound 1 not only possesses a one-dimensional rectangular channel but also contains infinite double-stranded helical chains. Compound 2 has two different types of channels, one being built up from pyridine rings and {CdO5N} and {CdO6} building units and the other being constructed from pyridine rings and {CdO5N} building units. Furthermore, both compounds show strong photoluminescence properties at room temperature.
344 citations
TL;DR: The participation of the normally inert A- site cation in the electronic structure near the Fermi level can be considered an inductive effect, as it utilizes substitution on the A-site to directly modify the electronic structures of the SnO(3)(2)(-) framework.
Abstract: Experimental and computational studies were performed to understand the electronic structure of ternary perovskites (ASnO3, A = Ca, Sr, Ba, Cd), pyrochlores (RE2Sn2O7, RE = Y, La, Lu; Cd2Sb2O7), and defect pyrochlore oxides (Ag2Sb2O6) containing the main group ions Sn4+ and Sb5+. In all compounds, the lowest energy states in the conduction band arise primarily from the antibonding Sn/Sb 5s−O 2p interaction. In the alkaline-earth stannate perovskites (BaSnO3, SrSnO3, and CaSnO3) the conduction bandwidth decreases strongly in response to the octahedral tilting distortion triggered by the decreasing size of the alkaline-earth cation. This in turn leads to a corresponding increase in the band gap from 3.1 eV in BaSnO3 to 4.4 eV in CaSnO3. The band gap of CdSnO3 is relatively small (3.0 eV) considering the large octahedral tilting distortion. The origin of this apparent anomaly is the mixing between the empty Cd 5s orbitals and the antibonding Sn 5s−O 2p states. This mixing leads to a widening of the conductio...
338 citations
TL;DR: Three isomorphous compounds M(CHOO)3[NH2(CH3)2] (M = Mn(1 x Mn), Co(2 x Co), Ni(3 x Ni)) have been synthesized in solvothermal conditions and single-crystal X-ray diffraction shows that they are all crystallized in the trigonal space group R c with small differences in the lattice parameters.
Abstract: Three isomorphous compounds M(CHOO)3[NH2(CH3)2] (M = Mn(1·Mn), Co(2·Co), Ni(3·Ni)) have been synthesized in solvothermal conditions. Single-crystal X-ray diffraction shows that they are all crystallized in the trigonal space group R 3c with small differences in the lattice parameters. Bridged by the three-atom single-bridge CHOO-, M ions form a three-dimensional distorted perovskite-like structure with dimethylamine (DMA) cations located in the cages of the network. Based on the magnetic data, these three 3D compounds are weak ferromagnets with the critical temperature Tc = 8.5 K (1·Mn), 14.9 K (2·Co), and 35.6 K (3·Ni), and for 2·Co and 3·Ni, spin reorientation might take place at 13.1 and 14.3 K, respectively. At 1.8 K, hysteresis loops can be observed for all three compounds with the coercivity field ca. 90 Oe (1·Mn), 920 Oe (2·Co), and 320 Oe (3·Ni). The canting angles are estimated to be 0.08°, 0.5°, and 0.6° for 1·Mn, 2·Co, and 3·Ni, respectively. The magnetic coupling between MnII ions in 1·Mn was...
321 citations
TL;DR: The phase behavior of a variety of quaternary ammonium halides/ZnCl(2) mixtures is characterized and it is shown that the depression of freezing point is related to the increase in size of the component ions.
Abstract: The synthesis of ionic liquids based upon functionalized quaternary ammonium salts and metal salts of zinc, tin, or iron is demonstrated. The freezing point of these ionic liquids was studied as a function of the quaternary ammonium cation. The complex anions were identified and quantified using mass spectrometry and potentiometry. It is shown that the primary zinc anion is Zn2Cl5- with Zn3Cl7- becoming more abundant in more Lewis basic solutions. Similar results were observed for ionic liquids containing SnCl2. The surface tension was also measured and was used to explain the high viscosity of the ionic liquids in terms of the large ion:hole size ratio and the small probability of finding a hole of suitable dimensions adjacent to a given ion to permit movement. The phase behavior of a variety of quaternary ammonium halides/ZnCl2 mixtures is characterized and it is shown that the depression of freezing point is related to the increase in size of the component ions.
300 citations
TL;DR: For the first time, a structural characterization of the zinc(II) and copper( II) complexes of clioquinol is reported, finding a ligand to metal stoichiometry of 2:1 is found in both cases, though in the presence of quite different coordination polyhedra.
Abstract: Clioquinol, a 8-hydroxyquinoline derivative, is producing very encouraging results in the treatment of Alzheimer's disease (AD). Its biological effects are most likely ascribed to complexation of specific metal ions, such as copper(II) and zinc(II), critically associated with protein aggregation and degeneration processes in the brain. We report here, for the first time, a structural characterization of the zinc(II) and copper(II) complexes of clioquinol. A ligand to metal stoichiometry of 2:1 is found in both cases, though in the presence of quite different coordination polyhedra. The present findings are discussed in the frame of modern approaches to AD treatment.
268 citations
TL;DR: A simple sonochemical route was developed for the crystal growth of uniform silver nanoplates and ringlike gold nanocrystals in a N,N-dimethylformamide solution and the platelike structures generated from the selective growth on different crystal planes in the presence of poly(vinylpyrrolidone) and the ultrasonic-assisted Ostwald ripening processes.
Abstract: A simple sonochemical route was developed for the crystal growth of uniform silver nanoplates and ringlike gold nanocrystals in a N,N-dimethylformamide solution. The platelike structures were generated from the selective growth on different crystal planes in the presence of poly(vinylpyrrolidone) and the ultrasonic-assisted Ostwald ripening processes. The silver nanoplates in solution served as the templates for the synthesis of ringlike gold crystals via a displacement reaction. Both the silver nanoplates and gold nanorings were highly oriented single crystals with (111) planes as the basal planes.
243 citations
TL;DR: The ac susceptibility measurements on the complex with octa(dodecoxy)-substituted Pc ligand proved that the significant rise of the temperatures occurs as an intrinsic single-molecular property of the complex possessing both J = 6 and S = (1)/(2) systems, and is not due to long-range magnetic order or interactions between adjacent unpaired pi-electrons.
Abstract: An alternating-current (ac) magnetic susceptibility measurement for the [(Pc)2TbIII]0 complex (Pc = phthalocyaninato) has shown that ligand oxidation of the anionic [(Pc)2TbIII]- complex gives rise to a significant upward shift of the temperature range where the magnetization response shows a phase lag behind the time-varying external magnetic field. The peaks of the out-of-phase component of the ac susceptibility of the π-radical [(Pc)2TbIII]0 were observed at 50, 43, and 36 K with ac magnetic fields of 103, 102, and 10 Hz, respectively, which were more than 10 K higher than the corresponding values of the anionic complex with a closed-shell π-system. The ac susceptibility measurements on the complex with octa(dodecoxy)-substituted Pc ligand, which is readily dilutable in diamagnetic media, proved that the significant rise of the temperatures occurs as an intrinsic single-molecular property of the complex possessing both J = 6 and S = 1/2 systems, and is not due to long-range magnetic order or interactio...
224 citations
TL;DR: Close Ag..Ag interionic contacts of 3.226(1) A were observed in the one-dimensional anionic chain, and the relatively high melting point among the EMI salts with a monoanion appears to be governed essentially by these direct Ag...Ag interactions.
Abstract: New 1-ethyl-3-methylimidazolium (EMI) salts [EMI][C(CN)3] and [EMI][Ag(CN)2] were prepared and characterized. The C(CN)3 salt has a melting point at −11 °C and shows a low viscosity (18 cP) and a high ionic conductivity (1.8 × 10-2 S cm-1) at room temperature. This conductivity is less than that of [EMI][N(CN)2] salt (2.7 × 10-2 S cm-1), possibly due to the larger molecular weight of the anion. The first EMI salt containing Ag(I) complexes [EMI][Ag(CN)2] has a higher melting point of 73 °C. In the crystal, the C−H···π interionic interactions between cations construct zigzag chains in the cationic two-dimensional layer. Close Ag··Ag interionic contacts of 3.226(1) A were observed in the one-dimensional anionic chain, and the relatively high melting point among the EMI salts with a monoanion appears to be governed essentially by these direct Ag···Ag interactions.
TL;DR: Polymers 2-4 display strong fluorescent emissions in the solid state at room temperature and the effects of temperature on the hydrothermal reaction system of btx and CdSO(4) and found that different products can be obtained at different temperatures.
Abstract: Four novel cadmium−btx (btx = 1,4-bis(triazol-1-ylmethyl)benzene) coordination polymers [Cd(btx)2(NO3)2]n (1), [Cd(btx)2Cl2]n (2), [Cd(btx)(SO4)(H2O)2]n (3), and [Cd(btx)(S2O7)(H2O)]n (4) have been prepared by hydrothermal reaction (140 or 180 °C) and characterized. Both 1 and 2 have two-dimensional rhombohedral grid structures, 3 possesses a two-dimensional rectangular grid structure, and 4 displays a three-dimensional framework, which is formed by btx bridging parallel layers. To the author's best knowledge, polymer 4 is the first Cd(II) polymer in which the Cd(II) ion is eight-coordinated in a hexagonal bipyrimidal geometry. In addition, we studied the effects of temperature on the hydrothermal reaction system of btx and CdSO4 and found that different products can be obtained at different temperatures. Furthermore, polymer 3 possesses a very strong third-order NLO absorptive effect with an α2 value of 1.15 × 10-9 m W-1. Polymers 2−4 display strong fluorescent emissions in the solid state at room temper...
TL;DR: It was envisaged that these ionic liquids could act as both solvent and ligand for catalyzed reactions, and this application is demonstrated in hydrogenation reactions, which show that retention of the catalyst in the ionic liquid during product extraction is extremely high.
Abstract: A series of imidazolium salts with the nitrile functional group attached to the alkyl side chain, viz. [CnCNmim][X] (where CnCNmim is the 1-alkylnitrile-3-methylimidazolium cation and Cn = (CH2)n, n = 1−4; X = Cl, PF6, and BF4) and [C3CNdmim][X] (where CnCNdmim is the 1-alkylnitrile-2,3-dimethylimidazolium cation and Cn = (CH2)n, n = 3; X = Cl, PF6, and BF4), have been prepared and characterized using spectroscopic methods. The majority of the nitrile-functionalized imidazolium salts can be classed as ionic liquids since they melt below 100 °C. Four of the imidazolium salts have been characterized in the solid state using single-crystal X-ray diffraction analysis to reveal an extensive series of hydrogen bonds between H atoms on the cation and the anion. The relationship between the solid-state structure and the melting point is discussed. Key physical properties (density, viscosity, and solubility in common solvents) of the low melting ionic liquid have been determined and are compared with those of the ...
TL;DR: Efficient photocyclization from a low-lying triplet state is reported for a photochromic dithienylperfluorocyclopentene with Ru(bpy)3 units attached via a phenylene linker to the thiophene rings.
Abstract: Efficient photocyclization from a low-lying triplet state is reported for a photochromic dithienylperfluorocyclopentene with Ru(bpy)3 units attached via a phenylene linker to the thiophene rings. The ring-closure reaction in the nanosecond domain is sensitized by the metal complexes. Upon photoexcitation into the lowest Ru-to-bpy 1MLCT state followed by intersystem crossing to emitting 3MLCT states, photoreactive 3IL states are populated by an efficient energy-transfer process. The involvement of these 3IL states explains the quantum yield of the photocyclization, which is independent of the excitation wavelength but decreases strongly in the presence of dioxygen. This behavior differs substantially from the photocyclization of the nonemissive dithienylperfluorocyclopentene free ligand, which occurs from the lowest 1IL state on a picosecond time scale and is insensitive to oxygen quenching. Cyclic voltammetric studies have also been performed to gain further insight into the energetics of the system. The ...
TL;DR: Despite the proximity of spin-excited states, ac susceptibility data reveal frequency-dependent out-of-phase signals characteristic of single-molecule magnets with spin-reversal barriers of U(eff) = 16 and 25 cm(-)(1), respectively.
Abstract: Reactions between K(3)[M(CN)(6)] and [Mn(5-Brsalen)(H(2)O)(2)](+) (5-Brsalen = N,N'-ethylenebis(5-bromosalicylidene)aminato dianion) in a mixture of methanol and water afford the compounds K[(5-Brsalen)(2)(H(2)O)(2)Mn(2)M(CN)(6)].2H(2)O, with M = Cr (1) or Fe (2). The two compounds are isostructural, each containing a molecular cluster with a linear Mn(III)-NC-M(III)-CN-Mn(III) core and tetragonally elongated coordination about the Mn(III) centers. Magnetic data indicate the presence of weak exchange interactions within the clusters, giving rise to ground states of S = (5)/(2) and (9)/(2) with significant zero-field splitting. Despite the proximity of spin-excited states, ac susceptibility data reveal frequency-dependent out-of-phase signals characteristic of single-molecule magnets with spin-reversal barriers of U(eff) = 16 and 25 cm(-)(1), respectively.
TL;DR: Reaction of 5,5'-(1,4-phenylene)bis(1H-tetrazole), which was prepared in two steps, with cadmium nitrate in DMF produced a three-dimensional framework with one-dimensional channels, in which unprecedented hydrogen-bond-supported D(2)(h)() tetrameric cyclic water clusters ranked.
Abstract: Reaction of 5,5‘-(1,4-phenylene)bis(1H-tetrazole), which was prepared in two steps, with cadmium nitrate in DMF produced a three-dimensional framework with one-dimensional channels (35% void volume), in which unprecedented hydrogen-bond-supported D2h tetrameric cyclic water clusters ranked
TL;DR: Thermodynamic evaluation shows that the analyte specificity of chemodosimeter 1 is attributable to the relative stability of the donor-acceptor complex to that of adducts formed between the acceptor metal center and the analytes.
Abstract: A trinuclear heterobimetallic Ru(II)-Cu(II) donor-acceptor complex, [Ru(II)((t)Bubpy)(CN)(4)-[Cu(II)(dien)](2)](ClO(4))(2) ((t)Bubpy = 4,4'-di-tert-butyl-2,2'-bipyridine; dien = diethylenetriamine) (1), has been synthesized and successfully used as an chemodosimetric ensemble for the specific detection of cyanide in aqueous DMF. X-ray crystallography, solid and solution IR spectroscopy, and conductivity measurements reveal that complex 1 is a one-dimensional polymer in the crystalline state and dissociates into its [Ru(II)((t)Bubpy)(CN)(2)[(CN)Cu(II)(dien)L](2)](2+) (L = solvent) monomeric units in polar solvents. The MLCT transition and luminescence properties of the solvatochromic [Ru(II)((t)Bubpy)(CN)(4)](2)(-) donor are perturbed by the coordination of two Cu(II) acceptors but restored in the presence of CN(-). Spectroscopic and mass spectrometric studies confirm the cleavage of the cyano bridge between Ru(II) and Cu(II) of the chemodosimetric ensemble after the binding of cyanide to the Cu(II) centers. The overall binding constant, K(B), between 1 and CN(-) is measured to be (7.39 +/- 0.23) x 10(6) M(-2). A detection limit of 1.2 microM (0.03 ppm) of CN(-) in aqueous DMF (pH 7.4) is achievable. Thermodynamic evaluation shows that the analyte specificity of chemodosimeter 1 is attributable to the relative stability of the donor-acceptor complex to that of adducts formed between the acceptor metal center and the analytes.
TL;DR: Results from this laboratory are surveyed, emphasizing the synthesis of metal sulfides and the preparation of functional and structural models for bio-organometallic reaction centers.
Abstract: Results from this laboratory are surveyed, emphasizing the synthesis of metal sulfides. Four themes are described. Continuing studies exploit the exothermic desulfurization of polysulfido complexes as a means to generate new clusters and rings. Illustrative inorganic rings prepared in this way include 1,5-[L2M]2(S3)2 and 1,4-[L2M]2(S2)2, where L2M = CpRu(PPh3) and Cp2Ti. Fundamentally new clusters prepared in this project included the cubanes [(C5R5)MS]4 for M = Ti, V, Ru, Ir. Associated redox studies led to the discovery of the phenomenon of mobile metal−metal bonds, as manifested in [Cp*4Ir4S4]2+ wherein the localized Ir−Ir bond migrates over the six Ir- - -Ir edges of the cluster. Other desulfurization experiments led to the preparation of the reactive species IrII2S2(PPh3)4 from [IrS16]3- and the synthesis of the first high polymers of ferrocene, [(RC5H3S)2Fe]n (n ∼ 500). A second theme uncovered the useful role of donor solvents on the reaction of metals with sulfur. It was found that pyridine accele...
TL;DR: The complex [Gd(AAZTA)]- shows outstanding magnetic properties connected with high thermodynamic stability in aqueous solution and a nearly complete inertness toward the influence of bidentate endogenous anions, placing this compound as one of the most promising candidates for the development of high performance MRI contrast agents.
Abstract: An innovative MRI contrast agent based on the unprecedented and easily obtained ligand AAZTA is described. The simple and straightforward synthesis of the ligand, together with the potentiometric and relaxometric behavior of the corresponding Gd(III) chelate, is reported. The complex [Gd(AAZTA)]- shows outstanding magnetic properties connected with high thermodynamic stability in aqueous solution and a nearly complete inertness toward the influence of bidentate endogenous anions, placing this compound as one of the most promising candidates for the development of high performance MRI contrast agents.
TL;DR: Six complexes exhibit six types of bridging modes of N1,N2-triazole in combination with single-atom bridges, whereas 3 is the first example of the micro(3)-Cl bridging mode in triazole-metal complexes.
Abstract: Cadmium salts with different triazole ligands have led to a series of novel triazole−cadmium compounds varying from zero- to three-dimensionality. [Cd2(deatrz)2(H2O)Br4] (1) (deatrz = 3,5-diethyl-4-amino-1,2,4-triazole) is a zero-dimensional complex which uses a triazole ligand together with μ-OH2 as bridges to form a 1D chain via hydrogen-bonding contacts. {[Cd3(deatrz)2Cl6(H2O)2]·2H2O}n (2), {[Cd(dmtrz)Cl2]·1.5H2O}n (3) (dmtrz = 3,5-dimethyl-1,2,4-triazole), and {[Cd3(deatrz)4Cl2(SCN)4]·2H2O}n (4) are polymeric 1D chains. 2 and 4 were constructed via trinuclear cadmium units bridged by triazole ligands and chloride atoms, while 3 consists of μ2-Cl, μ3-Cl, and triazole bridges, cross-linked by hydrogen bonding to give a 3D framework. {[Cd3(dmatrz)4(SCN)6]}n (5) (dmatrz = 3,5-dimethyl-4-amino-1,2,4-triazole) shows a two-dimensional structure whose fundamental units are trinuclear metal cations bridged via triazole ligands. The complex {[Cd(dmtrz)(SCN)2]}n (6) is the first three-dimensional example in N1,N...
TL;DR: A new three-dimensional (3-D) jungle-gym-like open metal-organic framework has been synthesized from a two-dimensional layer compound using a heterogeneous pillar insertion reaction.
Abstract: A new three-dimensional (3-D) jungle-gym-like open metal-organic framework has been synthesized from a two-dimensional (2-D) layer compound using a heterogeneous pillar insertion reaction. Both the starting 2-D layer and the resulting 3-D open compounds have been characterized using X-ray crystallography.
TL;DR: Two novel heptanuclear lanthanide clusters of the dicubane-like type [Ln(7)(micro(3)-OH)(8)](13+) (Ln = Ho (1), Yb (2) (13+) were obtained via hydrothermal reaction, and as building blocks, they were formally assembled into porous three-dimensional networks through the linkage of 1,4-naphthalenedicarboxylate.
Abstract: Two novel heptanuclear lanthanide clusters of the dicubane-like type [Ln7(μ3-OH)8]13+ (Ln = Ho (1), Yb (2)) were obtained via hydrothermal reaction, and as building blocks, they were formally assembled into porous three-dimensional networks through the linkage of 1,4-naphthalenedicarboxylate (1,4-NDA), forming first examples of porous lanthanide polymers with 1,4-NDA, [Ln7(μ3-OH)8(1,4-NDA)6(OH)0.5(Ac)0.5(H2O)7]·4H2O (Ln = Ho, Yb). The coordinating water molecules and lattice water molecules are enclathrated in the cavities.
TL;DR: In this paper, α-ketoglutaric acid thiosemicarbazone (H3ct) derivatives and their copper complexes were synthesized and characterized by analytical and spectroscopic (IR and NMR) methods.
Abstract: New α-ketoglutaric acid thiosemicarbazone (H3ct) derivatives and their copper complexes were synthesized and characterized by analytical and spectroscopic (IR and NMR) methods. For two of the ligands, Me-H3ct and Allyl-H3ct, and for a complex, [Cu(Me-Hct)(OH2)]n·2nH2O, the X-ray structures were also determined. In the latter the copper atom shows a 4 + 1 pyramidal coordination, a water oxygen appears in the apical position, and three of the basal positions are occupied by the SNO tridentate ligand and the fourth by a carboxylic oxygen of an adjacent molecule that gives rise to a polymeric chain. DNA binding constants were determined, and studies of thermal denaturation profiles and nuclease activity were also performed. Tests in vitro on human leukemia cell line U937 were carried out on cell growth inhibition, cell cycle, and apoptosis induction.
TL;DR: All of these complexes were studied by (1)H NMR spectroscopy, and complexes 3-9 were additionally characterized by X-ray crystallography.
Abstract: Reaction of 1,3-bis(2-pyridinylmethyl)-1H-imidazolium tetrafluoroborate, [H(pyCH2)2im]BF4, with silver oxide in dichloromethane readily yields [Ag((pyCH2)2im)2]BF4, 1·BF4 1·BF4 is converted to the analogous Au(I)-containing species, [Au((pyCH2)2im)2]BF4, 3, by a simple carbene transfer reaction in dichloromethane Further treatment with two equivalents of AgBF4 produces the trimetallic species [AuAg2((pyCH2)2im)2(NCCH3)2](BF4)3, 4, which contains two silver ions each coordinated to the pyridine moieties on one carbene ligand and to an acetonitrile molecule in a T-shaped fashion Monometallic [Ag((py)2im)2]BF4, 5, and [Au((py)2im)2]BF4, 6, are made analogously to 1·BF4 and 3 starting from 1,3-bis(2-pyridyl)-imidazol-2-ylidene tetrafluoroborate, [H(py)2im]BF4 Addition of excess AgBF4 to 6 yields the helical mixed-metal polymer, {[AuAg((py)2im)2(NCCH3)](BF4)2}n, 7 which contains an extended Au(I)−Ag(I) chain with short metal−metal separations of 28359(4) and 29042(4) A Colorless, monometallic [Hg((pyCH2
TL;DR: A well-resolved uudd cyclic water tetramer was reported in the crystal host of [Cu(adipate)(4,4-bipyridine)].(H(2)O)(2), showing the contribution of the water cluster to the stability of the crystalHost and the role of cooperative association of theWater cluster and the crystalhost in the formation of thewater cluster.
Abstract: A well-resolved uudd cyclic water tetramer was reported in the crystal host of [Cu(adipate)(4,4-bipyridine)]·(H2O)2, showing the contribution of the water cluster to the stability of the crystal host and the role of cooperative association of the water cluster and the crystal host in the formation of the water cluster.
TL;DR: The X-ray structure determination on 4-6 revealed the chiral twisting of the central imidazole rings from the metal coordination plane, which implies the low rotational barrier about the Pd-NHC bond.
Abstract: A new imidazolium salt, 1,3-bis(2-diphenylphosphanylethyl)-3H-imidazol-1-ium chloride (2), for the phosphine/N-heterocyclic carbene-based pincer ligand, PC(NHC)P, and its palladium complexes were reported. The complex, [Pd(PC(NHC)P)Cl]Cl (4), was prepared by the common route of silver carbene transfer reaction and a novel direct reaction between the ligand precursor, PC(NHC)P.HCl and PdCl(2) without the need of a base. Metathesis reactions of 4 with AgBF(4) in acetonitrile produced [Pd(PC(NHC)P)(CH(3)CN)](BF(4))(2) (5). The same reaction in the presence of excess pyridine gave [Pd(PC(NHC)P)(py)](BF(4))(2) (6). The X-ray structure determination on 4-6 revealed the chiral twisting of the central imidazole rings from the metal coordination plane. In solution, fast interconversion between left- and right-twisted forms occurs. The twisting reflects the weak pi-accepting property of the central NHC in PC(NHC)P. The uneven extent of twisting among the three complexes further implies the low rotational barrier about the Pd-NHC bond. Related theoretical computations confirm the small rotational energy barrier about the Pd-NHC bond (ca. 4 kcal/mol). Catalytic applications of 4 and 5 have shown that the complexes are modest catalysts in Suzuki coupling. The complexes were active catalysts in Heck coupling reactions with the dicationic complex 5 being more effective than the monocationic complex 4.
TL;DR: Puckered-boat-shaped hexameric water clusters resulting from four free water molecules and two water molecules coordinating to metal ions join these sheets to make a 3D network and behave as pillars to join those sheets which is the key factor stabilizing the3D network.
Abstract: 1,2,4,5-Benzenetetracarboxylic acid (btcH4) reacts with Cu(NO3)2·6H2O to form 2D coordination polymeric structure {[Cu2(btc)(Py)4·2H2O]·4H2O}n, 1, in the presence of pyridine from water at room temperature. Puckered-boat-shaped hexameric water clusters resulting from four free water molecules and two water molecules coordinating to metal ions join these sheets to make a 3D network. These water clusters behave as pillars to join those sheets which is the key factor stabilizing the 3D network. Thermal analysis, X-ray powder diffraction, and X-ray structure analysis have been used to characterize this compound. Crystal data for 1 follow: triclinic space group P1, a = 8.905(3) A, b = 11.137(4) A, c = 17.484(2) A, α = 82.342(6)°, β = 81.312(3)°, γ = 82.361(4)° V= 1687.5(1)A3, Z = 2, R1 = 0.0331, wR2 = 0.0886, S =1.066.
TL;DR: The PB nanoparticles with the PVP protection show high solubility in a variety of organic solvents and a solvent-dependent CT absorption and the magnetic properties showed unprecedented size-dependency, surface effect, and superparamagnetic properties.
Abstract: Prussian blue (PB) nanoparticles protected by organic polymers such as poly(vinylpyrrolidone) (PVP) and poly(diallyldimethylammonium chloride) (PDDA) were prepared. Different experimental conditions (concentrations of Fe ions and feed ratios of Fe to the polymers) have been investigated to control the size of the PB nanoparticles. For example, the averaged dimensions of the PB nanoparticles were tuned from 12 to 27 nm by use of PVP in the different conditions. Addition of PDDA produced the PB nanoparticles with very small dimensions (5−8 nm) by an effective electrostatic interaction. We found that the surface environments of the PB nanoparticles affect the inherent properties of PB. The shifts of charge transfer (CT) absorptions from Fe2+ to Fe3+ in the PB nanoparticles resulted from the surface-protecting polymers. Especially, the PB nanoparticles with the PVP protection show high solubility in a variety of organic solvents and a solvent-dependent CT absorption. Measurement of the magnetic properties of ...
TL;DR: Tridentate/tetradentate Schiff base ligands L(1) and L(2), derived from the condensation of o-vanillin or pyridine-2-aldehyde with N,N-dimethylethylenediammine, react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of dinuclear complexes.
Abstract: Tridentate/tetradentate Schiff base ligands L1 and L2, derived from the condensation of o-vanillin or pyridine-2-aldehyde with N,N-dimethylethylenediammine, react with nickel acetate or perchlorate salt and azide, cyanate, or thiocyanate to give rise to a series of dinuclear complexes of formulas [Ni(L1)(μ1,1-N3)Ni(L1)(N3)(OH2)]·H2O (1), {[Ni(L1)(μ1,1-NCS)Ni(L1)(NCS)(OH2)][Ni(L1)(μ-CH3COO)Ni(L1)( NCS) (OH2)]} (2) {[2A][2B]}, [Ni(L1)(μ1,1-NCO)Ni(L1)(NCO)(OH2)]·H2O (3), and [Ni(L2-OMe)(μ1,1-N3)(N3)]2 (4), where L1 = Me2N(CH2)2NCHC6H3(O-)(OCH3) and L2 = Me2N(CH2)2NCHC6H3N. We have characterized these complexes by analytical, spectroscopic, and variable-temperature magnetic susceptibility measurements. The coordination geometry around all of the Ni(II) centers is a distorted octahedron with bridging azide, thiocyanate/acetate, or cyanate in a μ1,1 mode and μ2-phenolate oxygen ion for 1−3, respectively, or with a double-bridging azide for 4. The magnetic properties of the complexes were studied by magnetic sus...
TL;DR: The results suggest that intercalation or strong DNA binding may not be a desirable property of a potential PDT agent.
Abstract: Two new dirhodium(II) complexes possessing the intercalating dppz ligand (dppz = dipyrido[3,2-a:2‘,3‘-c]phenazine), cis-[Rh2(μ-O2CCH3)2(dppz)(η1-O2CCH3)(CH3OH)]+ (1) and cis-[Rh2(μ-O2CCH3)2(dppz)2]2+ (2), were synthesized and characterized as potential agents for photochemotherapy Various techniques show that 1 binds to DNA through intercalation, although some aggregation of the complex on the DNA surface is also present In contrast, 2 does not intercalate between the DNA bases; however, strong hypochromic behavior is observed in the presence of DNA, which can be attributed to intermolecular π-stacking of 2 enhanced by the polyanion The apparent DNA binding constants determined using optical titrations are compared to those from dialysis experiments Both complexes photocleave pUC18 plasmid in vitro under irradiation with visible light (λirr ≥ 395 nm, 15 min), resulting in the nicked, circular form Greater photocleavage is observed for 1 relative to 2, which may be due to the ability of 1 to intercala