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Sample records for 4d-4f ln-ag heterometallic

  1. Synthesis, crystal structures and luminescent properties of two 4d-4f Ln-Ag heterometallic coordination polymers based on anion template

    SciTech Connect

    Fan, Le-Qing; Chen, Yuan; Wu, Ji-Huai; Huang, Yun-Fang

    2011-04-15

    Two new 4d-4f Ln-Ag heterometallic coordination polymers, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been synthesized under hydrothermal conditions by reactions of Ln{sub 2}O{sub 3}, AgNO{sub 3}, HIN and HClO{sub 4}, and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. It is proved that HClO{sub 4} not only adjusts the pH value of the reaction mixture, but also acts as anion template. The structure determination reveals that 1 and 2 are isostructural and feature a novel two-dimensional (2D) layered hetrometallic structure constructed from one-dimensional Ln-carboxylate chains and pillared Ag(IN){sub 2} units. The 2D layers are further interlinked through Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions, which form a rare Ag-ClO{sub 4} ribbon in lanthanide-transition metal coordination polymers, to give rise to a three-dimensional supramolecular architecture. Moreover, the luminescent properties of these two compounds have also been investigated at room temperature. -- Graphical abstract: Two new anion-templated 2D 4d-4f Ln-Ag heterometallic coordination polymers based on novel lanthanide-carboxylate chains and pillared Ag(IN){sub 2} units, {l_brace}[Ln{sub 3}Ag{sub 5}(IN){sub 10}(H{sub 2}O){sub 7}].4(ClO{sub 4}).4(H{sub 2}O){r_brace}{sub n} (Ln=Eu (1) and Sm (2), HIN=isonicotinic acid), have been hydrothermally synthesized and structurally characterized. 1 and 2 exhibit good luminescent properties. Display Omitted Research highlights: > Two 2D Eu (Sm)-Ag coordination polymers templated by perchlorate anion have been synthesized. > Polymers consist of novel 1D lanthanide-carboxylate chains. > In both structures, there are rare Ag...Ag and Ag...O(ClO{sub 4}{sup -}) multiple weak interactions. > Both compounds exhibit good luminescent properties.

  2. Cation-Exchange Porosity Tuning in a Dynamic 4d-4f-3d Framework for Ni(II) Ion-Selective Luminescent Probe.

    PubMed

    Wang, Ying; Wang, Xiu-Guang; Yuan, Bin; Shao, Cheng-Yuan; Chen, Yuan-Yuan; Zhou, Bing-Bing; Li, Ming-Shu; An, Xiao-Mai; Cheng, Peng; Zhao, Xiao-Jun

    2015-05-01

    A heterometallic complex {[Yb2(L)6Cd2][Cd(H2O)6]·6H2O}n (Yb-Cd) (H2L = oxidiacetic acid) was synthesized under hydrothermal conditions. In Yb-Cd, each L chelates to one Yb(3+) center and bonds to two Cd(2+) ions in an anti-anti configuration. Yb and Cd atoms are arrayed alternatively and connected by O-C-O bridges to form a cubic octahedral cage as the secondary building unit. Consequently, topological NaCl nets with high symmetry in the cubic space group Fd-3c have been constructed. The [Cd(H2O)6](2+) moieties lying in the porosity of anionic metal-organic framework (MOF) act as the thermodynamically stable species, required to balance the two negative charges of [Yb2(L)6Cd2](2-) in Yb-Cd. Interestingly, when Yb-Cd was employed as a precursor and emerged in the aqueous solution of Mn(ClO4)2·6H2O or Zn(ClO4)2·6H2O, a reversible single-crystal-to-single-crystal transformation process driven by [Cd(H2O)6](2+) cations has been exhibited to generate the heterotrimetallic coordination polymer {[Yb2(L)6Cd2][Mn(H2O)6]·6H2O}n (Yb-Cd-Mn) or {[Yb2(L)6Cd2][Zn(H2O)6]·6H2O}n (Yb-Cd-Zn). To the best of out knowledge, Yb-Cd-Mn and Yb-Cd-Zn are the first examples representing 4d-4f-3d polymers based on multicarboxylic acid. Luminescent studies reveal that Yb-Cd-Zn may serve as a good candidate of Ni(2+) a luminescent probe. To our knowledge, Yb-Cd-Zn represent the fist example of the 4d-4f-3d framework to exhibit luminescent selectivity for Ni(2+). PMID:25885253

  3. Step-by-step assembly of 4d-4f-3d complex based on heptamolybdate anion

    SciTech Connect

    Wu, Shuting; Deng, Binbin; Jiang, Xiuling; Li, Ronghua; Guo, Jiangbin; Lai, Fulong; Huang, Xihe; Huang, Changcang

    2012-12-15

    Four new complexes, (NH{sub 4}){sub 11.9}[Ln{sub 4.7}(MoO{sub 4})(H{sub 2}O){sub 23}(Mo{sub 7}O{sub 24}){sub 4}]{center_dot}xH{sub 2}O (Ln=Pr, x=34 (1); Ln=Nd, x=19 (2)), [NH{sub 4}]{sub 28}[Ce{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 31}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}74H{sub 2}O (3), and (NH{sub 4}){sub 26}[CoPr{sub 8}(MoO{sub 4}){sub 2}(H{sub 2}O){sub 33}(Mo{sub 7}O{sub 24}){sub 8}]{center_dot}54H{sub 2}O (4) have been synthesized and characterized by single-crystal and powder X-ray diffraction, CHN elemental analyses TGA analyses, IR and UV-Vis spectroscopy. Complex 1-3 are 0D compounds constructed by the connection between Ln{sup III} ions and [Mo{sub 7}O{sub 24}]{sup 6-} unit. In complex 4, the existence of Co{sup II} connects the polyanion clusters into 1D chain. The introduction of 3d metal (cobalt cation) and 4f metal (Ln=Pr{sup III}, Nd{sup III}, Ce{sup III}) encourages the coordination capability for [Mo{sub 7}O{sub 24}]{sup 6-} unit, which shows interesting coordination modes. The [Mo{sub 7}O{sub 24}]{sup 6-} unit in 1-4 shows three new coordination modes, connecting up to four metal cations. Complexes 1-4 show antiferromagnetic behavior via variable temperature magnetic study. The photoluminescence spectrum indicates the photoluminescence property for 4. - Graphical abstract: Heptamolybdate anion shows extraordinary coordination geometry in the presence of both lanthanide cation (Pr{sup III}) and transitional metal cation (Co{sup II}), which give rise to a new 4d-4f-3d complex. Black-Small-Square Highlights: Black-Right-Pointing-Pointer A new 4d-4f-3d complex that containing 1D chain was obtained and discussed. Black-Right-Pointing-Pointer New coordination geometry with higher coordination number of heptamolybdate. Black-Right-Pointing-Pointer Series of heptamolybdate contained complexes were synthesized and characterized. Black-Right-Pointing-Pointer Complexes mentioned above show antiferromagnetic behavior.

  4. A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution.

    PubMed

    Hao, Ji-Na; Yan, Bing

    2016-06-01

    A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag(+) ions can tune the dual-emissive characters of the material. FA can interact with the Ag(+) ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection. PMID:27243359

  5. A dual-emitting 4d-4f nanocrystalline metal-organic framework as a self-calibrating luminescent sensor for indoor formaldehyde pollution

    NASA Astrophysics Data System (ADS)

    Hao, Ji-Na; Yan, Bing

    2016-06-01

    A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection.A dual-emissive 4d-4f Ag(i)-Eu(iii) functionalized MOF nanocomposite was fabricated and utilized as a self-calibrating luminescent nanoprobe for detecting indoor formaldehyde (FA). The implantation of Ag+ ions can tune the dual-emissive characters of the material. FA can interact with the Ag+ ions and induce opposite luminescence behaviors of the two emitters in the singular molecular material, thus realizing its recognition. This nanoprobe for FA exhibits many merits, such as excellent selectivity, high sensitivity with a detection limit of 51 ppb, fast response, room-temperature testing ability, easy preparation and low cost. This is the first example of a MOF-implicated self-calibrated sensor for indoor FA detection. Electronic supplementary information (ESI) available: Experimental procedure, N2 adsorption-desorption isotherms, IR spectra, EDX mappings, ICP data, luminescence data, PXRD patterns, UV-Vis spectra, and XPS spectra. See DOI: 10.1039/c6nr02446g

  6. Syntheses, structure and properties of three-dimensional pillared-layer Ag(I)-Ln(III) heterometallic coordination polymers based on mixed isonicotinate and hemimellitate ligands

    SciTech Connect

    Li, Xinfa; Cao, Rong

    2012-12-15

    Three pillared-layer 4d-4f Ag(I)-Ln(III) heterometallic coordination polymers (HCPs), formulated as [Ln{sub 2}Ag(hma){sub 2}(ina)(H{sub 2}O){sub 2}]{sub n} nH{sub 2}O [Ln=La(1), Pr(2), Nd(3); Hina=isonicotinic acid, H{sub 3}hma=hemimellitic acid], have been synthesized under hydrothermal conditions. Single-crystal and powder X-ray diffractions confirm that they are isostructural, which features a three-dimensional (3D) pillared-layer heterometallic structure built upon the strictly alternate arrangement of lanthanide-organic layers and [Ag(ina)] pillars. The layers and pillars are connected to each other by Ln-O and Ag-O coordination bonds. The photoluminescent property of the Nd derivative (3) has also been investigated. - Graphical abstract: Three pillared-layer 4d-4f Ag(I)-Ln(III) heterometallic coordination polymers have been synthesized and structurally characterized. Highlights: Black-Right-Pointing-Pointer Three 3D pillared-layer 4d-4f HCPs were synthesized by hydrothermal reactions. Black-Right-Pointing-Pointer The synergistic coordination strategy was employed. Black-Right-Pointing-Pointer It opens new perspective for the construction of structurally diversified 4d-4f HCPs.

  7. Structural variation from heterometallic cluster-based 1D chain to heterometallic tetranuclear cluster: Syntheses, structures and magnetic properties

    SciTech Connect

    Zhang, Shu-Hua; Zhao, Ru-Xia; Li, He-Ping; Ge, Cheng-Min; Li, Gui; Huang, Qiu-Ping; Zou, Hua-Hong

    2014-08-15

    Using the solvothermal method, we present the comparative preparation of ([Co{sub 3}Na(dmaep){sub 3}(ehbd)(N{sub 3}){sub 3}]·DMF){sub n} (1) and [Co{sub 2}Na{sub 2}(hmbd){sub 4}(N{sub 3}){sub 2}(DMF){sub 2}] (2), where Hehbd is 3-ethoxy-2-hydroxy-benzaldehyde, Hhmbd is 3-methoxy-2-hydroxy-benzaldehyde, and Hdmaep is 2-dimethylaminomethyl-6-ethoxy-phenol, which was synthesized by an in-situ reaction. Complexes 1 and 2 were characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. Complex 1 is a novel heterometallic cluster-based 1-D chain and 2 is a heterometallic tetranuclear cluster. The (Co{sub 3}{sup II}Na) and (Co{sub 2}{sup II}Na{sub 2}) cores display dominant ferromagnetic interaction from the nature of the binding modes through μ{sub 1,1,1}-N{sub 3}{sup –} (end-on, EO). - Graphical abstract: Two novel cobalt complexes have been prepared. Compound 1 consists of tetranuclear (Co{sub 3}{sup II}Na) units, which further formed a 1-D chain. Compound 2 is heterometallic tetranuclear cluster. Two complexes display dominant ferromagnetic interaction. - Highlights: • Two new heterometallic complexes have been synthesized by solvothermal method. • The stereospecific blockade of the ligands in the synthesis system seems to be the most important synthetic parameter. • The magnetism studies show that 1 and 2 exhibit ferromagnetic interactions. • Complex 1 shows slowing down of magnetization and not blocking of magnetization.

  8. Optical activity of catalytic elements of hetero-metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Antosiewicz, Tomasz J.; Apell, S. Peter; Wadell, Carl; Langhammer, Christoph

    2015-05-01

    Interaction of light with metals in the form of surface plasmons is used in a wide range of applications in which the scattering decay channel is important. The absorption channel is usually thought of as unwanted and detrimental to the efficiency of the device. This is true in many applications, however, recent studies have shown that maximization of the decay channel of surface plasmons has potentially significant uses. One of these is the creation of electron-hole pairs or hot electrons which can be used for e.g. catalysis. Here, we study the optical properties of hetero-metallic nanostructures that enhance light interaction with the catalytic elements of the nanostructures. A hybridized LSPR that matches the spectral characteristic of the light source is excited. This LSPR through coupling between the plasmonic elements maximizes light absorption in the catalytic part of the nanostructure. Numerically calculated visible light absorption in the catalytic nanoparticles is enhanced 12-fold for large catalytic disks and by more 30 for small nanoparticles on the order of 5 nm. In experiments we measure a sizable increase in the absorption cross section when small palladium nanoparticles are coupled to a large silver resonator. These observations suggest that heterometallic nanostructures can enhance catalytic reaction rates.

  9. Heterometallic Rings: Their Physics and use as Supramolecular Building Blocks.

    PubMed

    McInnes, Eric J L; Timco, Grigore A; Whitehead, George F S; Winpenny, Richard E P

    2015-11-23

    An enormous family of heterometallic rings has been made. The first were Cr7 M rings where M = Ni(II), Zn(II), Mn(II), and rings have been made with as many as fourteen metal centers in the cyclic structure. They are bridged externally by carboxylates, and internally by fluorides or a penta-deprotonated polyol. The size of the rings is controlled through templates which have included a range of ammonium or imidazolium ions, alkali metals and coordination compounds. The rings can be functionalized to act as ligands, and incorporated into hybrid organic-inorganic rotaxanes and into molecules containing up to 200 metal centers. Physical studies reported include: magnetic measurements, inelastic neutron scattering (including single crystal measurements), electron paramagnetic resonance spectroscopy (including measurements of phase memory times), NMR spectroscopy (both solution and solid state), and polarized neutron diffraction. The rings are hence ideal for understanding magnetism in elegant exchange-coupled systems. PMID:26459810

  10. First tetrazole-bridged d-f heterometallic MOFs with a large magnetic entropy change.

    PubMed

    Hu, Huan-Cheng; Kang, Xiao-Min; Cao, Chun-Shuai; Cheng, Peng; Zhao, Bin

    2015-07-11

    A novel 3D tetrazole-bridged 3d-4f heterometallic MOF {(H3O)3[Gd3Mn2(Trz)4]·12H2O}n (1) with a hexanuclear [Gd6] cluster was obtained via in situ [2+3] cycloaddition reaction and structurally characterized, possessing good solvent and thermal stabilities, as well as a large magnetic entropy change -ΔS(m) = 40.3 J kg(-1) K(-1) for ΔH = 7 T at 2.0 K. To our knowledge, it is the first example of tetrazole-bridged 3d-4f heterometallic MOFs. PMID:26051815

  11. Exceptionally water stable heterometallic gyroidal MOFs: tuning the porosity and hydrophobicity by doping metal ions.

    PubMed

    Zhu, Xiao-Wei; Zhou, Xiao-Ping; Li, Dan

    2016-05-01

    A strategy to improve the framework porosity and hydrophobicity of the pore surface by doping metal ions (Cu(2+), Cd(2+), or Fe(2+)) into a gyroidal MOF STU-1 has been developed. It is found that the obtained heterometallic MOFs are exceptionally water stable. PMID:27094095

  12. Water-soluble noncovalent adducts of the heterometallic copper subgroup complexes and human serum albumin with remarkable luminescent properties.

    PubMed

    Chelushkin, P S; Krupenya, D V; Tseng, Yu-Jui; Kuo, Ting-Yi; Chou, Pi-Tai; Koshevoy, I O; Burov, S V; Tunik, S P

    2014-01-25

    Novel water-soluble noncovalent adducts of the heterometallic copper subgroup complexes and human serum albumin (HSA) display strong phosphorescence, internalize into HeLa cells and can be used in time-resolved fluorescent imaging. PMID:24296768

  13. Heterometallic europium disiloxanediolates: synthesis, structural diversity, and photoluminescence properties.

    PubMed

    Rausch, Janek; Lorenz, Volker; Hrib, Cristian G; Frettlöh, Vanessa; Adlung, Matthias; Wickleder, Claudia; Hilfert, Liane; Jones, Peter G; Edelmann, Frank T

    2014-11-01

    This contribution presents a full account of a structurally diverse class of heterometallic europium disiloxanediolates. The synthetic protocol involves in situ metalation of (HO)SiPh2OSiPh2(OH) (1) with either (n)BuLi or KN(SiMe3)2 followed by treatment with EuCl3 in suitable solvents such as 1,2-dimethoxyethane (DME) or tetrahydrofuran (THF). Reaction of EuCl3 with 2 equiv of (LiO)SiPh2OSiPh2(OLi) in DME afforded the Eu(III) bis(disiloxanediolate) "ate" complex [{(Ph2SiO)2O}2{Li(DME)}3]EuCl2 (2), which upon attempted reduction with Zn gave the tris(disiloxanediolate) [{(Ph2SiO)2O}3{Li(DME)}3]Eu (3). Treatment of EuCl3 with (LiO)SiPh2OSiPh2(OLi) in a molar ratio of 1:2 yielded both the ate complex [{(Ph2SiO)2O}3Li{Li(THF)2}{Li(THF)}]EuCl·Li(THF)3 (4) and the LiCl-free europium(III) complex [{(Ph2SiO)2O}2{Li(THF)2}2]EuCl (5). Compound 5 was found to exhibit a brilliant red triboluminescence. When (KO)SiPh2OSiPh2(OK) was used as starting material in a 3:1 reaction with EuCl3, the Eu(III) tris(disiloxanediolate) [{(Ph2SiO)2O}3{K(DME)}3]Eu (6) was isolated. Attempted ligand transfer between 5 and (DAD(Dipp))2Ba(DME) (DAD(Dipp) = N,N'-bis(2,6-diisopropylphenyl)-1,4-diaza-1,3-butadiene) afforded the unique mixed-valent Eu(III)/Eu(II) disiloxanediolate cluster [(Ph2SiO)2O]6Eu(II)4Eu(III)2Li4O2Cl2 (7). All new complexes were structurally characterized by X-ray diffraction. Photoluminescence studies were carried out for complex 5 showing an excellent color quality, due to the strong (5)D0→(7)F2 transition, but a weak antenna effect. PMID:25330143

  14. Copper(I) and copper(II) uranyl heterometallic hybrid materials.

    PubMed

    Weng, Zhehui; Zhang, Zhi-hui; Olds, Travis; Sterniczuk, Marcin; Burns, Peter C

    2014-08-01

    Two copper-uranium heterometallic compounds, [(UO2)3Cu(II)O2(C6NO2)5] (1) and [(UO2)Cu(I)(C6NO2)3] (2), have been synthesized by the reaction of uranyl acetate with copper salts in the presence of isonicotinic acid. Both compounds have been characterized by single-crystal X-ray diffraction, IR, Raman, and UV-vis spectroscopy. In compound 1, interactions between copper and uranium centers occur and result in a three-dimensional pillar layered structure. Compound 1 is also the first example of a heterometallic uranyl organic framework with a trinuclear U3O18 building block. Compound 2 is the first uranyl organic framework that contains monovalent copper, which arises from the reaction of Cu(II) chloride and is assumed to be due to the oxidation of chloride at low pH. PMID:25029287

  15. Mixed-Ligand Approach to Changing the Metal Ratio in Bismuth-Transition Metal Heterometallic Precursors.

    PubMed

    Lieberman, Craig M; Wei, Zheng; Filatov, Alexander S; Dikarev, Evgeny V

    2016-04-18

    A new series of heteroleptic bismuth-transition metal β-diketonates [BiM(hfac)3(thd)2] (M = Mn (1), Co (2), and Ni (3); hfac = hexafluoroacetylacetonate, thd = tetramethylheptanedionate) with Bi:M = 1:1 ratio have been synthesized by stoichiometric reactions between homometallic reagents [Bi(III)(hfac)3] and [M(II)(thd)2]. On the basis of analysis of the metal-ligand interactions in heterometallic structures, the title compounds were formulated as ion-pair {[Bi(III)(thd)2](+)[M(II)(hfac)3](-)} complexes. The direct reaction between homometallic reagents proceeds with a full ligand exchange between main group and transition metal centers, yielding dinuclear heterometallic molecules. In heteroleptic molecules 1-3, the Lewis acidic, coordinatively unsaturated Bi(III) centers are chelated by two bulky, electron-donating thd ligands and maintain bridging interactions with three oxygen atoms of small, electron-withdrawing hfac groups that chelate the neighboring divalent transition metals. Application of the mixed-ligand approach allows one to change the connectivity pattern within the heterometallic assembly and to isolate highly volatile precursors with the proper Bi:M = 1:1 ratio. The mixed-ligand approach employed in this work opens broad opportunities for the synthesis of heterometallic (main group-transition metal) molecular precursors with specific M:M' ratio in the case when homoleptic counterparts either do not exist or afford products with an incorrect metal:metal ratio for the target materials. Heteroleptic complexes obtained in the course of this study represent prospective single-source precursors for the low-temperature preparation of multiferroic perovskite-type oxides. PMID:27054922

  16. Silver Ion-Mediated Heterometallic Three-Fold Interpenetrating Uranyl-Organic Framework.

    PubMed

    Mei, Lei; Wu, Qun-yan; An, Shu-wen; Gao, Zeng-qiang; Chai, Zhi-fang; Shi, Wei-qun

    2015-11-16

    A unique case of a uranyl-silver heterometallic 3-fold interpenetrating network (U-Ag-2,6-DCPCA) from a multifunctionalized organic ligand, 2,6-dichloroisonicotinic acid, in the presence of uranyl and silver ions is reported. It is the first report of a heterometallic uranyl-organic interpenetrating network or framework. Notably, a (4,4)-connected uranyl building unit in U-Ag-2,6-DCPCA, which is available through combined influences of structural halogenation and silver ion additive on uranyl coordination, plays a vital role in the formation of a 3-fold interpenetrating network. Halogen substitution effectively changes structural features and coordination behaviors of isonicotinate ligand and contributes to the control of uranyl coordination. Meanwhile, it exerts influence on the stabilization of 3-fold interpenetrating networks by halogen-halogen interactions. Theoretical calculation suggests that the silver ion should mainly serve as an inductive factor of uranyl species through strong Ag-N binding affinity, directly leading to the formation of a (4,4)-connected uranyl building unit and finally a heterometallic 3-fold interpenetrating network. Related experimental results, especially an interesting postsynthetic metalation, afford further evidence of this induction effect. PMID:26491817

  17. Rectifying Properties of Oligo(Phenylene Ethynylene) Heterometallic Molecular Junctions: Molecular Length and Side Group Effects

    PubMed Central

    Fu, Xiao-Xiao; Zhang, Rui-Qin; Zhang, Guang-Ping; Li, Zong-Liang

    2014-01-01

    The rectifying properties of α,ω-dithiol terminated oligo(phenylene ethynylene) molecules sandwiched between heterometallic electrodes, including the molecular length and side group effects, are theoretically investigated using the fully self-consistent nonequilibrium Green's function method combined with density functional theory. The results show nonlinear variation with changes in molecule length: when the molecule becomes longer, the current decreases at first and then increases while the rectification shifts in the opposite direction. This stems from the change in molecular eigenstates and the coupling between the molecule and electrodes caused by different molecular lengths. The rectifying behavior of heterometallic molecular junctions can be attributed to the asymmetric molecule-electrode contacts, which lead to asymmetric electronic tunneling spectra, molecular eigenvalues, molecular orbitals, and potential drop at reversed equivalent bias voltages. Our results provide a fundamental understanding of the rectification of heterometallic molecular junction, and a prediction of rectifiers with different rectification properties from those in the experiment, using electrodes with reduced sizes. PMID:25220880

  18. A series of M-M' heterometallic coordination polymers: syntheses, structures and surface photoelectric properties (M=Ni/Co, M'=Cd/Zn)

    SciTech Connect

    Li, Lei; Niu, Shu-Yun; Jin, Jing; Meng, Qin; Chi, Yu-Xian; Xing, Yong-Heng; Zhang, Guang-Ning

    2011-05-15

    Four new heterometallic polymers, [NiCd(mal){sub 2}(H{sub 2}O){sub 2}]n.2nH{sub 2}O 1, [NiZn{sub 2}(Hcit){sub 2}(H{sub 2}O){sub 2}]n 2, [CoCd{sub 2}(Hcit){sub 2}(H{sub 2}O){sub 2}]n 3, [CoZn{sub 2}(Hcit){sub 2}(H{sub 2}O){sub 2}]n 4 (H{sub 2}mal=malonic acid, H{sub 4}cit=citric acid) were synthesized and characterized. The photoelectric properties of the polymers were discussed by the surface photovoltage spectroscopy (SPS). The structural analyses indicate 1 is a Ni-Cd heterometallic polymer with 3D structure bridged by the mal{sup 2-} group. 2-4 are all heterometallic polymers with 2D structures bridged by the Hcit{sup 3-} group. The results of SPS for the four polymers reveal that there are wide photovoltage response bands in the range of 300-800 nm, which indicates that they all possess photoelectric conversion properties. By the introduction of the other metals, the SPS of heterometallic polymers are broadened obviously than the SPS of monometallic complexes. Moreover, the relationships between SPS and UV-Vis absorption spectra have been discussed. -- Graphical Abstract: Four heterometallic polymers, Ni-Cd, Ni-Zn, Co-Cd, Co-Zn, were synthesized and characterized. The photoelectric properties of heterometallic polymers were discussed by SPS. The introduction of heterometallic ions will broaden the SPS of corresponded monometallic complexes. Display Omitted highlights: > Four new heterometallic coordination polymers were reported. > The surface photoelectric properties of heterometallic polymers were studied by SPS. > They all possess photoelectric conversion properties. > The SPS of heterometallic polymers are broadened than that of monometallic complexes.

  19. Designed Assembly of Heterometallic Cluster Organic Frameworks Based on Anderson-Type Polyoxometalate Clusters.

    PubMed

    Li, Xin-Xiong; Wang, Yang-Xin; Wang, Rui-Hu; Cui, Cai-Yan; Tian, Chong-Bin; Yang, Guo-Yu

    2016-05-23

    A new approach to prepare heterometallic cluster organic frameworks has been developed. The method was employed to link Anderson-type polyoxometalate (POM) clusters and transition-metal clusters by using a designed rigid tris(alkoxo) ligand containing a pyridyl group to form a three-fold interpenetrated anionic diamondoid structure and a 2D anionic layer, respectively. This technique facilitates the integration of the unique inherent properties of Anderson-type POM clusters and cuprous iodide clusters into one cluster organic framework. PMID:27061042

  20. First water-soluble backbone Ru-Ru-Ni heterometallic organometallic polymer.

    PubMed

    Scalambra, Franco; Serrano-Ruiz, Manuel; Romerosa, Antonio

    2015-04-01

    The water-soluble backbone heterometallic polymer {[(PTA)2 CpRu-μ-CN-RuCp(PTA)2 -μ-NiCl3 ]}n (2) is synthesized using a reproducible and robust method and fully characterized by X-ray single crystal diffraction. The Ru-Ru-Ni polymer is found to be stable in the solid state and soluble in water. Nuclear magnetic resonance (NMR) and light scattering studies show that the polymer is stable in water for several days in air. PMID:25739739

  1. Early-Late Heterometallic Complexes of Gold and Zirconium: Photoluminescence and Reactivity.

    PubMed

    Bestgen, Sebastian; Schoo, Christoph; Zovko, Christina; Köppe, Ralf; Kelly, Rory P; Lebedkin, Sergei; Kappes, Manfred M; Roesky, Peter W

    2016-05-17

    OH functionalized triarylphosphines were used to assemble zirconocene-based metalloligands with phosphine donor sites in varying positions. These complexes were subsequently treated with different gold precursors to obtain early-late heterometallic compounds in which the metal atoms exhibit different intermetallic distances. All compounds were fully investigated by spectroscopic techniques, photoluminescence measurements and single crystal X-ray diffraction. Quantum chemical calculations were also performed. Some compounds show bright emission even at room temperature with quantum yields of up to 19 % (excitation at 350 nm). Furthermore, the reactivity of dimethyl zirconocene derivatives towards gold complexes was investigated, revealing simultaneous ligand exchange and transmetallation reactions. PMID:27062296

  2. Energy level properties of 4p4d, 4p4d4f, and 4p4d configurations of the W ion

    NASA Astrophysics Data System (ADS)

    Bogdanovich, P.; Kisielius, R.

    2014-11-01

    The ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectroscopic parameters of heavy atoms and highly charged ions was used to derive spectral data for the multicharged tungsten ion W35+. The configuration interaction method was applied to include the electron-correlation effects. The relativistic effects were taken into account in the Breit-Pauli approximation for quasirelativistic Hartree-Fock radial orbitals. The energy level spectra, radiative lifetimes τ, and Lande g-factors have been calculated for the 4p64d3, 4p64d24f, and 4p54d4 configurations of the W35+ ion.

  3. Influence of lead(II) lone pairs on the serpentine structures for heterometallic alkoxides

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1995-05-10

    Heterometallic alkoxides, M{sub a}M{sub b}{prime}(OR){sub m}, most often adopts closed polyhedral structures, in part to give suitably high coordination numbers to all metals. In general, the ratio m/(a + b) is typically low (because one or more of M and M{prime} are low valent) so that {mu}{sub 2}- and {mu}{sub 3}-OR functionalities are required, and a closed polyhedron best accommodates such demands. Thus the metals of KZr{sub 2}(O{sup i}Pr){sub 9}{sup 2} and [BaZr{sub 2}(O{sup i}Pr){sub 10}]{sub 2}{sup 3} form triangles, those of K{sub 2}Zr{sub 2}(O{sup t}Bu){sub 10}{sup 4} form a diamond, and those of K{sub 4}Zr{sub 2}O(O{sup i}Pr){sub 10}{sup 2} form an octahedron. The authors report here the very different outcome of combining Zr(IV) with the soft divalent metal Pb(II). These results demonstrate that rational synthetic control of two different stoichiometries can be effected in heterometallic alkoxide chemistry.

  4. Structure and spectroscopic studies of homo-and heterometallic complexes of adipic acid dihydrazide.

    PubMed

    Jeragh, Bakir; El-Asmy, Ahmed A

    2014-05-01

    A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Ag(+), Pd(2+) and/or Pt(2+) gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, (1)H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn(0.73)Cu(ADH)Cl4·H2O; Zn(0.71)Hg(0.36)(ADH)Cl4·H2O; Zn(0.65)Cd(0.46)(ADH)Cl4·½H2O; Zn(0.75)Co(0.41)(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral+tetrahedral; tetrahedral+square-planar; tetrahedral+tetrahedral and/or tetrahedral+octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240 °C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn(0.73)Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex>Cd complex>Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA. PMID:24530707

  5. Structure and spectroscopic studies of homo-and heterometallic complexes of adipic acid dihydrazide

    NASA Astrophysics Data System (ADS)

    Jeragh, Bakir; El-Asmy, Ahmed A.

    A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Ag+, Pd2+ and/or Pt2+ gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, 1H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn0.73Cu(ADH)Cl4·H2O; Zn0.71Hg0.36(ADH)Cl4·H2O; Zn0.65Cd0.46(ADH)Cl4·½H2O; Zn0.75Co0.41(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral + tetrahedral; tetrahedral + square-planar; tetrahedral + tetrahedral and/or tetrahedral + octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240 °C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn0.73Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex > Cd complex > Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA.

  6. The metamorphosis of heterometallic trinuclear antiferromagnetic complexes into nano-sized superparamagnetic spinels

    PubMed Central

    Vasylenko, Inna V.; Gavrylenko, Konstiantyn S.; Il’yin, Vladimir G.; Golub, Vladimir; Goloverda, Galina; Kolesnichenko, Vladimir; Addison, Anthony W.; Pavlishchuk, Vitaly V.

    2010-01-01

    Thermal decomposition of the trinuclear heterometallic oxoacetates [Fe2M(μ3-O)(CH3COO)6(H2O)3] has been used as a single-precursor method for synthesis of the spinel-structured ternary oxides MFe2O4 (M = MnII, CoII, and NiII). This facile process occurring at 320 °C results in the formation of nanocrystalline, (7–20 nm) highly pure stoichiometric ferrites in quantitative yield. The magnetic properties of these nanoparticulate ferrites were studied in the 10–300 K temperature range, revealing superparamagnetic behaviour for the Ni and Mn particles and ferromagnetic behavior for the Co ones at room temperature. Their blocking temperatures follow the order: CoFe2O4 > MnFe2O4 > NiFe2O4. PMID:20824196

  7. Homometallic and Heterometallic Antiferromagnetic Rings: Magnetic Properties Studied by Nuclear Magnetic Resonance

    SciTech Connect

    Casadei, Cecilia

    2011-01-01

    The aim of the present thesis is to investigate the local magnetic properties of homometallic Cr8 antiferromagnetic (AFM) ring and the changes occurring by replacing one Cr3+ ion with diamagnetic Cd2+ (Cr7Cd) and with Ni2+ (Cr7Ni). In the heterometallic ring a redistribution of the local magnetic moment is expected in the low temperature ground state. We have investigated those changes by both 53Cr-NMR and 19F-NMR. We have determined the order of magnitude of the transferred hyperfine coupling constant 19F - M+ where M+ = Cr3+, Ni2+ in the different rings. This latter result gives useful information about the overlapping of the electronic wavefunctions involved in the coordinative bond.

  8. Synthesis, crystal structure and luminescent property of heterometallic d10-d8 porous complex

    NASA Astrophysics Data System (ADS)

    Zhang, Mei-Li; Wang, Ji-Jiang; Chen, Xiao-Li

    2015-02-01

    One new heterometallic complex [Cd2Cu(BTC)2(H2O)2]ṡ2H2O (1) (BTC = benzene-1,3,5-tricarboxylate), has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction techniques. The structure indicates that the complex 1 crystallizes in triclinic, space group Pī, in which, the carboxylate groups of BTC ligand adopt μ2-η1:η1, and μ2-η2:η1 coordination modes, bridging Cd(II) and Cu(II) atoms to generate 2D Cd-BTC bilayer then to a (4,6)-connected open 3D framework with 1D channels occupied by guest water molecules. In addition, thermal gravimetric analysis (TGA) and luminescent property of 1 were investigated.

  9. Chemically directing d-block heterometallics to nanocrystal surfaces as molecular beacons of surface structure

    SciTech Connect

    Rosen, Evelyn L.; Gilmore, Keith; Sawvel, April M.; Hammack, Aaron T.; Doris, Sean E.; Aloni, Shaul; Altoe, Virginia; Nordlund, Dennis; Weng, Tsu -Chien; Sokaras, Dimosthenis; Cohen, Bruce E.; Urban, Jeffrey J.; Ogletree, D. Frank; Milliron, Delia J.; Prendergast, David; Helms, Brett A.

    2015-07-28

    Our understanding of structure and bonding in nanoscale materials is incomplete without knowledge of their surface structure. Needed are better surveying capabilities responsive not only to different atoms at the surface, but also their respective coordination environments. We report here that d-block organometallics, when placed at nanocrystal surfaces through heterometallic bonds, serve as molecular beacons broadcasting local surface structure in atomic detail. This unique ability stems from their elemental specificity and the sensitivity of their d-orbital level alignment to local coordination environment, which can be assessed spectroscopically. Re-surfacing cadmium and lead chalcogenide nanocrystals with iron- or ruthenium-based molecular beacons is readily accomplished with trimethylsilylated cyclopentadienyl metal carbonyls. For PbSe nanocrystals with iron-based beacons, we show how core-level X-ray spectroscopies and DFT calculations enrich our understanding of both charge and atomic reorganization at the surface when beacons are bound.

  10. Chemically directing d-block heterometallics to nanocrystal surfaces as molecular beacons of surface structure

    DOE PAGESBeta

    Rosen, Evelyn L.; Gilmore, Keith; Sawvel, April M.; Hammack, Aaron T.; Doris, Sean E.; Aloni, Shaul; Altoe, Virginia; Nordlund, Dennis; Weng, Tsu -Chien; Sokaras, Dimosthenis; et al

    2015-07-28

    Our understanding of structure and bonding in nanoscale materials is incomplete without knowledge of their surface structure. Needed are better surveying capabilities responsive not only to different atoms at the surface, but also their respective coordination environments. We report here that d-block organometallics, when placed at nanocrystal surfaces through heterometallic bonds, serve as molecular beacons broadcasting local surface structure in atomic detail. This unique ability stems from their elemental specificity and the sensitivity of their d-orbital level alignment to local coordination environment, which can be assessed spectroscopically. Re-surfacing cadmium and lead chalcogenide nanocrystals with iron- or ruthenium-based molecular beacons ismore » readily accomplished with trimethylsilylated cyclopentadienyl metal carbonyls. For PbSe nanocrystals with iron-based beacons, we show how core-level X-ray spectroscopies and DFT calculations enrich our understanding of both charge and atomic reorganization at the surface when beacons are bound.« less

  11. Porous heterometallic Cd(II)-Ca(II)-terephthalate: Synthesis, structure, luminescent and gas adsorption properties

    NASA Astrophysics Data System (ADS)

    Liu, Haiping; Dong, Yanli; Ren, Hailiang

    2016-03-01

    A new heterometallic poly(dihydrate-one and a half terephthalate-cadmium calcium) coordination polymer, namely [CdCa(pdc)1.5(H2O)2]n (1, H2pdc = terephthalic acid), has been successfully obtained by the solvothermal reactions of H2pdc, Cd(NO3)2·4H2O and Ca(NO3)2·4H2O. Single crystal X-ray diffraction analysis reveals that compound 1 features a 3D porous framework based on 1D chain subunits. Moreover, compound 1 is luminescent and exhibits high adsorption capacities for H2, CH4 and CO2 at room temperature.

  12. Discrete Rectangles, Prisms, and Heterometallic Cages from a Conjugated Cp*Rh-Based Building Block.

    PubMed

    Shen, Xu-Yu; Zhang, Ying-Ying; Zhang, Long; Lin, Yue-Jian; Jin, Guo-Xin

    2015-11-16

    By carefully selecting an existing synthetic strategy and suitable coordination subunits, constructing desired coordination geometries is no longer that difficult to accomplish. Herein, a new strategy to construct a series of unprecedented structures by using conjugated Cp*Rh-based complex BN-OTf (Cp* = η(5)-C5Me5) as the building block is proposed. DFT calculations revealed extensive delocalized π bonds in the subunit. With BN-OTf, rectangular macrocycles TN-bpy and TN-bpe were controllably synthesized. Single-crystal XRD studies confirmed one-dimensional stacking channels for the tetranuclear structure. Notably, the starting ligand imidazole-4,5-dicarboxylate was found to act not only as a tetradentate but also as a hexadentate ligand that can coordinate to further metal ions. Subsequently, [4 Rh+1 M] heterometallic complexes HMZ (M = Cu and Zn) were accessed by chelating borderline hard/soft Lewis acids. With TN-Linker or HMZ, two routes resulted in the [8 Rh+2 M] heterometallic cages HMC (M = Cu and Zn) with excellent crystallinity and stability. Surprisingly, when BN-OTf bonded to rhodium itself, triangular prisms TP-Linker were obtained with high solubility after being linked by bipyridine linkers. Both the X-ray structure and (1)H NMR spectrum confirmed the novel isomerization of the triangular structures. All of the compounds were obtained in high yields and were fully characterized by (1)H NMR spectroscopy, elemental analysis, IR spectroscopy, and in most cases single-crystal X-ray structure determination. PMID:26437679

  13. Polymeric heterometallic Pb-Ag iodometallates, iodoplumbates and iodoargentates with lanthanide complex cations as templates.

    PubMed

    Fang, Wang; Tang, Chunying; Chen, Ruihong; Jia, Dingxian; Jiang, Wenqing; Zhang, Yong

    2013-11-14

    Heterometallic Pb-Ag iodometallates [Ln(DMF)8]2Pb3Ag10I22 [Ln = Ce(1), Pr(2)] were prepared by the reactions of PbI2, AgNO3 and KI in dimethylformamide (DMF) templated by [Ln(DMF)8](3+) complexes formed in situ by stirring LnCl3 in DMF. The same reactions in the absence of AgNO3 or PbI2 afforded iodoplumbate [Pr(DMF)9]2[Pr(DMF)8]Pb11I31 (3), and iodoargentates [Ln(DMF)8]Ag6I9 [Ln = Ce(4), Pr(5)], respectively. Compounds 1 and 2 contain a ternary one-dimensional polymeric [Pb3Ag10I22](6-) anion self-assembled from five AgI4, one PbI6 and one PbI4 primary units via edge- and face-sharing. Twelve PbI6 octahedra are interlinked via sharing of common faces to generate a 1D zigzag [Pb11I31(9-)]n chain in 3, which represents a new member of iodoplumbate aggregates. In 4 and 5, three AgI4 tetrahedra connect through common edges to form the [Ag6I12](6-) building block. The [Ag6I12](6-) blocks are further interlinked by sharing common edges, resulting in the 1D [Ag6I9(3-)]n chain. Optical absorption spectra showed that the synthesized Ag-iodoplumbate and iodoplumbate have potential for being used as semiconductors. Our results show that heterometallic halometallate properties can be tuned by combining structural units with different symmetries, enabling the synthesis of specific functional materials. PMID:24005846

  14. Highly selective luminescence sensing of nitrite and benzaldehyde based on 3d-4f heterometallic metal-organic frameworks.

    PubMed

    Du, Pei-Yao; Gu, Wen; Liu, Xin

    2016-06-01

    Framework-isomeric three-dimensional (3D) Zn-Ln heterometallic metal-organic frameworks, {[Ln2Zn(abtc)2(H2O)4]·2H2O}∞ {Ln = Sm(1), Tb(2)}, were synthesized using a convenient solvothermal reaction. They can serve as excellent sensors for the specific identification of benzaldehyde and NO2(-) through a fluorescence quenching process. PMID:27117937

  15. Novel heterometallic metal–azido complex synthesized by “one-step” reaction: synthetic strategy and magnetic properties

    SciTech Connect

    Jiao, Yong-Kun; Li, Xiu-Ping; Zhao, Cui; Wang, Hai-Chao; Xue, Min; Zhao, Jiong-Peng; Liu, Fu-Chen

    2013-06-15

    A novel heterometallic complex, [Ni{sub 2}Mn(N{sub 3}){sub 2}(nic){sub 4}·(H{sub 2}O){sub 2}]{sub n} (1) (nic=nicotinate), was obtained by assembling MnCl{sub 2}·4H{sub 2}O, Ni(NO{sub 3}){sub 2}·6H{sub 2}O, NaN{sub 3} and nicotinic acid with a “one step” synthetic strategy—hydrothermal reaction. The 3D structure of the complex can be described as end-on (EO) azido and syn,syn carboxylates mixed bridged by alternate Ni–Mn–Ni trimers linked by the nicotinate. Dominant ferromagnetic interactions were observed between the Ni{sup II} and Mn{sup II} ions in the trimer. - Graphical abstract: A novel heterometallic 3D complex [Ni{sub 2}Mn(N{sub 3}){sub 2}(nic){sub 4}·(H{sub 2}O){sub 2}]{sub n} (1) (nic=nicotinate) was synthesized by hydrothermal reaction. This complex exhibits interesting structural and magnetic properties. - Highlights: • It is difficult to construct simple coordination complexes with azide as “ligands” to obtain heterometallic metal–azido compounds. • A “one-step” method—hydrothermal reaction— was introduced to avoid the disadvantages of azide mentioned above. • The magnetic property is different with the isostructural homometal–azido complex due to the changed metal center.

  16. Control of Metal Arrays Based on Heterometallics Masquerading in Heterochiral Aggregations of Chiral Clothespin-Shaped Complexes.

    PubMed

    Naito, Masaya; Inoue, Ryo; Iida, Masayuki; Kuwajima, Yuuki; Kawamorita, Soichiro; Komiya, Naruyoshi; Naota, Takeshi

    2015-09-01

    Heterometal arrays in molecular aggregations were obtained by the spontaneous and ultrasound-induced gelation of organic liquids containing the chiral, clothespin-shaped trans-bis(salicylaldiminato) d8 transition-metal complexes 1. Heterometallic mixtures of complexes 1 a (Pd) and 1 b (Pt) underwent strict heterochiral aggregation entirely due to the organic shell structure of the clothespin shape, with no effect of the metal cores. This phenomenon provides an unprecedented means of generating highly controlled heterometallic arrangements such as alternating sequences [(+)-Pd(-)-Pt(+)-Pd(-)-Pt⋅⋅⋅] as well as a variety of single metal-enriched arrays (e.g., [(+)-Pt(-)-Pd(+)-Pd(-)-Pd(+)-Pd(-)-Pd⋅⋅⋅] and [(+)-Pd(-)-Pt(+)-Pt(-)-Pt(+)-Pt(-)-Pt⋅⋅⋅]) upon the introduction of an optically active masquerading unit with a different metal core in the heterochiral single-metal sequence. The present method can be applied to form various new aggregates with optically active Pd and Pt units, to allow 1) tuning of the gelation ultrasound sensitivity based on the different hearing abilities of the metal units; 2) aggregation-induced chirality transfer between heterometallic species; and 3) aggregation-induced chirality enhancement. A mechanistic rationale is proposed for these molecular aggregations based on the molecular structures of the units and the morphologies of the aggregates. PMID:26212577

  17. Hexanuclear, heterometallic, Ni₃Ln₃ complexes possessing O-capped homo- and heterometallic structural subunits: SMM behavior of the dysprosium analogue.

    PubMed

    Goura, Joydeb; Guillaume, Rogez; Rivière, Eric; Chandrasekhar, Vadapalli

    2014-08-01

    The reaction of hetero donor chelating mannich base ligand 6,6'-{(2-(dimethylamino)ethylazanediyl)bis(methylene)}bis(2-methoxy-4-methylphenol) with Ni(ClO4)2·6H2O and lanthanide(III) salts [Dy(III) (1); Tb(III) (2); Gd (III) (3); Ho(III) (4); and Er(III) (5)] in the presence of triethylamine and pivalic acid afforded a series of heterometallic hexanuclear Ni(II)-Ln(III) coordination compounds, [Ni3Ln3(μ3-O)(μ3-OH)3(L)3(μ-OOCCMe3)3]·(ClO4)·wCH3CN·xCH2Cl2·yCH3OH·zH2O [for 1, w = 8, x = 3, y = 0, z = 5.5; for 2, w = 0, x = 5, y = 0, z = 6.5; for 3, w = 15, x = 18, y = 3, z = 7.5; for 4, w = 15, x = 20, y = 6, z = 9.5; and for 5, w = 0, x = 3, y = 2, z = 3]. The molecular structure of these complexes reveals the presence of a monocationic hexanuclear derivative containing one perchlorate counteranion. The asymmetric unit of each of the hexanuclear derivatives comprises the dinuclear motif [NiLn(L)(μ3-O)(μ3-OH)(μ-Piv)]. The cation contains three interlinked O-capped clusters: one Ln(III)3O and three Ni(II)Ln(III)2O. Each of the lanthanide centers is eight- coordinated (distorted trigonal-dodecahedron), while the nickel centers are hexacoordinate (distorted octahedral). The study of the magnetic properties of all compounds are reported and suggests single molecule magnet behavior for the Dy(III) derivative (1). PMID:25050753

  18. Heterometallic Cu(II)-Dy(III) Clusters of Different Nuclearities with Slow Magnetic Relaxation.

    PubMed

    Modak, Ritwik; Sikdar, Yeasin; Cosquer, Goulven; Chatterjee, Sudipta; Yamashita, Masahiro; Goswami, Sanchita

    2016-01-19

    The synthesis, structures, and magnetic properties of two heterometallic Cu(II)-Dy(III) clusters are reported. The first structural motif displays a pentanuclear Cu(II)4Dy(III) core, while the second one reveals a nonanuclear Cu(II)6Dy(III)3 core. We employed o-vanillin-based Schiff base ligands combining o-vanillin with 3-amino-1-propanol, H2vap, (2-[(3-hydroxy-propylimino)-methyl]-6-methoxy-phenol), and 2-aminoethanol, H2vae, (2-[(3-hydroxy-ethylimino)-methyl]-6-methoxy-phenol). The differing nuclearities of the two clusters stem from the choice of imino alcohol arm in the Schiff bases, H2vap and H2vae. This work is aimed at broadening the diversity of Cu(II)-Dy(III) clusters and to perceive the consequence of changing the length of the alcohol arm on the nuclearity of the cluster, providing valuable insight into promising future synthetic directions. The underlying topological entity of the pentanuclear Cu4Dy cluster is reported for the first time. The investigation of magnetic behaviors of 1 and 2 below 2 K reveals slow magnetic relaxation with a significant influence coming from the variation of the alcohol arm affecting the nature of magnetic interactions. PMID:26702645

  19. Sequential Synthesis of 3d-3d'-4f Heterometallic Heptanuclear Clusters in between Lacunary Polyoxometalates.

    PubMed

    Sato, Rinta; Suzuki, Kosuke; Minato, Takuo; Yamaguchi, Kazuya; Mizuno, Noritaka

    2016-03-01

    In this work, we have successfully created several unprecedented discrete 3d-3d'-4f heterotrimetallic clusters in between lacunary polyoxometalates (POMs). By the three-step sequential introduction of metal cations into a trivacant lacunary POM TBA4H6[A-α-SiW9O34] (TBA = tetra-n-butylammonium) in organic media, five kinds of sandwich-type POMs with double-diamond-shaped 3d-3d'-4f heptanuclear clusters (IIIFeM4Ln2, TBAnHm[FeM4{Ln(L)2}2O2(A-α-SiW9O34)2], M = Mn(3+), Cu(2+); Ln = Gd(3+), Dy(3+), Lu(3+); L = acac (acetylacetonate), hfac (hexafluoroacetylacetonate)) were successfully synthesized for the first time. By introduction of two [Ln(L)2](+) units on the ends of pentanuclear clusters [FeMn4O18(OH)2](23-) and [FeCu4O18(OH)2](27-), the magnetic interactions between Mn(3+)-Mn(3+) and Cu(2+)-Cu(2+) could be modulated. Among a series of the heterometallic heptanuclear compounds, IIIFeMn4Lu2 exhibited the slow magnetic relaxation characteristic for a single-molecule magnet under the zero applied magnetic fields. PMID:26914662

  20. [Ln(III)-Mn(II)-Ln(III)] heterometallic compounds: rare linear SMMs with divalent manganese ions.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-02-21

    The reaction of Mn(OAc)2·4H2O and Ln(NO3)3·6H2O with N-(2-aminopropyl)-2-hydroxybenzamide and salicylic aldehyde in methanol/methylene dichloride produces yellow crystals of Ln2Mn(C7H5O2)8 (Ln = Gd (), Tb (), Dy (), Ho () and Er ()), in the presence of triethylamine. Three metal ions are connected by six μ2-phenolate oxygen atoms of six salicylic aldehyde ligands, resulting in perfect linear [Ln(III)-Mn(II)-Ln(III)] structures. Magnetic studies of these complexes have been performed and AC susceptibility measurements show the presence of a temperature-dependent out-of-phase ac signal for complexes and indicating single-molecule magnet (SMM) behavior. The Dy(III)2Mn(II) compound shows double relaxation pathways which may originate from the single ion behavior of individual Dy(III) ions and the weak coupling between Dy(III) and Mn(II) ions, respectively. The Ueff of 92.4(2) K is a relatively high value among 3d-4f SMMs. Moreover, complexes and represent the first linear Mn-Ln SMMs containing only divalent manganese ions as far as we know. The result suggests the positive effects of magnetic coupling to enhance their SMM behavior, presenting a promising strategy for constructing efficient heterometallic SMMs. PMID:25601415

  1. Potential anticancer heterometallic Fe-Au and Fe-Pd agents: initial mechanistic insights.

    PubMed

    Lease, Nicholas; Vasilevski, Vadim; Carreira, Monica; de Almeida, Andreia; Sanaú, Mercedes; Hirva, Pipsa; Casini, Angela; Contel, María

    2013-07-25

    A series of gold(III) and palladium(II) heterometallic complexes with new iminophosphorane ligands derived from ferrocenylphosphanes [{Cp-P(Ph2)═N-Ph}2Fe] (1), [{Cp-P(Ph2)═N-CH2-2-NC5H4}2Fe] (2), and [{Cp-P(Ph2)═N-CH2-2-NC5H4}Fe(Cp)] (3) have been synthesized and structurally characterized. Ligands 2 and 3 afford stable coordination complexes [AuCl2(3)]ClO4, [{AuCl2}2(2)](ClO4)2, [PdCl2(3)], and [{PdCl2}2(2)]. The complexes have been evaluated for their antiproliferative properties in human ovarian cancer cells sensitive and resistant to cisplatin (A2780S/R), in human breast cancer cells (MCF7) and in a nontumorigenic human embryonic kidney cell line (HEK-293T). The highly cytotoxic trimetallic derivatives M2Fe (M = Au, Pd) are more cytotoxic to cancer cells than their corresponding monometallic fragments. Moreover, these complexes were significantly more cytotoxic than cisplatin in the resistant A2780R and the MCF7 cell lines. Studies of the interactions of the trimetallic compounds with DNA and the zinc-finger protein PARP-1 indicate that they exert anticancer effects in vitro based on different mechanisms of actions with respect to cisplatin. PMID:23786413

  2. Potential Anticancer Heterometallic Fe-Au and Fe-Pd Agents: Initial Mechanistic Insights

    PubMed Central

    Lease, Nicholas; Vasilevski, Vadim; Carreira, Monica; de Almeida, Andreia; Sanaú, Mercedes; Hirva, Pipsa; Casini, Angela; Contel, Maria

    2013-01-01

    A series of gold(III) and palladium(II) heterometallic complexes with new iminophosphorane ligands derived from ferrocenyl-phosphanes [{Cp-P(Ph2)=N-Ph}2Fe] (1), [{Cp-P(Ph2)=N-CH2-2-NC5H4}2Fe] (2) and [{Cp-P(Ph2)=N-CH2-2-NC5H4}Fe(Cp)] (3) have been synthesized and structurally characterized. Ligands 2 and 3 afford stable coordination complexes [AuCl2(3)]ClO4, [{AuCl2}2(2)](ClO4)2, [PdCl2(3)] and [{PdCl2}2(2)]. The complexes have been evaluated for their antripoliferative properties in human ovarian cancer cells sensitive and resistant to cisplatin (A2780S/R), in human breast cancer cells (MCF7) and in a non-tumorigenic human embryonic kidney cell line (HEK-293T). The highly cytotoxic trimetallic derivatives M2Fe (M = Au, Pd) are more cytotoxic to cancer cells than their corresponding monometallic fragments. Moreover, these complexes were significantly more cytotoxic than cisplatin in the resistant A2780R and the MCF7 cell lines. Studies of the interactions of the trimetallic compounds with DNA and the zinc-finger protein PARP-1 indicate that they exert anticancer effects in vitro based on different mechanisms of actions with respect to cisplatin. PMID:23786413

  3. Allosteric effects in binuclear homo- and heterometallic triple-stranded lanthanide podates.

    PubMed

    Ryan, Patrick E; Canard, Gabriel; Koeller, Sylvain; Bocquet, Bernard; Piguet, Claude

    2012-09-17

    This work illustrates a simple approach for deciphering and exploiting the various free energy contributions to the global complexation process leading to the binuclear triple-stranded podates [Ln(2)(L9)](6+) (Ln is a trivalent lanthanide). Despite the larger microscopic affinities exhibited by the binding sites for small Ln(3+), the stability constants measured for [Ln(2)(L9)](6+) decrease along the lanthanide series; a phenomenon which can be ascribed to the severe enthalpic penalty accompanying the intramolecular cyclization around small Ln(III), combined with increasing anticooperative allosteric interligand interactions. Altogether, the microscopic thermodynamic characteristics predict β(1,1,1)(La,Lu,L9)/β(1,1,1)(Lu,La,L9) = 145 for the ratio of the formation constants of the target heterobimetallic [LaLu(L9)](6+) and [LuLa(L9)](6+) microspecies, a value in line with the quantitative preparation (>90%) of [LaLu(L9)](6+) at millimolar concentrations. Preliminary NMR titrations indeed confirm the rare thermodynamic programming of a pure heterometallic f-f' complex. PMID:22946598

  4. Heterometallic Triiron-Oxo/Hydroxo Clusters: Effect of Redox-Inactive Metals

    PubMed Central

    Herbert, David E.; Lionetti, Davide; Rittle, Jonathan; Agapie, Theodor

    2014-01-01

    A series of tetranuclear oxo/hydroxo clusters comprised of three Fe centers and a redox-inactive metal (M) of various charge is reported. Crystallographic studies show an unprecedented Fe3M(μ4-O)(μ2-OH) core that remains intact upon changing M or the oxidation state of iron. Electrochemical studies reveal that the reduction potentials (E1/2) span a window of 500 mV and depend upon the Lewis acidity of M. Using the pKa of the redox-inactive metal aqua complex as a measure of Lewis acidity, these compounds display a linear dependence between E1/2 and acidity with a slope of ca. 70 mV per pKa unit. The current study of [Fe3MO(OH)] and previous ones of [Mn3MOn] (n = 2, 4) moieties support the generality of the above relationship between the reduction potentials of heterometallic oxido clusters and the Lewis acidity of incorporated cations, as applied to clusters of different redox-active metals. PMID:24304416

  5. Heterometallic triiron-oxo/hydroxo clusters: effect of redox-inactive metals.

    PubMed

    Herbert, David E; Lionetti, Davide; Rittle, Jonathan; Agapie, Theodor

    2013-12-26

    A series of tetranuclear oxo/hydroxo clusters comprised of three Fe centers and a redox-inactive metal (M) of various charge is reported. Crystallographic studies show an unprecedented Fe3M(μ4-O)(μ2-OH) core that remains intact upon changing M or the oxidation state of iron. Electrochemical studies reveal that the reduction potentials (E1/2) span a window of 500 mV and depend upon the Lewis acidity of M. Using the pKa of the M-aqua complex as a measure of Lewis acidity, these compounds display a linear dependence between E1/2 and acidity, with a slope of ∼70 mV per pKa unit. The current study of [Fe3MO(OH)] and previous ones of [Mn3MOn] (n = 2,4) moieties support the generality of the above relationship between the reduction potentials of heterometallic oxido clusters and the Lewis acidity of incorporated cations, as applied to clusters of different redox-active metals. PMID:24304416

  6. Synthesis and characterization of heterometallic carbonyl clusters containing ruthenium and a highly coordinated oxo, acetamidato, or sulfido ligand

    SciTech Connect

    Voss, E.J.

    1992-01-01

    This thesis describes investigations of carbonyl clusters containing a highly coordinated oxo, acetamidato, or sulfido ligand supported on a low oxidation mixed-metal framework. These heterometallic complexes contain a triangle of ruthenium atoms and result from the reaction of an electron rich three-metal oxo or sulfido cluster with a lightly stabilized electrophilic cluster building reagent. Chapter One details the formation of the five-metal oxo cluster [Fe[sub 2]Ru[sub 3](CO)[sub 14]([mu][sub 4]-O)][sup 2[minus

  7. Room temperature syntheses, crystal structures and properties of two new heterometallic polymers based on 3-ethoxy-2-hydroxybenzaldehyde ligand

    SciTech Connect

    Zhang, Shu-Hua Zhao, Ru-Xiao; Li, Gui; Zhang, Hai-Yang; Huang, Qiu-Ping; Liang, Fu-Pei

    2014-12-15

    Two new heterometallic coordination polymers [ZnNa(ehbd){sub 2}(N{sub 3})]{sub n} (1) and [Cu{sub 3}Na{sub 2}(ehbd){sub 2}(N{sub 3}){sub 6}]{sub n} (2) (Hehbd is 3-ethoxy-2-hydroxybenzaldehyde) have been synthesized under room temperature and structurally characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. Complex 1 crystallizes in the orthorhombic space group Pbca, showing a one-dimensional (1-D) chain. Complex 2 crystallizes in the triclinic space group Pī, constructing a heterometallic 2D layer structure. Luminescent properties and magnetic properties have been studied for 1 and 2, respectively and the fluorescence quantum yield of 1 is 0.077. - Highlights: • Two novel complexes 1 and 2 have been synthesized. • Complex 1 represents a novel qualitative change of luminescence property. • Complex 2 displays ferromagnetic interaction through symmetric μ{sub 1,1}–N{sub 3} bridges. • Complex 2 displays anti-ferromagnetic interaction through asymmetric μ{sub 1,1}–N{sub 3} bridges.

  8. Heterometallic [Mn5-Ln4] single-molecule magnets with high anisotropy barriers.

    PubMed

    Mereacre, Valeriu; Ako, Ayuk M; Clérac, Rodolphe; Wernsdorfer, Wolfgang; Hewitt, Ian J; Anson, Christopher E; Powell, Annie K

    2008-01-01

    The reaction of [Mn6O2(Piv)(10)(4-Me-py)(2.5)(PivH)(1.5)] (1) (py: pyridine, Piv: pivilate) with N-methyldiethanolamine (mdeaH2) and Ln(NO3)3 x 6 H2O in MeCN leads to a series of nonanuclear compounds [Mn5Ln4(O)6(mdea)2(mdeaH)2(Piv)6(NO3)4(H2O)2]2 MeCN (Ln=Tb(III) (2), Dy(III) (3), Ho(III) (4), Y(III) (5)). Single-crystal X-ray diffraction shows that compounds 2-5 are isostructural, with the central core composed of two distorted {Mn(IV)Mn(III)Ln2O4} cubanes sharing a Mn(IV) vertex, representing a new heterometallic 3d-4f motif for this class of ligand. The four new compounds display single-molecule magnet (SMM) behaviour, which is modulated by the lanthanide ion used. Moreover, the values found for Delta(eff) and tau(o) for 3 of 38.6 K and 3.0 x 10(-9) s respectively reveal that the complex 3 exhibits the highest energy barrier recorded so far for 3d-4f SMMs. The slow relaxation of the magnetisation for 3 was confirmed by mu-SQUID measurements on an oriented single crystal and the observation of M versus H hysteresis loops below 1.9 K. PMID:18348132

  9. Utilizing 3d-4f magnetic interaction to slow the magnetic relaxation of heterometallic complexes.

    PubMed

    Li, Xiao-Lei; Min, Fan-Yong; Wang, Chao; Lin, Shuang-Yan; Liu, Zhiliang; Tang, Jinkui

    2015-05-01

    The synthesis, structural characterization, and magnetic properties of four related heterometallic complexes with formulas [Dy(III)2Co(II)(C7H5O2)8]·6H2O (1), [Dy(III)2Ni(II)(C7H5O2)8]·(C7H6O2)2 (2), Tb(III)2Co(II)(C7H5O2)8 (3), and Dy(III)2Cd(II)(C7H5O2)8 (4) were reported. Each of complexes has a perfectly linear arrangement of the metal ions with two terminal Ln(III) (Ln(III) = Dy(III), Tb(III)) ions and one central M(II) (M(II) = Co(II), Ni(II), Cd(II)) ion. It was found that 1-3 displayed obvious magnetic interactions between the spin carriers according to the direct current (dc) susceptibility measurements. Alternating current (ac) magnetic susceptibility measurements indicate that complexes 1-4 all exhibit single-molecule magnet (SMM) behavior, while the replacement of the diamagnetic Cd(II) by paramagnetic ions leads to a significant slowing of the relaxation thanks to the magnetic interactions between 3d and 4f ions, resulting in higher relaxation barrier for complexes 1 and 2. Moreover, both Dy2Co and Dy2Ni compounds exhibit dual relaxation pathways that may originate from the single ion behavior of individual Dy(III) ions and the coupling between Dy(III) and Co(II)/Ni(II) ions, respectively, which can be taken as the feature of 3d-4f SMMs. The Ueff for 1 of 127 K is a relatively high value among the reported 3d-4f SMMs. The results demonstrate that the magnetic coupling between 3d and 4f ions is crucial to optimize SMM parameters. The synthetic approach illustrated in this work represents an efficient route to design nd-4f based SMMs via incorporating suitable paramagnetic 3d and even 4d and 5d ions into the d-f system. PMID:25906391

  10. Structure and magnetic exchange in heterometallic 3d-3d transition metal triethanolamine clusters.

    PubMed

    Langley, Stuart K; Chilton, Nicholas F; Moubaraki, Boujemaa; Murray, Keith S

    2012-01-21

    Synthetic methods are described that have resulted in the formation of seven heterometallic complexes, all of which contain partially deprotonated forms of the ligand triethanolamine (teaH(3)). These compounds are [Mn(III)(4)Co(III)(2)Co(II)(2)O(2)(teaH(2))(2)(teaH)(0.82)(dea)(3.18)(O(2)CMe)(2)(OMe)(2)](BF(4))(2)(O(2)CMe)(2)·3.18MeOH·H(2)O (1), [Mn(II)(2)Mn(III)(2)Co(III)(2)(teaH)(4)(OMe)(2)(acac)(4)](NO(3))(2)·2MeOH (2), [Mn(III)(2)Ni(II)(4)(teaH)(4)(O(2)CMe)(6)]·2MeCN (3), [Mn(III)(2)Co(II)(2)(teaH)(2)(sal)(2)(acac)(2)(MeOH)(2)]·2MeOH (4), [Mn(II)(2)Fe(III)(2)(teaH)(2)(paa)(4)](NO(3))(2)·2MeOH·CH(2)Cl(2) (5), [Mn(II)Mn(III)(2)Co(III)(2)O(teaH)(2)(dea)(Iso)(OMe)(F)(2)(Phen)(2)](BF(4))(NO(3))·3MeOH (6) and [Mn(II)(2)Mn(III)Co(III)(2)(OH)(teaH)(3)(teaH(2))(acac)(3)](NO(3))(2)·3CH(2)Cl(2) (7). All of the compounds contain manganese, combined with 3d transition metal ions such as Fe, Co and Ni. The crystal structures are described and examples of 'rods', tetranuclear 'butterfly' and 'triangular' Mn(3) cluster motifs, flanked in some cases by diamagnetic cobalt(III) centres, are presented. Detailed DC and AC magnetic susceptibility and magnetization studies, combined with spin Hamiltonian analysis, have yielded J values and identified the spin ground states. In most cases, the energies of the low-lying excited states have also been obtained. The features of note include the 'inverse butterfly' spin arrangement in 2, 4 and 5. A S = 5/2 ground state occurs, for the first time, in the Mn(III)(2)Mn(II) triangular moiety within 6, the many other reported [Mn(3)O](6+) examples having S = ½ or 3/2 ground states. Compound 7 provides the first example of a Mn(II)(2)Mn(III) triangle, here within a pentanuclear Mn(3)Co(2) cluster. PMID:22113523

  11. Surface-confined heterometallic triads on the basis of terpyridyl complexes and design of molecular logic gates.

    PubMed

    Mondal, Prakash Chandra; Singh, Vikram; Jeyachandran, Yekkoni Lakshmanan; Zharnikov, Michael

    2015-04-29

    Surface-confined heterometallic molecular triads (SURHMTs) were fabricated on SiOx-based solid substrates using optically rich and redox-active Fe-, Os-, and Ru-based terpyridyl complexes as metalloligands and Cu(2+) ions as linkers. Optical and electrochemical studies reveal efficient electronic intramolecular communication in these assemblies. The UV-vis spectra of the triads exhibit a superposition of the metal-to-ligand charge-transfer bands of individual complexes, providing a significant enlargement of the optical window, useful for application. Similarly, cyclic voltammograms of SURHMT layers show a variety of redox peaks corresponding to individual complexes as well as multi-redox states at a low potential. Interaction of a representative SURHMT assembly with redox-active NOBF4 was investigated and used as a basis for configuring molecular logic gates. PMID:25853640

  12. Heterometallic [MnPtn(L)2n](x+) Macrocycles from Dichloromethane-Derived Bis-2-pyridyl-1,2,3-triazole Ligands.

    PubMed

    Preston, Dan; Tucker, Robert A J; Garden, Anna L; Crowley, James D

    2016-09-01

    There is continued interest in the assembly of heterometallic metallosupramolecular assemblies due to the potential for new structural types and/or interesting chemical and physical properties. Two novel methylene-linked bis-2-pyridyl-1,2,3-triazole ligands (1a, 1b) were synthesized through CuAAC "click" chemistry between dichloromethane (DCM), sodium azide, and the appropriate ethynylpyridine, giving the shortest possible "regular" bis-pyridyl-1,2,3-triazole. The first example of bis-coordination of two 2-pyridyl-1,2,3-triazoles (Rpytri) around one Pt(II) center is reported, giving exclusive formation of head-to-tail [Pt(Rpytri)2](2+) complexes with vacant binding sites suitable for complexation with other metals and the formation of heterometallic assemblies. The concentration-dependent formation of an equilibrium mixture of a heterometallic [Pd2Pt2(L)4](8+) [4 + 4] square and [Pd3Pt3(L)6](12+) [6 + 6] hexagon was observed, and at lower concentrations ([reactants] = 1.5 mM) hexamer formation was negligible. The [Pt(L)2](2+) building block could also be utilized in the synthesis of a concentration-independent [Cu2Pt2(L)4](6+) metallomacrocyle. These compounds were characterized with (1)H, (13)C, and (1)H DOSY NMR spectroscopies, elemental analysis, mass spectrometry, and in some cases X-ray crystallography. PMID:27537620

  13. 2D and 3D Anilato-Based Heterometallic M(I)M(III) Lattices: The Missing Link.

    PubMed

    Benmansour, Samia; Vallés-García, Cristina; Gómez-Claramunt, Patricia; Mínguez Espallargas, Guillermo; Gómez-García, Carlos J

    2015-06-01

    The similar bis-bidentate coordination mode of oxalato and anilato-based ligands is exploited here to create the first examples of 2D and 3D heterometallic lattices based on anilato ligands combining M(I) and a M(III) ions, phases already observed with oxalato but unknown with anilato-type ligands. These lattices are prepared with alkaline metal ions and magnetic chiral tris(anilato)metalate molecular building blocks: [M(III)(C6O4X2)3](3-) (M(III) = Fe and Cr; X = Cl and Br; (C6O4X2)(2-) = dianion of the 3,6-disubstituted derivatives of 2,5-dihydroxy-1,4-benzoquinone, H4C6O4). The new compounds include two very similar 2D lattices formulated as (PBu3Me)2[NaCr(C6O4Br2)3] (1) and (PPh3Et)2[KFe(C6O4Cl2)3](dmf)2 (2), both presenting hexagonal [M(I)M(III)(C6O4X2)3](2-) honeycomb layers with (PBu3Me)(+) in 1 or (PPh3Et)(+) and dmf in 2 inserted between them. Minor modifications in the synthetic conditions yield the novel 3D lattice (NEt3Me)[Na(dmf)][NaFe(C6O4Cl2)3] (3), in which hexagonal layers analogous to 1 and 2 are interconnected through Na(+) cations, and (NBu3Me)2[NaCr(C6O4Br2)3] (4), the first heterometallic 3D lattice based on anilato ligands. This compound presents two interlocked chiral 3D (10,3) lattices with opposite chiralities. Attempts to prepare 4 in larger quantities result in the 2D polymorph of compound 4 (4'). Magnetic properties of compounds 1, 3, and 4' are reported, and in all cases we observe, as expected, paramagnetic behaviors that can be satisfactorily reproduced with simple monomer models including a zero field splitting (ZFS) of the corresponding S = 3/2 for Cr(III) in 1 and 4' or S = 5/2 for Fe(III) in 3. PMID:25965415

  14. Low-temperature N-O bond cleavage of nitrogen monoxide in heterometallic carbonyl complexes. An experimental and theoretical study.

    PubMed

    García, M Esther; Melón, Sonia; Ruiz, Miguel A; López, Ramón; Sordo, Tomás; Marchiò, Luciano; Tiripicchio, Antonio

    2008-11-17

    The reaction of Na[RuCp(CO) 2] with [MnCp'(CO) 2(NO)]BF 4 gives the corresponding heterometallic derivative [MnRuCpCp'(mu-CO) 2(CO)(NO)] (Cp = eta (5)-C 5H 5; Cp' = eta (5)-C 5H 4Me). In contrast, the group 6 metal carbonyl anions [MCp(CO) 2L] (-) (M = Mo, W; L = CO, P(OMe) 3, PPh 3) react with the Mn and Re complexes [M'Cp'(CO) 2(NO)]BF 4 to give the heterometallic derivatives [MM'CpCp'(mu-N)(CO) 3L] having a nitride ligand linearly bridging the metal centers (W-N = 1.81(3) A, N-Re = 1.97(3) A, W-N-Re = 179(1) (o), in [WReCpCp'(mu-N)(CO) 3{P(OMe) 3}]). Density-functional theory calculations on the reactions of [WCp(CO) 3] (-) and [RuCp(CO) 2] (-) with [MnCp(CO) 2(NO)] (+) revealed a comparable qualitative behavior. Thus, two similar and thermodynamically allowed reaction pathways were found in each case, one implying the displacement of CO from the cation and formation of a metal-metal bond, the other implying the cleavage of the N-O bond of the nitrosyl ligand and release of a carbonyl from the anion as CO 2. The second pathway is more exoergonic and is initiated through an orbitally controlled attack of the anion on the N atom of the NO ligand in the cation. In contrast, the first pathway is initiated through a charge-controlled attack of the anion to the C atom of a CO ligand in the cation. The CO 2-elimination pathway requires at the intermediate stages a close approach of the NO and CO ligands, which is more difficult for the Ru compound because of its lower coordination number (compared to W). This effect, when combined with a stronger stabilization of the initial intermediate in the Ru reaction, makes the CO 2-elimination pathway slower in that case. PMID:18928276

  15. Two dimensional cyano-bridged hetero-metallic coordination polymers containing metal⋅⋅⋅π interactions.

    PubMed

    Karaağaç, Dursun; Kürkçüoğlu, Güneş Süheyla; Yeşilel, Okan Zafer; Hökelek, Tuncer

    2014-01-01

    Three cyano bridged hetero-metallic complexes of general formula, [Cu(NH3)2(μ-ampy)M(μ-CN)2(CN)2]n [ampy=4-aminomethylpyridine, M=Ni(II) (1), Pd(II) (2) and Pt(II) (3)] have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The complexes crystallize in triclinic system with space group P-1. In all complexes, M(II) ions are coordinated by four cyano ligands, and four N atoms in the equatorial plane around the Cu atom form a slightly distorted square-planar arrangement, while the slightly distorted octahedral coordination is completed by the cyanide N atoms in the axial positions. In one-dimensional structures of all the complexes, [Cu(ampy)](2+) cations and [M(CN)4](2-) anions are linked via bridging cyano ligands. The adjacent one-dimensional structures form a 2D network to connect by the μ-ampy bridging ligands. The 2D layers are further linked by metal⋯π and hydrogen bonding interactions to generate a three dimensional network. PMID:24239763

  16. Syntheses, crystal structures and properties of two unusual pillared-layer 3d-4f Ln-Cu heterometallic coordination polymers

    SciTech Connect

    Fan Leqing; Wu Jihuai; Huang Yunfang

    2011-09-15

    Two unusual pillared-layer 3d-4f Ln-Cu heterometallic coordination polymers, {l_brace}[Ln{sub 2}Cu{sub 5}Br{sub 4}(IN){sub 7}(H{sub 2}O){sub 6}].H{sub 2}O{r_brace}{sub n} (Ln=Eu (1) and Gd (2), HIN=isonicotinic acid), have been synthesized under hydrothermal conditions, and characterized by elemental analysis, IR, thermal analysis and single-crystal X-ray diffraction. The structure determination reveals that 1 and 2 are isostructural and feature a novel three-dimensional pillared-layer hetrometallic structure built upon the linkages of one-dimensional (1D) linear Ln-carboxylate chains, zero-dimensional (0D) Ln-carboxylate Ln{sub 2}(IN){sub 8} dimers, rare 1D zigzag [Cu{sub 5}Br{sub 4}]{sub n} inorganic chains and IN{sup -} pillars. In both 3D structures, there are Ln-carboxylate layers resulted from the connections of 1D Ln-carboxylate chains and 0D Ln{sub 2}(IN){sub 8} dimers through O-H...O hydrogen bondings. The luminescent properties of 1 have been investigated. The magnetic properties of 1 and 2 have also been studied. - Graphical abstract: Two unusual pillared-layer Eu (Gd)-Cu heterometallic coordination polymers have been hydrothermally synthesized. The luminescent properties of Eu-Cu compound and magnetic properties of both compounds are investigated. Highlights: > Two unusual 3D pillared-layer Eu (Gd)-Cu heterometallic coordination polymers have been synthesized. > 1D and 0D Ln-carboxylate motifs construct layers by O-H...O hydrogen bondings. > In both the structures, there are rare 1D zigzag Cu/Br inorganic chains. > Luminescent properties of Eu-Cu compound and magnetic properties of both the compounds are investigated.

  17. A Mixed-Ligand Approach for a Gigantic and Hollow Heterometallic Cage {Ni64 RE96 } for Gas Separation and Magnetic Cooling Applications.

    PubMed

    Chen, Wei-Peng; Liao, Pei-Qin; Yu, Youzhu; Zheng, Zhiping; Chen, Xiao-Ming; Zheng, Yan-Zhen

    2016-08-01

    Nanosized aggregations of metal ions shielded by organic ligands possessing both exquisite structural aesthetics and intriguing properties are fundamentally interesting. Three isostructural gigantic transition-metal-rare-earth heterometallic coordination cages are reported, abbreviated as {Ni64 RE96 } (RE=Gd, Dy, and Y) and obtained by a mixed-ligand approach, each possessing a cuboidal framework made of 160 metal ions and a nanosized spherical cavity in the center. Along with the structural novelty, these hollow cages show highly selective adsorptions for CO2 over CH4 or N2 at ambient temperatures. Moreover, the gadolinium analogue exhibits large magnetocaloric effect at ultralow temperatures. PMID:27345594

  18. Research progress on polyoxometalate-based transition-metal-rare-earth heterometallic derived materials: synthetic strategies, structural overview and functional applications.

    PubMed

    Zhao, Jun-Wei; Li, Yan-Zhou; Chen, Li-Juan; Yang, Guo-Yu

    2016-03-15

    With the rapid development of science and technology and the trend of multidisciplinary pervasion, POM-based TM-RE heterometallic chemistry (POM = polyoxometalate, TM = transition-metal, RE = rare-earth) has become one of the most rapidly growing and challengeable areas of inorganic chemistry due to the impressive structural diversities, various chemical compositions and potential applications of these materials in magnetism, optics, electrochemistry, electrocatalysis and materials science. Over the past several years, continuous interest and persisting efforts have been dedicated to the preparation and exploration of POM-based TM-RE heterometallic derived materials (PTRHDMs), which have led to more than two hundred PTRHDMs. In this review, we summarize the structural types of reported PTRHDMs together with synthetic strategies, structural motifs and relevant functional applications. The exciting array of this emerging research theme presages continuous growth and great vitality. In the last section, some prospects of this branch are also presented and possible guidance for future work is outlined. PMID:26894638

  19. Magnetocaloric Properties of Heterometallic 3d-Gd Complexes Based on the [Gd(oda)3 ](3-) Metalloligand.

    PubMed

    Qiu, Jiang-Zhen; Wang, Long-Fei; Chen, Yan-Cong; Zhang, Ze-Min; Li, Quan-Wen; Tong, Ming-Liang

    2016-01-11

    A series of heterometallic 3d-Gd(3+) complexes based on a lanthanide metalloligand, [M(H2 O)6 ][Gd(oda)3 ]⋅3 H2 O [M=Cr(3+) (1-Cr)] (H2 oda=2,2'-oxydiacetic acid), [M(H2 O)6 ][MGd(oda)3 ]2 ⋅3 H2 O [M=Mn(2+) (2-Mn), Fe(2+) (2-Fe) and Co(2+) (2-Co)], and [M3 Gd2 (oda)6 (H2 O)6 ]⋅12 H2 O [M=Ni(2+) (3-Ni), Cu(2+) (3-Cu), and Zn(2+) (3-Zn)], are reported. Magnetic and heat-capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of -ΔSm between complexes 2-Co and 1-Cr. In these two complexes, the 3d metal ions have the same spin (S=3/2 for Co(2+) and Cr(3+) ions), and the theoretical calculation suggested a larger -ΔSm value for 2-Co (47.8 J K(-1)  kg(-1) ) than 1-Cr (37.5 J K(-1)  kg(-1) ); however, the significant anisotropy of Co(2+) ions in 2-Co, which can result in smaller effective spins, gives a smaller value of -ΔSm for 2-Co (32.2 J K(-1)  kg(-1) ) than for 1-Cr (35.4 J K(-1)  kg(-1) ) at ΔH=9 T. PMID:26636285

  20. A 3D Heterometallic Coordination Polymer Constructed by Trimeric {NiDy2} Single-Molecule Magnet Units.

    PubMed

    Zhang, Shaowei; Li, Han; Duan, Eryue; Han, Zongsu; Li, Leilei; Tang, Jinkui; Shi, Wei; Cheng, Peng

    2016-02-01

    The solvothermal reaction of DyCl3·6H2O, Ni(NO3)2·6H2O, and H4abtc ligands (H4abtc = 3,3',5,5'-azobenzene-tetracarboxylic acid) in the mixed DMF/H2O solvents (DMF = N,N-dimethylformamide) produced a three-dimensional (3D) Ni(II)-Dy(III) heterometallic coordination polymer (HCP) formulated as {[NH2(CH3)2]2[NiDy2(HCOO)2(abtc)2]}n (1). In 1, Dy(III) and Ni(II) ions interconnect through carboxylic O donors of abtc(4-) ligands to generate a linear trimer "Hourglass"-type {NiDy2} cluster, and the adjacent trinuclear {NiDy2} units are bridged by HCOO(-) groups to give a 1D "ladder" chain, which is further bridged by abtc(4-) ligands to form a new topology and named as "zsw3". Alternating-current magnetic susceptibility results indicate that 1 exhibits frequency-dependent out-of-phase signals with two relaxation processes, which suggests that it shows single-molecule magnet (SMM) behavior and represents the first example by using an SMM cluster as the building block to create a 3D Ni-Ln HCP, to the best of our knowledge. The energy barriers for 1 under a 1000 Oe applied direct current magnetic field are estimated from Arrhenius plots to be 40 and 42 K at higher and lower frequencies, respectively. Additionally, the crystalline structure of 1 could be stable to at least 310 °C, supported by thermogravimetric analyses and in situ variable-temperature powder X-ray diffraction patterns. PMID:26751740

  1. Syntheses, structures, spectroscopic and electrochemical properties of two 1D organic-inorganic CuII-LnIII heterometallic germanotungstates.

    PubMed

    Zhang, Jingli; Li, Jie; Li, Lijie; Zhao, Haozhe; Ma, Pengtao; Zhao, Junwei; Chen, Lijuan

    2013-10-01

    Two organic-inorganic hybrid copper-lanthanide heterometallic germanotungstates KNa2H7[enH2]3[Cu(en)2(H2O)]2[Cu(en)2]2{Cu(en)2[Eu(α-GeW11O39)2]2}·13H2O (1) and Na2H4[Cu(en)2(H2O)]2[Cu(en)2]6[Cu(en)2]{Cu(en)2[La(α-GeW11O39)2]2}·12H2O (2) have been hydrothermally synthesized by reaction of K8Na2[A-α-GeW9O34]·25H2O with CuCl2·2H2O and EuCl3/LaCl3 in the presence of en (en=ethylenediamine) and structurally characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. 1 exhibits the 1D chain motif built by tetrameric {[Cu(en)2(H2O)]2[Cu(en)2]2{Cu(en)2[Eu(α-GeW11O39)2]2}}(16-) moieties through square antiprismatic K(+) cations while 2 displays the 1D architecture made by tetrameric [[Cu(en)2]6[Cu(en)2]{Cu(en)2[La(α-GeW11O39)2]2}](10-) units via octahedral [Cu(en)2](2+) cations. Furthermore, the solid-state electrochemical and electrocatalytic properties of 1 have been investigated and 1 indicates the good electrocatalytic activity for nitrite reduction. In addition, the photoluminescence property of 1 has been investigated. PMID:23786977

  2. Calcium and heterometallic manganese-calcium complexes supported by tripodal pyridine-carboxylate ligands: structural, EPR and theoretical investigations.

    PubMed

    Gerey, Bertrand; Gennari, Marcello; Gouré, Eric; Pécaut, Jacques; Blackman, Allan; Pantazis, Dimitrios A; Neese, Frank; Molton, Florian; Fortage, Jérôme; Duboc, Carole; Collomb, Marie-Noëlle

    2015-07-28

    Carboxylate-bridged Mn(II)-Ca(II) complexes are potentially relevant for mimicking the first stages of the Oxygen-Evolving Complex (OEC) assembly process. Here, we report on new homonuclear Ca(II) and heteronuclear Mn(II)–Ca(II) complexes with carboxylate-functionalized tripodal tris(2-pyridylmethyl)amine ligands, the heptadentate H3tpaa, previously reported, and the new hexadentate H2tpada, containing respectively three and two carboxylate units. The mononuclear [Ca(Htpaa)(OH2)] (Ca1) and dinuclear [Ca(tpada)(OH2)2]2 (Ca2) calcium complexes, as well as the tetranuclear [{Mn(tpaa)}2{Ca(OH2)5(μ-OH2)}2][Mn(tpaa)]2 (Mn2Ca2·2Mn) and dinuclear [Mn(tpada)ClCa(OH2)2.67(MeOH)2.33]Cl (MnCa) heterometallic species have been structurally characterized; the syntheses of Ca1 and Mn2Ca2·2Mn being previously reported by us (Inorg. Chem., 2015, 54, 1283). The Mn(II) and Ca(II) are linked by two μ1,1-bridging carboxylates in MnCa, while only one μ1,3-carboxylate bridge connects each Ca2+ ion to each Mn(II) in Mn2Ca2. A variable number of water molecules (n = 1 to 7) are coordinated to Ca in all complexes, most of them being involved in hydrogen-bond networks, in analogy to what occurs in the photosystem II. All donor atoms of the tpaa3- and tpada2- ligands are coordinated to the Mn2+ ions, despite the unusually long distance between the Mn2+ ion and the tertiary amine imposed by the constraining nature of the ligands, as supported by theoretical calculations. Solid state EPR spectroscopy, in combination with DFT calculations, has also shown that the Ca2+ ion has an effect on the electronic parameters (zero field splitting) of the linked Mn(II) in the case of MnCa (μ1,1-carboxylate bridges). In Mn2Ca2 (μ1,3-carboxylate bridge) the Ca2+ ion induces only slight structural changes in the Mn coordination sphere. PMID:26089197

  3. Syntheses and structures of three heterometallic coordination polymers derived from 4-pyridin-3-yl-benzoic acid

    SciTech Connect

    Fang, Wei-Hui; Yang, Guo-Yu

    2014-04-01

    Three lanthanide–transition-metal coordination polymers, namely, [Er{sub 2}L{sub 6}(H{sub 2}O)][Cu{sub 2}I{sub 2}] (1), [ErL{sub 3}][CuI] (2), and [Dy{sub 2}L{sub 6}(BPDC){sub 0.5}(H{sub 2}O){sub 4}][Cu{sub 3}I{sub 2}] (3) (HL=4-pyridin-3-yl-benzoic acid, H{sub 2}BPDC=4,4′-biphenyldicarboxylic acid) have been made by reacting Ln{sub 2}O{sub 3} and CuI with HL at different temperatures under hydrothermal conditions. All the complexes are characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction, respectively. 1–3 all construct from dimeric (Ln{sub 2}) and (Cu{sub 2}) units and exhibit two types of the structural features: 1 is a two-dimensional layer, 2–3 are three-dimensional frameworks. Interestingly, the in situ formation of the BPDC ligand is found in the structure of 3. The distinct architectures of these complexes indicated that the reaction temperature plays an important role in the formation of higher dimensional coordination polymers. - Graphical abstract: By hydrothermal reaction of lanthanide oxide, copper halide, and 4-pyridin-3-yl-benzoic ligand at different temperatures, a series of 1-D to 3-D 3d–4f coordination polymers, namely [ErL{sub 3}(H{sub 2}O){sub 2}][CuI], [Er{sub 2}L{sub 6}(H{sub 2}O)][Cu{sub 2}I{sub 2}], [ErL{sub 3}][CuI], and [Dy{sub 2}L{sub 6}(BPDC){sub 0.5}(H{sub 2}O){sub 4}][Cu{sub 3}I{sub 2}], have been made, respectively. - Highlights: • Three novel heterometallic coordination polymers derived from 4-pyridin-3-yl-benzoic acid have been hydrothermally synthesized. • Mixed dinuclear motifs of (Ln{sub 2}) and (Cu{sub 2}) serve as secondary building units to generate 2-D layer and 3-D frameworks. • It is proved that higher temperature is apt to permit construction of high dimensional architectures.

  4. Structural observations of heterometallic uranyl copper(II) carboxylates and their solid-state topotactic transformation upon dehydration.

    PubMed

    Olchowka, Jakub; Falaise, Clément; Volkringer, Christophe; Henry, Natacha; Loiseau, Thierry

    2013-02-01

    The hydrothermal reactions of uranyl nitrate and metallic copper with aromatic polycarboxylic acids gave rise to the formation of five heterometallic UO(2)(2+)-Cu(2+) coordination polymers: (UO(2))Cu(H(2)O)(2)(1,2-bdc)(2) (1; 1,2-bdc = phthalate), (UO(2))Cu(H(2)O)(2)(btec)⋅4 H(2)O (2) and (UO(2))Cu(btec) (2'; btec = pyromellitate), (UO(2))(2)Cu(H(2)O)(4)(mel) (3; mel = mellitate), and (UO(2))(2)O(OH)(2)Cu(H(2)O)(2)(1,3-bdc)⋅H(2)O (4; 1,3-bdc = isophthlalate). Single-crystal X-ray diffraction (XRD) analysis of compound 1 revealed 2D layers of chains of UO(8) and CuO(4)(H(2)O)(2) units that were connected through the phthalate ligands. In compound 2, these sheets were connected to each other through the two additional carboxylate arms of the pyromellitate, thus resulting in a 3D open-framework with 1D channels that trapped water molecules. Upon heating, free and bonded water species (from Cu-OH(2)) were evacuated from the structure. This thermal transition was followed by in situ XRD and IR spectroscopy. Heating induced a solid-state topotactic transformation with the formation of a new set of Cu-O interactions in the crystalline anhydrous structure (2'), in order to keep the square-planar environment around the copper centers. The structure of compound 3 was built up from trinuclear motifs, in which one copper center, CuO(4)(OH(2))(2), was linked to two uranium units, UO(5)(H(2)O)(2). The assembly of this trimer, "U(2)Cu", with the mellitate generated a 3D network. Complex 4 contained a tetranuclear uranyl core of UO(5)(OH)(2) and UO(6)(OH) units that were linked to two copper centers, CuO(OH)(2)(H(2)O)(2), which were then connected to each other through isophthalate ligands and U=O-Cu interactions to create a 3D structure. The common structural feature of these different compounds is a bridging oxo group of U=O-Cu type, which is reflected by apical Cu-O distances in the range 2.350(3)-2.745(5) Å. In the case of a shorter Cu-O distance, a slight lengthening

  5. Two dodecanuclear heterometallic [Zn6Ln6] clusters constructed by a multidentate salicylamide salen-like ligand: synthesis, structure, luminescence and magnetic properties.

    PubMed

    Song, Xue-Qin; Liu, Pan-Pan; Liu, Yuan-Ang; Zhou, Jing-Jing; Wang, Xiao-Long

    2016-05-10

    The employment of a multidentate salicylamide salen-like ligand, 2-hydroxy-N-(2-(2-hydroxybenzylidene)amino)ethyl)benzamide (H3L), in aid of NO3(-) anions under weak basic conditions in Zn(II)-Ln(III) chemistry (Ln = Eu, and Dy, ) led to the isolation of two novel butterfly heterometallic dodecanuclear clusters with six Ln(III) ions occupying the body position and six Zn(II) ions the outer wing-tip sites. All of them are fully characterized by elemental analysis, FT-IR spectroscopy, TG analysis, single-crystal X-ray diffraction, and X-ray powder diffraction (XRPD) techniques. Luminescence studies indicate that exhibits dual emission, while exhibits a bright blue emission under visible light excitation. Furthermore, magnetic susceptibility studies carried out for indicate that the magnetic exchange between Dy(III) ions revealed ferromagnetic interactions with interesting slow relaxation of magnetization of the SMM behavior. PMID:27092471

  6. Synthesis of the molecular amalgam [{AuHg₂(o-C₆F₄)₃}{Hg₃(o-C₆F₄)₃}]⁻: a rare example of a heterometallic homoleptic metallacycle.

    PubMed

    Lasanta, Tania; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Pascual, David

    2016-04-21

    The preparation of homoleptic heterometallic complexes still remains a challenge. Herein, we report the synthesis and characterization of [Au(PMe3)2][{AuHg2(o-C6F4)3}{Hg3(o-C6F4)3}] (), a gold-mercury homoleptic metallacycle. The crystal structure of displays two [Hg2M(o-C6F4)3] (M = Au(I), Hg(II)) units linked through a short AuHg contact of 3.097(2) Å, the strongest unsupported Au(I)Hg(II) interaction described to date. Theoretical calculations quantify the interaction between the trimetalic units as -199 kJ mol(-1), a surprisingly strong value. PMID:26983855

  7. Luminescent pillared Ln{sup III}–Zn{sup II} heterometallic coordination frameworks with two kinds of N-heterocyclic carboxylate ligands

    SciTech Connect

    Liu, Sui-Jun; Jia, Ji-Min; Cui, Yu; Han, Song-De; Chang, Ze

    2014-04-01

    In our efforts toward rational design and systematic synthesis of ‘pillar-layer’ structure coordination frameworks, four new Ln{sup III}–Zn{sup II} heterometallic coordination polymers (CPs) based on two kinds of N-heterocyclic carboxylic ligands with formula ([LnZn(L1){sub 2}(L2)(H{sub 2}O){sub m}]·nH{sub 2}O){sub ∞} (Ln=La (1), Eu (2), Gd (3) and Dy (4), m=3 (for 1) and 2 (for 2–4), n=8 (for 1) and 7 (for 2–4), H{sub 2}L1=pyridine-2,3-dicarboxylate acid, HL2=isonicotinic acid), have been synthesized under hydrothermal reaction of Ln{sub 2}O{sub 3}, ZnO, H{sub 2}L1 and HL2. CP 1 has a three-dimensional (3D) structure with a (3,6)-connected sit topology network, while CPs 2–4 are isostructural with 3D single-node pcu alpha-Po topology network. Also, luminescent properties of these CPs have also been investigated. The emission of 1 and 3 should be attributed to the coordination-perturbed ligand-centered luminescence and the emission spectra of 2 and 4 show the characteristic bands of the corresponding Ln{sup III} ions. - Graphical abstract: Four new 3D Ln{sup III}–Zn{sup II} coordination frameworks with “pillar-layer” sit or pcu alpha-Po topology have been successfully obtained. Moreover, the photoluminescent properties of compounds 1–4 have also been investigated. - Highlights: • Four new Ln{sup III}–Zn{sup II} heterometallic coordination frameworks with two types of topologies have been synthesized. • Metal oxides and two kinds of N-heterocyclic carboxylate ligands were used for the construction of targeted coordination polymers. • The luminescent properties of the coordination polymers are investigated.

  8. Heterometallic Alkaline Earth-Lanthanide Ba(II)-La(III) Microporous Metal-Organic Framework as Bifunctional Luminescent Probes of Al(3+) and MnO4(.).

    PubMed

    Ding, Bin; Liu, Shi Xin; Cheng, Yue; Guo, Chao; Wu, Xiang Xia; Guo, Jian Hua; Liu, Yuan Yuan; Li, Yan

    2016-05-01

    In this work a rigid asymmetrical tricarboxylate ligand p-terphenyl-3,4″,5-tricarboxylic acid (H3L) has been employed, and a unique heterometallic alkaline earth-lanthanide microporous luminescent metal-organic framework (MOF) {[Ba3La0.5(μ3-L)2.5(H2O)3(DMF)]·(3DMF)}n (1·3DMF) (DMF = dimethylformamide) has been isolated under solvothermal conditions. Single-crystal X-ray structural analysis demonstrates that 2D inorganic Ba-O-La connectivity can be observed in 1, which are further bridged via rigid terphenyl backbones of L(3-), forming a unique I(2)O(1)-type microporous luminescent framework. A 1D microporous channel with dimensionality of 9.151(3) Å × 10.098(1) Å can be observed along the crystallographic a axis. PXRD patterns have been investigated indicating pure phases of 1. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive sensing for Al(3+) over other cations with high quenching efficiency Ksv value of 1.445 × 10(4) L·mol(-1) and low detection limit (1.11 μM (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive sensing for MnO4(-) over other anions with quenching efficiency Ksv = 7.73 × 10(3) L·mol(-1) and low detection limit (0.28 μM (S/N = 3)). It is noted that, when different concentrations of MnO4(-) solutions (0.5 to 100 μM) were dropped into the suspension of 1, the bright blue luminescence of the suspension observed under UV light can gradually change into pink color, indicating visually luminescent sensing, which makes the detection process of MnO4(-) more convenient in practical. The result also reveals that 1 represents the first example of bifunctional heterometallic alkaline earth-lanthanide MOF-based luminescent probes for selectively detecting Al(3+) and MnO4(-) in the water solutions. PMID:27088966

  9. Two-dimensional 3d-4f heterometallic coordination polymers: syntheses, crystal structures, and magnetic properties of six new Co(II)-Ln(III) compounds.

    PubMed

    Díaz-Gallifa, Pau; Fabelo, Oscar; Pasán, Jorge; Cañadillas-Delgado, Laura; Lloret, Francesc; Julve, Miguel; Ruiz-Pérez, Catalina

    2014-06-16

    Six new heterometallic cobalt(II)-lanthanide(III) complexes of formulas [Ln(bta)(H2O)2]2[Co(H2O)6]·10H2O [Ln = Nd(III) (1) and Eu(III) (2)] and [Ln2Co(bta)2(H2O)8]n·6nH2O [Ln = Eu(III) (3), Sm(III) (4), Gd(III) (5), and Tb(III) (6)] (H4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized via single-crystal X-ray diffraction. 1 and 2 are isostructural compounds with a structure composed of anionic layers of [Ln(bta)(H2O)2]n(n-) sandwiching mononuclear [Co(H2O)6](2+) cations plus crystallization water molecules, which are interlinked by electrostatic forces and hydrogen bonds, leading to a supramolecular three-dimensional network. 3-6 are also isostructural compounds, and their structure consists of neutral layers of formula [Ln2Co(bta)2(H2O)8]n and crystallization water molecules, which are connected through hydrogen bonds to afford a supramolecular three-dimensional network. Heterometallic chains formed by the regular alternation of two nine-coordinate lanthanide(III) polyhedra [Ln(III)O9] and one compressed cobalt(II) octahedron [Co(II)O6] along the crystallographic c-axis are cross-linked by bta ligands within each layer of 3-6. Magnetic susceptibility measurements on polycrystalline samples for 3-6 have been carried out in the temperature range of 2.0-300 K. The magnetic behavior of these types of Ln(III)-Co(II) complexes, which have been modeled by using matrix dagonalization techniques, reveals the lack of magnetic coupling for 3 and 4, and the occurrence of weak antiferromagnetic interactions within the Gd(III)-Gd(III) (5) and Tb(III)-Tb(III) (6) dinuclear units through the exchange pathway provided by the double oxo(carboxylate) and double syn-syn carboxylate bridges. PMID:24901707

  10. Polydentate-ligand-supported self-assembly of heterometallic T-shaped Co4RE (RE = Gd, Tb, Y) clusters: synthesis, structure and magnetism.

    PubMed

    Ke, Hongshan; Zhao, Lang; Guo, Yang; Tang, Jinkui

    2012-08-28

    A series of mixed-valent heterometallic pentanuclear Co(III)(3)Co(II)RE(III) (RE = Gd (1), Tb (2), Y (3)) clusters have been rationally assembled by taking advantage of a bifunctional ligand with o-vanillin and tripodal tris(hydroxymethyl)aminomethane units. Structural determinations reveal that all compounds are isomorphous and possess a T-shaped Co(4)RE core, which comprises two nearly linear Co(2)RE subunits sharing a common RE ion. Their magnetic properties were thoroughly studied. The static magnetic susceptibility studies of 1 demonstrate the presence of weak ferromagnetic interactions between the magnetic centres and magnetic anisotropy reflected by the single ion zero-field splitting (ZFS) D term. Both 1 and 2 behave magnetically as heterodinuclear metal systems, while the magnetic behaviour of 3 is identical to an isolated Co(II) ion. Moreover, alternating-current susceptibility measurements did not exhibit any out-of-phase signal, suggesting that slow magnetic relaxation is absent above 2 K within them. These isomorphous Co(4)RE clusters offer an opportunity to systematically probe the contribution of different metal ions to the overall magnetic behaviour in Co(II)-RE(III) systems. PMID:22767361

  11. Heterometallic Cu/Co and Cu/Co/Zn complexes bearing rare asymmetric tetranuclear cores: synthesis, structures, and magnetic and catalytic properties toward the peroxidative oxidation of cycloalkanes.

    PubMed

    Nesterov, Dmytro S; Kokozay, Volodymyr N; Jezierska, Julia; Pavlyuk, Oleksiy V; Boča, Roman; Pombeiro, Armando J L

    2011-05-16

    The three novel heterometallic complexes [CuCo(III)Co(II)(2)(MeDea)(3)Cl(3)(CH(3)OH)(0.55)(H(2)O)(0.45)](H(2)O)(0.45) (1), [CuCo(III)Zn(2)(MeDea)(3)Cl(3)(CH(3)OH)(0.74)(H(2)O)(0.26)](H(2)O)(0.26) (2), and [CuCo(III)Zn(2)(MeDea)(3)Cl(3)(DMF)] (3) have been prepared using a one-pot reaction of copper powder with cobalt chloride (1) and zinc nitrate (2, 3) in a methanol (1, 2) or dimethylformamide (3) solution of N-methyldiethanolamine. A search of the Cambridge Structural Database shows that the tetranuclear asymmetric cores M(4)(μ(3)-X)(μ-X)(5) of 1-3 represent an extremely rare case of M(4)X(6) arrays. The magnetic investigations of 1 disclose antiferromagnetic coupling in a Co(II)-Cu(II)-Co(II) exchange fragment with J(Co-Cu)/hc = -4.76 cm(-1), J(Co-Co)/hc = -2.76 cm(-1), and D(Co)/hc = +34.3 cm(-1). Compounds 1-3 act as precursors for the mild peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone with overall yields up to 23%. The synthetic and structural features as well as the thermogravimetric behavior and electrospray ionization mass spectrometry data are discussed. PMID:21506552

  12. In-Situ Ligand Formation-Driven Preparation of a Heterometallic Metal-Organic Framework for Highly Selective Separation of Light Hydrocarbons and Efficient Mercury Adsorption.

    PubMed

    Han, Yi; Zheng, Hao; Liu, Kang; Wang, Hongli; Huang, Hongliang; Xie, Lin-Hua; Wang, Lei; Li, Jian-Rong

    2016-09-01

    By means of the in situ ligand formation strategy and hard-soft acid-base (HSAB) theory, two types of independent In(COO)4 and Cu6S6 clusters were rationally embedded into the heterometallic metal-organic framework (HMOF) {[(CH3)2NH2]InCu4L4·xS}n (BUT-52). BUT-52 exhibits a three-dimensional (3D) anionic framework structure and has sulfur decorating the dumbbell-shaped cages with the external edges of 24 and 14 Å by the internal edges. Remarkably, because of the stronger charge-induced interactions between the charged MOF skeleton and the easily polarized C2 hydrocarbons (C2s), BUT-52 was used for C2s over CH4 and shows both high adsorption heats of C2s and selective separation abilities for C2s/CH4. Furthermore, BUT-52 also displays efficient mercury adsorption resulting from the stronger-binding ability beween the sulfur and the mercury and can remove 92% mercury from methanol solution even with the initial concentration as low as 100 mg/L. The results in this work indicate the feasibility of BUT-52 for the separation of light hydrocarbons and efficient adsorption/removal of mercury. PMID:27548083

  13. Synthesis, structures, and fluorescence properties of two d-d heterometallic cluster-based complexes constructed by N-(phosphonomethyl) iminodiacetic acid

    NASA Astrophysics Data System (ADS)

    Li, Sa-Ying

    2016-12-01

    Two novel d-d heterometallic cluster-based complexes constructed by N-(Phosphonomethyl)imino-diacetic acid (H4PMIDA) multifunctional ligand, [Cu2Zn2(PMIDA)2(H2O)3]·3H2O(1), [ZnNi14(PMIDA)6(H2O)18]·(NO3)6·15H2O(2), have been synthesized under hydrothermal conditions and characterized by elemental analyses, IR spectra, thermal analyses, and single-crystal X-ray diffraction. The complex 1 is one-dimensional heteronuclear molecular chain, which is further extends into a 3D supramolecular network through very extensive Osbnd H⋯O hydrogen bonds. The compound 2 is a rare novel zero-dimensional heteronuclear molecular cluster, which is further extends into a 3D supramolecular network through very extensive Osbnd H⋯O hydrogen bonds. Moreover, the solid-state fluorescence properties of the two complexes have also been investigated at room temperature.

  14. Synthesis, structure, solid-state thermolysis, and thermodynamic properties of new heterometallic complex Li{sub 2}Co{sub 2}(Piv){sub 6}(NEt{sub 3}){sub 2}

    SciTech Connect

    Dobrohotova, Zn.V.; Sidorov, A.A.; Kiskin, M.A.; Aleksandrov, G.G.; Gavrichev, K.S.; Tyurin, A.V.; Emelina, A.L.; Bykov, M.A.; Bogomyakov, A.S.; Malkerova, I.P.; Alihanian, A.S.; Novotortsev, V.M.; Eremenko, I.L.

    2010-10-15

    The reaction of lithium pivalate, polymeric cobalt pivalate [Co(Piv){sub 2}]{sub n}, and triethylamine in THF at 60 {sup o}S afforded the new heterometallic antiferromagnetic complex Li{sub 2}Co{sub 2}(Piv){sub 6}(NEt{sub 3}){sub 2} (2). The molecular and crystal structure of complex 2 was established and its magnetic behavior was studied. The vaporization and solid-state thermolysis of 2 were investigated. The thermodynamic characteristics of complex 2 were determined. The results of the present study show that complex 2 can be used as a potential molecular precursor for the synthesis of thin films of lithium cobaltate LiCoO{sub 2}. - Graphical abstract: The solid-state thermolysis, study of the vaporization process, and temperature dependence of S{sub p} for the new heterometallic complex Co{sub 2}Li{sub 2}(Piv){sub 6}(NEt{sub 3}){sub 2} were performed. Decomposition of Co{sub 2}Li{sub 2}(Piv){sub 6}(NEt{sub 3}){sub 2} results in the formation of LiCoO{sub 2}.

  15. Heterometallic clusters arising from cubic Ni{sub 3}M'O{sub 4} (M'=K and Na) entity: Solvothermal synthesis with/without the assistance of microwave

    SciTech Connect

    Zhang Shuhua; Zhou Yanling; Sun Xiaojun; Wei, Lian-Qiang; Zeng Minghua; Liang Hong

    2009-11-15

    Solvothermal reaction assisted with microwave leads to the formation of two unique heterometallic cubic clusters [Ni{sub 3}M'(L){sub 3}(OH)(CH{sub 3}CN){sub 3}]{sub 2}.CH{sub 3}CN (M'=K for 1 and M'=Na for 2, where L is an anion of 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-ethanesulfonate) with higher efficiency, yields and purity than those without it. The 6-metallacrown-3 [Ni{sub 3}(OH)(L){sub 3}]{sup -} groups exhibit interesting ion trapping and self-assembly of size-different Na{sup +} and K{sup +} through form recognition and coordination activity in 1 and 2. The magnetic studies for 1 and 2 suggest that the {l_brace}Ni{sub 3}M'O{sub 4}{r_brace} (M'=K and Na) cores both display dominant ferromagnetic interactions from the nature of the binding modes of mu{sub 3}-O (oxidophenyl) and mu{sub 3}-OH. - Graphical abstract: Solvothermal reaction assisted with microwave leads to two heterometallic cubic clusters with 6-metallacrown-3 structure [Ni{sub 3}O{sub 3}(OH)]{sup -} acting as a host for a K{sup +} or Na{sup +} ion. The {l_brace}Ni{sub 3}M'O{sub 4}{r_brace} (M'=K, Na) cores display dominant ferromagnetic interactions.

  16. Self-assembled 3D heterometallic Cu(II)/Fe(II) coordination polymers with octahedral net skeletons: structural features, molecular magnetism, thermal and oxidation catalytic properties.

    PubMed

    Karabach, Yauhen Y; Guedes da Silva, M Fátima C; Kopylovich, Maximilian N; Gil-Hernández, Beatriz; Sanchiz, Joaquin; Kirillov, Alexander M; Pombeiro, Armando J L

    2010-12-01

    The new three-dimensional (3D) heterometallic Cu(II)/Fe(II) coordination polymers [Cu(6)(H(2)tea)(6)Fe(CN)(6)](n)(NO(3))(2n)·6nH(2)O (1) and [Cu(6)(Hmdea)(6)Fe(CN)(6)](n)(NO(3))(2n)·7nH(2)O (2) have been easily generated by aqueous-medium self-assembly reactions of copper(II) nitrate with triethanolamine or N-methyldiethanolamine (H(3)tea or H(2)mdea, respectively), in the presence of potassium ferricyanide and sodium hydroxide. They have been isolated as air-stable crystalline solids and fully characterized including by single-crystal X-ray diffraction analyses. The latter reveal the formation of 3D metal-organic frameworks that are constructed from the [Cu(2)(μ-H(2)tea)(2)](2+) or [Cu(2)(μ-Hmdea)(2)](2+) nodes and the octahedral [Fe(CN)(6)](4-) linkers, featuring regular (1) or distorted (2) octahedral net skeletons. Upon dehydration, both compounds show reversible escape and binding processes toward water or methanol molecules. Magnetic susceptibility measurements of 1 and 2 reveal strong antiferromagnetic [J = -199(1) cm(-1)] or strong ferromagnetic [J = +153(1) cm(-1)] couplings between the copper(II) ions through the μ-O-alkoxo atoms in 1 or 2, respectively. The differences in magnetic behavior are explained in terms of the dependence of the magnetic coupling constant on the Cu-O-Cu bridging angle. Compounds 1 and 2 also act as efficient catalyst precursors for the mild oxidation of cyclohexane by aqueous hydrogen peroxide to cyclohexanol and cyclohexanone (homogeneous catalytic system), leading to maximum total yields (based on cyclohexane) and turnover numbers (TONs) up to about 22% and 470, respectively. PMID:21028781

  17. Synthesis, relaxivity, and in vitro fluorescence imaging studies of a novel d-f heterometallic trinuclear complex as a potential bimodal imaging probe for MRI and optical imaging.

    PubMed

    Nithyakumar, A; Alexander, V

    2015-10-28

    A new trinuclear heterometallic Ru(II)-Gd complex of 4-aminopyridine appended DO3A (DO3A = 1,4,7-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecane) with 2,2'-bipyridine as ancillary ligands is synthesized and its relaxometry and in vitro fluorescence imaging studies are reported. The complex [Ru(bpy)2{Gd(DOTA-AMpy)(H2O)}2]Cl2 (7) exhibits a "per Gd" longitudinal relaxivity (r1p) of 5.80 and 14.30 mM(-1) s(-1) in aqueous solution and in the presence of HSA, respectively (20 MHz, pH = 7.4, PBS, 37 °C). The complex 7 exhibits an intense (1)MLCT absorption band at 480 nm and luminesces at 595 nm with a luminescence quantum yield of 3.2%. The fluorescence microscopy imaging study of HeLa cells incubated with 7 and stained with ethidium bromide and acridine orange confirms that the cells are viable throughout the imaging experiments and its cytotoxicity against HeLa cells, studied by the MTT assay, demonstrates its use for bioimaging studies. HeLa cell lines treated with the complex 7 and stained with Hoechst-33342 showed marked morphological signs of apoptosis in a dose-dependent manner by inducing changes in cell cycle arrest at the G2/M phase. Furthermore, apoptosis of HeLa cells, studied by the DNA ladder assay, indicates apoptotic cell death lending support for the antitumor activity of 7. A molecular docking study reveals that the complex 7 intercalates into the major groove of the DNA stabilized by hydrogen bonding and it binds with HSA by electrostatic- and hydrogen bonding interactions. The relaxometry, luminescence and fluorescence imaging studies indicate that the Ru(II)-Gd complex 7 has a good cell membrane permeability and could be considered as a potential bimodal imaging probe. PMID:26400754

  18. 2-D and 3-D phosphotungstate-based TM-Ln heterometallic derivatives constructed from dimeric [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} fragments and copper-organic complex linkers

    SciTech Connect

    Shang, Sensen; Zhao, Junwei; State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 ; Chen, Lijuan; Basic Experiment Teaching Center, Henan University, Kaifeng, Henan 475004 ; Li, Yuye; Zhang, Jingli; Li, Yanzhou; Niu, Jingyang

    2012-12-15

    Three organic-inorganic hybrid TM-Ln heterometallic phosphotungstates [Cu(dap){sub 2}(H{sub 2}O)][Cu(dap){sub 2}]{sub 3.5}[La({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (1) [Cu(dap){sub 2}(H{sub 2}O)]{sub 0.5}[Cu(dap){sub 2}]{sub 4}[Nd({alpha}-HPW{sub 11}O{sub 39}){sub 2}]{center_dot}4H{sub 2}O (2) and [Cu(dap){sub 2}(H{sub 2}O)]{sub 2}[Cu(dap){sub 2}]{sub 3.5}[Eu({alpha}-PW{sub 11}O{sub 39}){sub 2}]{center_dot}6H{sub 2}O (3) (dap=1,2-diaminopropane) have been hydrothermally synthesized and structurally characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, powder X-ray diffraction (PXRD), thermogravimetric (TG) analyses and single-crystal X-ray diffraction. Their common features are that 1-3 all consist of asymmetric sandwich-type subunits [Ln({alpha}-PW{sub 11}O{sub 39}){sub 2}]{sup 11-} and [Cu(dap){sub 2}]{sup 2+} bridges. Both 1 and 2 display the 2-D (4,4)-topological sheets whereas 3 exhibits the 3-D 5-connected (4{sup 6}{center_dot}6{sup 4}) topological framework. The magnetic properties of 2 and 3 and the luminescence performance of 3 have been measured. - Graphical Abstract: Three TM-Ln heterometallic phosphotungstates 1-3 have been synthesized and characterized by elemental analyses, IR spectra, optical diffuse reflectance spectra, X-ray diffraction, thermogravimetric analyses magnetic susceptibility and luminescent properties. Highlights: Black-Right-Pointing-Pointer Cu{sup II}-Ln{sup III} heterometallic polyoxometalates. Black-Right-Pointing-Pointer 2-D and 3-D organic-inorganic hybrid phosphotungstates. Black-Right-Pointing-Pointer 2-D and 3-D structures consisting of Cu{sup II}-Ln{sup III} heterometals.

  19. Supramolecular 2D/3D isomerism in a compound containing heterometallic Cu(II)2Co(II) nodes and dicyanamide bridges.

    PubMed

    Biswas, Saptarshi; Gómez-García, Carlos J; Clemente-Juan, Juan M; Benmansour, Samia; Ghosh, Ashutosh

    2014-03-01

    Three new heterometallic copper(II)-cobalt(II) complexes [(CuL(2))2Co{dca}2]·H2O(1), [(CuL(1))2Co{dca}2]n (2a), and [(CuL(1))2Co{dca}2]n (2b) [dca(-) = dicyanamide = N(CN)2(-)] have been synthesized by reacting the "metallo-ligand" [CuL(1)] or [CuL(2)] with cobalt(II) perchlorate and sodium dicyanamide in methanol-water medium (where H2L(1) = N,N'-bis(salicylidene)-1,3-propanediamine and H2L(2) = N,N'-bis(α-methylsalicylidene)-1,3-propanediamine). The three complexes have been structurally and magnetically characterized. Complex 1 is a discrete trinuclear species in which two metallo-ligands coordinate to a cobalt(II) ion through the phenoxido oxygen atoms along with two terminally coordinated dicyanamide ions. On the other hand, complexes 2a and 2b are one of the very scarce examples of supramolecular isomers since they present the same [(CuL(1))2Co{dca}2] trinuclear units (very similar to the trinuclear core in 1) and differ only in their superstructures. Thus, although each Cu2Co trimer in 2a and 2b is connected to four other Cu2Co trimers through four μ1,5-dca(-) bridges, 2a presents a square two-dimensional structure (each Cu2Co trimer is connected to four in-plane Cu2Co trimers); whereas, 2b shows a triangular three-dimensional lattice (each Cu2Co trimer is connected to three in-plane and one out-of-plane trimers). Variable-temperature magnetic susceptibility measurements show the presence of moderate antiferromagnetic exchange interactions (ferrimagnetic) in all the cases mediated through the double phenoxido bridges that have been fitted with an anisotropic model including spin-orbit coupling in the central Co(II) ion. PMID:24552535

  20. S-shaped decanuclear heterometallic [Ni8Ln2] complexes [Ln(III) = Gd, Tb, Dy and Ho]: theoretical modeling of the magnetic properties of the gadolinium analogue.

    PubMed

    Hossain, Sakiat; Das, Sourav; Chakraborty, Amit; Lloret, Francesc; Cano, Joan; Pardo, Emilio; Chandrasekhar, Vadapalli

    2014-07-14

    The reaction of 8-quinolinol-2-carboaldoxime (LH2) with Ni(II) and Ln(III) salts afforded the heterometallic decanuclear compounds [Ni8Dy2(μ3-OH)2(L)8(LH)2(H2O)6](ClO4)2·16H2O (1), [Ni8Gd2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](NO3)2·12H2O (2), [Ni8Ho2(μ3-OH)2(L)8(LH)2(H2O)4(MeOH)2](ClO4)2·2MeOH·12H2O (3) and [Ni8Tb2 (μ3-OH)2(L)8(LH)2(MeOH)4(OMe)2]·2CH2Cl2·8H2O (4). While compounds 1-3 are dicationic, compound 4 is neutral. These compounds possess an S-shaped architecture and comprise a long chain of metal ions bound to each other. In all the complexes, the eight Ni(II) and two Ln(III) ions of the multimetallic ensemble are hold together by two μ3-OH, eight dianionic (L(2-)) and two monoanionic oxime ligands (LH(-)) whereas compound 4 has two μ3-OH, eight dianionic (L(2-)), two monoanionic oxime ligands (LH(-)) and two terminal methoxy (MeO(-)) ligands. The central portion of the S-shaped molecular wire is made up of an octanuclear Ni(II) ensemble which has at its two ends the Ln(III) caps. Magnetic studies on 1-4 reveal that the magnetic interactions between neighboring metal ions are negligible at room temperature. On the other hand, at lower temperatures in all the compounds anti-ferromagnetic interactions seem to be dominated. Analysis of the magnetic data for the Gd(III) derivative indicates Ni(II)-Ni(II) anti-ferromagnetic interactions and Gd(III)-Ni(II) ferromagnetic interactions at low temperatures. A theoretical density functional study on the magnetic behavior of the Gd(III) derivative suggests that while the weak ferromagnetic interaction between Gd(III) and Ni(II) is in line with the expectation of the magnetic interactions between orthogonal d and f orbitals, antiferromagnetic Ni(II)-Ni(II) interactions are related to the wide Ni-O-Ni angles (∼102°) and quasi-planar conformation of the Ni2O2 core. PMID:24876072

  1. Cyclo- and carbophosphazene-supported ligands for the assembly of heterometallic (Cu2+/Ca2+, Cu2+/Dy3+, Cu2+/Tb3+) complexes: synthesis, structure, and magnetism.

    PubMed

    Chandrasekhar, Vadapalli; Senapati, Tapas; Dey, Atanu; Das, Sourav; Kalisz, Marguerite; Clérac, Rodolphe

    2012-02-20

    The carbophosphazene and cyclophosphazene hydrazides, [{NC(N(CH(3))(2))}(2){NP{N(CH(3))NH(2)}(2)}] (1) and [N(3)P(3)(O(2)C(12)H(8))(2){N(CH(3))NH(2)}(2)] were condensed with o-vanillin to afford the multisite coordination ligands [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-OH)(m-OCH(3))}(2)}] (2) and [{N(2)P(2)(O(2)C(12)H(8))(2)}{NP{N(CH(3))N═CH-C (6)H(3)-(o-OH)(m-OCH(3))}(2)}] (3), respectively. These ligands were used for the preparation of heterometallic complexes [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuCa(NO(3))(2)}] (4), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{Cu(2)Ca(2)(NO(3))(4)}]·4H(2)O (5), [{NC(N(CH(3))(2))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(4)}]·CH(3)COCH(3) (6), [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuDy(NO(3))(3)}] (7), and [{NP(O(2)C(12)H(8))}(2){NP{N(CH(3))N═CH-C(6)H(3)-(o-O)(m-OCH(3))}(2)}{CuTb(NO(3))(3)}] (8). The molecular structures of these compounds reveals that the ligands 2 and 3 possess dual coordination pockets which are used to specifically bind the transition metal ion and the alkaline earth/lanthanide metal ion; the Cu(2+)/Ca(2+), Cu(2+)/Tb(3+), and Cu(2+)/Dy(3+) pairs in these compounds are brought together by phenoxide and methoxy oxygen atoms. While 4, 6, 7, and 8 are dinuclear complexes, 5 is a tetranuclear complex. Detailed magnetic properties on 6-8 reveal that these compounds show weak couplings between the magnetic centers and magnetic anisotropy. However, the ac susceptibility experiments did not reveal any out of phase signal suggesting that in these compounds slow relaxation of magnetization is absent above 1.8 K. PMID:22320309

  2. Syntheses, structures, and magnetic analyses of a family of heterometallic hexanuclear [Ni4M2] (M = Gd, Dy, Y) compounds: observation of slow magnetic relaxation in the Dy(III) derivative.

    PubMed

    Ke, Hongshan; Zhao, Lang; Guo, Yang; Tang, Jinkui

    2012-02-20

    We described the syntheses, crystal structures, and magnetic behavior of a novel series of heterometallic [Ni(4)M(2)] [M = Gd (1), Dy (2) and Y (3)] hexanuclear compounds afforded by the reaction of rare-earth(III) nitrate, nickel(II) acetate, and Schiff-base ligand 2-(2-hydroxy-3-methoxybenzylideneamino)phenol (H(2)L) in a mixture of ethanol and dichloromethane in the presence of triethylamine. Single-crystal X-ray diffraction measurements reveal that all three compounds have a metal core made up of two Ni(2)MO(4) defective cubanes. The magnetic properties of all compounds have been studied. Solid-state direct-current magnetic susceptibility analyses demonstrate competing antiferromagnetic and ferromagnetic interactions within both compounds 1 and 3. Solid-state alternating-current magnetic susceptibility investigations show a frequency-dependent out-of-phase signal for compound 2 below 4 K, suggestive of slow magnetic relaxation. PMID:22320187

  3. Heterometallic alumo- and gallodisilicates with M(O-Si-O)2M' and [M(O-Si-O)2]2M' cores (M = Al, Ga; M' = Ti, Zr, Hf).

    PubMed

    Huerta-Lavorie, Raúl; Solis-Ibarra, Diego; Báez-Rodríguez, Dana Victoria; Reyes-Lezama, Marisol; de las Nieves Zavala-Segovia, M; Jancik, Vojtech

    2013-06-17

    The synthesis and stabilization of alumo- and gallodisilicates [HC{C(Me)N(2,6-iPr2C6H3)}2]M[(μ-O)Si(OH)(OtBu)2]2 [M = Al (1), Ga (2)] containing two silicate subunits have been achieved through reactions between 2 equiv of the silanediol (tBuO)2Si(OH)2 and the aluminum hydride [HC{C(Me)N(2,6-iPr2C6H3)}2]AlH2 or the gallium amide [HC{C(Me)N(2,6-iPr2C6H3)}2]Ga(NHEt)2, respectively. Compounds 1 and 2 exhibit M(O-SiO2-OH)2 moiety and represent the first molecular metallosilicate-based analogues of neighboring silanol groups found in silicate surfaces. The substitution of both SiOH groups led to the formation of bimetallic compounds with 4R topologies, which are regularly found in zeolitic materials. Thus, reactions between group 4 metal amides M'(NEt2)4 (M' = Ti, Zr, Hf) and 1 and 2 resulted in the formation of nine heterometallic silicates (3-11) containing inorganic M(O-Si-O)2M' and [M(O-Si-O)2]2M' cores with 4R and spiro-4R topologies, respectively. The latter have M···M distances of 0.81 nm. NMR studies of the heterometallic derivatives showed a fluxional behavior at room temperature due to a high flexibility of the eight-membered ring. PMID:23718324

  4. Heterometallic modular metal-organic 3D frameworks assembled via new tris-β-diketonate metalloligands: nanoporous materials for anion exchange and scaffolding of selected anionic guests.

    PubMed

    Carlucci, Lucia; Ciani, Gianfranco; Maggini, Simona; Proserpio, Davide M; Visconti, Marco

    2010-11-01

    The modular engineering of heterometallic nanoporous metal-organic frameworks (MOFs) based on novel tris-chelate metalloligands, prepared using the functionalised β-diketone 1,3-bis(4'-cyanophenyl)-1,3-propanedione (HL), is described. The complexes [M(III)L(3)] (M=Fe(3+), Co(3+)) and [M(II)L(3)](NEt(4)) (M=Mn(2+), Co(2+), Zn(2+), Cd(2+)) have been synthesised and characterised, all of which exhibit a distorted octahedral chiral structure. The presence of six exo-oriented cyano donor groups on each complex makes it a suitable building block for networking through interactions with external metal ions. We have prepared two families of MOFs by reacting the metalloligands [M(III)L(3)] and [M(II)L(3)](-) with many silver salts AgX (X=NO(3)(-), BF(4)(-), PF(6)(-), AsF(6)(-), SbF(6)(-), CF(3)SO(3)(-), tosylate), specifically the [M(III)L(3)Ag(3)]X(3)·Solv and [M(II)L(3)Ag(3)]X(2)·Solv network species. Very interestingly, all of these network species exhibit the same type of 3D structure and crystallise in the same trigonal space group with similar cell parameters, in spite of the different metal ions, ionic charges and X(-) counteranions of the silver salts. We have also succeeded in synthesising trimetallic species such as [Zn(x)Fe(y)L(3)Ag(3)](ClO(4))((2x+3y))·Solv and [Zn(x)Cd(y)L(3)Ag(3)](ClO(4))(2)·Solv (with x+y=1). All of the frameworks can be described as sixfold interpenetrated pcu nets, considering the Ag(+) ions as simple digonal spacers. Each individual net is homochiral, containing only Δ or Λ nodes; the whole array contains three nets of type Δ and three nets of type Λ. Otherwise, taking into account the presence of weak Ag-C σ bonds involving the central carbon atoms of the β-diketonate ligands of adjacent nets, the six interpenetrating pcu networks are joined into a unique non-interpenetrated six-connected frame with the rare acs topology. The networks contain large parallel channels of approximate hexagonal-shaped sections that represent 37

  5. Heterometallic derivatives of [Fe2Cp2(μ-PCy)(μ-CO)(CO)2]: rational synthesis of polynuclear complexes from neutral precursors having pyramidal-phosphinidene bridges.

    PubMed

    Alvarez, M Angeles; García, M Esther; González, Rocío; Ramos, Alberto; Ruiz, Miguel A

    2011-08-15

    The title complex (Cp = η(5)-C(5)H(5)) reacted with the labile carbonyl complexes [M(CO)(5)(THF)] (M = Cr, Mo, W) and [MnCp'(CO)(2)(THF)] (Cp' = η(5)-C(5)H(4)Me) to give phosphinidene-bridged trimetallic compounds of formula [Fe(2)MCp(2)(μ(3)-PCy)(μ-CO)(CO)(7)] (Cr-P = 2.479(1) Å) and [Fe(2)MnCp(2)Cp'(μ(3)-PCy)(μ-CO)(CO)(4)], respectively, after formation of a new M-P bond in each case, and related heterometallic complexes [Fe(2)MClCp(2)(μ(3)-PCy)(μ-CO)(CO)(2)] (M = Cu, Au; Au-P = 2.262(1) Å) were cleanly formed upon reaction with CuCl or the labile tetrahydrothiophene (THT) complex [AuCl(THT)]. The reaction with [Fe(2)(CO)(9)] proceeded analogously to give the triiron derivative [Fe(3)Cp(2)(μ(3)-PCy)(μ-CO)(CO)(6)] in high yield (new Fe-P bond =2.318(1) Å), along with a small amount of the pentanuclear compound [{Fe(CO)(3)}{(μ(3)-PCy)Fe(2)Cp(2)(μ-CO)(CO)(2)}(2)], the latter displaying a central Fe(CO)(3)P(2) core with a distorted bipyramidal geometry (P-Fe-P = 164.2(1)°). In contrast, the reaction with [Co(2)(CO)(8)] resulted in a full disproportionation process to give the salt [{Co(CO)(3)}{(μ(3)-PCy)Fe(2)Cp(2)(μ-CO)(CO)(2)}(2)][Co(CO)(4)], having a pentanuclear Fe(4)Co cation comparable to the above Fe(5) complex (P-Co-P = 165.3(2)°). The attempted photochemical decarbonylation of the above trinuclear complexes gave results strongly dependent on the added metal fragment. Thus, the irradiation with visible or visible-UV light of the new Fe(3) and Fe(2)Cr species caused no decarbonylation but a tautomerization of the metal framework to give the corresponding isomers [Fe(2)MCp(2)(μ(3)-PCy)(μ-CO)(CO)(n)] now exhibiting a dangling FeCp(CO)(2) moiety (M = Cr, n = 7, Cr-Fe = 2.7370(3) Å; M = Fe, n = 6, new Fe-Fe bond = 2.6092(9) Å) as a result of the cleavage of the Fe-Fe bond in the precursor and subsequent formation of a new M-Fe bond. These processes are reversible, since the new isomers gave back the starting complexes under low (Cr) or

  6. Cyanide bridged hetero-metallic polymeric complexes: Syntheses, vibrational spectra, thermal analyses and crystal structures of complexes [M(1,2-dmi)2Ni(μ-CN)4]n (M = Zn(II) and Cd(II))

    NASA Astrophysics Data System (ADS)

    Kürkçüoğlu, Güneş Süheyla; Sayın, Elvan; Şahin, Onur

    2015-12-01

    Two cyanide bridged hetero-metallic complexes of general formula, [M(1,2-dmi)2Ni(μ-CN)4]n (1,2-dmi = 1,2-dimethylimidazole and M = Zn(II) or Cd(II)) have been synthesized and characterized by vibrational (FT-IR and Raman) spectroscopy, single crystal X-ray diffraction, thermal analyses and elemental analyses. The crystallographic analyses reveal that the complexes, [Zn(1,2-dmi)2Ni(μ-CN)4] (1) and [Cd(1,2-dmi)2Ni(μ-CN)4] (2), have polymeric 2D networks. In the complexes, four cyanide groups of [Ni(CN)4]2- coordinated to the adjacent M(II) ions and distorted octahedral geometries of complexes are completed by two nitrogen atoms of trans 1,2-dmi ligands. The structures of 1 and 2 are similar and linked via intermolecular hydrogen bonding, C-H⋯Ni interactions to give rise to 3D networks. Vibration assignments are given for all the observed bands and the spectral features also supported to the crystal structures of heteronuclear complexes. The FT-IR and Raman spectra of the complexes are very much consistent with the structural data presented.

  7. Luminescence, magnetic and vibrational properties of novel heterometallic niccolites [(CH3)2NH2][CrIIIMII(HCOO)6] (MII=Zn, Ni, Cu) and [(CH3)2NH2][AlIIIZnII(HCOO)6]:Cr3+

    NASA Astrophysics Data System (ADS)

    Mączka, Mirosław; Pietraszko, Adam; Pikul, Adam; Hermanowicz, Krzysztof

    2016-01-01

    We report synthesis of three novel heterometallic MOFs, [(CH3)2NH2][CrIIIMII(HCOO)6] with M=Zn (DMCrZn), Ni (DMCrNi) and Cu (DMCrCu), crystallizing in the niccolite type structure. We also successfully synthesized [(CH3)2NH2][AlCu(HCOO)6] (DMAlCu) and [(CH3)2NH2][AlZn(HCOO)6] doped with 5.8 mol% of Cr3+ (DMAlZn: Cr). X-ray diffraction shows that DMCrZn, DMCrNi and DMAlZn: Cr3+ crystallize in the trigonal structure (space group P 3 bar1c) while DMCrCu and DMAlCu crystallize in the monoclinic structure (space group C2/c). Magnetic investigation of the chromium-based niccolites reveals no magnetic order in DMCrZn and ferromagnetic order in DMCrNi and DMCrCu below 23 and 11 K, respectively. Optical studies show that DMCrZn and DMAlZn: Cr samples exhibit efficient emission typical for chromium ions located at sites of strong crystal field with the Dq/B values 2.62 and 2.67, respectively. We also discuss role of geometrical parameters in stability of the perovskite and niccolite structures.

  8. Synthesis of a new Cd(II)-Ni(II) hetero-metallic coordination polymer base on citric acid ligand. X-ray structure, thermal stability, XPS and fluorescence studies

    NASA Astrophysics Data System (ADS)

    Mtioui-Sghaier, O.; Mendoza-Meroño, R.; Fernández-Zapico, E.; García-Granda, S.; Fernández-González, A.; Ktari, L.; Dammak, M.

    2016-02-01

    A new hetero-metallic polymer, NiCd(cit)(H2O) (cit = citrate), was synthesized under hydrothermal conditions. The structural analysis indicates the formation of a 2D structure, bridged by the cit4- group. This compound crystallizes in the monoclinic P21/c space group, with lattice parameters: a = 6.0817(3) Å, b = 14.9725(6) Å, c = 9.6817(5) Å, β = 101.353(5)°. Full characterization by powder diffraction analysis, thermocalorimetry and scanning electron microscopy, XPS and fluorescence have been carried out. The TG-MS and DSC results show that this compound is thermally stable up to 250 °C and the DSC profile shows a medium-intense endotherm centred at approximately 300 °C. The distances of Cd-O are in the range of 2.169(4)-2.647(4) Å, similar to pure cadmium(II)-citrate aqueous complex Cd(C6H6O7)(H2O). The six-coordinated Cd2+ is linked by carboxylate groups to form an infinite chain, which is further connected through NiO6 octahedral bridges to generate 2D structure in the bc plane.

  9. Heterometallic trinuclear {CoLn(III)} (Ln = Gd, Tb, Ho and Er) complexes in a bent geometry. Field-induced single-ion magnetic behavior of the Er(III) and Tb(III) analogues.

    PubMed

    Goura, Joydeb; Brambleby, Jamie; Topping, Craig V; Goddard, Paul A; Suriya Narayanan, Ramakirushnan; Bar, Arun Kumar; Chandrasekhar, Vadapalli

    2016-05-31

    Through the use of a multi-site compartmental ligand, 2-methoxy-6-[{2-(2-hydroxyethylamino)ethylimino}methyl]phenol (LH3), the family of heterometallic, trinuclear complexes of the formula [CoLn(L)2(μ-O2CCH3)2(H2O)3]·NO3·xMeOH·yH2O has been expanded beyond Ln = Dy(III) to include Gd(III) (), Tb(III) (), Ho(III) () and Er(III) () for , and (x = 1; y = 1) and for (x = 0; y = 2). The metallic core of these complexes consists of a (Co(III)-Ln(III)-Co(III)) motif bridged in a bent geometry resulting in six-coordinated distorted Co(III) octahedra and nine-coordinated Ln(III) monocapped square-antiprisms. The magnetic characterization of these compounds reveals the erbium and terbium analogues to display a field induced single-ion magnetic behavior similar to the dysprosium analogue but at lower temperatures. The energy barrier for the reversal of the magnetization of the CoTb(III) analogue is Ueff ≥ 15.6(4) K, while for the CoEr(III) analogue Ueff ≥ 9.9(8) K. The magnetic properties are discussed in terms of distortions of the 4f electron cloud. PMID:27180723

  10. Synthesis, crystal structure and magnetic properties of a two-dimensional cyanide-based heterometallic coordination polymer with cationic piperazinium ligands: poly[aquatetra-μ2-cyanido-κ(8)C:N-dicyanido-κ(2)C-(piperazinium-κN(4))cobalt(III)copper(II)].

    PubMed

    Qin, Ying Lian; Yao, Chen Zhong; Yang, Bin Wu; Qin, Jian Fang; Gong, Qiao Juan

    2016-01-01

    Cyanide as a bridge can be used to construct homo- and heterometallic complexes with intriguing structures and interesting magnetic properties. These ligands can generate diverse structures, including clusters, one-dimensional chains, two-dimensional layers and three-dimensional frameworks. The title cyanide-bridged Cu(II)-Co(III) heterometallic compound, [Cu(II)Co(III)(CN)6(C4H11N2)(H2O)]n, has been synthesized and characterized by single-crystal X-ray diffraction analysis, magnetic measurement, thermal study, vibrational spectroscopy (FT-IR) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS). The crystal structure analysis revealed that it has a two-dimensional grid-like structure built up of [Cu(Hpip)(H2O)](3+) cations (Hpip is piperazinium) and [Co(CN)6](3-) anions that are linked through bridging cyanide ligands. The overall three-dimensional supramolecular network is expanded by a combination of interlayer O-H...N and N-H...O hydrogen bonds involving the coordinated water molecules and the N atoms of the nonbridging cyanide groups and monodentate cationic piperazinium ligands. A magnetic investigation shows that antiferromagnetic interactions exist in the title compound. PMID:26742823

  11. A cyanide-bridged heterometallic coordination polymer constructed from square-planar [Ni(CN)4](2-): synthesis, crystal structure, thermal decomposition, electron paramagnetic resonance (EPR) spectrum and magnetic properties.

    PubMed

    Qin, Ying Lian; Yang, Bin Wu; Wang, Gao Feng; Sun, Hong

    2016-07-01

    Square-planar complexes are commonly formed by transition metal ions having a d(8) electron configuration. Planar cyanometallate anions have been used extensively as design elements in supramolecular coordination systems. In particular, square-planar tetracyanometallate(II) ions, i.e. [M(CN)4](2-) (M(II) = Ni, Pd or Pt), are used as good building blocks for bimetallic Hofmann-type assemblies and their analogues. Square-planar tetracyanonickellate(II) complexes have been extensively developed with N-donor groups as additional co-ligands, but studies of these systems using O-donor ligands are scarce. A new cyanide-bridged Cu(II)-Ni(II) heterometallic compound, poly[[diaquatetra-μ2-cyanido-κ(8)C:N-nickel(II)copper(II)] monohydrate], {[Cu(II)Ni(II)(CN)4(H2O)2]·H2O}n, has been synthesized and characterized by X-ray single-crystal diffraction analyses, vibrational spectroscopy (FT-IR), thermal analysis, electron paramagnetic resonance (EPR) and magnetic moment measurements. The structural analysis revealed that it has a two-dimensional grid-like structure built up of cationic [Cu(H2O)2](2+) and anionic [Ni(CN)4](2-) units connected through bridging cyanide ligands. The overall three-dimensional supramolecular network is expanded by a combination of interlayer O-H...N and intralayer O-H...O hydrogen-bond interactions. The first decomposition reactions take place at 335 K under a static air atmosphere, which illustrates the existence of guest water molecules in the interlayer spaces. The electron paramagnetic resonance (EPR) spectrum confirms that the Cu(II) cation has an axial coordination symmetry and that the unpaired electrons occupy the d(x(2)-y(2)) orbital. In addition, magnetic investigations showed that antiferromagnetic interactions exist in the Cu(II) atoms through the diamagnetic [Ni(CN)4](2-) ion. PMID:27377277

  12. Synthesis and characterization of magnetic solids featuring 3d-4f heterometallic oxides comprised of spin chains and 3d-6p noncentrosymmetric oxides templated by acentric salt units

    NASA Astrophysics Data System (ADS)

    West, Jennings Palmer

    solvent media is the fact that the salt itself or the alkali/alkaline-earth oxides formed in situ can be incorporated in phase formations. Both of the aforementioned cases, if incorporated, lead to an additional and different type of nonmagnetic spacer for the formation of low-dimensional 3d-4 f extended solids. It is believed that these nonmagnetic, ionic spacers are more disruptive to magnetic super-super-exchange in comparison to the nonmagnetic oxyanionic spacers, and should assist further in achieving truly confined magnetic sublattices. In the studies presented, the overall highlight considering structure and property correlations will be most exemplified through the comparison of two different pseudo-one-dimensional (1D), 3d-4 f arsenate systems (Chapters 3 and 4) where it is observed that further spacing of the 3d-4f sublattices leads to interesting low-dimensional magnetic behavior. In addition, an extension of one of these pseudo-1D, 3d-4f systems (Chapter 5) will highlight the intriguing properties resulting from the study of a family of compounds whereby a double aliovalent substitution has been performed with respect to the parent family. This particular system features a solid solution series where charge disorder exists, and in terms of magnetic properties, there are unique variations in comparison to the parent family. And finally, in relation to heterometallic system types, a new noncentrosymmetric phosphate family containing mixed 3d-6p (where 3 d = Mn, Fe; 6p = Bi3+) will be discussed (Chapter 6). As will be mentioned, new 3d-6p systems were explored originally for host materials where lanthanides could be substituted. Independent of lanthanide substitutions that are yet to be proven, the combination of both bulk acentricity and magnetically active ions makes systems of this type worthy of study due to multiferroic potentials aimed toward the coupling of polarization and magnetization.

  13. Heterometallic antenna-reactor complexes for photocatalysis.

    PubMed

    Swearer, Dayne F; Zhao, Hangqi; Zhou, Linan; Zhang, Chao; Robatjazi, Hossein; Martirez, John Mark P; Krauter, Caroline M; Yazdi, Sadegh; McClain, Michael J; Ringe, Emilie; Carter, Emily A; Nordlander, Peter; Halas, Naomi J

    2016-08-01

    Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna-reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates. PMID:27444015

  14. Heterometallic antenna−reactor complexes for photocatalysis

    PubMed Central

    Swearer, Dayne F.; Zhao, Hangqi; Zhou, Linan; Zhang, Chao; Robatjazi, Hossein; Martirez, John Mark P.; Krauter, Caroline M.; Yazdi, Sadegh; McClain, Michael J.; Ringe, Emilie; Carter, Emily A.; Nordlander, Peter; Halas, Naomi J.

    2016-01-01

    Metallic nanoparticles with strong optically resonant properties behave as nanoscale optical antennas, and have recently shown extraordinary promise as light-driven catalysts. Traditionally, however, heterogeneous catalysis has relied upon weakly light-absorbing metals such as Pd, Pt, Ru, or Rh to lower the activation energy for chemical reactions. Here we show that coupling a plasmonic nanoantenna directly to catalytic nanoparticles enables the light-induced generation of hot carriers within the catalyst nanoparticles, transforming the entire complex into an efficient light-controlled reactive catalyst. In Pd-decorated Al nanocrystals, photocatalytic hydrogen desorption closely follows the antenna-induced local absorption cross-section of the Pd islands, and a supralinear power dependence strongly suggests that hot-carrier-induced desorption occurs at the Pd island surface. When acetylene is present along with hydrogen, the selectivity for photocatalytic ethylene production relative to ethane is strongly enhanced, approaching 40:1. These observations indicate that antenna−reactor complexes may greatly expand possibilities for developing designer photocatalytic substrates. PMID:27444015

  15. The secondary phosphite selenide, CpFe(CO)2P(Se)(O(i)Pr)2, as an organometalloligand in heterometallic M-Se-P-Fe(Cp)-type complexes [M = Cr(0), W(0), Pd(II), Pt(II), Au(I)].

    PubMed

    Liao, Ping-Kuei; Chang, Wen-Shiang; Lee, Yu-Chen; Liao, Jian-Hong; van Zyl, Werner E; Liu, C W

    2013-04-21

    The neutral metalloligand [CpFe(CO)2P(Se)(O(i)Pr)2] (Cp = η(5)-C5H5), which contains the rare secondary phosphite selenide moiety, reacts with different metal complex precursors to form six new heterobimetallic complexes containing M-Se-P-Fe(Cp) bond connectivity. The complexes [M(CO)5{CpFe(CO)2P(Se)(O(i)Pr)2}] (M = Cr, 1; M = W, 2), [MCl2{CpFe(CO)2P(Se)(O(i)Pr)2}2] (M = Pd, 3; M = Pt, 4), [Au4Cl4{CpFe(CO)2P(Se)(O(i)Pr)2}2], 5, and [AuI{CpFe(CO)2P(Se)(O(i)Pr)2}], 6, are all heterometallic, neutral, dinuclear (1, 2, 6), trinuclear (3, 4), and hexanuclear (5) complexes. The complexes were all prepared from straightforward substitution reactions (1-5) or as an adduct, 6. All new complexes were characterized by (1)H, (31)P, (77)Se NMR, infrared spectroscopy, elemental analysis and single crystal X-ray diffraction. PMID:23358569

  16. Synthesis and crystal and molecular structure of three heterometallic polymeric compounds (Ln{sub 2}[LnGe{sub 6}(μ-Oedph){sub 6}(μ-O){sub 3}(μ-OH){sub 3}(H{sub 2}O){sub 4}] · xH{sub 2}O){sub n} [Ln = Nd, x ∼ 26 (I); Er, x ∼ 24 (II); Tm, x ∼ 20 (III); H{sub 4}Oedph = 1-hydroxyethylidenediphosphonic acid

    SciTech Connect

    Sergienko, V. S.; Martsinko, E. E.; Ilyukhin, A. B.; Seifullina, I. I.

    2015-03-15

    The synthesis and X-ray diffraction study of three heterometallic compounds of general formula (Ln{sub 2}[LnGe{sub 6}(μ-Oedph){sub 6}(μ-O){sub 3}(μ-OH){sub 3}(H{sub 2}O){sub 4}] · xH{sub 2}O){sub n} [Ln = Nd, x ∼ 26 (I); Er, x ∼ 24 (II); Tm, x ∼20 (III); H{sub 4}Oedph = 1-hydroxyethylidenediphosphonic acid] are performed. The basis element of structures I–III is a hexanuclear complex anion [Ge(μ-Oedph)(μ-O){sub 0.5}(μ-OH){sub 0.5}]{sub 6}{sup 9−}, in which bridging hydroxo and oxo ligands are statistically disordered with equally probability. Hexameric units are connected by Ln1(H{sub 2}O){sub 4} fragments into a framework whose channels are completely populated by disordered lanthanide atoms and water molecules.

  17. Di-heterometalation of thiol-functionalized peptide nucleic acids

    PubMed Central

    Joshi, Tanmaya; Patra, Malay; Spiccia, Leone; Gasser, Gilles

    2013-01-01

    As a proof-of-principle, two hetero-bimetallic PNA oligomers containing a ruthenium(II) polypyridyl and a cyclopentadienyl manganese tricarbonyl complex have been prepared by serial combination of solid-phase peptide coupling and in-solution thiol chemistry. Solid-phase N-terminus attachment of Ru(II)-polypyridyl carboxylic acid derivative, C1, onto the thiol-functionalized PNA backbone (H-a-a-g-t-c-t-g-c-linker-cys-NH2) has been performed by standard peptide coupling method. As two parallel approaches, the strong affinity of thiols for maleimide and haloacetyl group has been exploited for subsequent post-SPPS addition of cymantrene-based organometallic cores, C2 and C3. Michael-like addition and thioether ligation of thiol functionalized PNA1 (H-gly-a-a-g-t-c-t-g-c-linker-cys-NH2) and PNA2 (C1-a-a-g-t-c-t-g-c-linker-cys-NH2) to cymantrene maleimide and chloroacetyl derivatives, C2 and C3, respectively, has been performed. The synthesized ruthenium(II)-cymantrenyl PNA oligomers have been characterized by mass spectrometry (ESI-MS) and IR spectroscopy. The distinct Mn-CO vibrational IR stretches, between 1,924–2,074 cm−1, have been used as markers to confirm the presence of cymantrenyl units in the PNA sequences and the purity of the HPLC-purified PNA thioethers assessed using LC-MS. PMID:23422249

  18. On the synthesis, measurement and applications of octanuclear heterometallic rings

    NASA Astrophysics Data System (ADS)

    Faust, T. B.

    Inorganic macrocycles have stimulated interest in recent years for their magnetic properties, their associated host-guest chemistry and their aesthetically appealing structures. These characteristics have led to suggestions that they could be exploited for the purposes of ion recognition, catalysis, as single molecule magnets, MRI agents, antibacterial agents and as part of larger architectures in a molecular machine. This thesis explores the properties of a group of chromium(III) macrocycles, with functionality tailored towards different pursuits. Firstly the magnetic properties of a newly synthesised family of ring dimers are investigated. The nature of magnetic exchange within each ring leads to a net electronic spin which, it has been proposed, could represent a quantum binary digit within a quantum information processing system. By linking together pairs of rings, the degree of inter-ring communication can be determined. Such interactions are important for the correlation of spin as initiation of quantum entanglement, a pre-requisite for quantum computing. The rings can also act as fluoro-metallocrown, hosting the molecule which templated their formation. A range of rings with different guests are synthesised and their solid and solution state structures are explored. On templating about bulky dialykyl amines hybrid organic-inorganic rotaxanes are formed where the guest is fixed. In contrast when using small amines and alkali metals, exchange of guests is possible. The dynamics of all of these systems are investigated with proton NMR, quite remarkable for such highly paramagnetic complexes.

  19. Modular "Click" Preparation of Bifunctional Polymeric Heterometallic Catalysts.

    PubMed

    Wang, Wenlong; Zhao, Liyuan; Lv, Hui; Zhang, Guodong; Xia, Chungu; Hahn, F Ekkehardt; Li, Fuwei

    2016-06-27

    Heterobimetallic molecular complexes or strictly alternating metallated polymers are obtained by a click reaction between mononuclear metal complexes (secondary building units, SBUs) bearing NHCs functionalized with either p-azidophenyl or p-ethynylphenyl wingtips. With a copper-NHC complex as SBU the formation of molecular or polymeric compounds did not require any additives as the copper complex catalyzes the click reaction. Transmetallation from heterobimetallic Cu/Ag derivatives to Cu/Pd derivatives was achieved. The linker between the SBUs (flexible or rigid) influences the catalytic activity of the heterobimetallic compounds. The polymer with alternating copper-NHC and silver-NHC units and a flexible methylene-triazole bridge between them shows the highest activity in the catalytic alkynylation of trifluoromethyl ketones to give fluorinated propargylic alcohols. PMID:27331787

  20. Monolacunary Keggin polyoxometalates connected to ten 4d or 4f metal atoms.

    PubMed

    Pang, Haijun; Gómez-García, Carlos J; Peng, Jun; Ma, Huiyuan; Zhang, Chunjing; Wu, Qingyin

    2013-12-21

    The rational self-assembly of mono-lacunary Keggin clusters with 4d and 4f metal salts via a conventional method has yielded two novel polyoxometalate-based 4d-4f heterometallic compounds containing lacunary Keggin anions connected to ten metal atoms: {[Ag{Ag2(H2O)4}{Ln(H2O)6}2H ⊂ {SiW11Ln(H2O)4O39}2]·nH2O (Ln = Ce and n = 7 for 1, Ln = Pr and n = 3 for 2). Their structures were determined by single crystal X-ray diffraction analyses and further characterized by elemental analyses, IR spectra, and thermogravimetric (TG) analyses. A structural feature in 1 and 2 is that each [SiW11O39](8-) cluster (SiW11) is connected to ten metals (five Ag(+) and five Ln(3+) cations), representing the highest number of connected metal atoms to any mono-lacunary Keggin anion to date. This large connectivity leads to a structure with a purely inorganic 3D framework with two kinds of channels along the [100] and [010] directions. The magnetic properties of both compounds show the expected magnetic moments (0.8 and 1.6 amu K mol(-1) per Ce(3+) and Pr(3+) ion, respectively) and confirm the presence of isolated Ce(3+) and Pr(3+) ions. PMID:24067933

  1. CuO-ZnO heterometallic hollow spheres: Morphology and defect structure

    SciTech Connect

    Shi Xuemin; Yang Xuzhuang; Gu Xiaojun; Su Haiquan

    2012-02-15

    The Cu-ZnO hollow spheres, where CuO nanocrystals were dispersed in the shell of ZnO nanoparticals, were synthesized by using highly uniform and monodispersed Cu-embedded carbon spheres as sacrificial templates via a simple route under hydrothermal conditions. The morphology and structure of the spheres were characterized by FTIR, XRD, SEM, TEM and N{sub 2} adsorption-desorption. It was suggested that the OH and C=O groups in the surface of the Cu-embedded carbon spheres facilitated the adsorption of Zn{sup 2+} in the aqueous solution, giving rise to the final CuO-ZnO hollow structure after these Zn{sup 2+}-adsorbed spheres were calcined in air. Moreover, the photoluminescence (PL) study showed that the as-prepared CuO-ZnO hollow spheres and the annealed counterpart exhibited strong and dramatically weakened emissions, respectively. This remarkably different photoluminescent behavior afforded the evidence regarding the oxygen vacancy defects in the CuO-ZnO hollow spheres. - Graphical abstract: CuO-ZnO hollow spheres were obtained using Cu-embedded carbon spheres as template, and the photoluminescent spectra afforded the evidence regarding the oxygen vacancies in the hollow spheres. Highlights: Black-Right-Pointing-Pointer A approach was presented to prepare carbon spheres in a high yield. Black-Right-Pointing-Pointer The fabrication of CuO-ZnO hollow spheres was a simple route. Black-Right-Pointing-Pointer The photoluminescence afforded the evidence of the oxygen vacancies in the hollows. Black-Right-Pointing-Pointer The synthetic approach might be applicable to preparing other hollow structures.

  2. Molecular tectonics: heterometallic coordination networks based on a Pt(II) organometallic metallatecton.

    PubMed

    Zigon, Nicolas; Kyritsakas, Nathalie; Hosseini, Mir Wais

    2015-08-28

    Combinations of a neutral organometallic tecton based on a square planar Pt(ii) complex bearing two triphenylphosphine groups and two 4-ethynylpyridyl coordinating moieties in trans positions, with various metal halides (MX2, M = Co(ii), Ni(ii), Cd(ii), X = Cl(-) or Br(-)) lead to the formation of 2D grid type heterobimetallic coordination networks in the crystalline phase. PMID:26204438

  3. Heterometallic Metal-Organic Frameworks That Catalyze Two Different Reactions Sequentially.

    PubMed

    Saha, Debraj; Hazra, Dipak K; Maity, Tanmoy; Koner, Subratanath

    2016-06-20

    A series of copper- and alkaline-earth-metal-based multidimensional metal-organic frameworks, {[CuMg(pdc)2(H2O)4]·2H2O}n (1), [CuCa(pdc)2]n (2), [CuSr(pdc)2(H2O)3]n (3), and {[CuBa(pdc)2(H2O)5]·H2O}n (4), where H2Pdc = pyridine-2,5-dicarboxylic acid, were hydrothermally synthesized and characterized. Two different metals act as the active center to catalyze two kinds of reactions, viz., olefin to its epoxide followed by epoxide ring opening to afford the corresponding vicinal diol in a sequential manner. PMID:27232433

  4. Assembly of Heterometallic Rigid-Rod Complexes and Coordination Oligomers from Gold(I) Metalloligands.

    PubMed

    Cámara, Verónica; Barquero, Natalia; Bautista, Delia; Gil-Rubio, Juan; Vicente, José

    2015-07-01

    The reactions of TpylC6H4C≡CAuL (Tpyl = 2,2':6',2″-terpyridin-4'-yl; L = PPh3, CNXy; Xy = 2,6-dimethylphenyl) with MX2·nH2O (M = Fe, X = ClO4; M = Co, X = BF4; M = Zn, X = TfO, ClO4) in a 2:1 molar ratio give complexes [M(TpylC6H4C≡CAuL)2]X2. Similarly, the reactions of PPN[(TpylC6H4C≡C)2Au] (PPN = (Ph3P)2N) with an equimolar amount of MX2·nH2O give coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn (M = Fe, Zn, X = ClO4; M = Co, X = BF4). The complexes and oligomers have been isolated and characterized. The crystal structures of [Fe(TpylC6H4C≡CAuCNXy)2](ClO4)2 and [Co(TpylC6H4C≡CAuPPh3)2](BF4)2 have been determined by X-ray diffraction. The hydrodynamic sizes of complexes [M(TpylC6H4C≡CAuPPh3)2]X2 and coordination oligomers [M{(TpylC6H4C≡C)2Au}]nXn have been studied by NMR diffusion spectroscopy and dynamic light scattering measurements. PMID:26087239

  5. New water soluble heterometallic complex showing unpredicted coordination modes of EDTA

    NASA Astrophysics Data System (ADS)

    Mudsainiyan, R. K.; Jassal, A. K.; Chawla, S. K.

    2015-10-01

    A mesoporous 3D polymeric complex (I) having formula {[Zr(IV)O-μ3-(EDTA)Fe(III)OH]·H2O}n has been crystallized and characterized by various techniques. Single-crystal X-ray diffraction analysis revealed that complex (I) crystallized in chiral monoclinic space group Cc (space group no. 9) with unexpected coordination modes of EDTA and mixture of two transition metal ions. In this complex, the coordination number of Zr(IV) ion is seven where four carboxylate oxygen atoms, two nitrogen atoms, one oxide atom are coordinating with Zr(IV). Fe(III) is four coordinated and its coordination environment is composed of three different carboxylic oxygen atoms from three different EDTA and one oxygen atom of -OH group. The structure consists of 4-c and 16-c (2-nodal) net with new topology and point symbol for net is (336·454·530)·(36). TGA study and XRPD pattern showed that the coordination polymer is quite stable even after losing water molecule and -OH ion. Quenching behavior in fluorescence of ligand is observed by complexation with transition metal ions is due to n-π* transition. The SEM micrograph shows the morphology of complex (I) exhibits spherical shape with size ranging from 50 to 280 nm. The minimum N2 (SBET=8.7693 m2/g) and a maximum amount of H2 (high surface area=1044.86 m2/g (STP)) could be adsorbed at 77 K. From DLS study, zeta potential is calculated i.e. -7.94 shows the negative charges on the surface of complex. Hirshfeld surface analysis and fingerprint plots revealed influence of weak or non bonding interactions in crystal packing of complex.

  6. Synthesis and thermal and hydrolytic conversion of heterometallic copper oxide-alkoxides

    SciTech Connect

    Samuels, J.A.; Chiang, Wen-C.; Huffman, J.C. |

    1994-05-11

    The synthesis, characterization, thermal decomposition, and full hydrolysis of Cu{sup I}{sub 2}Zr{sub 2}(O{sup i}Pr){sub 10} (1), Cu{sup I}{sub 4}Zr{sub 4}O(O{sup i}-Pr){sub 18}(2), and Cu{sup II}{sub 4}Zr{sub 4}O{sub 3}(O{sup i}Pr){sub 18}(3) are reported. Compound 1 is converted to compound 2 via hydrolysis. Species 1 and 2 are converted to 3 via oxidation with dioxygen. The molecular structure for 2 consists of two [Cu{sub 2}({mu}{sub 2}-OR){sub 2}Zr{sub 2}Zr{sub 2}({mu}{sub 2}-OR){sub 3}(OR){sub 4}]{sup +} fragments bound together via a pseudoterahedron {mu}{sub 4}-O{sup 2{minus}} ligand bridging the copper centers. The X-ray structure of 3 consists of a planar Cu{sub 4}O(O{sup i}Pr){sub 2}{sup 4+} fragment capped by two Zr{sub 2}O(O{sup i}Pr){sub 8}{sup 2{minus}} face-sharing bioctahedral units. The central oxo of the copper fragment is rigorously square-planar. Magnetic studies of 3 reveal a singlet ground state both in solution and the solid state. TGA studies of 1-3 reveal that all the systems undergo internal redox, producing copper metal, acetone, and H{sub 2}. The final products contained an increasing amount of zirconia with increasing number f oxo ligands in the precursor species. Full hydrolysis of 1 and 3, followed by thermolysis, produced Cu{sup o}, Cu{sub 2}O, and CuO with zirconia depending on thermolysis conditions. Results also indicate that precursor design influences the thermolysis behavior of the solid-state product.

  7. Substituent effect on formation of heterometallic molecular wheels: synthesis, crystal structure, and magnetic properties.

    PubMed

    Ni, Zhong-Hai; Zhang, Li-Fang; Tangoulis, Vassilis; Wernsdorfer, Wolfgang; Cui, Ai-Li; Sato, Osamu; Kou, Hui-Zhong

    2007-07-23

    The reaction of manganese(III) Schiff bases of the type salen(2-) (N,N'-ethylenebis(salicylideneaminato)) with X-substituted (X = CH(3), Cl) pyridinecarboxamide dicyanoferrite(III) [Fe(X-bpb)(CN)(2)](-) gave rise to a series of cyanide-bridged Mn(6)Fe(6) molecular wheels, [Mn(III)(salen)](6)[Fe(III)(bpmb)(CN)(2)](6) x 7H(2)O (1), [Mn(salen)](6)[Fe(bpClb)(CN)(2)](6) x 4H(2)O x 2CH(3)OH (2), [Mn(salen)](6)[Fe(bpdmb)(CN)(2)](6) x 10H(2)O x 5CH(3)OH (3), [Mn(5-Br(salpn))](6)[Fe(bpmb)(CN)(2)](6) x 24H(2)O x 8CH(3)CN (4), and [Mn(5-Cl(salpn))](6)[Fe(bpmb)(CN)(2)](6) x 25H(2)O x 5CH(3)CN (5). Compared with [Fe(bpb)(CN)(2)](-), which always gives rise to 1D or polynuclear species when reacting with Mn(III) Schiff bases, the introduction of substituents (X) to the bpb(2-) ligand has a driving force in formation of the novel wheel structure. Magnetic studies reveal that high-spin ground state S = 15 is present in the wheel compounds originated from the ferromagnetic Mn(III)-Fe(III) coupling. For the first time, the quantum Monte Carlo study has been used to modulate the magnetic susceptibility of the huge Mn(6)Fe(6) metallomacrocycles, showing that the magnetic coupling constants J range from 3.0 to 8.0 K on the basis of the spin Hamiltonian [Formula: see text]. Hysteresis loops for 1 have been observed below 0.8 K, indicative of a single-molecule magnet with a blocking temperature (TB) of 0.8 K. Molecular wheels 2-5 exhibit frequency dependence of alternating-current magnetic susceptibility under zero direct-current magnetic field, signifying the slow magnetization relaxation similar to that of 1. Significantly, an unprecedented archlike Mn(2)Fe(2) cluster, [Mn(5-Cl(salpn))](2)[Fe(bpmb)(CN)(2)](2) x 3H(2)O x CH(3)CN (6), has been isolated as an intermediate of the Mn(6)Fe(6) wheel 5. Ferromagnetic Mn(III)-Fe(III) coupling results in a high-spin S = 5 ground state. Combination of the high-spin state and a negative magnetic anisotropy (D) results in the observation of slow magnetization relaxation in 6. PMID:17602553

  8. Luminescent homo- and hetero-metallic hybrid molecular materials constructed by covalent grafting

    NASA Astrophysics Data System (ADS)

    Wang, F. F.; Yan, B.

    2013-01-01

    In this paper, 3-(triethoxysilyl)-propyl isocyanate (abbreviated as TESPIC) was modified by ethylparaben (EPB) to produce corresponding organic-inorganic monomers (EPB-TESPIC) with two components equipped with covalent bonds, which not only can coordinate to RE ions (Tb3+ and Eu3+) but also act as a sol-gel precursor. Luminescent hybrid materials consisting of terbium-europium complex, covalently bonded to silica-based network, have been obtained in situ via a sol-gel approach. Proton nuclear magnetic resonance spectroscopy (1HNMR) and Fourier transform infrared spectroscopy (FT-IR) were applied to characterize the structure of EPB-TESPIC. UV-visible, phosphorescence, and luminescence spectra were obtained to characterize the photophysical properties of the obtained hybrid material. Through co-hydrolysis and polycondensation, Tb3+ and Eu3+ can be introduced into the same organic-inorganic hybrid monomer, forming Si-O backbones. The experimental results show that the strong luminescence of rare-earth ions substantiates the optimum energy match and effective intramolecular energy transfer between the triplet state energy of coordination complex and the emissive energy level of the rare-earth ions. The hybrid material systems are expected to have potential applications in photophysical sensors.

  9. New water soluble heterometallic complex showing unpredicted coordination modes of EDTA

    SciTech Connect

    Mudsainiyan, R.K. Jassal, A.K.; Chawla, S.K.

    2015-10-15

    A mesoporous 3D polymeric complex (I) having formula ([Zr(IV)O-μ{sup 3}-(EDTA)Fe(III)OH]·H{sub 2}O){sub n} has been crystallized and characterized by various techniques. Single-crystal X-ray diffraction analysis revealed that complex (I) crystallized in chiral monoclinic space group Cc (space group no. 9) with unexpected coordination modes of EDTA and mixture of two transition metal ions. In this complex, the coordination number of Zr(IV) ion is seven where four carboxylate oxygen atoms, two nitrogen atoms, one oxide atom are coordinating with Zr(IV). Fe(III) is four coordinated and its coordination environment is composed of three different carboxylic oxygen atoms from three different EDTA and one oxygen atom of –OH group. The structure consists of 4-c and 16-c (2-nodal) net with new topology and point symbol for net is (3{sup 36}·4{sup 54}·5{sup 30})·(3{sup 6}). TGA study and XRPD pattern showed that the coordination polymer is quite stable even after losing water molecule and –OH ion. Quenching behavior in fluorescence of ligand is observed by complexation with transition metal ions is due to n–π⁎ transition. The SEM micrograph shows the morphology of complex (I) exhibits spherical shape with size ranging from 50 to 280 nm. The minimum N{sub 2} (S{sub BET}=8.7693 m{sup 2}/g) and a maximum amount of H{sub 2} (high surface area=1044.86 m{sup 2}/g (STP)) could be adsorbed at 77 K. From DLS study, zeta potential is calculated i.e. −7.94 shows the negative charges on the surface of complex. Hirshfeld surface analysis and fingerprint plots revealed influence of weak or non bonding interactions in crystal packing of complex. - Graphical abstract: The complex (I) crystallized with unexpected coordination modes of EDTA having 4-c, 16-c net with new topology and point symbol is (3{sup 36}·4{sup 54}·5{sup 30})·(3{sup 6}). TGA study and XRPD pattern proved its stability with high preference of H{sub 2} uptake by complex. - Highlights: • 3D complex having unexpected coordination modes of EDTA with Zr(IV) and Fe(III). • The structure consists of 4-c and 16-c (2-nodal) net with new topology. • Reasonable S{sub BET} (8.7693 m{sup 2}/g) but high H{sub 2} uptake (1044.86 m{sup 2}/g) due to limited pore size. • Quenching behavior due to n–π⁎ transition by complexation with transition metal ions. • From DLS study, zeta potential value is −7.94.

  10. New heterometallic zirconium metalloporphyrin frameworks and their heteroatom-activated high-surface-area carbon derivatives.

    PubMed

    Lin, Qipu; Bu, Xianhui; Kong, Aiguo; Mao, Chengyu; Zhao, Xiang; Bu, Fei; Feng, Pingyun

    2015-02-18

    Four cubic zirconium-porphyrin frameworks, CPM-99(H2, Zn, Co, Fe), were synthesized by a molecular-configuration-guided strategy. Augmentation of meso-substituted side arms (with double-torsional biphenyl rings) of tetratopic porphyrin linkers leads to a successful implementation of zirconium-carboxylate frameworks with cubic 2.5 nm cage. The hard-templating effect of Zr6-polyoxo-cluster and uniformly embedded (metallo)porphyrin centers endow CPM-99 with highly desirable properties as precursors for oxygen reduction reaction (ORR) catalysts. The pyrolytic products not only retain the microcubic morphology of the parent CPM-99 but also possess porphyrinic active sites, hierarchical porosity, and highly conducting networks. CPM-99Fe-derived material, denoted CPM-99Fe/C, exhibits the best ORR activity, comparable to benchmark 20% Pt/C in alkaline and acidic media, but CPM-99Fe/C is more durable and methanol-tolerant. This work demonstrates a new route for the development of nonprecious metal ORR catalysts from stable metalloporphyrinic MOFs. PMID:25651395

  11. Highly efficient spin polarizer based on individual heterometallic cubane single-molecule magnets

    NASA Astrophysics Data System (ADS)

    Dong, Damin

    2015-09-01

    The spin-polarized transport across a single-molecule magnet [Mn3Zn(hmp)3O(N3)3(C3H5O2)3].2CHCl3 has been investigated using a density functional theory combined with Keldysh non-equilibrium Green's function formalism. It is shown that this single-molecule magnet has perfect spin filter behaviour. By adsorbing Ni3 cluster onto non-magnetic Au electrode, a large magnetoresistance exceeding 172% is found displaying molecular spin valve feature. Due to the tunneling via discrete quantum-mechanical states, the I-V curve has a stepwise character and negative differential resistance behaviour.

  12. Luminescent Ag i-Cu i heterometallic hexa-, octa-, and hexadecanuclear alkynyl complexes.

    PubMed

    Wei, Qiao-Hua; Yin, Gang-Qiang; Zhang, Li-Yi; Shi, Lin-Xi; Mao, Zong-Wan; Chen, Zhong-Ning

    2004-05-31

    A series of Ag(I)-Cu(I) heteronuclear alkynyl complexes were prepared by reaction of polymeric (MCCC(6)H(4)R-4)(n)() (M = Cu(I) or Ag(I); R = H, CH(3), OCH(3), NO(2), COCH(3)) with [M'(2)(mu-Ph(2)PXPPh(2))(2)(MeCN)(2)](ClO(4))(2) (M' = Ag(I) or Cu(I); X = NH or CH(2)). Heterohexanuclear complexes [Ag(4)Cu(2)(mu-Ph(2)PNHPPh(2))(4)(CCC(6)H(4)R-4)(4)](ClO(4))(2) (R = H, 1; CH(3), 2) were afforded when X = NH, and heterooctanuclear complexes [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)R-4)(6)(MeCN)](ClO(4))(2) (R = H, 3; CH(3), 4; OCH(3), 5; NO(2), 6) were isolated when X = CH(2). Self-assembly reaction between (MCCC(6)H(4)COCH(3)-4)(n) and [M'(2)(mu-Ph(2)PCH(2)PPh(2))(2)(MeCN)(2)](ClO(4))(2), however, gave heterohexadecanuclear complex [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)COCH(3)-4)(6)](2)(ClO(4))(4) (7). The heterohexanuclear complexes 1 and 2 show a bicapped cubic skeleton (Ag(4)Cu(2)C(4)) consisting of four Ag(I) and two Cu(I) atoms and four acetylide C donors. The heterooctanuclear complexes 3-6 exhibit a waterwheel-like structure that can be regarded as two Ag(3)Cu(CCC(6)H(5))(3) components put together by three bridging Ph(2)PCH(2)PPh(2) ligands. The heterohexadecanuclear complex 7 can be viewed as a dimer of heterooctanuclear complex [Ag(6)Cu(2)(micro-Ph(2)PCH(2)PPh(2))(3)(CCC(6)H(4)COCH(3)-4)(6)](ClO(4))(2) through the silver and acetyl oxygen (Ag-O = 2.534 (4) A) linkage between two waterwheel-like Ag(6)Cu(2) units. All of the complexes show intense luminescence in the solid states and in fluid solutions. The microsecond scale of lifetimes in the solid state at 298 K reveals that the emission is phosphorescent in nature. The emissive state in compounds 1-5 is likely derived from a (3)LMCT (CCC(6)H(4)R-4 --> Ag(4)Cu(2) or Ag(6)Cu(2)) transition, mixed with a metal cluster-centered (d --> s) excited state. The lowest lying excited state in compounds 6 and 7 containing electron-deficient 4-nitrophenylacetylide and 4-acetylphenylacetylide, respectively, however, is likely dominated by an intraligand (3)[pi --> pi] character. PMID:15154812

  13. Synthesis and thermolytic behavior of mixed-valence homo- and heterometallic group 14 alkoxides

    SciTech Connect

    Teff, D.J.; Minear, C.D.; Baxter, D.V.; Caulton, K.G.

    1998-05-18

    The mixed-valence molecule Sn{sup II}Sn{sup IV} (OPr){sub 6} is conveniently synthesized and is shown to exchange bridging and terminal alkoxides in solution in its Sn({micro}-OPr){sub 3}Sn(OPr){sub 3} structure. Pb{sub 3}SnO(POr){sub 8} is synthesized and shown to undergo an intramolecular fluxional process in solution. Both molecules are sufficiently volatile for CVD study, and comparison of CVD behaviors of these and of M(OPr){sub 2} (M = Sn, Pb), Sn(POr){sub 4}, SnZr(OPr){sub 6}, and Pb{sub 3}-ZrO(OPr){sub 8} shows the reducing capacity of the isopropoxide moiety dominates the thermolytic behavior of all these species, giving metallic Sn or Pb in all cases. Only Zr, when it is present, forms ZrO{sub 2}. The oxide in Pb{sub 3}SnO(POr){sub 8}yields PbO (and 2 Pb{sup 0} and 1 Sn{sup 0}), in contrast to the relative electropositivity of Sn and Pb, a fact attributed to kinetic control of CVD behavior.

  14. Heterometallic alkoxides of zirconium with tin(II) or lead(II)

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1996-05-08

    Syntheses of SnZr(OR){sub 6} (R = {sup i}Pr, {sup t}Bu) and PbZr(O{sup t}Bu){sub 6} are described. With Pb and the smaller ligand O{sup i}Pr, no 1:1 compound forms, but instead Pb{sub 4}Zr{sub 2}(O{sup i}Pr){sub 16} and Pb{sub 2}Zr{sub 4}(O{sup i}Pr){sub 20} are isolated. The latter two compounds are shown to have serpentine (not closo) structures with six-coordinate Zr and three- and four-coordinate Pb. Spectroscopic studies show fluxionality (including Pb site exchange) and retention of structure in aromatic solvents. Synthetic interconversions are effected with addition of the appropriate alkoxide (Pb(O{sup i}Pr){sub 2} or Zr(O{sup i}Pr){sub 4}) with the correct stoichiometry. Titanium forms no analogous compounds. Crystallographic data (both P2{sub 1}/c at {minus}174{degrees}C) for Pb{sub 4}Zr{sub 2}(O{sup i}Pr){sub 16}, a = 12.190(6) {angstrom}, b = 14.701(7) {angstrom}, c = 19.978(13) {angstrom}, and {beta} = 105.57(3){degrees} with Z = 2; for Pb{sub 2}Zr{sub 4}(O{sup i}Pr){sub 20}, {alpha} = 16.996(6) {angstrom}, b = 10.014(3) {angstrom}, c = 24.924(9) {angstrom}, and {beta} = 105.86(1){degrees} with Z = 2.

  15. Large zero-field splittings of the ground spin state arising from antisymmetric exchange effects in heterometallic triangles.

    PubMed

    Magee, Samantha A; Sproules, Stephen; Barra, Anne-Laure; Timco, Grigore A; Chilton, Nicholas F; Collison, David; Winpenny, Richard E P; McInnes, Eric J L

    2014-05-19

    [Ru2Mn(O)(O2CtBu)6(py)3] has an S=5/2 ground state with a very large zero-field splitting (ZFS) of D=2.9 cm(-1), as characterized by EPR spectroscopy at 4-330 GHz. This is far too large to be due to the Mn(II) ion (D <0.2 cm(-1)), as shown from the {Fe2Mn} analogue, but can be modeled by antisymmetric exchange effects. PMID:24737709

  16. Two-dimensionally stacked heterometallic layers hosting a discrete chair dodecameric ring of water clusters: synthesis and structural study.

    PubMed

    Kenfack Tsobnang, Patrice; Wenger, Emmanuel; Biache, Coralie; Lambi Ngolui, John; Ponou, Siméon; Dahaoui, Slimane; Lecomte, Claude

    2014-10-01

    The stacked two-dimensional supramolecular compound catena-{Co(amp)3Cr(ox)3·6H2O} (amp = 2-picolylamine, ox = oxalate) has been synthesized from the bimolecular approach using hydrogen bonds. It is built from layers in which both Co(amp)(3+) (D) and Cr(ox)(3-) (A) ions are bonded in a repeating DADADA… pattern along the a and c axes by multiple hydrogen bonds. These layers host a well resolved R12 dodecameric discrete ring of water clusters built by six independent molecules located around the 2c centrosymmetric Wyckoff positions of the P21/n space group in which the compound crystallizes. These clusters are ranged along the [001] direction, occupy 733.5 Å(3) (22.0%) of the unit cell and have a chair conformation via 12 hydrogen bonds. The water molecules of the cluster are linked with stronger hydrogen bonds than those between the cluster and its host, which explains the single continuous step of the dehydration process of the compound. PMID:25274525

  17. Heterometallic Fe(III) /K Coordination Polymer with a Wide Thermal Hysteretic Spin Transition at Room Temperature.

    PubMed

    Kang, Soonchul; Shiota, Yoshihito; Kariyazaki, Akira; Kanegawa, Shinji; Yoshizawa, Kazunari; Sato, Osamu

    2016-01-11

    The anionic Fe(III) complex exhibiting cooperative spin transition with a wide thermal hysteresis near room temperature, K[Fe(5-Brthsa)2 ] (5-Brthsa-H2 =5-bromosalicylaldehyde thiosemicarbazone), is reported. The hysteresis (Δ=69 K in the first cycle) shows a one-step transition in heating mode and a two-step transition in cooling mode. X-ray structure analysis showed that the coexistence of hydrogen bond and cation-π interactions, as well as alkali metal coordination bonds, to give 2D coordination polymer structure. This result is contrary to previous reports of broad thermal hysteresis induced by coordination bonds of Fe(II) spin crossover coordination polymers (with 1D/3D structures), and by strong intermolecular interactions in the molecular packing through π-π stacking or hydrogen-bond networks. As a consequence, the importance, or the very good suitability of alkali metal-based coordination bonds and cation-π interactions for communicating cooperative interactions in spin-crossover (SCO) compounds must be reconsidered. PMID:26564335

  18. Heterometallic 3d-4f single-molecule magnets: ligand and metal ion influences on the magnetic relaxation.

    PubMed

    Langley, Stuart K; Le, Crystal; Ungur, Liviu; Moubaraki, Boujemaa; Abrahams, Brendan F; Chibotaru, Liviu F; Murray, Keith S

    2015-04-01

    Six tetranuclear 3d–4f single-molecule magnet (SMM) complexes formed using N-n-butyldiethanolamine and N-methyldiethanolamine in conjunction with ortho- and para-substituted benzoic acid and hexafluoroacetoacetone ligands yield two families, both having a butterfly metallic core. The first consists of four complexes of type {Co2(III)Dy2(III)} and {Co2(III)Co(II)Dy(III)} using N-n-butyldiethanolamine with variation of the carboxylate ligand. The anisotropy barriers are 80 cm–1, (77 and 96 cm–1—two relaxation processes occur), 117 and 88 cm–1, respectively, each following a relaxation mechanism from a single DyIII ion. The second family consists of a {Co2(III)Dy2(III)} and a {Cr2(III)Dy2(III)} complex, from the ligand combination of N-methyldiethanolamine and hexafluoroacetylacetone. Both show SMM behavior, the Co(III) example displaying an anisotropy barrier of 23 cm–1. The Cr(III) complex displays a barrier of 28 cm–1, with longer relaxation times and open hysteresis loops, the latter of which is not seen in the Co(III) case. This is a consequence of strong Dy(III)–Cr(III) magnetic interactions, with the relaxation arising from the electronic structure of the whole complex and not from a single DyIII ion. The results suggest that the presence of strong exchange interactions lead to significantly longer relaxation times than in isostructural complexes where the exchange is weak. The study also suggests that electron-withdrawing groups on both bridging (carboxylate) and terminal (β-diketonate) ligands enhance the anisotropy barrier. PMID:25796958

  19. Ferrocene-based compartmental ligand for the assembly of neutral Zn(II)/Ln(III) heterometallic complexes.

    PubMed

    Chandrasekhar, Vadapalli; Chakraborty, Amit; Sañudo, E Carolina

    2013-10-01

    A ferrocene-based compartmental ligand, H2L, was synthesized by the reaction of diacetyl ferrocene with hydrazine hydrate followed by a condensation reaction with o-vanillin. [L](2-) possesses a dual coordination pocket, an inner pocket of 2 imino nitrogens and two phenolate oxygens and an outer pocket of two phenolate and two methoxy oxygen atoms. Utilizing this ligand, several Zn(II)/Ln(III) heterobimetallic complexes were assembled: [LZn(μ-OAc)Dy(NO3)2] (2), [LZn(μ-OAc)Tb(NO3)2] (3), [LZn(μ-OAc)Gd(NO3)2·2CHCl3] (4), [LZn(μ-OAc)Er(NO3)2] (5), [LZn(μ-OAc)Ho(NO3)2] (6), [LZn(μ-OAc)Eu(NO3)2] (7). All of these metal complexes are neutral and isostructural: the Zn(II) ion occupies the inner coordination pocket while the Ln(III) ion occupies the outer coordination pocket of the doubly deprotonated ligand [L](2-). Zn(II) has a coordination number of 5 (2N, 3O) in a square pyramidal coordination geometry while Ln(III) has a coordination number of 9 (9O) in a distorted tricapped trigonal prismatic geometry. Zn(II) and the 4f metal ion are bridged to each other by two phenolate oxygen atoms and an acetate ligand. ESI-MS reveals that 2-7 retain their structural integrity in solution. Cyclic voltammetry of 1-7 revealed a quasi-reversible oxidation (involving the ferrocene motif) and an irreversible reduction of the hydrazone unit. Magnetic studies of 2, 3 and 6 were carried out. Ac susceptibility studies did not reveal slow relaxation of magnetization. PMID:23893198

  20. Integration of Paramagnetic Diruthenium Complexes into an Extended Chain by Heterometallic Metal-Metal Bonds with Diplatinum Complexes.

    PubMed

    Uemura, Kazuhiro; Uesugi, Naoyuki; Matsuyama, Akina; Ebihara, Masahiro; Yoshikawa, Hirofumi; Awaga, Kunio

    2016-07-18

    We successfully obtained a paramagnetic one-dimensional (1D) chain complex [{Ru2(O2CCH3)4}{Pt2(piam)2(NH3)4}2]n(PF6)4n·4nH2O (2; piam = pivalamidate) extended by metal-metal bonds. Compound 2 comprises two types of metal species, ruthenium and platinum, where an acetate-bridged dinuclear ruthenium complex (i.e., [Ru2]) and a pivalamidate-bridged platinum complex (i.e., [Pt2]) are connected by axial metal-metal bonds, forming an attractive quasi-1D infinite chain that can be expressed as -{[Pt2]-[Ru2]-[Pt2]}n-. Such axial metal-metal bonds are attributed to the interaction between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) along the z axis, where both the HOMO in [Pt2(II,II)] and the LUMO in [Ru2(II,II)] are σ* orbitals associated with metal cores. The crystal structure and X-ray photoelectron spectrum for 2 reveal that metal oxidation states are -{[Pt2(II,II)]-[Ru2(II,II)]-[Pt2(II,II)]}n-, where [Ru2(II,II)] can have an electronic configuration of σ(2)π(4)δ(2)δ*(2)π*(2) or σ(2)π(4)δ(2)π*(4). The magnetic susceptibility of 2 has a μeff [∝(χT)(1/2)] value of 2.77 μB per [Pt2(II,II)]-[Ru2(II,II)]-[Pt2(II,II)] unit at 300 K, showing that two unpaired electrons lie on π*(Ru2). Magnetic measurements performed at temperatures of 2-300 K indicate that S = 1 Ru2(II,II) units are weakly antiferromagnetically coupled (zJ = -1.4 cm(-1)) with a large zero-field splitting (D = 221 cm(-1)). PMID:27348516

  1. Self-assembly of a unique 3d/4f heterometallic square prismatic box-like coordination cage.

    PubMed

    Li, Li; Zhang, Yingjie; Avdeev, Maxim; Lindoy, Leonard F; Harman, David G; Zheng, Rongkun; Cheng, Zhenxiang; Aldrich-Wright, Janice R; Li, Feng

    2016-06-21

    We present the synthesis and characterization of a unique, slightly distorted square prismatic, box-like coordination cage of type [Cu6Dy8L8(MeOH)8(H2O)6](NO3)12·χsolvent obtained via the supramolecular assembly between a non-centrosymmetric Dy(iii) metalloligand and Cu(ii) nitrate. Magnetic susceptibility measurements indicate that the complex behaves as a single-molecule magnet. PMID:27227419

  2. Binary and Ternary Heterometallic (La3+, Gd3+, Y3+)-Eu3+ Functionalized SBA-15 Mesoporous Hybrids: Chemically Bonded Assembly and Photoluminescence

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Kong, Li-Li

    2010-07-01

    A novel kind of organic-inorganic monomer SUASi has been achieved by modifying 5-sulfosalicylic acid (SUA) with 3-aminopropyltrimethoxysilane (APS), subsequently binary and ternary Eu3+ mesoporous hybrid materials with 5-sulfosalicylic acid (SUA)-functionalized SBA-15 and 1,10-phenanthroline (phen) are synthesized by co-condensation of SUASi and TEOS in the presence of Eu3+ complex and Pluronic P123 as a template. Finally, luminescent hybrid mesoporous materials consisting of active rare earth ions (Eu3+)—inert rare earth ions (Y3+, La3+, Gd3+) complex covalently bonded to the mesoporous materials network have been obtained via this sol-gel approach. The physical characterization and photoluminescence of all these resulting materials are studied in detail. Especially the luminescent behavior has been studied with the different ratios of Eu3+-(Y3+, La3+, Gd3+), which suggests that the existence of inert rare earth ions can enhance the luminescence intensity of Eu3+. This may be due to the intramolecular energy transfer between Y3+, La3+, Gd3+, and Eu3+ through the covalently bonded mesoporous framework.

  3. Building complexity in O2-binding copper complexes. Site-selective metalation and intermolecular O2-binding at dicopper and heterometallic complexes derived from an unsymmetric ligand.

    PubMed

    Serrano-Plana, Joan; Costas, Miquel; Company, Anna

    2014-12-15

    A novel unsymmetric dinucleating ligand (L(N3N4)) combining a tridentate and a tetradentate binding sites linked through a m-xylyl spacer was synthesized as ligand scaffold for preparing homo- and dimetallic complexes, where the two metal ions are bound in two different coordination environments. Site-selective binding of different metal ions is demonstrated. L(N3N4) is able to discriminate between Cu(I) and a complementary metal (M' = Cu(I), Zn(II), Fe(II), Cu(II), or Ga(III)) so that pure heterodimetallic complexes with a general formula [Cu(I)M'(L(N3N4))](n+) are synthesized. Reaction of the dicopper(I) complex [Cu(I)2(L(N3N4))](2+) with O2 leads to the formation of two different copper-dioxygen (Cu2O2) intermolecular species (O and (T)P) between two copper atoms located in the same site from different complex molecules. Taking advantage of this feature, reaction of the heterodimetallic complexes [CuM'(L(N3N4))](n+) with O2 at low temperature is used as a tool to determine the final position of the Cu(I) center in the system because only one of the two Cu2O2 species is formed. PMID:25424176

  4. Cr(III)-Cr(III) interactions in two alkoxo-bridged heterometallic Zn2Cr2 complexes self-assembled from zinc oxide, Reinecke's salt, and diethanolamine.

    PubMed

    Semenaka, Valentyna V; Nesterova, Oksana V; Kokozay, Volodymyr N; Dyakonenko, Viktoriya V; Zubatyuk, Roman I; Shishkin, Oleg V; Boca, Roman; Jezierska, Julia; Ozarowski, Andrew

    2010-06-21

    Two new tetranuclear complexes, [Zn(2)Cr(2)(NCS)(4)(Dea)(2)(HDea)(2)].4DMSO (1; DMSO = dimethyl sulfoxide) and [Zn(2)Cr(2)(NCS)(4)(Dea)(2)(HDea)(2)].2CH(3)CN (2), were prepared from zinc oxide, Reinecke's salt, NH(4)[Cr(NCS)(4)(NH(3))(2)].H(2)O, ammonium thiocyanate, and a nonaqueous solution of diethanolamine (H(2)Dea) in a reaction carried out under open air. Both compounds have similar centrosymmetric crystal structures based on a tetranuclear {Zn(2)Cr(2)(mu(3)-O)(2)(mu-O)(4)} core. Variable-temperature magnetic susceptibility measurements of 1 and 2 show weak antiferromagnetic coupling between chromium centers. The magnetic data and high-field, high-frequency electron paramagnetic resonance spectra were analyzed in terms of the spin Hamiltonian H = JS(1).S(2) - j(S(1).S(2) + mu(B)B{g(1)}S(1) + D(Cr){S(z1)(2) - S(1)(S(1) + 1)/3} + E(Cr)(S(x1)(2) - S(y1)(2)) + mu(B)B{g(2)}S(2) + D(Cr){S(z2)(2) - S(2)(S(2) + 1)/3} + E(Cr)(S(x2)(2) - S(y2)(2)) + D(12){S(z1)S(z2) - S(1).S(2)/3} + E(12)(S(x1)S(x2) - S(y1)S(y2)) with J = 13.7 cm(-1), j = 1.1 cm(-1), D(Cr) = 0.3864 cm(-1), E(Cr) = -0.1104 cm(-1), D(12) = -0.1873 cm(-1), and E(12) = -0.0155 cm(-1) for 1 and J = 9.4 cm(-1), j = 0.8 cm(-1), D(Cr) = 0.3564 cm(-1), E(Cr) = -0.0647 cm(-1), D(12) = -0.1850 cm(-1), and E(12) = -0.0112 cm(-1) for 2. Density functional theory (DFT) calculations were employed to calculate the zero-field splitting on Cr(3+) ions. Calculations of the exchange integrals J were attempted by using the "broken-symmetry" DFT method. PMID:20540565

  5. Syntheses, crystal structures and properties of series of 4d–4f ln(III)–Ag(I) heterometallic coordination polymers

    SciTech Connect

    Ran, Xing-Rui; Wang, Ning; Xie, Wei-Ping; Xiong, Yan-Ju; Cheng, Qian; Long, Yi; Yue, Shan-Tang; Liu, Ying-Liang

    2015-05-15

    By control of the experimental parameters such as ligands, pH value and reacting temperature, series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction, namely, ([Ln{sup III}Ag{sup I}(na)(ina)(ox)]·2(H{sub 2}O)){sub n} [Ln=Sm(1), Eu(2), Gd(3), Tb(4), Dy(5), Ho(6), Y(7), Yb(8)], have been successfully synthesized under hydrothermal conditions and structurally characterized. All the complexes are characterized by elemental analyses, FT-IR spectroscopy, Powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). Furthermore, the luminescence properties of compounds 2 and 4 and the magsnetic properties of complexes 3 and 5 were also investigated in detail. - Graphical abstract: Series of three-dimensional (3D) 4d–4f Ln(III)–Ag(I) porous coordination polymers (PCPs) with interesting chain-layer construction which are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. - Highlights: • Complexes 1–8 are first built by three kinds of organic ligands based on nicotinic acid and isonicotinic acid. • PCPs 1–8 are featured by tetranuclear Ln{sub 2}Ag{sub 2} and ‘non-linear’ N–Ag–N linkages. • The total solvent-accessible volume of PCP 2 comprises 11.6% of the crystal volume after dislodging the free water molecules. • Complexes 2 and 4 exhibit characteristic lanthanide-centered luminescence, while compounds 3 and 5 show antiferromagnetic behaviors.

  6. Heterometallic Coordination Polymers Assembled from Trigonal Trinuclear Fe2Ni-Pivalate Blocks and Polypyridine Spacers: Topological Diversity, Sorption, and Catalytic Properties.

    PubMed

    Sotnik, Svetlana A; Polunin, Ruslan A; Kiskin, Mikhail A; Kirillov, Alexander M; Dorofeeva, Victoria N; Gavrilenko, Konstantin S; Eremenko, Igor L; Novotortsev, Vladimir M; Kolotilov, Sergey V

    2015-06-01

    Linkage of the trigonal complex [Fe2NiO(Piv)6] (where Piv(-) = pivalate) by a series of polypyridine ligands, namely, tris(4-pyridyl)triazine (L(2)), 2,6-bis(3-pyridyl)-4-(4-pyridyl)pyridine (L(3)), N-(bis-2,2-(4-pyridyloxymethyl)-3-(4-pyridyloxy)propyl))pyridone-4 (L(4)), and 4-(N,N-diethylamino)phenyl-bis-2,6-(4-pyridyl)pyridine (L(5)) resulted in the formation of novel coordination polymers [Fe2NiO(Piv)6(L(2))]n (2), [Fe2NiO(Piv)6(L(3))]n (3), [Fe2NiO(Piv)6(L(4))]n·nHPiv (4), and [{Fe2NiO(Piv)6}4{L(5)}6]n·3nDEF (5, where DEF is N,N-diethylformamide), which were crystallographically characterized. The topological analysis of 3, 4, and 5 disclosed the 3,3,4,4-connected 2D (3, 4) or 3,4,4-connected 1D (5) underlying networks which, upon further simplification, gave rise to the uninodal 3-connected nets with the respective fes (3, 4) or SP 1-periodic net (4,4)(0,2) (5) topologies, driven by the cluster [Fe2Ni(μ3-O)(μ-Piv)6] nodes and the polypyridine μ3-L(3,4) or μ2-L(5) blocks. The obtained topologies were compared with those identified in other closely related derivatives [Fe2NiO(Piv)6(L(1))]n (1) and {Fe2NiO(Piv)6}8{L(6)}12 (6), where L(1) and L(6) are tris(4-pyridyl)pyridine and 4-(N,N-dimethylamino)phenyl-bis-2,6-(4-pyridyl)pyridine, respectively. It was shown that a key structure-driven role in defining the dimensionality and topology of the resulting coordination network is played by the type of polypyridine spacer. Compounds 2 and 3 possess a porous structure, as confirmed by the N2 and H2 sorption data at 78 K. Methanol and ethanol sorption by 2 was also studied indicating that the pores filled by these substrates did not induce any structural rearrangement of this sorbent. Additionally, porous coordination polymer 2 was also applied as a heterogeneous catalyst for the condensation of salicylaldehyde or 9-anthracenecarbaldehyde with malononitrile. The best activity of 2 was observed in the case of salicylaldehyde substrate, resulting in up to 88% conversion into 2-imino-2H-chromen-3-carbonitrile. PMID:25953066

  7. Pentanuclear heterometallic {Ni2Ln3} (Ln = Gd, Dy, Tb, Ho) assemblies. Single-molecule magnet behavior and multistep relaxation in the dysprosium derivative.

    PubMed

    Chandrasekhar, Vadapalli; Bag, Prasenjit; Kroener, Wolfgang; Gieb, Klaus; Müller, Paul

    2013-11-18

    The reaction between Ln(III) chloride and NiCl2·4H2O salts in presence of a multidentate sterically unencumbered ligand, (E)-2,2'-(2-hydroxy-3-((2-hydroxyphenylimino)methyl)-5-methylbenzylazanediyl)diethanol (LH4) leads to the synthesis of four isostructural pentanuclear hetereometallic complexes [Ni2Dy3(LH)4]Cl (1), [Ni2Gd3(LH)4]Cl (2), [Ni2Tb3(LH)3(LH2)]Cl2 (3), [Ni2 Ho3 (LH)3 (LH2)]Cl2 (4) with unprecedented topology. Here the two compounds 1 are 2 are monocationic and crystallize in chiral space group, P2(1)2(1)2(1) whereas compounds 3 and 4 are dicationic and crystallize in achiral space group P2(1)/n. The total metal framework, {Ni2Ln3} unit is held by four triply deprotonated ligands [LH](3-) in 1 and 2 whereas in case of 3 and 4 three triply deprotonated [LH](3-) and one doubly deprotonated [LH2](2-) ligands are involved. In these complexes both the lanthanide ions and the nickel(II) ions are doubly bridged and the bridging is composed of oxygen atoms derived from either phenolate or ethoxide groups. The analysis of SQUID measurements reveal a high magnetic ground state and a slow relaxation of the magnetization with two relaxation regimes for 1. For the thermally activated regime we found an effective energy barrier of U(eff) = 85 K. Micro Hall probe loop measurements directly proof the single-molecule magnet (SMM) nature of 1 with a blocking temperature of T(B) = 3 K and an open hysteresis for sweep rates faster than 50 mT/s. PMID:24236759

  8. The use of phosphonates for constructing 3d-4f clusters at high oxidation states: synthesis and characterization of two unusual heterometallic CeMn complexes.

    PubMed

    Wang, Mei; Yuan, Da-Qiang; Ma, Cheng-Bing; Yuan, Ming-Jian; Hu, Ming-Qiang; Li, Na; Chen, Hui; Chen, Chang-Neng; Liu, Qiu-Tian

    2010-08-21

    The use of phosphonic acids in the synthesis of mixed-metal CeMn complexes has led to the formation of two phosphonate complexes with unusual topologies: [Ce(2)Mn(6)O(6)(OH)(5)(t-BuPO(3))(6)(O(2)CMe)(3)] x 53 H(2)O (1 x 53 H(2)O) and [Ce(22)Mn(12)O(34)(MePO(3))(12)(O(2)CMe)(33)(OMe)(6)(NO(3))(H(2)O)(12)](n) (2). The two mixed-metal CeMn complexes were both prepared from a reaction system containing Mn(O(2)CMe)(2) and (NH(4))(2)[Ce(NO(3))(6)] with similar procedures except for using different phosphonic acids (tert-butylphosphonic acid and methylphosphonic acid, respectively) as coligands. Both complexes possess rare topology of triangular type, with compound 1 being a 0D discrete cluster, whereas, compound 2 is a 1D polymer. The octanuclear core of complex 1 is composed of three symmetry equivalent distorted cubanes {Ce(IV)(2)Mn(IV)(2)O(2)(OH)(2)} sharing a trigonal-bipyramidal unit {Ce(IV)(2)(OH)(3)} in the centre. Compound 2 is a one-dimensional chain polymer of identical Ce(22)Mn(12)O(34) units linked together by NO(3)(-) and MeCO(2)(-) groups, while the Ce(22)Mn(12)O(34) unit is constituted by two centrosymmetric Ce(9)(IV)Ce(2)(III)Mn(IV)(6)O(17) subunits, which features three identical distorted cubanes {Ce(IV)(2)Mn(IV)(2)O(4)} connecting to a central trigonal-bipyramidal unit {Ce(IV)(3)O(2)}, and two additional Ce(III) ions capping the top and bottom of the central trigonal bipyramid by six MePO(3)(2-) ligands. Complexes 1 and 2 are the first high-nuclearity Mn/Ln aggregates reported to date using phosphonates as ligands. Magnetic susceptibility measurements reveal that compound 1 displays dominant ferromagnetic interactions between the adjacent metal ions with the best fit parameters for the exchanges are J(1) = 6.186 cm(-1), J(2) = 4.172 cm(-1), and with a result of S = 9 ground state confirmed by the M versus HT(-1) data, which indicates the spins of all the six Mn(IV) ions in the cluster are parallel to each other. In contrast, the data for 2 reveals overall antiferromagnetic couplings within the cluster and a resulting S = 6 ground state. Both the in-phase signal chi'(M)T and out-of-phase signal chi''(M) of the two complexes exhibit frequency-dependent below approximate 3 K. PMID:20585673

  9. Functionalized phosphonates as building units for multi-dimensional homo- and heterometallic 3d-4f inorganic-organic hybrid-materials.

    PubMed

    Köhler, C; Rentschler, E

    2016-08-01

    Using the multifunctional ligand H4L (2,2'-bipyridinyl-5,5'-diphosphonic acid), a new family of inorganic-organic hybrid-materials was prepared. The ligand shows a very high flexibility regarding the coordination mode, leading to a large structural diversity. The compounds 1a, 1b ([M(H2L)(H2O)4]·2.5H2O; M = Co(2+) (a), Ni(2+) (b)), 2 ([Gd2(H2H'L)2(H2H'2L)(H2O)6]Cl4·14H2O), 3a, 3b, 3c ([MCo(iii)(H2L)3(H2O)2]·6.5H2O; M = Gd(3+) (a), Dy(3+) (b) and Tb(3+) (c)), and 4 ([GdNi(ii)(H2L)3(H2O)3]NaCl·6H2O) were isolated and characterized with single crystal X-ray diffraction. Depending on the used metal ions and on the stoichiometry, either discrete entities (0D), extended 2D layers or 3D frameworks were obtained. In contrast to the general approach in phosphonate chemistry, the compounds were prepared without hydrothermal synthesis, but under ambient pressure. Variable temperature magnetic measurements were carried out to determine the magnetic properties. PMID:27472248

  10. First heterometallic Ga(III)-Dy(III) single-molecule magnets: implication of Ga(III) in extracting Fe-Dy interaction.

    PubMed

    Chen, Sihuai; Mereacre, Valeriu; Anson, Christopher E; Powell, Annie K

    2016-05-31

    The compounds of the system [M4M'2(μ3-OH)2(nbdea)4(C6H5CO2)8]·MeCN, where M = Ga(III), M' = Dy(III) (), M = Fe(III), M' = Y(III) () are isostructural to the known [Fe4Dy2] compound (). Those of the system [M4M'4(μ3-OH)4(nbdea)4(m-CH3C6H4CO2)12]·nMeCN, where M = Ga(III), M' = Dy(III), n = 4 (), M = Fe(III), M' = Y(III), n = 1 () are isostructural to the [Fe4Dy4] compound (). This allows for comparisons between single ion effects of the paramagnetic ions. The structures were determined using single crystal analysis. Magnetic susceptibility measurements reveal that the Ga(III)-Dy(III) compounds and are SMMs. The energy barrier for is close to that for the known isostructural Fe4Dy2 compound (), but with a significantly increased relaxation time. PMID:27184869

  11. Single-Crystal-to-Single-Crystal Transformations in One Dimensional Ag-Eu Helical System

    SciTech Connect

    Cai, Yue-Peng; Zhout, Xiu-Xia; Zhout, Zheng-Yuan; Zhu, Shi-Zheng; Thallapally, Praveen K.; Liu, Jun

    2009-07-06

    Single-crystal-to-single-crystal transformation of 1-D 4d-4f coordination polymers have been investigated for the first time. It displays high selectivity for Mg2+ and can be used as magnesium ion-selective luminescent probe. More importantly, we observed the transformation of meso-helical chain to rac-helical chain as a function of temperature.

  12. Synthesis, structure, and luminescence property of a series of Ag-Ln coordination polymers with the N-heterocyclic carboxylato ligand

    NASA Astrophysics Data System (ADS)

    Jin, Jing; Chen, Chong; Gao, Yan; Zhao, Ran; Wang, Xiuyan; Lü, Chunxin; Chi, Yuxian; Niu, Shuyun

    2016-03-01

    Six Ln-Ag coordination polymers {[LnAg2(IN)4(H2O)5]·NO3·2H2O}n (Ln=Ho (1) and Tb (2), HIN=isonicotinic acid), {[PrAg2(IN)4(H2O)2]·NO3·H2O}n (3), [LnAg(pdc)2]n (Ln=Eu(4) and Pr (5), H2pdc=3,4-pyridine-dicarboxylic acid) and [NdAg(bidc)2(H2O)4]n (6) (H2bidc=benzimidazole-5,6-dicarboxylic acid) have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, elemental analysis, IR, UV-vis-NIR absorption spectra, fluorescence spectra and thermogravimetric analysis. Structural analyses reveal that the six polymers exhibit 0D (polymer (1)), 1D (polymer (2)), 2D (polymers (3) and (5)) and 3D (polymers (4) and (6)) infinite structures, respectively. Polymers (1)-(6) exhibit the Ln(III) characteristic emission in the near-infrared (NIR) region or in the visible region. Especially, the NIR emission bands of polymers 1, 5 and 6 evidently present shift or splitting due to formation of the Ln-Ag coordination polymers. This can be attributed to the tune of inner levels in Ln-Ag system caused by the interact and influence between the 4d orbital of the Ag(I) ion and the 4f orbital of the Ln(III) ion, which can be confirmed by the UV-vis-NIR absorption spectra of the polymers. In addition, the distortion of coordination geometry as well as difference of the coordination number around the Ag(I) ion affect the structure framework.

  13. Theory of X-ray absorption and resonant X-ray emission spectra by electric quadrupole excitation in light rare-earth systems

    NASA Astrophysics Data System (ADS)

    Nakazawa, M.; Fukui, K.; Kotani, A.

    2003-02-01

    We have made precise theoretical calculations for both 2 p3/2→4 f X-ray absorption spectroscopy (XAS) and 4 d→2 p3/2 resonant X-ray emission spectroscopy (RXES) by electric quadrupole excitations at the L3 edge of light rare-earth elements, by means of atomic model with full multiplet effects. The calculation is based on the second-order optical formula, and the effect of the incident photon polarization is taken into account. It is shown that the 4 d-4 f interaction plays a more important role in 4 d→2 p3/2 RXES than the 4 f-4 f interaction does. Moreover, the calculated results of 4 d→2 p3/2 RXES show the strong polarization dependence, and it is originated from the spin multiplicity, which is derived from the 4 d-4 f interaction, of the RXES final states.

  14. Supplementary absolute differential cross sections for the excitation of atomic hydrogen's n=3 and 4 levels by electron impact

    SciTech Connect

    Sweeney, Christopher J.; Shyn, Tong W.; Grafe, Alan

    2004-05-01

    We have conducted measurements of absolute differential cross sections for the excitation of hydrogen atoms to their n=3(3S+3P+3D) and 4(4S+4P+4D+4F) levels. A modulated, crossed-beam method was employed, and the impact energies were 40 and 60 eV. Comparison of our results with those of others is quite favorable.

  15. Heterometallic Fe2 (II) -U(V) and Ni2 (II) -U(V) Exchange-Coupled Single-Molecule Magnets: Effect of the 3 d Ion on the Magnetic Properties.

    PubMed

    Chatelain, Lucile; Pécaut, Jacques; Tuna, Floriana; Mazzanti, Marinella

    2015-12-01

    Uranium-based compounds have been put forward as ideal candidates for the design of single-molecule magnets (SMMs) with improved properties, but to date, only two examples of exchange-coupled 3d-5f SMM containing uranium have been reported and both are based on the Mn(II) ion. Here we have synthesized the first examples of exchange-coupled uranium SMMs based on Fe(II) and Ni(II) . The SMM behavior of these complexes containing a quasi linear {M-O=U=O-M} core arises from intramolecular Fe-U and Ni-U exchange interactions combined with the high Ising anisotropy of the uranyl(V) moiety. The measured values of the relaxation barrier (53.9±0.9 K in the UFe2 complex and of 27.4±0.5 K in the UNi2 complex) show clearly the dependency on the spin value of the transition metal, providing important new information for the future design of improved uranium-based SMMs. PMID:26464190

  16. A family of 12-azametallacrown-4 structural motif with heterometallic Mn(III) -Ln-Mn(III) -Ln (Ln=Dy, Er, Yb, Tb, Y) alternate arrangement and single-molecule magnet behavior.

    PubMed

    Yang, Hua; Cao, Fan; Li, Dacheng; Zeng, Suyuan; Song, You; Dou, Jianmin

    2015-10-01

    Mixed 3d-4f 12-azametallacrown-4 complexes, [Mn2 Ln2 (OH)2 (hppt)4 (OAc)2 (DMF)2 ]⋅2 DMF⋅H2 O [Ln=Dy (1), Er (2), Yb (3), Tb (4) and Y (5), H2 hppt=3-(2-hydroxyphenyl)-5-(pyrazin-2-yl)-1,2,4-triazole)], were synthesized by reactions of H2 hppt with Mn(OAc)2 ⋅4 H2 O and Ln(NO3 )3 ⋅6 H2 O. This is the first 3d-4f azametallacrown family to incorporate Ln ions into the ring sets. These isostructural complexes exhibit alternating arrangements of two Mn and two Ln ions in the rings with each pair of metal centers bound by an NN group and μ2 -O bridging. Magnetic measurements revealed dominant antiferromagnetic interactions between metal centers, and frequency-dependent out-of-phase (${\\chi {^\\prime}{^\\prime}_{\\rm{M}} }$) signals below 4 K suggest slow relaxation of magnetization. PMID:26295925

  17. Pressure-induced isomerization of a heterometallic rhodium-gold cluster compound: (Rh sub 2 (. mu. -Cl) sub 2 (CNC sub 8 H sub 9 ) sub 4 (. mu. -AuPPh sub 3 )) sub 2 (PF sub 6 ) sub 2

    SciTech Connect

    Bray, K.L.; Drickamer, H.G.; Shapley, J.R. ); Mingos, D.M.P.; Watson, M.J. )

    1991-02-20

    Mingos et al. have prepared two isomers of the cluster compound (Rh{sub 2}(mu-Cl{sub 2})(CNC{sub 8}H{sub 9}){sub 4}(mu-AuPPh{sub 3})){sub 2}(PF{sub 6}){sub 2} and have characterized these isomers using single crystal x-ray techniques. The volumes per cluster cation were found to be very similar for both isomers, 1,430 and 1,413 angstroms, and the Rh-Rh bond lengths were found to be 3.262 and 3.008 angstroms for the same isomer. The cluster skeletal geometries were found to differ only at an interior link, and applied pressure appeared to induce a conformational transition around this bond.

  18. Crystal structure of [NaZn(BTC)(H2O)4]·1.5H2O (BTC = benzene-1,3,5-tri-carb-oxy-l-ate): a heterometallic coordination compound.

    PubMed

    Ni, Min; Li, Quanle; Chen, Hao; Li, Shengqing

    2015-07-01

    The title coordination polymer, poly[[μ-aqua-tri-aqua-(μ3-benzene-1,3,5-tri-carboxyl-ato)sodiumzinc] sesquihydrate], {[NaZn(C9H3O6)(H2O)4]·1.5H2O} n , was obtained in ionic liquid microemulsion at room temperture by the reaction of benzene-1,3,5-tri-carb-oxy-lic acid (H3BTC) with Zn(NO3)2·6H2O in the presence of NaOH. The asymmetric unit comprises two Na(+) ions (each located on an inversion centre), one Zn(2+) ion, one BTC ligand, four coordinating water mol-ecules and two solvent water molecules, one of which is disordered about an inversion centre and shows half-occupation. The Zn(2+) cation is five-coordinated by two carboxyl-ate O atoms from two different BTC ligands and three coordinating H2O mol-ecules; the Zn-O bond lengths are in the range 1.975 (2)-2.058 (3) Å. The Na(+) cations are six-coordinated but have different arrangements of the ligands: one is bound to two carboxyl-ate O atoms of two BTC ligands and four O atoms from four coordinating H2O mol-ecules while the other is bound by four carboxyl-ate O atoms from four BTC linkers and two O atoms of coordinating H2O mol-ecules. The completely deprotonated BTC ligand acts as a bridging ligand binding the Zn(2+) atom and Na(+) ions, forming a layered structure extending parallel to (100). An intricate network of O-H⋯O hydrogen bonds is present within and between the layers. PMID:26279893

  19. Crystal structure of [NaZn(BTC)(H2O)4]·1.5H2O (BTC = benzene-1,3,5-tri­carb­oxy­l­ate): a heterometallic coordination compound

    PubMed Central

    Ni, Min; Li, Quanle; Chen, Hao; Li, Shengqing

    2015-01-01

    The title coordination polymer, poly[[μ-aqua-tri­aqua­(μ3-benzene-1,3,5-tri­carboxyl­ato)sodiumzinc] sesquihydrate], {[NaZn(C9H3O6)(H2O)4]·1.5H2O}n, was obtained in ionic liquid microemulsion at room temperture by the reaction of benzene-1,3,5-tri­carb­oxy­lic acid (H3BTC) with Zn(NO3)2·6H2O in the presence of NaOH. The asymmetric unit comprises two Na+ ions (each located on an inversion centre), one Zn2+ ion, one BTC ligand, four coordinating water mol­ecules and two solvent water molecules, one of which is disordered about an inversion centre and shows half-occupation. The Zn2+ cation is five-coordinated by two carboxyl­ate O atoms from two different BTC ligands and three coordinating H2O mol­ecules; the Zn—O bond lengths are in the range 1.975 (2)–2.058 (3) Å. The Na+ cations are six-coordinated but have different arrangements of the ligands: one is bound to two carboxyl­ate O atoms of two BTC ligands and four O atoms from four coordinating H2O mol­ecules while the other is bound by four carboxyl­ate O atoms from four BTC linkers and two O atoms of coordinating H2O mol­ecules. The completely deprotonated BTC ligand acts as a bridging ligand binding the Zn2+ atom and Na+ ions, forming a layered structure extending parallel to (100). An intricate network of O—H⋯O hydrogen bonds is present within and between the layers. PMID:26279893

  20. Dicarboxylate assisted synthesis of the monoclinic heterometallic tetrathiocyanato bridged copper(II) and mercury(II) coordination polymer {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n}: Synthesis, structural, vibration, luminescence, EPR studies and DFT calculations

    SciTech Connect

    Khandar, Ali Akbar; Klein, Axel; Bakhtiari, Akbar; Mahjoub, Ali Reza; Pohl, Roland W.H.

    2011-02-15

    The synthesis of the monoclinic polymorph of {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} is reported. The compound, as determined by X-ray diffraction of a twinned crystal, consists of mercury and copper atoms linked by {mu}{sub 1,3}-SCN bridges. The crystal packing shows a highly porous infinite 3D structure. Diagnostic resonances for the SCN{sup -} ligand and metal-ligand bonds in the IR, far-IR and Raman spectra are assigned and discussed. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. The DFT calculations show that the observed luminescence of the compound arises mainly from an excited LLCT state with small MLCT contributions (from the copper to unoccupied {pi}{sup *} orbital of the thiocyanate groups). The X-band EPR spectrum of the powdered sample at room temperature reveals an axial signal with anisotropic g factors consistent with the unpaired electron of Cu(II) ion in the d{sub x}{sup 2}{sub -y}{sup 2} orbital. -- Graphical abstract: Synthesis and X-ray structure determination of the monoclinic {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} is reported. The IR, far-IR, Raman, photoluminescence as well as EPR spectra of the compound is discussed. Also, the emission and semiconducting behavior of the compound is illustrated through the density functional theory calculation of electronic band structure along with density of states. Display Omitted Research highlights: > The monoclinic {l_brace}Cu[Hg(SCN){sub 4}]{r_brace}{sub n} has been prepared. > The structure of the compound is determined by XRD of a twinned crystal. > The IR, far-IR, Raman, EPR and emission spectra of the compound is investigated. > As shown by DFT calculations, the emission bands of the compound are mainly LLCT. > Small MLCT from the copper to the thiocyanate groups contributes to these bands.

  1. New cyanide-bridged Mn(III)-M(III) heterometallic dinuclear complexes constructed from [M(III)(AA)(CN)4]- building blocks (M = Cr and Fe): synthesis, crystal structures and magnetic properties.

    PubMed

    Nastase, Silviu; Maxim, Catalin; Andruh, Marius; Cano, Joan; Ruiz-Pérez, Catalina; Faus, Juan; Lloret, Francesc; Julve, Miguel

    2011-05-14

    Three Mn(III)-M(III) (M = Cr and Fe) dinuclear complexes have been obtained by assembling [Mn(III)(SB)(H(2)O)](+) and [M(III)(AA)(CN)(4)](-) ions, where SB is the dianion of the Schiff-base resulting from the condensation of 3-methoxysalicylaldehyde with ethylenediamine (3-MeOsalen(2-)) or 1,2-cyclohexanediamine (3-MeOsalcyen(2-)): [Mn(3-MeOsalen)(H(2)O)(µ-NC)Cr(bipy)(CN)(3)]·2H(2)O (1), [Mn(3-MeOsalen)(H(2)O)(µ-NC)Cr(ampy)(CN)(3)][Mn(3-MeOsalen)(H(2)O)(2)]ClO(4)·2H(2)O (2) and [Mn(3-MeOsalcyen)(H(2)O)(µ-NC)Fe(bpym)(CN)(3)]·3H(2)O (3) (bipy = 2,2'-bipyridine, ampy = 2-aminomethylpyridine and bpym = 2,2'-bipyrimidine). The [M(AA)(CN)(4)](-) unit in 1-3 acts as a monodentate ligand towards the manganese(III) ion through one of its four cyanide groups. The manganese(III) ion in 1-3 exhibits an elongated octahedral stereochemistry with the tetradentate SB building the equatorial plane and a water molecule and a cyanide-nitrogen atom filling the axial positions. Remarkably, the neutral mononuclear complex [Mn(3-MeOsalen)(H(2)O)(2)]ClO(4) co-crystallizes with the heterobimetallic unit in 2. The values of the Mn(III)-M(III) distance across the bridging cyanide are 5.228 (1), 5.505 (2) and 5.265 Å (3). The packing of the neutral heterobimetallic units in the crystal is governed by the self-complementarity of the [Mn(SB)(H(2)O)](+) moieties, which interact each other through hydrogen bonds established between the aqua ligand from one fragment with the set of phenolate- and methoxy-oxygens from the adjacent one. The magnetic properties of the three complexes have been investigated in the temperature range 1.9-300 K. Weak antiferromagnetic interactions between the Mn(III) and M(III) ions across the cyanido bridge were found: J(MnM) = -5.6 (1), -0.63 (2) and -2.4 cm(-1) (3) the Hamiltonian being defined as H = -JS(Mn)·S(M). Theoretical calculations based on density functional theory (DFT) have been used to substantiate both the nature and magnitude of the exchange interactions observed and also to analyze the dependence of the magnetic coupling on the structural parameters within the Mn(III)-N-C-M(III) motif in 1-3. PMID:21442115

  2. Dicarboxylate assisted synthesis of the monoclinic heterometallic tetrathiocyanato bridged copper(II) and mercury(II) coordination polymer {Cu[Hg(SCN) 4]} n: Synthesis, structural, vibration, luminescence, EPR studies and DFT calculations

    NASA Astrophysics Data System (ADS)

    Khandar, Ali Akbar; Klein, Axel; Bakhtiari, Akbar; Mahjoub, Ali Reza; Pohl, Roland W. H.

    2011-02-01

    The synthesis of the monoclinic polymorph of {Cu[Hg(SCN) 4]} n is reported. The compound, as determined by X-ray diffraction of a twinned crystal, consists of mercury and copper atoms linked by μ1,3-SCN bridges. The crystal packing shows a highly porous infinite 3D structure. Diagnostic resonances for the SCN - ligand and metal-ligand bonds in the IR, far-IR and Raman spectra are assigned and discussed. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. The DFT calculations show that the observed luminescence of the compound arises mainly from an excited LLCT state with small MLCT contributions (from the copper to unoccupied π* orbital of the thiocyanate groups). The X-band EPR spectrum of the powdered sample at room temperature reveals an axial signal with anisotropic g factors consistent with the unpaired electron of Cu(II) ion in the dx2- y2 orbital.

  3. The heterometallic cadmium-silver complex cis-bis[dicyanidoargentato(I)-κN]bis(5,5'-dimethyl-2,2'-bipyridyl-κ(2)N,N')cadmium(II) monohydrate.

    PubMed

    Piromchom, Jureepan; Wannarit, Nanthawat; Pakawatchai, Chaveng; Youngme, Sujittra

    2013-10-01

    In the title complex, [Ag2Cd(CN)4(C12H12N2)2]·H2O or cis-[Cd{Ag(CN)2}2(5,5'-dmbpy)2]·H2O, where 5,5'-dmbpy is 5,5'-dimethyl-2,2'-bipyridyl, the asymmetric unit consists of a discrete neutral [Cd{Ag(CN)2}2(5,5'-dmbpy)2] unit and a solvent water molecule. The Cd(II) cation is coordinated by two bidentate chelate 5,5'-dmbpy ligands and two monodentate [Ag(I)(CN)2](-) anions, which are in a cis arrangement around the Cd(II) cation, leading to an octahedral CdN6 geometry. The overall structure is stabilized by a combination of intermolecular hydrogen bonding, and Ag(I)···Ag(I) and π-π interactions, forming a three-dimensional supramolecular network. PMID:24096502

  4. Detailed atomic modeling of Sn plasmas for the EUV source

    NASA Astrophysics Data System (ADS)

    Sasaki, A.; Sunahara, A.; Nishihawra, K.; Nishikawa, T.; Koike, F.; Tanuma, H.

    2008-05-01

    An atomic model of Sn plasmas is developed to calculate coefficients of radiative transfer, based on the calculated atomic data using the Hullac code. We find that the emission spectrum and conversion efficiency depend critically on the wavelength and spectral structure of the 4d-4f transition arrays. Satellite lines, which have a significant contribution to the emission, are determined after iterative calculations by changing the number of levels in the atomic model. We also correct transition wavelengths through comparison with experiments. Using the present emissivity and opacity, the radiation hydrodynamics simulation will be carried out toward the optimization of the EUV source.

  5. Extreme ultraviolet emission spectra of Gd and Tb ions

    SciTech Connect

    Kilbane, D.; O'Sullivan, G.

    2010-11-15

    Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d-4f and 4p-4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.

  6. Theoretical investigation of the spectrum and conversion efficiency of short wavelength extreme-ultraviolet light sources based on terbium plasmas

    SciTech Connect

    Sasaki, Akira; Nishihara, Katsunobu; Sunahara, Atsushi; Furukawa, Hiroyuki; Nishikawa, Takeshi; Koike, Fumihiro

    2010-12-06

    The emission spectrum and conversion efficiency of laser-produced terbium plasmas are theoretically investigated on the basis of computational atomic data. The theoretically calculated spectrum reproduces the main peak of observed spectrum at {lambda}=6.5 nm, which originates from 4d-4f transitions of near palladiumlike ions (Tb{sup 19+}). A simple model of the isothermal expansion of terbium plasma suggests that efficient emission can be achieved by pumping the plasma with a laser pulse at an intensity of approximately one order of magnitude greater than that used with tin sources at {lambda}=13.5 nm.

  7. Temporal behavior of unresolved transition array emission in water window soft x-ray spectral region from multiply charged ions

    NASA Astrophysics Data System (ADS)

    Dinh, Thanh-Hung; Suzuki, Yuhei; Arai, Goki; Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Fujioka, Shinsuke; Hasegawa, Noboru; Kawachi, Tetsuya; Nishikino, Masaharu; Higashiguchi, Takeshi

    2015-09-01

    We have characterized the spectral structure and the temporal history of the laser-produced high-Z multi-charged ion plasmas for the efficient water window soft x-ray sources. Strong unresolved transition array emission was observed due to 4d-4f and 4f-5g transitions from Au, Pb, and Bi plasmas in the 280-700 eV photon energy region. The temporal behavior of the emission was essentially similar of that of the laser pulse with a slight delay between different transitions. These results provide feedback for accurate modeling of the atomic processes with the radiative hydrodynamic simulations.

  8. On spectroscopic classification of autoionizing levels in Rb atoms

    NASA Astrophysics Data System (ADS)

    Kupliauskienė, A.; Borovik, A.; Kerevičius, G.; Roman, V.

    2014-04-01

    Large scale configuration interaction calculations of energy levels, autoionization probabilities and electron-impact excitation cross sections of the autoionizing states 4p5nln'l' (nl = 5s, 4d, 4f,n'l'=4d, 5s, 5p, 5d, 5f, 5g, 6s, 6p, 6d, 7s, 7p) of Rb up to 19.6 eV were performed for the first time. The relativistic effects were taken into account in the Dirac-Fock-Slater approximation. The calculated data were used for the novel classification of the lines in an experimental ejected-electron spectrum.

  9. Transition wavelengths and unresolved transition array statistics of ions with Z = 72-89

    NASA Astrophysics Data System (ADS)

    Kilbane, D.

    2011-08-01

    Potential extreme ultraviolet and soft x-ray radiation sources have been identified, using the flexible atomic code (FAC), as emission peaks arising from the 4d-4f and 4p-4d transitions in Pd-like to Rb-like ions of hafnium through actinium. The effects of configuration interaction are investigated and for increasing nuclear charge, these strong emitters are seen to separate and move to shorter wavelengths. Each source is characterized using the unresolved transition array model. They are proposed to complement the currently used nitrogen and argon sources in the 'water window', and as possible successors to tin in next-generation lithography.

  10. Synthesis of Novel Oxazolo[4,5-b]pyridine-2-one based 1,2,3-triazoles as Glycogen Synthase Kinase-3β Inhibitors with Anti-inflammatory Potential.

    PubMed

    Tantray, Mushtaq A; Khan, Imran; Hamid, Hinna; Alam, Mohammad Sarwar; Umar, Sadiq; Ali, Yakub; Sharma, Kalicharan; Hussain, Firasat

    2016-06-01

    A novel series of oxazolo[4,5-b]pyridine-2-one based 1,2,3-triazoles has been synthesized by click chemistry approach and evaluated for in vitro GSK-3β inhibitory activity. Compound 4g showed maximum inhibition with IC50 value of 0.19 μm. Keeping in view the effect of GSK-3β inhibition on inflammation, compounds 4g, 4d, 4f, 4i, 4n and 4q exhibiting significant GSK-3β inhibition were examined for in vivo anti-inflammatory activity in rat paw edema model. The compounds 4g, 4d, 4f and 4i showed pronounced in vivo anti-inflammatory activity (76.36, 74.54, 72.72 and 70.90%, respectively, after 5h post-carrageenan administration) and were further found to inhibit the pro-inflammatory mediators, viz. NO, TNF-α, IL-1β, and IL-6 substantially in comparison with indomethacin, an anti-inflammatory drug as well as SB216763, a GSK-3β inhibitor, reported to exert a similar effect. Histopathology studies confirmed the tolerance of gastric mucosa to these compounds. PMID:26804375

  11. Syntheses, Spectroscopic Data, and X-ray Diffraction Structures of the Heterometallic RuRe Face-shared Bioctahedral (eta(6)-cymene)Ru(mu-Cl)(3)Re(CO)(3) and MnRu2 Edge-shared Trioctahedral [fac-ClRu(CO)(3)](2)(mu-Cl)(4)Mn(H2O)(2) Complexes

    SciTech Connect

    Wang, Xiaoping; Hunt, Sean W; Richmond, Michael G.

    2009-01-01

    Thermolysis of the diruthenium compound [(eta(6)-cymene)RuCl2](2) (1) with ClRe(CO)(5) (2) leads to the formation of the new confacial bioctahedral compound (eta(6)-cymene) Ru(mu-Cl)(3)Re(CO)(3) (3) in good yields; the same product has also been isolated when a mixture of 1 and 2 is irradiated with near UV-vis light for an extended period of time. Heating 1 and ClMn(CO)(5) (4) does not furnish the corresponding manganese analogue of 3 but rather the trioctahedral halide-bridged product [fac-ClRu(CO)(3)](2)(mu-Cl)(4)Mn(H2O)(2) (5). 3 and 5 have been fully characterized in solution and their molecular structures established by X-ray crystallography.

  12. Synthesis and structure of a heterometallic cluster with a novel layered structure: (W(CO)/sub 5/SnClFe(CO)/sub 4/)/sub 2/(Na/sub 2/((C/sub 2/H/sub 5/)/sub 2/O)/sub 4/(C/sub 4/H/sub 8/O/sub 2/))

    SciTech Connect

    Balch, A.L.; Olmstead, M.M.; Oram, D.P.

    1988-11-16

    In an attempt to create an example of substituent-free complex derived from Sn(II), the reaction between (OC)/sub 5/WSnCl/sub 2/(tetrahydrofuran) and Fe(CO)/sub 4//sup /minus/2/ was studied. Instead of the expected compound (OC)/sub 5/WSn=Fe(CO)/sub 4/, the dimer (W(CO)/sub 5/SnClFe(CO)/sub 4/)/sub 2/Na/sub 2/(C/sub 2/H/sub 5/)O/sub 4/(C/sub 4/H/sub 8/O/sub 2/) was the product formed. The properties and structure of this dimer are reported herein. 17 refs., 3 figs., 3 tabs.

  13. Synthesis and structure of a new family of 3d-4f heterometallic compounds Rb{sub 7}LnFe{sub 6}O{sub 2}(PO{sub 4}){sub 8} (Ln=Sm, Eu, Gd, Dy): Magnetic properties of the Sm-, Gd-, Dy-derivatives

    SciTech Connect

    Sanjeewa, Liurukara D.; Palmer West, J.; Hwu, Shiou-Jyh

    2012-08-15

    A new family of mixed lanthanide(III) and iron(III) oxo-phosphate phases, Rb{sub 7}LnFe{sub 6}O{sub 2}(PO{sub 4}){sub 8} (Ln=Sm 1, Eu 2, Gd 3, Dy 4), was isolated by using a high-temperature, solid-state method in molten-salt media. The X-ray single-crystal structure analysis shows that these isomorphic derivatives crystallize in a triclinic space group P-1 (no. 2); Z=1. The 3-D framework of these 3d-4f oxo-phosphates are comprised of LnO{sub 6} octahedral, FeO{sub 5} trigonal bipyramidal (tbp), and {mu}{sub 3}-oxo [Fe{sub 4}O{sub 18}] tetrameric units interconnected through PO{sub 4} tetrahedra. The preliminary results of the temperature-dependent magnetic susceptibility measurements for selected compounds (1, 3, 4) reveal antiferromagnetic-like behavior. 1 shows a weak antiferromagnetric ordering at T{sub N}={approx}7 K while others show little evidence of long-range magnetic order down to 2 K. All three compounds have measured magnetic moments significantly smaller than the expected values. - Graphical abstract: The extended framework is described by the connectivity of three distinct types of paramagnetic units. The temperature-dependent, lower than expected effective magnetic moments are reported. Highlights: Black-Right-Pointing-Pointer A new family of mixed lanthanide(III) and iron(III) oxo-phosphates is isolated. Black-Right-Pointing-Pointer Features PO{sub 4}-linked paramagnetic units of LnO{sub 6}, FeO{sub 5}, and {mu}{sub 3}-oxo [Fe{sub 4}O{sub 18}]. Black-Right-Pointing-Pointer Sm-derivative orders at T{sub N}{approx}7 K while Gd- and Dy-derivatives show absence of order.

  14. Influence of the alkoxide moiety on heterometallic compound formation: Structure and dynamics of KZr{sub 2}(O{sup t}Bu){sub 9} and K{sub 2}Zr{sub 2}(O{sup 5}Bu){sub 10}

    SciTech Connect

    Teff, D.J.; Huffman, J.C.; Caulton, K.G.

    1994-12-21

    KZr{sub 2}(O{sup t}Bu){sub 9} was prepared by reaction of KO{sup t}Bu with Zr(O{sup t}Bu){sub 4} in a 1:2 molar ratio. Attempted sublimation results in dissociation of Zr(O{sup t}Bu){sub 4}, affording [KZr(O{sup t}Bu){sub 5}]{sub n}, which can also be synthesized using equimolar KO{sup t}Bu and Zr(O{sup t}Bu){sub 4}. Single-crystal X-ray diffraction revealed that n=2: K{sub 2}Zr{sub 2}(O{sup t}Bu){sub 10} crystallizes from pentane at -20 {degrees}C in the monoclinic space group P2{sub 1}/c, with the unit cell dimensions a = 10.532(1) {Angstrom}, b = 18.057(3) {Angstrom}, c = 27.618(5) {Angstrom}, {beta} = 95.54(1){degrees}, and Z = 4. The dimer is composed of two five-coordinate Zr centers, each having trigonal bipyramidal geometry; the axes of the trigonal bipyramide are orthogonal, and the Zr(O{sup t}Bu){sub 5}{sup {minus}} units encapsulate both potassiums. Due to fluxionality, this species appears as a singlet in {sup 1}H NMR in d{sub 8}-toluene even at -75 {degrees}C. Interconversions between and possible dissociative reactions of KZr{sub 2}(O{sup t}Bu){sub 9} and [KZr(O{sup t}Bu){sub 5}]{sub 2} are also tested experimentally.

  15. Direct synthesis of a {Co₆(III)Fe₆(III)} dodecanuclear complex, revealing an unprecedented molecular structure type.

    PubMed

    Chygorin, Eduard N; Kokozay, Vladimir N; Omelchenko, Irina V; Shishkin, Oleg V; Titiš, Ján; Boča, Roman; Nesterov, Dmytro S

    2015-06-28

    A novel heterometallic Co6Fe6 Schiff base complex, possessing an unprecedented {M12(μ-X)22} branched structure (according to the search via the Cambridge Structural Database), has been prepared using the "direct synthesis" approach and characterized by single crystal X-ray diffraction and magnetometry. PMID:25992842

  16. Titanocene–Gold Complexes Containing N-Heterocyclic Carbene Ligands Inhibit Growth of Prostate, Renal, and Colon Cancers in Vitro

    PubMed Central

    2016-01-01

    We report on the synthesis, characterization, and stability studies of new titanocene complexes containing a methyl group and a carboxylate ligand (mba = −OC(O)-p-C6H4-S−) bound to gold(I)–N-heterocyclic carbene fragments through the thiolate group: [(η5-C5H5)2TiMe(μ-mba)Au(NHC)]. The cytotoxicities of the heterometallic compounds along with those of novel monometallic gold–N-heterocyclic carbene precursors [(NHC)Au(mbaH)] have been evaluated against renal, prostate, colon, and breast cancer cell lines. The highest activity and selectivity and a synergistic effect of the resulting heterometallic species was found for the prostate and colon cancer cell lines. The colocalization of both titanium and gold metals (1:1 ratio) in PC3 prostate cancer cells was demonstrated for the selected compound 5a, indicating the robustness of the heterometallic compound in vitro. We describe here preliminary mechanistic data involving studies on the interaction of selected mono- and bimetallic compounds with plasmid (pBR322) used as a model nucleic acid and the inhibition of thioredoxin reductase in PC3 prostate cancer cells. The heterometallic compounds, which are highly apoptotic, exhibit strong antimigratory effects on the prostate cancer cell line PC3. PMID:27182101

  17. Circular serendipity: in situ ligand transformation for the self-assembly of an hexadecametallic [Cu(II)16] wheel.

    PubMed

    Kostopoulos, Andreas K; Katsenis, Athanassios D; Frost, Jamie M; Kessler, Vadim G; Brechin, Euan K; Papaefstathiou, Giannis S

    2014-12-11

    A [Cu(II)16] wheel was isolated serendipitously from the reaction of acetylacetone dioxime with copper(ii) chloride and lanthanide ions in a reaction initially designed to produce heterometallic 3d-4f cages. The ligand has been transformed in situ to three different forms, all found within the [Cu16] wheel, with the original ligand completely absent. PMID:25327306

  18. Volatile Single-Source Precursors for the Low-Temperature Preparation of Sodium-Rare Earth Metal Fluorides.

    PubMed

    Barry, Matthew C; Wei, Zheng; He, Tianyu; Filatov, Alexander S; Dikarev, Evgeny V

    2016-07-20

    Heterometallic single-source precursors for the preparation of sodium-rare earth metal fluorides are reported. Fluorinated β-diketonates NaRE(hfac)4 (RE = Y (1), Er (2), and Eu (3); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield, via one-pot reaction that utilizes commercially available starting reagents. The solid-state structures of the title complexes consist of 1D polymeric chains with alternating [Na] and [RE(hfac)4] units. Compounds 1-3 are highly volatile and exhibit a fair stability in open air. Mass spectrometric investigation indicates the presence of heterometallic fragments in the gas phase. The presence of heterometallic species in solutions of coordinating solvents has also been confirmed. Decomposition of heterometallic precursors in argon atmosphere was shown to yield phase-pure sodium-rare earth metal fluorides. Low decomposition temperature effectively allows for a high degree of control over the formation of both kinetic α-phases and thermodynamic β-phases of target NaREF4 (RE = Y, Er, and Eu) materials. PMID:27232230

  19. Stabilization of the previously unknown tautomer HP(OH)2 of hypophosphorous acid as ligand; preparation of [W3(Ni(HP(OH)2))Q4(H2O)9]4+ (Q = S, Se) complexes.

    PubMed

    Sokolov, Maxim N; Hernández-Molina, Rita; Clegg, William; Fedin, Vladimir P; Mederos, Alfredo

    2003-01-01

    Bis(hydroxy)phosphine, the isomer of hypophosphorous acid which remained elusive for a long time, coordinates to the Ni site of heterometallic clusters with a W3NiQ4 core (Q = S, Se) to give [W3(Ni(HP(OH)2))Q4(H2O)9]4+ (Q = S, Se). PMID:12611005

  20. Synthesis and antitumor activity of natural compound aloe emodin derivatives.

    PubMed

    Thimmegowda, Naraganahalli R; Park, Chanmi; Shwetha, Bettaswamigowda; Sakchaisri, Krisada; Liu, Kangdong; Hwang, Joonsung; Lee, Sangku; Jeong, Sook J; Soung, Nak K; Jang, Jae H; Ryoo, In-Ja; Ahn, Jong S; Erikson, Raymond L; Kim, Bo Y

    2015-05-01

    In this study, we have synthesized novel water soluble derivatives of natural compound aloe emodin 4(a-j) by coupling with various amino acid esters and substituted aromatic amines, in an attempt to improve the anticancer activity and to explore the structure-activity relationships. The structures of the compounds were determined by (1) H NMR and mass spectroscopy. Cell growth inhibition assays revealed that the aloe emodin derivatives 4d, 4f, and 4i effectively decreased the growth of HepG2 (human liver cancer cells) and NCI-H460 (human lung cancer cells) and some of the derivatives exhibited comparable antitumor activity against HeLa (Human epithelial carcinoma cells) and PC3 (prostate cancer cells) cell lines compared to that of the parent aloe emodin at low micromolar concentrations. PMID:25323822

  1. Emissive properties of xenon ions from a laser-produced plasma in the 100-140 Å spectral range: Atomic-physics analysis of the experimental data

    NASA Astrophysics Data System (ADS)

    Gilleron, F.; Poirier, M.; Blenski, T.; Schmidt, M.; Ceccotti, T.

    2003-08-01

    In order to design extreme ultraviolet (EUV) sources for nanolithography, xenon EUV emission has been experimentally studied in a plasma generated by the interaction of a high-power laser with a droplet jet. A theoretical model assuming that the resulting plasma is optically thick allows one to find the distribution of the relevant ions and transitions involved in the emission process. Atomic physics computations are performed using the HULLAC code to give a detailed account of the transitions involved. The importance of 4p-4d, 4d-4f, and 4d-5p transitions is stressed, as well as the need for configuration-interaction treatment of the Δn=0 transitions. Comparisons of a modeled local thermodynamical equilibrium spectrum with experiment provides qualitative agreement and permits an estimate of the plasma temperature, density, and dimensions.

  2. Rare earth 4f hybridization with the GaN valence band

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Wai-Ning; McHale, S. R.; McClory, J. W.; Petrosky, J. C.; Wu, J.; Palai, R.; Losovyj, Y. B.; Dowben, P. A.

    2012-11-01

    The placement of the Gd, Er and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4d-4f photoemission resonances for various rare-earth(RE)-doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4f state placement within the GaN. The resonant photoemission show that the major Er and Gd RE 4f weight is at about 5-6 eV below the valence band maximum, similar to the 4f weights in the valence band of many other RE-doped semiconductors. For Yb, there is a very little resonant enhancement of the valence band of Yb-doped GaN, consistent with a large 4f14-δ occupancy. The placement of the RE 4f levels is in qualitative agreement with theoretical expectations.

  3. The rare earth 4 f hybridization with the GaN valence band

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Mei, Wai-Ning; McHale, Steve; McClory, John; Petrosky, James; Wu, J.; Palai, Ratnakar; Losovyj, Yaroslav; Dowben, Peter

    2013-03-01

    The placement of the Gd, Er, and Yb 4f states within the GaN valence band has been explored by both experiment and theory. The 4 d - 4 f photoemission resonances for various rare earth doped GaN thin films (RE = Gd, Er, Yb) provide an accurate depiction of the occupied 4 f state placement within the GaN. The resonant photoemission show that the major Er and Gd rare earth 4 f weight is at about 5-6 eV below the valence band maximum, similar to the 4 f weights in the valence band of many other rare earth doped semiconductors. For Yb, there is very little resonant enhancement of the valence band of Yb doped GaN, consistent with a largely 4f 14 - δ occupancy. The placement of the rare earth 4 f levels is in qualitative agreement with theoretical expectations.

  4. Magnetic x-ray linear dichroism in resonant and non-resonant Gd 4f photoemission

    SciTech Connect

    Mishra, S.; Gammon, W.J.; Pappas, D.P.

    1997-04-01

    The enhancement of the magnetic linear dichroism in resonant 4f photoemission (MLDRPE) is studied from a 50 monolayer film of Gd/Y(0001). The ALS at beamline 7.0.1 provided the source of linearly polarized x-rays used in this study. The polarized light was incident at an angle of 30 degrees relative to the film plane, and the sample magnetization was perpendicular to the photon polarization. The linear dichroism of the 4f core levels is measured as the photon energy is tuned through the 4d-4f resonance. The authors find that the MLDRPE asymmetry is strongest at the resonance. Near the threshold the asymmetry has several features which are out of phase with the fine structure of the total yield.

  5. 'Water window' sources: Selection based on the interplay of spectral properties and multilayer reflection bandwidth

    SciTech Connect

    Li, Bowen; Dunne, Padraig; O'Sullivan, Gerry; Higashiguchi, Takeshi; Otsuka, Takamitsu; Jiang, Weihua; Endo, Akira

    2013-01-28

    Development of laser-produced plasma 'water window' sources poses a major challenge in x-ray research and most effort has focused on line sources for use with zone plate optics. Here, a comparison of carbon and nitrogen line emission with that from both 3d - 4f and 4d - 4f unresolved transition arrays shows that, at power densities available from 'table-top' solid-state lasers, 3d - 4f emission from zirconium plasmas is most intense, and calculations show that in an imaging system based on multilayer mirrors, for reflectance bandwidths >1% has superior performance than either line or broader-band sources. For bandwidths <1%, line sources are preferable.

  6. Heterometallic aggregates of copper(I) with metalloligand Sn(edt)2 (edt = ethane-1,2-dithiolate): syntheses and structures of [Sn(edt)2Cl(mu-I)(mu3-I)(CuPPh3)3], [Sn(edt)2(mu-Br)2(mu3-Br)2(CuPPh3)4], and [{Sn(edt)2}3(mu-OH)3Cu5(PPh3)8][PF6]2.

    PubMed

    Han, Yan-Gong; Xu, Chao; Duan, Taike; Wu, Fang-Hui; Zhang, Qian-Feng; Leung, Wa-Hung

    2009-09-21

    The treatment of a slurry of an equimolar mixture of [Sn(edt)(2)] (edt = ethane-1,2- dithiolate) and [Et(4)N]Cl.xH(2)O with CuI in the presence of PPh(3) gave a tetranuclear compound, [Sn(edt)(2)Cl(mu-I)(mu(3)-I)(CuPPh(3))(3)] (1), which consists of a rectangular-pyramidal [Sn(edt)(2)Cl](-) moiety ligated by three [Cu(PPh(3))](+) fragments via the sulfur atoms of the edt(2-) ligands. The treatment of a slurry of [Sn(edt)(2)] and excess [Et(4)N]Br with [Cu(MeCN)(4)][PF(6)] in the presence of PPh(3) afforded a pentanuclear compound, [Sn(edt)(2)(mu-Br)(2)(mu(3)-Br)(2)(CuPPh(3))(4)] (2), which comprises two [(CuPPh(3))(2)(mu-Br)](+) fragments symmetrically ligating an octahedral trans-[Sn(edt)(2)Br(2)](2-) moiety via the sulfur and bromide atoms. Reaction of [Sn(edt)(2)] with [Cu(MeCN)(4)][PF(6)] and PPh(3) in a mixed MeCN/CH(2)Cl(2) solution yielded a novel octanuclear compound, [{Sn(edt)(2)}(3)(mu-OH)(3)Cu(5)(PPh(3))(8)][PF(6)](2) (3), which may be described as a triangular [{Sn(edt)(2)}(3)(mu-OH)(3)](3-) core chelated by three [Cu(PPh(3))(2)](+) species and capped by two [Cu(PPh(3))](+) species. The luminescent properties of compounds 1, 2, and 3 were investigated in a CH(2)Cl(2) solution at room temperature. Upon excitation at lambda > 360 nm, these compounds are luminescent in CH(2)Cl(2) solution with emissions having maxima at 422, 515, and 494 nm, respectively. PMID:19746999

  7. Synthesis of heterometallic carbide clusters containing three iron atoms: (PPN)/sup 2/(MFe/sub 3/(CO)/sub 13/C) (M = Cr, W), (PPN)/sub 2/(Cr/sub 2/Fe/sub 3/(CO)/sub 16/C), Rh/sub 2/Fe/sub 3/(CO)/sub 14/C, and (PPN)(Rh/sub 3/Fenumber(CO)/sub 15/C)

    SciTech Connect

    Hriljac, J.A.; Holt, E.M.; Shriver, D.F.

    1987-09-09

    Redox-condensation reactions involving (PPN)/sub 2/(Fe/sub 3/(CO)/sub 9/(CCO)) and electrophilic transition-metal reagents lead to (PPN)/sub 2/(MFe/sub 3/(CO)/sub 13/C) (M = Cr, W), (PPN)/sub 2/(Cr/sub 2/Fe/sub 3/(CO)/sub 16/C), Rh/sub 2/Fe/sub 3/(CO)/sub 14/C, and (PPN)(Rh/sub 3/Fe/sub 3/(CO)/sub 15/C). Variable-temperature /sup 13/C NMR spectroscopy was employed to assign the structures of the tetranuclear clusters and Rh/sub 2/Fe/sup 3/(CO)/sub 14/C in solution. An improved synthesis of (PPN)(RhFe/sub 3/(CO)/sub 12/C) and more complete variable-temperature (ca. -130 to +20 /sup 0/C) /sup 13/C NMR spectra of this cluster and (PPN)(MnFe/sub 3/(CO)/sub 13/C) are discussed. All of the tetranuclear clusters are assigned butterfly metal geometries will the heterometals located at hinge sites. Attempts to prepare iron-molybdenum carbide clusters are discussed. The structure of (PPN)(Rh/sub 3/Fe/sub 3/(CO)/sub 15/C) was determined by a single-crystal x-ray diffraction study and was found to consist of a trigonal-antiprismatic metal array with the carbide ligand within the metal polyhedron. The iron atoms define one of the trigonal faces and the rhodium atoms define the other. Crystal data for (PPN)(Rh/sub 3/Fe/sub 3/(CO)/sub 15/C): monoclinic, space group P2/sub 1//n, a = 16.220 (6) A, b = 9.282 (3) A, c = 35.17 (3) A, ..beta.. = 94.84 (5)/sup 0/, Z = 4. 28 references, 5 figures, 6 tables.

  8. A photoluminescent indium-organic framework with discrete cages and one-dimensional channels for gas adsorption.

    PubMed

    Qian, Jinjie; Li, Qipeng; Liang, Linfeng; Yang, Yan; Cao, Zhen; Yu, Panpan; Huang, Shaoming; Hong, Maochun

    2016-07-12

    We have successfully obtained, for the first time, a new heterometallic indium-organic framework (InOF-14) with a functional and luminescent Eu(iii) component. Based on the mutually competitive [In(CO2)4] and [Eu2(CO2)4(H2O)4] units, this microporous structure possesses discrete nano-cages and one-dimensional channels for gas adsorption, and simultaneously exhibits excellent luminescence properties. PMID:26781465

  9. Self-Assembly of a Giant Tetrahedral 3 d-4 f Single-Molecule Magnet within a Polyoxometalate System.

    PubMed

    Ibrahim, Masooma; Mereacre, Valeriu; Leblanc, Nicolas; Wernsdorfer, Wolfgang; Anson, Christopher E; Powell, Annie K

    2015-12-14

    A giant tetrahedral heterometallic polyoxometalate (POM) [Dy30 Co8 Ge12 W108 O408 (OH)42 (OH2 )30 ](56-) , which shows single-molecule magnet (SMM) behavior, is described. This hybrid contains the largest number of 4f ions of any polyoxometalate (POM) reported to date and is the first to incorporate two different 3d-4f and 4f coordination cluster assemblies within same POM framework. PMID:26390858

  10. Regulating the anticancer properties of organometallic dendrimers using pyridylferrocene entities: synthesis, cytotoxicity and DNA binding studies.

    PubMed

    Govender, Preshendren; Riedel, Tina; Dyson, Paul J; Smith, Gregory S

    2016-06-21

    A new series of eight first- and second-generation heterometallic ferrocenyl-derived metal-arene metallodendrimers, containing ruthenium(ii)-p-cymene, ruthenium(ii)-hexamethylbenzene, rhodium(iii)-cyclopentadienyl or iridium(iii)-cyclopentadienyl moieties have been prepared. The metallodendrimers were synthesized by first reacting DAB-(NH2)n (where n = 4 or 8, DAB = diaminobutane) with salicylaldehyde, and then the Schiff-base dendritic ligands were reacted in a one-pot reaction with the appropriate [(η(6)-p-iPrC6H4Me)RuCl2]2, [(η(6)-C6Me6)RuCl2]2, [(η(5)-C5Me5)IrCl2]2 or [(η(5)-C5Me5)RhCl2]2 dimers, in the presence of 4-pyridylferrocene. Heterometallic binuclear analogues were prepared as models of the larger metallodendrimers. All complexes have been characterized using analytical and spectroscopic methods. The cytotoxicity of the heterometallic metallodendrimers and their binuclear analogues were evaluated against A2780 cisplatin-sensitive and A2780cisR cisplatin-resistant human ovarian cancer cell lines and against a non-tumorigenic HEK-293 human embryonic kidney cell line. The second generation Ru(ii)-η(6)-C6Me6 metallodendrimer is the most cytotoxic and selective compound. DNA binding experiments reveal that a possible mode-of-action of these compounds involves non-covalent interactions with DNA. PMID:27193373

  11. Modeling of radiative properties of Sn plasmas for extreme-ultraviolet source

    NASA Astrophysics Data System (ADS)

    Sasaki, Akira; Sunahara, Atsushi; Furukawa, Hiroyuki; Nishihara, Katsunobu; Fujioka, Shinsuke; Nishikawa, Takeshi; Koike, Fumihiro; Ohashi, Hayato; Tanuma, Hajime

    2010-06-01

    Atomic processes in Sn plasmas are investigated for application to extreme-ultraviolet (EUV) light sources used in microlithography. We develop a full collisional radiative (CR) model of Sn plasmas based on calculated atomic data using Hebrew University Lawrence Livermore Atomic Code (HULLAC). Resonance and satellite lines from singly and multiply excited states of Sn ions, which contribute significantly to the EUV emission, are identified and included in the model through a systematic investigation of their effect on the emission spectra. The wavelengths of the 4d-4f+4p-4d transitions of Sn5+ to Sn13+ are investigated, because of their importance for determining the conversion efficiency of the EUV source, in conjunction with the effect of configuration interaction in the calculation of atomic structure. Calculated emission spectra are compared with those of charge exchange spectroscopy and of laser produced plasma EUV sources. The comparison is also carried out for the opacity of a radiatively heated Sn sample. A reasonable agreement is obtained between calculated and experimental EUV emission spectra observed under the typical condition of EUV sources with the ion density and ionization temperature of the plasma around 1018 cm-3 and 20 eV, respectively, by applying a wavelength correction to the resonance and satellite lines. Finally, the spectral emissivity and opacity of Sn plasmas are calculated as a function of electron temperature and ion density. The results are useful for radiation hydrodynamics simulations for the optimization of EUV sources.

  12. Synthesis of 2,6-dicarbethoxy-3,5-diaryltetrahydro-1,4-thiazine-1,1-dioxide derivatives as potent anticonvulsant agents.

    PubMed

    Edayadulla, Naushad; Ramesh, Penugonda

    2015-12-01

    An efficient synthesis of 2,6-dicarbethoxy-3,5-diaryltetrahydro-1,4-thiazine-1,1-dioxide derivatives has been achieved under aqueous medium for the first time in good to excellent yields. All the synthesized compounds were tested for anticonvulsant activity using the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) screens, which are the most broadly employed seizure models for early identification of candidate anticonvulsants. Their neurotoxicity was determined applying the rotarod test. Seven compounds 4a, 4d, 4f, 4h, 4o, 4p and 4q showed promising anticonvulsant activities in both models employed for anticonvulsant evaluation. The most active compound 4d showed the MES-induced seizures with ED50 value of 10.2 mg/kg and TD50 value of 288.6 mg/kg after intraperitoneal injection to mice, which provided compound 4d with a protective index (TD50/ED50) of 28.3 in the MES test. PMID:26519928

  13. Resonances in positron-potassium (e +-K) system with natural and unnatural parities

    NASA Astrophysics Data System (ADS)

    Umair, M.; Jonsell, S.

    2016-01-01

    We present an investigation of resonances with natural and unnatural parities in the positron-potassium system using the complex scaling method. A model potential is used to represent the interaction between the core and the valence electron. Explicitly correlated Gaussian wave functions are used to represent the correlation effects between the valence electron, the positron and the K+ core. Resonance energies and widths for two partial waves (S- and P-wave) below the {{K}}(4p,5 s,5p,4 d,4f) excitation thresholds and positronium n = 2 formation threshold are calculated for natural parity. Resonance states for P e below the {{K}}(4d) excitation threshold and positronium n = 2, 3 formation thresholds are calculated for unnatural parity which has not been previously reported. Below both positronium thresholds we have found a dipole series of resonances, with binding energies scaling in good agreement with exceptions from an analytical calculation. The present results are compared with those in the literature.

  14. Electron correlation and relativistic effects in photoabsorption processes of heavy closed shell atoms: Intermediate shells of Mercury

    NASA Astrophysics Data System (ADS)

    Banerjee, Tanima; Deshmukh, P. C.; Manson, S. T.

    2015-05-01

    Accuracy in the study of the photoionization of heavy atomic systems requires the inclusion of both many-body effects (correlation) and relativistic interactions. The Relative Random Phase Approximation (RRPA) is a powerful theoretical model which includes many important electron corrections, along with relativity, in the calculation of atomic photoionization. Previously, valence photoionization in atomic mercury has been investigated using RRPA. To expand the understanding of the the correlation and relativistic effects further, photoionization of the intermediate subshells of atomic mercury, 4s, 4p, 4d, 4f, 5s and 5d, have been studied at different levels of truncations as a means of pinpointing the specific aspect(s) of correlation that is important in a given case. It has been found that the intermediate subshells are sensitive to the correlation and relativistic effects but not as significantly as in the case of valence shell photoionization. In this work we have systematically investigated the changes caused by relativistic and correlation effects on both dipole (E1) and quadrupole (E2) photoionization parameters for atomic mercury.

  15. Electronic structure of the heavy-fermion caged compound Ce3Pd20X6(X=Si,Ge) studied by density functional theory and photoelectron spectroscopy

    DOE PAGESBeta

    Yamaoka, Hitoshi; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jarrige, Ignace; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; et al

    2015-03-30

    The electronic structure of Ce₃Pd₂₀X₆ (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f⁰ (Ce⁴⁺) component with a small fraction of f¹more » (Ce³⁺) component. The spectral weight of f¹ component near the Fermi level Ce₃Pd₂₀Si₆ is stronger than that for Ce₃Pd₂₀Ge₆ at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce₃Pd₂₀Si₆ compared to Ce₃Pd₂₀Ge₆.« less

  16. Electronic structure of the heavy-fermion caged compound Ce3Pd20X6(X=Si,Ge) studied by density functional theory and photoelectron spectroscopy

    SciTech Connect

    Yamaoka, Hitoshi; Schwier, Eike F.; Arita, Masashi; Shimada, Kenya; Tsujii, Naohito; Jarrige, Ignace; Jiang, Jian; Hayashi, Hirokazu; Iwasawa, Hideaki; Namatame, Hirofumi; Taniguchi, Masaki; Kitazawa, Hideaki

    2015-03-30

    The electronic structure of Ce₃Pd₂₀X₆ (X = Si, Ge) has been studied using detailed density functional theory (DFT) calculations and high-resolution photoelectron spectroscopy (PES) measurements. The orbital decomposition of the electronic structure by DFT calculations indicates that Ce atoms at the (8c) site surrounded by 16 Pd atoms have a more localized nature and a tendency to be magnetic. Ce atoms in the (4a) site surrounded by 12 Pd and 6 X atoms, on the other, show only a negligible magnetic moment. In the photoemission valence-band spectra we observe a strong f⁰ (Ce⁴⁺) component with a small fraction of f¹ (Ce³⁺) component. The spectral weight of f¹ component near the Fermi level Ce₃Pd₂₀Si₆ is stronger than that for Ce₃Pd₂₀Ge₆ at the 4d-4f resonance, suggesting stronger c-f hybridization in the former. This may hint to the origin of the large electronic specific coefficient of Ce₃Pd₂₀Si₆ compared to Ce₃Pd₂₀Ge₆.

  17. Electron impact excitation of resonance transitions in atomic potassium

    SciTech Connect

    Tayal, S.S.; Msezane, A.Z.

    1993-05-01

    Cross sections for electron impact excitation of the 4 s{sup 2}S - 4p {sup 2}P{sup o} and 4s {sup 2}S - 5p {sup 2}P{sup o} transitions in atomic potassium are calculated in the low-energy region from 1.5 to 30 eV using the R-matrix method. We included eight target states (4s {sup 2}S, 4p {sup 2}P{sup o}, 5s {sup 2}S, 3d {sup 2}D, 5p {sup 2}P{sup o}, 4d {sup 2}D, 6S {sup 2}S, and 4f {sup 2}F{sup o}) in the close-coupling expansion. These states are represented by extensive configuration- interaction wavefunctions constructed from the orthogonal one-electron orbitals: 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, 4f, 5s, 5p, and 6s. The calculated results are compared with the available experiments and other calculations. The present calculation shows a resonance structure in the cross section for the excitation of the resonance 4s {sup 2}S - 4p {sup 2}P{sup o} transition around 2.5 eV.

  18. Spectrum and energy levels of kryptonlike ion Nb VI

    SciTech Connect

    Reader, J.; Ekberg, J.O.

    1993-05-01

    The spectrum of five-times ionized niobium, Nb, VI, was observed from 238 to 2700 {angstrom} with sliding spark discharges on 10.7-m normal- and grazing-incidence spectrographs. Experimental energies were determined for all levels of the 4s{sup 2}4p{sup 6}, 4s{sup 2}4p{sup 6}, 4s{sup 2}4p{sup 5}4d, 4f, 5s, 5p, 5g, 6s, and 4s4p{sup 6}4d configurations as well as some levels of 4p{sup 5}6g. A total of 291 lines were classified as transitions between 88 observed levels. A previous analysis of this spectrum was found to be totally erroneous. Large hyperfine splittings were found for several levels of the 4p{sup 5}5s and 5p configurations. The observed configurations were theoretically interpreted by means of Hartree-Fock calculations and least squares fits of the energy parameters to the observed levels. A revised value of the ionization energy was obtained from the 4p{sup 5}5g and 6g configurations.

  19. Tuning electronic properties of metallic atom in bondage to a nanospace.

    PubMed

    Tang, Jun; Xing, Gengmei; Yuan, Hui; Cao, Wenbin; Jing, Long; Gao, Xingfa; Qu, Li; Cheng, Yue; Ye, Chang; Zhao, Yuliang; Chai, Zhifang; Ibrahim, Kurash; Qian, Haijie; Su, Run

    2005-05-12

    The possibility of modulating the electronic configurations of the innermost atoms inside a nanospace, nano sheath with chemical modification was investigated using synchrotron X-ray photoelectron spectroscopy. Systems of definite nanostructures were chosen for this study. Systematic variations in energy, intensity, and width of pi and sigma O 1s core level spectra, in absorption characteristics of C 1s-->pi transition, in photoabsorption of pre-edge and resonance regions of the Gd 4d-->4f transition, were observed for Gd@C(82) (an isolated nanospace for Gd), Gd@C(82)(OH)(12) (a modified nanospace for Gd), and Gd@C(82)(OH)(22) (a differently modified nanospace for Gd), and the reference materials Gd-DTPA (a semi-closed space for Gd) and Gd(2)O(3). A sandwich-type electronic interaction along [outer modification group]-[nano sheaths]-[inner metallic atom] was observed in the molecules of modifications. This makes it possible to control electron-donation directions, either from the innermost metallic atom toward the outer nano sheaths or the reverse. The results suggest that one may effectively tune the fine structures of electronic configurations of such a metallic atom being astricted into nanostructures through changing the number or category of outer groups of chemical modifications. This may open a door to realizing the desired designs for electronic and magnetic properties of functionalized nanomaterials. PMID:16852042

  20. New atomic data for Ge XX

    NASA Astrophysics Data System (ADS)

    Younis, Waleed Othman; Hibbert, Alan

    2015-12-01

    We have performed large-scale configuration interaction (CI) calculations using CIV3for the lowest (in energy) 155 fine-structure levels of aluminum-like germanium ion. We have calculated the energies and lifetimes of these levels, together with oscillator strengths, and transition probabilities for the electric-dipole (optically allowed and intercombination) transitions among the levels of ground state 3s23p (2P) and higher energy levels of states 3s3p2, 3s23d, 3p3, 3s3p3d, 3p23d, 3s3d2,3p3d2, 3d3,3s2 (4s, 4p, 4d, 4f) of Ge XX in the LSJ coupling scheme. The present results include relativistic effects through the Breit-Pauli operator. Improvements to the ab initio calculations are made by applying a "fine-tuning" technique in which small adjustments are made to some diagonal elements of the Hamiltonian matrix so as to bring the calculated energy separations into as close agreement as possible with experimental values. Comparisons are made with other available experimental and theoretical results and the accuracy of the present results is assessed.

  1. Heterometal silver/copper(I) modulated thermochromism of two isostructural iodoplumbates

    SciTech Connect

    Li, Honghong; Yu, Tanlai; An, Li; Wang, Yilin; Shen, Junju; Fu, Yangbo; Fu, Yunlong

    2015-01-15

    Two isostructrual heterometallic iodoplumbates [Y(DMF){sub 8}]{sub 2n}[Pb{sub 7}M{sub 2}I{sub 22}]{sub n} [M=Cu(1), Ag(2)] have been prepared. Chargely balanced by [Y(DMF){sub 8}]{sup 3+}, [Pb{sub 7}M{sub 2}I{sub 22}]{sub n}{sup 6n−} displays a 1D zigzag chain constructed from MI{sub 4} tetrahedron and Pb{sub 7}I{sub 24} unit similar to a fragment of commonly observed (PbI{sub 3}){sub n}{sup n−} chain. Their band gaps (Eg) can be estimated as 2.66 and 2.72 eV, revealing potential semiconducting properties. Interestingly, thermochromism exhibits different response to the temperature for two compounds, which is verified by the diffuse-reflectance UV–visible spectra and crystallographic data at different temperatures. Moreover, this phenomenon is attributed to the difference of heterometal Ag and Cu(I). - Graphical abstract: Two isostructrual heterometallic iodoplumbates [Y(DMF){sub 8}]{sub 2n}[Pb{sub 7}M{sub 2}I{sub 22}]{sub n} [M=Cu(1),Ag(2)] have been prepared. [Pb{sub 7}M{sub 2}I{sub 22}]{sub n}{sup 6n−} displays a 1D zigzag chain constructed from MI{sub 4} tetrahedron and Pb{sub 7}I{sub 24} unit similar to a fragment of commonly observed (PbI{sub 3}){sub n}{sup n−} chain. Interestingly, the thermochromism for two compounds exhibits different response to the temperature, which is attributed to the difference of heterometal Ag and Cu. - Highlights: • Two isostructrual heterometallic iodoplumbates have been prepared. • Single-crystal-X-ray diffraction data were collected at different temperatures. • Spectroscopic characterization showed semiconducting and thermochromic properties. • The difference of thermochromic properties for two compounds was studied.

  2. Ultrafine Metal-Organic Right Square Prism Shaped Nanowires.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-05-23

    We report the structural design and control of electronic states of a new series of ultrafine metal-organic right square prism-shaped nanowires. These nanowires have a very small inner diameter of about 2.0 Å, which is larger than hydrogen and similar to xenon atomic diameters. The electronic states of nanowires can be widely controlled by substitution of structural components. Moreover, the platinum homometallic nanowire shows a 100 times higher proton conductivity than a palladium/platinum heterometallic one depending on the electronic states. PMID:27080935

  3. Syntheses, structures, and properties of a series of novel high-nuclear 3d-4f clusters with mixed amino acids as ligands: {Ln6Cu24}(Ln = Gd, Tb, Pr and Sm).

    PubMed

    Shen, Chao-Jun; Hu, Sheng-Min; Sheng, Tian-Lu; Xue, Zhen-Zhen; Wu, Xin-Tao

    2015-04-14

    The first examples of high-nuclear 3d-4f heterometallic clusters with mixed amino acid ligands are reported. Four 30-nuclear clusters {Ln6Cu24}(Ln = Gd, Tb, Pr and Sm) were obtained through the self-assembly of Ln(III), Cu(II) and mixed amino acid ligands of glycine (HGly) and β-alanine (HAla). The metal skeleton of clusters may be described as a huge {Ln6Cu12} octahedron connected with 12 additional Cu(II) ions. The temperature dependence of magnetic susceptibilities of compounds were also studied. PMID:25756855

  4. Synthesis and the crystal and molecular structure of the Sn(IV)-Nd(III) coordination polymer based on the tartaric acid [NdSn2{H( Tart)3} · 12H2O] n

    NASA Astrophysics Data System (ADS)

    Sergienko, V. S.; Chebanenko, E. A.; Seifullina, I. I.; Churakov, A. V.; Martsinko, E. E.

    2016-03-01

    The polymeric heterometallic [NdSn2{H( Tart)3} • 12H2O] n ( I) compound, where H4 Tart is the tartaric acid, is synthesized and characterized by elemental analysis, X-ray diffraction, thermogravimetry, and IR spectroscopy. The structural elements of crystal I, namely, polymeric [{Nd(H2O)6}(μ3-H n Tart 4- n ) {Sn(μ2-H n Tart 4- n )}2} ( n = 0, 1) complex molecules and crystallization water molecules, are connected by an extended hydrogen-bond system.

  5. Copper(I)-assisted red-shifted phosphorescence in Au(I)···Cu(I) heteropolynuclear complexes.

    PubMed

    Catalano, Vincent J; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Pascual, David

    2014-11-21

    Reactions between [Au(C6Cl2F3)(tht)] and P,N-donor bridging ligands of the type PPh2py and (PPh2)2phen lead to the homonuclear gold complexes [Au(C6Cl2F3)(PPh2py)] (1) and [Au2(C6Cl2F3)2{(PPh2)2phen}] (2). Subsequent addition of [Cu(CH3CN)4](BF4) leads to the formation of the corresponding gold-copper heterometallic complexes [Au2Cu(C6Cl2F3)2(PPh2py)2](BF4) (3) and [Au2Cu(C6Cl2F3)2{(PPh2)2phen)}(CH3CN)](BF4) (4). The four complexes have been structurally characterized and are luminescent. The gold precursors show emissions arising from metal-perturbed intraligand transitions. The heterometallic complexes show a red shift of the emissions that is proposed to arise from an admixture of IL (intraligand) and MLCT (metal-to-ligand-charge-transfer) transitions. DFT and TD-DFT calculations agree well with these results. PMID:25251359

  6. Making hybrid [n]-rotaxanes as supramolecular arrays of molecular electron spin qubits

    NASA Astrophysics Data System (ADS)

    Fernandez, Antonio; Ferrando-Soria, Jesus; Pineda, Eufemio Moreno; Tuna, Floriana; Vitorica-Yrezabal, Iñigo J.; Knappke, Christiane; Ujma, Jakub; Muryn, Christopher A.; Timco, Grigore A.; Barran, Perdita E.; Ardavan, Arzhang; Winpenny, Richard E. P.

    2016-01-01

    Quantum information processing (QIP) would require that the individual units involved--qubits--communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic-inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2CtBu)16]- coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron-electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates.

  7. Making hybrid [n]-rotaxanes as supramolecular arrays of molecular electron spin qubits.

    PubMed

    Fernandez, Antonio; Ferrando-Soria, Jesus; Pineda, Eufemio Moreno; Tuna, Floriana; Vitorica-Yrezabal, Iñigo J; Knappke, Christiane; Ujma, Jakub; Muryn, Christopher A; Timco, Grigore A; Barran, Perdita E; Ardavan, Arzhang; Winpenny, Richard E P

    2016-01-01

    Quantum information processing (QIP) would require that the individual units involved--qubits--communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic-inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2C(t)Bu)16](-) coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron-electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates. PMID:26742716

  8. Making hybrid [n]-rotaxanes as supramolecular arrays of molecular electron spin qubits

    PubMed Central

    Fernandez, Antonio; Ferrando-Soria, Jesus; Pineda, Eufemio Moreno; Tuna, Floriana; Vitorica-Yrezabal, Iñigo J.; Knappke, Christiane; Ujma, Jakub; Muryn, Christopher A.; Timco, Grigore A.; Barran, Perdita E.; Ardavan, Arzhang; Winpenny, Richard E.P.

    2016-01-01

    Quantum information processing (QIP) would require that the individual units involved—qubits—communicate to other qubits while retaining their identity. In many ways this resembles the way supramolecular chemistry brings together individual molecules into interlocked structures, where the assembly has one identity but where the individual components are still recognizable. Here a fully modular supramolecular strategy has been to link hybrid organic–inorganic [2]- and [3]-rotaxanes into still larger [4]-, [5]- and [7]-rotaxanes. The ring components are heterometallic octanuclear [Cr7NiF8(O2CtBu)16]– coordination cages and the thread components template the formation of the ring about the organic axle, and are further functionalized to act as a ligand, which leads to large supramolecular arrays of these heterometallic rings. As the rings have been proposed as qubits for QIP, the strategy provides a possible route towards scalable molecular electron spin devices for QIP. Double electron–electron resonance experiments demonstrate inter-qubit interactions suitable for mediating two-qubit quantum logic gates. PMID:26742716

  9. [Experimental investigation of laser plasma soft X-ray source with gas target].

    PubMed

    Ni, Qi-liang; Gong, Yan; Lin, Jing-quan; Chen, Bo; Cao, Jian-lin

    2003-02-01

    This paper describes a debris-free laser plasma soft X-ray source with a gas target, which has high operating frequency and can produce strong soft X-ray radiation. The valve of this light source is drived by a piezoelectrical ceramic whose operating frequency is up to 400 Hz. In comparison with laser plasma soft X-ray sources using metal target, the light source is debris-free. And it has higher operating frequency than gas target soft X-ray sources whose nozzle is controlled by a solenoid valve. A channel electron multiplier (CEM) operating in analog mode is used to detect the soft X-ray generated by the laser plasma source, and the CEM's output is fed to to a charge-sensitive preamplifier for further amplification purpose. Output charges from the CEM are proportional to the amplitude of the preamplifier's output voltage. Spectra of CO2, Xe and Kr at 8-14 nm wavelength which can be used for soft X-ray projection lithography are measured. The spectrum for CO2 consists of separate spectral lines originate mainly from the transitions in Li-like and Be-like ions. The Xe spectrum originating mainly from 4d-5f, 4d-4f, 4d-6p and 4d-5p transitions in multiply charged xenon ions. The spectrum for Kr consists of separate spectral lines and continuous broad spectra originating mainly from the transitions in Cu-, Ni-, Co- and Fe-like ions. PMID:12939982

  10. Analysis of extreme ultraviolet spectra from laser produced rhenium plasmas

    NASA Astrophysics Data System (ADS)

    Wu, Tao; Higashiguchi, Takeshi; Li, Bowen; Suzuki, Yuhei; Arai, Goki; Dinh, Thanh-Hung; Dunne, Padraig; O'Reilly, Fergal; Sokell, Emma; Liu, Luning; O'Sullivan, Gerry

    2015-08-01

    Extreme ultraviolet spectra of highly-charged rhenium ions were observed in the 1-7 nm region using two Nd:YAG lasers with pulse lengths of 150 ps and 10 ns, respectively, operating at a number of laser power densities. The maximum focused peak power density was 2.6 × 1014 W cm-2 for the former and 5.5 × 1012 W cm-2 for the latter. The Cowan suite of atomic structure codes and unresolved transition array (UTA) approach were used to calculate and interpret the emission properties of the different spectra obtained. The results show that n = 4-n = 4 and n = 4-n = 5 UTAs lead to two intense quasi-continuous emission bands in the 4.3-6.3 nm and 1.5-4.3 nm spectral regions. As a result of the different ion stage distributions in the plasmas induced by ps and ns laser irradiation the 1.5-4.3 nm UTA peak moves to shorter wavelength in the ps laser produced plasma spectra. For the ns spectrum, the most populated ion stage during the lifetime of this plasma that could be identified from the n = 4-n = 5 transitions was Re23+ while for the ps plasma the presence of significantly higher stages was demonstrated. For the n = 4-n = 4 4p64dN-4p54dN+1 + 4p64dN-14f transitions, the 4d-4f transitions contribute mainly in the most intense 4.7-5.5 nm region while the 4p-4d subgroup gives rise to a weaker feature in the 4.3-4.7 nm region. A number of previously unidentified spectral features produced by n = 4-n = 5 transitions in the spectra of Re XVI to Re XXXIX are identified.

  11. Energy levels, radiative rates, and lifetimes for transitions in W XL

    SciTech Connect

    Aggarwal, Kanti M. Keenan, Francis P.

    2014-11-15

    Energy levels and radiative rates are reported for transitions in Br-like tungsten, W XL, calculated with the general-purpose relativistic atomic structure package (GRASP). Configuration interaction (CI) has been included among 46 configurations (generating 4215 levels) over a wide energy range up to 213 Ryd. However, for conciseness results are only listed for the lowest 360 levels (with energies up to ∼43 Ryd), which mainly belong to the 4s{sup 2}4p{sup 5},4s{sup 2}4p{sup 4}4d,4s{sup 2}4p{sup 4}4f,4s4p{sup 6},4p{sup 6}4d,4s4p{sup 5}4d,4s{sup 2}4p{sup 3}4d{sup 2}, and 4s{sup 2}4p{sup 3}4d4f configurations, and provided for four types of transitions, E1, E2, M1, and M2. Comparisons are made with existing (but limited) results. However, to fully assess the accuracy of our data, analogous calculations have been performed with the flexible atomic code, including an even larger CI than in GRASP. Our energy levels are estimated to be accurate to better than 0.02 Ryd, whereas results for radiative rates (and lifetimes) should be accurate to better than 20% for a majority of the strong transitions.

  12. Emission lines in the optical spectrum of 3 Cen A

    NASA Astrophysics Data System (ADS)

    Wahlgren, G. M.; Hubrig, S.

    2004-05-01

    Previously, weak emission lines had been detected at red wavelengths in the spectra of a limited sample of mid to late B type main sequence stars. A fuller description of the occurrence and origins of these lines has yet to be forwarded, in part due to the lack of observations detailing the spectral transitions involved. To address this deficiency, we present a line list of weak emission features found in the optical and near infrared spectral region of the chemically peculiar He-weak star 3 Cen A (HD 120709). Nearly 350 features, mostly associated with allowed transitions from high-excitation states of first ions, are catalogued along with identifications. Prominent among the emission lines are the spectra P II, Mn II, Fe II, Ni II and Cu II. Emission lines from Ca II, Si II and Hg II are also evident. Abundances are determined for several elements from synthetic spectrum fitting, with anomalies detected for the ions O I/II, P II/III and Si II/III. The LTE synthetic spectrum fitting also revealed that the low excitation 4s-4p transitions of Fe II predict an abundance that is greater than that determined from higher excitation 4d-4f transitions. Several of these latter transitions have upper energy levels that are found to be associated with emission lines. We also present empirical considerations for the excitation processes leading to the weak emission lines. Based on observations obtained at the European Southern Observatory, La Silla, Chile, No. 65.L-0316 and Paranal, Chile No. 266.D-5655. Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/1073

  13. Coordination-Cluster-Based Molecular Magnetic Refrigerants.

    PubMed

    Zhang, Shaowei; Cheng, Peng

    2016-08-01

    Coordination polymers serving as molecular magnetic refrigerants have been attracting great interest. In particular, coordination cluster compounds that demonstrate their apparent advantages on cryogenic magnetic refrigerants have attracted more attention in the last five years. Herein, we mainly focus on depicting aspects of syntheses, structures, and magnetothermal properties of coordination clusters that serve as magnetic refrigerants on account of the magnetocaloric effect. The documented molecular magnetic refrigerants are classified into two primary categories according to the types of metal centers, namely, homo- and heterometallic clusters. Every section is further divided into several subgroups based on the metal nuclearity and their dimensionalities, including discrete molecular clusters and those with extended structures constructed from molecular clusters. The objective is to present a rough overview of recent progress in coordination-cluster-based molecular magnetic refrigerants and provide a tutorial for researchers who are interested in the field. PMID:27381662

  14. Heterometal silver/copper(I) modulated thermochromism of two isostructural iodoplumbates

    NASA Astrophysics Data System (ADS)

    Li, Honghong; Yu, Tanlai; An, Li; Wang, Yilin; Shen, Junju; Fu, Yangbo; Fu, Yunlong

    2015-01-01

    Two isostructrual heterometallic iodoplumbates [Y(DMF)8]2n[Pb7M2I22]n [M=Cu(1), Ag(2)] have been prepared. Chargely balanced by [Y(DMF)8]3+, [Pb7M2I22]n6n- displays a 1D zigzag chain constructed from MI4 tetrahedron and Pb7I24 unit similar to a fragment of commonly observed (PbI3)nn- chain. Their band gaps (Eg) can be estimated as 2.66 and 2.72 eV, revealing potential semiconducting properties. Interestingly, thermochromism exhibits different response to the temperature for two compounds, which is verified by the diffuse-reflectance UV-visible spectra and crystallographic data at different temperatures. Moreover, this phenomenon is attributed to the difference of heterometal Ag and Cu(I).

  15. Composition dependence of magnetic relaxation for CoNi chain-based compounds with mixed double azide-tetrazolate bridges.

    PubMed

    Cheng, Min; Ding, You-Song; Gao, En-Qing; Zhang, Zhicheng; Jia, Qin-Xiang

    2016-05-10

    Seven isomorphous 2D CoNi (0 ≤ x ≤ 1) compounds based on ferromagnetic chains with mixed double [(μ-EO-N3)(μ-N-N-tetrazolate)] (EO = end-on) were synthesized and then structurally and magnetically characterized. They are formulated as [CoNi(L)(N3)(H2O)]·H2O (), (x = 1 (), 0.86 (), 0.74 (), 0.39 (), 0.14 (), 0.10 (), 0 (); L = 3-(5-tetrazole)-N-oxide-pyridine). Magnetic studies revealed that the homo-metallic compounds ( and ) behave as metamagnets, while the hetero-metallic compounds () show interesting composition-dependent slow relaxation due to the synergy effect of Co(II) and Ni(II) ions. PMID:27071813

  16. Two novel FeII-oxalate architectures: Solvent-free synthesis, structures, thermal and magnetic studies

    NASA Astrophysics Data System (ADS)

    Li, Jin-Hua; Liu, Hui; Wei, Li; Wang, Guo-Ming

    2015-10-01

    Two novel FeII-oxalate framework with the formulas of [NH4][FeIILi3(C2O4)3] (1) and [NH4]2[FeII(C2O4)2]·H2O (2) have been prepared by an oxalic acid flux approach and structurally characterized by IR, elemental analysis, thermogravimetric analysis, single-crystal and powder X-ray diffraction. Heterometallic compound 1 displays a three-dimensional (3D) framework with a pto topology, while homometallic compound 2 features a pillar-layer architecture with a hms topology. Thermal analysis indicates that the two compounds can be stable up to 300 °C and 200 °C, respectively. Magnetic investigations suggest that the FeII ions in 1 and 2 exhibit weak magnetic exchange interactions.

  17. Highly Luminescent, Water-Soluble Lanthanide Fluorobenzoates: Syntheses, Structures and Photophysics, Part I: Lanthanide Pentafluorobenzoates.

    PubMed

    Kalyakina, Alena S; Utochnikova, Valentina V; Bushmarinov, Ivan S; Ananyev, Ivan V; Eremenko, Igor L; Volz, Daniel; Rönicke, Franziska; Schepers, Ute; Van Deun, Rik; Trigub, Alexander L; Zubavichus, Yan V; Kuzmina, Natalia P; Bräse, Stefan

    2015-12-01

    Highly luminescent, photostable, and soluble lanthanide pentafluorobenzoates have been synthesized and thoroughly characterized, with a focus on Eu(III) and Tb(III) complexes as visible emitters and Nd(III) , Er(III) , and Yb(III) complexes as infrared emitters. Investigation of the crystal structures of the complexes in powder form and as single crystals by using X-ray diffraction revealed five different structural types, including monomeric, dimeric, and polymeric. The local structure in different solutions was studied by using X-ray absorption spectroscopy. The photoluminescence quantum yields (PLQYs) of terbium and europium complexes were 39 and 15 %, respectively; the latter value was increased almost twice by using the heterometallic complex [Tb0.5 Eu0.5 (pfb)3 (H2 O)] (Hpfb=pentafluorobenzoic acid). Due to the effectively utilized sensitization strategy (pfb)(-) →Tb→Eu, a pure europium luminescence with a PLQY of 29 % was achieved. PMID:26489887

  18. Applications of extended X-ray absorption fine-structure spectroscopy to studies of bimetallic nanoparticle catalysts.

    PubMed

    Frenkel, Anatoly I

    2012-12-21

    Extended X-ray absorption fine structure (EXAFS) spectroscopy has been used to study short range order in heterometallic alloys for almost four decades. In this critical review, experimental, theoretical and data analytical approaches are revisited to examine their power, and limitations, in studies of bimetallic nanocatalysts. This article covers the basics of EXAFS experiments, data analysis, and modelling of nanoscale clusters. It demonstrates that, in the best case scenario, quantitative information about the nanocatalyst's size, shape, details of core-shell architecture, as well as static and dynamic disorder in metal-metal bond lengths can be obtained. The article also emphasizes the main challenge accompanying such insights: the need to account for the statistical nature of the EXAFS technique, and discusses corrective strategies. PMID:22833100

  19. Charge-Transfer Phase Transition of a Cyanide-Bridged Fe(II) /Fe(III) Coordination Polymer.

    PubMed

    Zhang, Kuirun; Kang, Soonchul; Yao, Zi-Shuo; Nakamura, Kazusa; Yamamoto, Takashi; Einaga, Yasuaki; Azuma, Nobuaki; Miyazaki, Yuji; Nakano, Motohiro; Kanegawa, Shinji; Sato, Osamu

    2016-05-10

    Heterometallic Prussian blue analogues are known to exhibit thermally induced charge transfer, resulting in switching of optical and magnetic properties. However, charge-transfer phase transitions have not been reported for the simplest FeFe cyanide-bridged systems. A mixed-valence Fe(II) /Fe(III) cyanide-bridged coordination polymer, {[Fe(Tp)(CN)3 ]2 Fe(bpe)⋅5 H2 O}n , which demonstrates a thermally induced charge-transfer phase transition, is described. As a result of the charge transfer during this phase transition, the high-spin state of the whole system does not change to a low-spin state. This result is in contrast to FeCo cyanide-bridged systems that exhibit charge-transfer-induced spin transitions. PMID:27061860

  20. Bis{μ2-2-[(2-hy­droxy­eth­yl)(meth­yl)amino]­ethano­lato}bis­(μ3-N-methyl-2,2′-aza­nediyldiethano­lato)tetra­kis­(thio­cyan­atato-κN)dichromium(III)dimanganese(II) dimethyl­formamide tetra­solvate

    PubMed Central

    Semenaka, Valentyna V.; Nesterova, Oksana V.; Kokozay, Volodymyr N.; Zubatyuk, Roman I.; Shishkin, Oleg V.

    2011-01-01

    The heterometallic title complex, [Cr2Mn2(C5H11NO2)2(C5H12NO2)2(NCS)4]·4C3H7NO, was prepared using manganese powder, Reineckes salt, ammonium thio­cyanate and a non-aqueous solution of N-methyl­diethano­lamine in air. The centrosymmetric mol­ecular structure of the complex is based on a tetra­nuclear {Mn2Cr2(μ-O)6} core. The tetra­nuclear complex mol­ecule and the two uncoordinated dimethyl­formamide mol­ecules are linked by O—H⋯O hydrogen bonds, while the two other mol­ecules of dimethyl­formamide do not participate in hydrogen bonding. PMID:22199632

  1. Ca K-Edge XAS as a Probe of Calcium Centers in Complex Systems

    PubMed Central

    2014-01-01

    Herein, Ca K-edge X-ray absorption spectroscopy (XAS) is developed as a means to characterize the local environment of calcium centers. The spectra for six, seven, and eight coordinate inorganic and molecular calcium complexes were analyzed and determined to be primarily influenced by the coordination environment and site symmetry at the calcium center. The experimental results are closely correlated to time-dependent density functional theory (TD-DFT) calculations of the XAS spectra. The applicability of this methodology to complex systems was investigated using structural mimics of the oxygen-evolving complex (OEC) of PSII. It was found that Ca K-edge XAS is a sensitive probe for structural changes occurring in the cubane heterometallic cluster due to Mn oxidation. Future applications to the OEC are discussed. PMID:25492398

  2. Poly[μ3-acetato-di-μ3-isonicotinato-μ2-isonicotinato-samarium(III)silver(I)

    PubMed Central

    Zhu, Li-Cai

    2009-01-01

    In the title homochiral three-dimensional heterometallic complex, [AgSm(C6H4NO2)3(C2H3O2)]n, the eight-coordinate SmIII ion displays a bicapped trigonal-prismatic geometry, being coordinated by two O atoms from one acetate ligand, four O atoms from four bridging isonicotinate ligands and two O atoms from two terminal isonicotinate ligands. The four-coordinate AgI ion adopts a tetra­hedral geometry, being bonded to two N atoms from two bridging isonicotinate ligands and two O atoms from two acetate ligands. These metal coordination units are connected by bridging isonicotinate and acetate ligands, generating a three-dimensional network. PMID:21578640

  3. Designed enclosure enables guest binding within the 4200 å(3) cavity of a self-assembled cube.

    PubMed

    Ramsay, William J; Szczypiński, Filip T; Weissman, Haim; Ronson, Tanya K; Smulders, Maarten M J; Rybtchinski, Boris; Nitschke, Jonathan R

    2015-05-01

    Metal-organic self-assembly has proven to be of great use in constructing structures of increasing size and intricacy, but the largest assemblies lack the functions associated with the ability to bind guests. Here we demonstrate the self-assembly of two simple organic molecules with Cd(II) and Pt(II) into a giant heterometallic supramolecular cube which is capable of binding a variety of mono- and dianionic guests within an enclosed cavity greater than 4200 Å(3) . Its structure was established by X-ray crystallography and cryogenic transmission electron microscopy. This cube is the largest discrete abiological assembly that has been observed to bind guests in solution; cavity enclosure and coulombic effects appear to be crucial drivers of host-guest chemistry at this scale. The degree of cavity occupancy, however, appears less important: the largest guest studied, bound the most weakly, occupying only 11 % of the host cavity. PMID:25873434

  4. Bottom-Up Self-Assembly of the Sphere-Shaped Icosametallic Oxo Clusters {Cu20} and {Cu12Zn8}.

    PubMed

    Chen, Juan; Zhou, Hulan; Xu, Feng

    2016-05-16

    A discrete nanospheric icosametallic cluster comprised of 20 Cu ions (1) was self-assembled from facile synthesis. Adjustment of the synthesis by the choice of ligands gave rise to another cluster (2) with an intact icosacupric core and improved stability. Referring to the synthesis of 1 and 2, a heterometallic cluster (3), which contains 12 Cu(II) and 8 Zn(II), was designed and characterized by single-crystal X-ray diffraction, combined with elemental analysis, energy-dispersive X-ray, X-ray photoelectron spectroscopy, thermogravimetric analysis, and element mapping. The magnetic measurements of 2 and 3 and the scanning electron microscopy images and UV-visible diffuse-reflectance measurements of metal oxides from 2 and 3 indicate that isolation of {Cu12M8} is a new synthetic route to materials with engineered properties. PMID:27116596

  5. Isolation and characterization of the [Ga2Al18O8(OH)36(H2O)12](8+) cluster: cationic variations on the Wells-Dawson topology.

    PubMed

    Fairley, M; Corum, K W; Johns, A; Unruh, D K; Basile, M; de Groot, J; Mason, S E; Forbes, T Z

    2015-08-11

    The structural chemistry of Group 13 polyoxometalates lags far behind related negatively charged transition metal species and limits the development of advanced materials. A novel heterometallic cluster [Ga2Al18O8(OH)36(H2O)12](8+) (Ga2Al18) has been isolated using a supramolecular approach and structurally characterized using single-crystal X-ray diffraction. Ga2Al18 represents the Wells-Dawson structure polycations and variations in the structural topology may be related to the initial stabilization of the Keggin isomer. DFT calculations on the related ε-Keggins (GaAl12 and Al13), Ga2Al18, and theoretical Al2Al18 clusters reveal similar features of electronic structure, suggesting additional heteroatom substitution in other isostructural clusters should be possible. PMID:26146343

  6. Synthesis and characterization of homo- and heterobimetallic niobium{sup v} and tantalum{sup v} peroxo-polyaminocarboxylato complexes and their use as single or multiple molecular precursors for Nb-Ta mixed oxides

    SciTech Connect

    Bayot, Daisy . E-mail: devillers@chim.ucl.ac.be

    2005-09-15

    New water-soluble bimetallic peroxo complexes of niobium{sup V} and/or tantalum{sup V} with high-denticity polyaminocarboxylate ligands have been prepared, characterized from the spectroscopic point of view, and used as molecular precursors for Nb-Ta mixed oxides. Four new homobimetallic complexes (gu){sub 3}[Nb{sub 2}(O{sub 2}){sub 4}(dtpaO{sub 3})].3H{sub 2}O 1 (gu){sub 3}[Ta{sub 2}(O{sub 2}){sub 4}(dtpaO{sub 3})].5H{sub 2}O 2 (gu){sub 3}[Nb{sub 2}(O{sub 2}){sub 4}(HtthaO{sub 4})].2H{sub 2}O 4 and (gu){sub 3}[Ta{sub 2}(O{sub 2}){sub 4}(HtthaO{sub 4})].3H{sub 2}O 5 and the corresponding heterometallic complexes (gu){sub 3}[NbTa(O{sub 2}){sub 4}(dtpaO{sub 3})].2.5H{sub 2}O 3 and (gu){sub 3}[NbTa(O{sub 2}){sub 4}(HtthaO{sub 4)}].2H{sub 2}O 6 have been obtained. In these compounds, the in situ oxidation of the nitrogen atoms of the PAC ligands into N-oxide groups has been evidenced by IR spectroscopy and mass spectrometry. The thermal treatment of the homonuclear complexes in air at 700 or 800 deg. C, depending on the Ta content, provided Nb{sub 2}O{sub 5} or Ta{sub 2}O{sub 5} while the heteronuclear compounds led to the solid solution TaNbO{sub 5}. BET and SEM measurements have been carried out and comparison of the morphology of the samples prepared from homo- and heterometallic precursors is discussed.

  7. On the reliability of heteronuclear precursors-ligand effects in the Li-MOCVD synthesis of SrTiO3 films.

    PubMed

    Seisenbaeva, Gulaim A; Gohil, Suresh; Kessler, Vadim G; Andrieux, Michel; Legros, Corinne; Ribot, Patrick; Brunet, Magali

    2011-09-01

    Strontium titanate SrTiO3 thin films are highly perspective as gate dielectric material. Difference in volatility of the common homometallic precursors-strontium beta-diketonates and titanium alkoxides remains major hinder for preparation of high quality coatings based on this phase. An attractive alternative in its synthesis by MOCVD is provided by application of heterometallic mixed-ligand complexes, Sr2Ti2(beta-diket)4(OR)8(ROH)x. Mass-spectrometric study reveals, however, that none of these species can be considered a true single-source precursor. The relative stability of the molecules in solution and the congruence of in-situ release of homometallic species on evaporation are, on the other hand, crucial for the quality of the produced films and are strongly influenced by the nature of alkoxide ligands, OR. The historically first discovered representative of this heterometallic family, a sec-alkoxide derivative Sr2Ti2(thd)4(O(i)Pr)8, is in fact unexpectedly unstable, transforming in solution into Sr2Ti(thd)4(O(i)Pr)4((i)PrOH), which explains difficulties in keeping the correct stoichiometry using isopropoxide precursor. The primary alkoxide complexes, Sr2Ti2(thd)4(OR)8(ROH)2, R = Et, (n)Pr are also unstable yielding Sr4Ti2(thd)4(OR)8(ROH)2 on decomposition. The best solution stability and most uniform evaporation was observed for the iso-derivative, Sr2Ti2(thd)4(O(i)Bu)8, permitting to apply it in long term experiments under industrial process conditions. Present contribution provides detailed experimental comparison between and sec-and iso-alkoxide derivatives and sheds light on the influence of the ligand on molecular stability of a precursor and how it influences the quality of the derived oxide film, especially in relation to its electrophysical properties. PMID:22097573

  8. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Technical progress report, October--December 1993

    SciTech Connect

    Schmidt, E.; Kirby, S.; Song, Chunshan; Schobert, H.H.

    1994-04-01

    Development of new catalysts is a promising approach to more, efficient coal liquefaction. It has been recognized that dispersed catalysts can be superior to supported catalysts for primary liquefaction of coals, because the control of initial coal dissolution or depolymerization requires infinite contact between the catalyst and coal. The primary objective of this research is to explore the potential of bimetallic dispersed catalysts from heterometallic molecular precursors in their use in model compound liquefaction reactions. This quarterly report describes the use of three precursors in model compound reactions. The first catalyst is a heterometallic complex consisting of two transition metals, Mo and Ni, and sulfur in a single molecule. The second is a thiocubane type complex consisting of cobalt, molybdenum and sulfur. The third is a thiocubane type cluster consisting of iron and sulfur and the fourth, the pure inorganic salt ammonium tetrathiomolybdate (ATM). It was found that the structure and the ligands in the model complexes affect the activity of the resulting catalyst significantly. The optimum reaction at a pressure of 6.9 MPa hydrogen gas varied for different catalysts. The bimetallic catalysts generated in situ from the organometallic precursor are more active than monometallic catalysts like ATTM and the thiocubane type cluster Fe{sub 4}. Main products are hydrogenated phenanthrene derivatives, like DBP, THP, sym-OHP, cis- and trans-unsym-OHP with minor isomerization products such as sym-OHA. Our results indicate that other transition metal and ligand combinations in the organometallic precursors and the use of another model compound could result in substantially higher conversion activity.

  9. Magnetic properties and hyperfine interactions in Cr8, Cr7Cd, and Cr7Ni molecular rings from 19F-NMR

    SciTech Connect

    Bordonali, L; Garlatti, E; Casadei, C M; Furukawa, Y; Lascialfari, A; Carretta, S; Troiani, F; Timco, G; Winpenny, R E; Borsa, F

    2014-04-14

    A detailed experimental investigation of the 19F nuclear magnetic resonance is made on single crystals of the homometallic Cr₈ antiferromagnetic molecular ring and heterometallic Cr₇Cd and Cr₇ Ni rings in the low temperature ground state. Since the F- ion is located midway between neighboring magnetic metal ions in the ring, the 19F-NMR spectra yield information about the local electronic spin density and ¹⁹F hyperfine interactions. In Cr8, where the ground state is a singlet with total spin S T = 0, the ¹⁹F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the ¹⁹F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S T = 1. In the heterometallic rings, Cr₇Cd and Cr₇ Ni, whose ground state is magnetic with S T = 3/2 and S T = 1/2, respectively, the ¹⁹F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the 19F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F⁻-Ni2⁺ and the F⁻-Cd2⁺ bonds. The values of the hyperfine constants compare well to the ones known for F⁻-Ni2⁺ in KNiF₃ and NiF₂ and for F⁻-Cr³⁺ in K₂NaCrF₆. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F⁻ ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

  10. Luminescent gold-silver complexes derived from neutral bis(perfluoroaryl)diphosphine gold(I) precursors.

    PubMed

    Bojan, R Vilma; Czerwieniec, Rafal; Laguna, Antonio; Lasanta, Tania; López-de-Luzuriaga, José M; Monge, Miguel; Olmos, M Elena; Yersin, Harmut

    2013-03-28

    Complex [Au{4-C(6)F(4)(4-C(6)BrF(4))}(tht)] reacts with diphosphines (L-L) such as bis(diphenylphosphino)methane (dppm) or 1,2-bis(diphenylphosphino)benzene (dppb) in a 2 : 1 molar ratio in dichloromethane, leading to neutral products of stoichiometry [(Au{4-C(6)F(4)(4-C(6)BrF(4))})(2)(μ-L-L)] (L-L = dppm (1), dppb (2)). In the crystal structure of complex 2 short Au···Au interactions of 2.9367(5) and 2.9521(5) Å appear. This complex displays an orange emission, which is assigned to arise from a charge transfer transition from a metal centered Au-Au orbital to an orbital located at the diphosphine ligand. Addition of silver trifluoroacetate to these complexes in a 1 : 1 or a 2 : 1 molar ratio generates polymeric heterometallic gold-silver compounds of stoichiometry [Ag(2)Au(2){4-C(6)F(4)(4-C(6)BrF(4))}(2)(CF(3)CO(2))(2)(μ-L-L)](n) (L-L = dppm (3), dppb (4)), which confirms the capability of the neutral [(Au{4-C(6)F(4)(4-C(6)BrF(4))})(2)(μ-diphosphine)] units to act as electron density donors when treated with a Lewis acid substrate. These heterometallic derivatives show blue emissions indicating large HOMO-LUMO band gaps, due to the stabilization that the gold-based HOMO orbitals suffer when the electron withdrawing silver trifluoroacetate fragments interact with them. PMID:23340740

  11. Lanthanoid Template Isolation of the α-1,5 Isomer of Dicobalt(II)-Substituted Keggin Type Phosphotungstates: Syntheses, Characterization, and Magnetic Properties.

    PubMed

    Gupta, Rakesh; Hussain, Firasat; Sadakane, Masahiro; Kato, Chisato; Inoue, Katsuya; Nishihara, Sadafumi

    2016-09-01

    A new series of heterometallic 3d-4f sandwich type phosphotungstates, [Ln{PCo2W10O38(H2O)2}2](11-) (Ln = Sm(III), Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Tm(III), Yb(III), and Lu(III), denoted 1a-10a, respectively), have been synthesized by a one-pot reaction procedure on reacting the dilacunary K14[P2W19O69(H2O)]·24H2O precursor with Ln(NO3)3·nH2O and Co(NO3)2·6H2O in an aqueous potassium chloride solution. All the compounds were isolated as potassium salts and further characterized with different analytical techniques such as single-crystal X-ray diffraction, Fourier transform infrared spectroscopy, high-resolution electrospray ionization mass spectrometry, elemental analysis by inductively coupled plasma atomic emission spectroscopy, magnetic measurement, and thermogravimetric analysis. Single-crystal X-ray diffraction analysis of the compounds reveals that all these compounds are isostructural and crystallized in the orthorhombic crystal system in space group Iba2. The polyanions contain the α-1,5 isomer of dicobalt-substituted α-Keggin phosphotungstate, which sandwiched lanthanoid cation and formed novel heterometallic dimer species. The temperature-dependent magnetic susceptibilities of 1a, 2a, 4a, and 7a-10a indicate the dominant contribution of the ferromagnetic interaction between Co(II) and Co(II) within the cluster, while the antiferromagnetic interaction between Co(II) and Ln(III) dominates for 3a, 5a, and 6a. The isothermal magnetizations of 1a-10a show a gradual increase in magnetization at low fields and do not reach saturation even at 50 kOe. PMID:27509227

  12. Charge exchange spectroscopy of multiply charged ions for the development of the EUV light source for the next generation photo lithography

    NASA Astrophysics Data System (ADS)

    Tanuma, Hajime

    2015-09-01

    As a candidate of an extreme ultra-violet (EUV) light source for a next generation lithography, laser produced plasmas (LPP) of Xe and Sn have been investigated intensively in this decade because these plasmas have a strong emission around 13.5 nm which had been determined as the wavelength for the EUV lithography. This emission was considered to be due to multiply charged Xe and Sn ions in hot plasmas. However, the detail atomic spectroscopic data of these multiply charged heavy ions had not been reported yet. To provide atomic data for the understanding and development of the LPP as the EUV light source, we have observed the EUV emission spectra from individual charge states of Xe and Sn ions by means of a charge exchange spectroscopy method. Multiply charged Xeq+ (q = 7-23) and Snq+ (q = 5-21) ions were produced with a 14.25 GHz electron cyclotron resonance ion source, and a charge-selected ion beam was directed into a collision chamber, where the ion interact with a target gas of He and Xe. EUV emissions from the collision center were observed with a compact flat-field grazing-incident spectrometer equipped with a liquid nitrogen cooled CCD camera. In experiments using Xe ions, we have found only Xe XI has a strong UTA (unresolved transition array) around 13.5 nm. On the other hand, various charge states of Sn from VIII to XIV contribute to the 13.5 nm emission. Identification of the transition lines was carried out by calculations using the Hebrew university Livermore laboratory atomic physics code and the Cowan code. Most of the emissions in the EUV region are attributed to the 4p-4d and 4d- nl (nl = 4f, 5p, and 5f) transitions. However, the 4d-4f transitions have approximately constant differences of about 0.5 nm between the experimental and theoretical results. This can be explained by considering the strong configuration interactions in the n=4 subshells. Using the experimental transition wavelengths of multiply charged Sn ions, theoretical modeling of

  13. Heteropentanuclear Oxalato-Bridged nd-4f (n=4, 5) Metal Complexes with NO Ligand: Synthesis, Crystal Structures, Aqueous Stability and Antiproliferative Activity.

    PubMed

    Kuhn, Paul-Steffen; Cremer, Laura; Gavriluta, Anatolie; Jovanović, Katarina K; Filipović, Lana; Hummer, Alfred A; Büchel, Gabriel E; Dojčinović, Biljana P; Meier, Samuel M; Rompel, Annette; Radulović, Siniša; Tommasino, Jean Bernard; Luneau, Dominique; Arion, Vladimir B

    2015-09-21

    A series of heteropentanuclear oxalate-bridged Ru(NO)-Ln (4d-4f) metal complexes of the general formula (nBu4N)5[Ln{RuCl3(μ-ox)(NO)}4], where Ln=Y (2), Gd (3), Tb (4), Dy (5) and ox=oxalate anion, were obtained by treatment of (nBu4N)2[RuCl3(ox)(NO)] (1) with the respective lanthanide salt in 4:1 molar ratio. The compounds were characterized by elemental analysis, IR spectroscopy, electrospray ionization (ESI) mass spectrometry, while 1, 2, and 5 were in addition analyzed by X-ray crystallography, 1 by Ru K-edge XAS and 1 and 2 by (13)C NMR spectroscopy. X-ray diffraction showed that in 2 and 5 four complex anions [RuCl3(ox)(NO)](2-) are coordinated to Y(III) and Dy(III), respectively, with formation of [Ln{RuCl3(μ-ox)(NO)}4](5-) (Ln=Y, Dy). While Y(III) is eight-coordinate in 2, Dy(III) is nine-coordinate in 5, with an additional coordination of an EtOH molecule. The negative charge is counterbalanced by five nBu4N(+) ions present in the crystal structure. The stability of complexes 2 and 5 in aqueous medium was monitored by UV/Vis spectroscopy. The antiproliferative activity of ruthenium-lanthanide complexes 2-5 were assayed in two human cancer cell lines (HeLa and A549) and in a noncancerous cell line (MRC-5) and compared with those obtained for the previously reported Os(NO)-Ln (5d-4f) analogues (nBu4N)5[Ln{OsCl3(ox)(NO)}4] (Ln=Y (6), Gd (7), Tb (8), Dy (9)). Complexes 2-5 were found to be slightly more active than 1 in inhibiting the proliferation of HeLa and A549 cells, and significantly more cytotoxic than 5d-4f metal complexes 6-9 in terms of IC50 values. The highest antiproliferative activity with IC50 values of 20.0 and 22.4 μM was found for 4 in HeLa and A549 cell lines, respectively. These cytotoxicity results are in accord with the presented ICP-MS data, indicating five- to eightfold greater accumulation of ruthenium versus osmium in human A549 cancer cells. PMID:26260662

  14. Synthesis, crystal structure determination and antiproliferative activity of novel 2-amino-4-aryl-4,10-dihydro[1,3,5]triazino[1,2- a]benzimidazoles

    NASA Astrophysics Data System (ADS)

    Hranjec, Marijana; Pavlović, Gordana; Karminski-Zamola, Grace

    2012-01-01

    This manuscript describes the synthesis of novel 2-amino-4-aryl-4,10-dihydro-[1,3,5]triazino[1,2- a]benzimidazoles as hydrochloride salts 4a-n and 5b which were prepared in the reaction of cyclocondensation between 2-guanidinobenzimidazole and versatile heteroaromatic aldehydes. Structures of all prepared compounds have been studied by using 1H and 13C NMR, IR and UV/Vis spectroscopy. The crystal and molecular structure of 4f was determined by X-ray diffraction on single crystals. The molecule of 2-amino-4-(4'-methylphenyl)-4,10-dihydro[1,3,5]triazino[1,2- a]benzimidazole hydrochloride 4f (C 16H 16N 5+·Cl -) exists in the solid state in one of the possible tautomeric forms, being protonated at the one of the nitrogen atoms of the 1,4-dihydrotriazine ring. The molecule is highly delocalized within the 4,10-dihydro[1,3,5]triazino[1,2- a]benzimidazole moiety with the highest deviation from the plane for the methine carbon atom and the protonated nitrogen atom of the 1,4-dihydrotriazine ring. The cations are joined via N-H⋯N hydrogen bonds into R22(8) centrosymmetric dimers. Cation dimers are further connected with Cl - ions via N-H⋯Cl and C-H⋯Cl hydrogen bonds into 2D chains spreading along the b axis. The obtained single-crystal X-ray structure determination unequivocally confirms tautomeric form of the compound present in the solid-state and can represent tantative pattern for other prepared compounds. All prepared compounds were tested on their antiproliferative activity in vitro on several human cancer cell lines. Compound 4m was the most active one (IC 50 ≈ 20 μM), while compounds 4d, 4f, 4k, 4l4m showed moderate, but non-selective, antiproliferative activity with IC 50 25-60 μM.

  15. Copper(II)-lanthanide(III) coordination polymers constructed from pyridine-2,5-dicarboxylic acid: Preparation, crystal structure and photoluminescence

    SciTech Connect

    Xia Zhengqiang; Wei Qing; Chen Sanping; Feng Xinming; Xie Gang; Qiao Chengfang; Zhang Guochun; Gao Shengli

    2013-01-15

    A series of 3d-4f heterometallic coordination polymers, formulated as {l_brace} [Cu{sub 3}Ln{sub 2}(pydc){sub 6}(H{sub 2}O){sub 12}]{center_dot}4H{sub 2}O{r_brace} {sub n} [Ln=Tb (1), Eu (2), Dy (3), Ho (4), Lu (5)], {l_brace} [CuNd{sub 2}(pydc){sub 4}(H{sub 2}O){sub 3}]{center_dot}H{sub 2}O{r_brace} {sub n} (6) and {l_brace} [Cu{sub 3}Pr{sub 2}(pydc){sub 6}(H{sub 2}O){sub 13}]{center_dot}4H{sub 2}O{r_brace} {sub n} (7) (where H{sub 2}pydc=pyridine-2,5-dicarboxylic acid), have been hydrothermally prepared by reactions of H{sub 2}pydc ligand with lanthanide ions in the presence of Cu(II) ion. X-ray crystal structure analysis reveals that these compounds exhibit rich structural chemistry. 1-5 are isomorphous and present a two-dimensional network constructed from Ln{sub 2}Cu{sub 2}L{sub 2}(H{sub 2}O){sub 2} SBU rings and CuL{sub 2}(H{sub 2}O) building blocks. In 6, two-dimensional ladder-like layers based on Nd(III) belts and CuL{sub 2}O{sub 2} units are assembled by H{sub 2}pydc ligands into a three-dimensional open framework. Polymer 7 displays a two-dimensional wave-like layer structure containing two distinct ring units, in which a new coordination mode of the pydc{sup 2-} ligand is observed. The results indicate that the coordination flexibility of the pydc{sup 2-} ligand and lanthanide contraction effect play cooperative roles in the formation of coordination polymers with different polymeric architectures. Compounds 1-2 exhibit intense green and red luminescence emission characteristics of Tb(III) and Eu(III), respectively. Furthermore, elemental analyses (EA), infrared spectra (IR) and thermogravimetric analyses (TGA) of these compounds were also studied. - Graphical abstract: Seven 3d-4f heterometallic coordination polymers were synthesized by reactions of H{sub 2}pydc with lanthanide metal ions in the presence of Cu{sup 2+}, the effects of Cu{sup 2+} on the structures and photoluminescent properties of Ln-pydc{sup 2-} systems were investigated. Highlights

  16. Heteronuclear Ni(ii)-Ln(iii) (Ln = La, Pr, Tb, Dy) complexes: synthesis and single-molecule magnet behaviour.

    PubMed

    Upadhyay, Apoorva; Das, Chinmoy; Langley, Stuart K; Murray, Keith S; Srivastava, Anant K; Shanmugam, Maheswaran

    2016-02-28

    The reaction of hydrated nickel(II) salts (chloride or nitrate) and hydrated lanthanide nitrate salts with the Schiff base ligand 2-methoxy-6-[(E)-phenyliminomethyl] phenol (HL) in methanol resulted in the isolation of three isostructural linear heterometallic trinuclear complexes and a heterometallic tetranuclear complex. The molecular structures of these complexes were determined via single crystal X-ray diffraction revealing molecular structures of formulae [Ni2La(L-)6](NO3)0.55(OH)0.45 (1), [Ni2Pr(L-)6](NO3)0.48(OH)0.52 (2), [Ni2Tb(L-)6](NO3)0.5(Cl)0.5 (3) and [Ni2Dy2(L-2(o-vanillin)2(CO3)2(NO3)2(MeOH)2] (4). Structural analysis for 1-3 reveals that the lanthanide ion is sandwiched between two Ni(II) ions and the Ni⋯Ln⋯Ni metallic core displays a linear arrangement, with an average ∠Ni⋯Ln⋯Ni bond angle of 179.7°. Analysis of 4 reveals the metal ions are arranged such that two Ni-Dy subunits are bridged by two carbonate ligands via the Dy sites. Direct current magnetic susceptibility measurements for complexes 1-4 reveal that the Ni(II) ions are coupled ferromagnetically with the Tb(III) (3) and Dy(III) (4) ions, and antiferromagnetically with the Pr(III) ion (2). For complex 1 a long range intramolecular ferromagnetic interaction is witnessed between the Ni(II) ions (Ni⋯Ni = 6.873(9) Å) via a closed shell La(III) ion. The magnetic data of 1 were fitted using the HDVV Hamiltonian revealing the following parameters; J = +0.46 cm(-1), g = 2.245, D = +4.91 cm(-1). Alternating current magnetic susceptibility measurements performed on complexes 2-4 revealed that 3 and 4 displayed frequency dependent χ′′M signals (Hac = 3.5 Oe and Hdc = 0 Oe) which is a characteristic signature of a single-molecule magnet behaviour. PMID:26810917

  17. Magnetic properties and hyperfine interactions in Cr{sub 8}, Cr{sub 7}Cd, and Cr{sub 7}Ni molecular rings from {sup 19}F-NMR

    SciTech Connect

    Bordonali, L.; Borsa, F.; Consorzio INSTM, Via Giusti 9, I-50121 Firenze; Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 ; Garlatti, E.; Dipartimento di Fisica e Scienze della Terra, Università di Parma, Viale G. P. Usberti 7 Casadei, C. M.; Department of Physics and Astronomy, Ames Laboratory, Iowa State University, Ames, Iowa 50011 ; Furukawa, Y.; Lascialfari, A.; Consorzio INSTM, Via Giusti 9, I-50121 Firenze; Department of Physics, Università degli Studi di Milano, Via Celoria 16, 20133 Milano ; Carretta, S.; Timco, G.; Winpenny, R. E. P.

    2014-04-14

    A detailed experimental investigation of the {sup 19}F nuclear magnetic resonance is made on single crystals of the homometallic Cr{sub 8} antiferromagnetic molecular ring and heterometallic Cr{sub 7}Cd and Cr{sub 7}Ni rings in the low temperature ground state. Since the F{sup −} ion is located midway between neighboring magnetic metal ions in the ring, the {sup 19}F-NMR spectra yield information about the local electronic spin density and {sup 19}F hyperfine interactions. In Cr{sub 8}, where the ground state is a singlet with total spin S{sub T} = 0, the {sup 19}F-NMR spectra at 1.7 K and low external magnetic field display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the {sup 19}F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S{sub T} = 1. In the heterometallic rings, Cr{sub 7}Cd and Cr{sub 7}Ni, whose ground state is magnetic with S{sub T} = 3/2 and S{sub T} = 1/2, respectively, the {sup 19}F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the {sup 19}F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F{sup −}-Ni{sup 2+} and the F{sup −}-Cd{sup 2+} bonds. The values of the hyperfine constants compare well to the ones known for F{sup −}-Ni{sup 2+} in KNiF{sub 3} and NiF{sub 2} and for F{sup −}-Cr{sup 3+} in K{sub 2}NaCrF{sub 6}. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F{sup −} ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.

  18. Cyano-bridged coordination polymer hydrogel-derived Sn-Fe binary oxide nanohybrids with structural diversity: from 3D, 2D, to 2D/1D and enhanced lithium-storage performance.

    PubMed

    Zhang, Weiyu; Zhu, Xiaoshu; Chen, Xuguang; Zhou, Yiming; Tang, Yawen; Ding, Liangxin; Wu, Ping

    2016-05-14

    Metal oxide nanohybrids with uniform dimensions and controlled architectures possess unique compositional and structural superiorities, and thus harbor promising potential for a series of applications in energy, catalysis, and sensing systems. Herein, we propose a facile, general, and scalable cyano-bridged coordination polymer hydrogel-derived thermal-oxidation route for the construction of main-group metal and transition-metal heterometallic oxide nanohybrids with controlled constituents and architectures. The formation of Sn-Fe binary oxide nanohybrids has been demonstrated as an example by using cyano-bridged Sn(iv)-Fe(ii) bimetallic coordination polymer hydrogels (i.e., SnCl4-K4Fe(CN)6 cyanogels, Sn-Fe cyanogels) as precursors. The physicochemical properties of Sn-Fe cyanogels with different Sn/Fe ratios have been systematically examined, and it is found that perfect Sn-Fe cyanogels without unbridged Sn(iv) or Fe(ii) can be formed with Sn/Fe ratios from 2 : 1 to 1 : 2. More importantly, the simple adjustment of Sn/Fe ratios in the Sn-Fe cyanogel precursors can realize flexible dimensional control of the Sn-Fe binary oxide nanohybrids, and 2D/1D SnO2-Fe2O3 hierarchitectures, 2D SnO2-Fe2O3 nanosheets, and 3D SnO2-Fe2O3 networks have been synthesized using the Sn-Fe 1 : 2, Sn-Fe 1 : 1, and Sn-Fe 2 : 1 cyanogels as precursors, respectively. To demonstrate their compositional/structural superiorities and potential applications, the lithium-storage utilization of the Sn-Fe binary oxide nanohybrids has been selected as an objective application, and the nanohybrids exhibit Sn/Fe ratio-dependent lithium-storage performance. As a representative example, the 2D/1D SnO2-Fe2O3 hierarchitectures manifest markedly enhanced Li-storage performance in terms of reversible capacities and cycling stability in comparison with their constituent units, i.e., bare SnO2 nanosheets and Fe2O3 nanorods. The proposed cyanogel-derived thermal-oxidation strategy could

  19. Probing the magnetic and magnetothermal properties of M(II)-Ln(III) complexes (where M(II) = Ni or Zn; Ln(III) = La or Pr or Gd).

    PubMed

    Ahmed, Naushad; Das, Chinmoy; Vaidya, Shefali; Srivastava, Anant Kumar; Langley, Stuart K; Murray, Keith S; Shanmugam, Maheswaran

    2014-12-14

    We establish the coordination potential of the Schiff base ligand (2-methoxy-6-[(E)-2'-hydroxymethyl-phenyliminomethyl]-phenolate (H2L)) via the isolation of various M(II)-Ln(III) complexes (where M(II) = Ni or Zn and Ln(III) = La or Pr or Gd). Single crystals of these five complexes were isolated and their solid state structures were determined by single crystal X-ray diffraction. Structural determination revealed molecular formulae of [NiGd(HL)2(NO3)3] (1), [NiPr(HL)2(NO3)3] (2) and [Ni2La(HL)4(NO3)](NO3)2 (3), [Zn2Gd(HL)4(NO3)](NO3)2 (4), and [Zn2Pr(HL)4(NO3)](NO3)2 (5). Complexes and were found to be neutral heterometallic dinuclear compounds, whereas 3-5 were found to be linear heterometallic trinuclear cationic complexes. Direct current (dc) magnetic susceptibility and magnetization measurements conclusively revealed that complexes 1 and 4 possess a spin ground state of S = 9/2 and 7/2 respectively. Empirically calculated ΔχMT derived from the variable temperature susceptibility data for all complexes undoubtedly indicates that the Ni(II) ion is coupled ferromagnetically with the Gd(III) ion, and antiferromagnetically with the Pr(III) ion in 1 and 2 respectively. The extent of the exchange interaction for was estimated by fitting the magnetic susceptibility data using the parameters (g = 2.028, S = 9/2, J = 1.31 cm(-1) and zJ = +0.007), supporting the phenomenon observed in an empirical approach. Similarly using a HDVV Hamiltonian, the magnetic data of 3 and 4 were fitted, yielding parameters g = 2.177, D = 3.133 cm(-1), J = -0.978 cm(-1), (for 3) and g = 1.985, D = 0.508 cm(-1) (for 4). The maximum change in magnetic entropy (-ΔSm) estimated from the isothermal magnetization data for was found to be 5.7 J kg(-1) K(-1) (ΔB = 7 Tesla) at 7.0 K, which is larger than the -ΔSm value extracted from 4 of 3.5 J kg(-1) K(-1) (ΔB = 7 Tesla) at 15.8 K, revealing the importance of the exchange interaction in increasing the overall ground state of a molecule for

  20. Synthesis and characterization of tridecameric Group 13 hydroxide clusters

    NASA Astrophysics Data System (ADS)

    Mensinger, Zachary Lee

    In the research area of Group 13 hydroxide clusters, progress is often hampered by difficult and inefficient synthetic procedures. This has greatly limited the numerous potential applications of Group 13 hydroxide compounds, many of which require large amounts of material. Most relevant to this dissertation is their application as precursors for high quality amorphous metal oxide thin films. Addressing this issue, this dissertation presents a series of Group 13 containing hydroxide compounds of general formula [M13(mu 3-OH)6(mu-OH)18(H2O)24](NO 3)15 which are generated through an efficient, scalable synthetic procedure. Throughout this dissertation, the compounds are generally referred to by their metal content, i.e. [Ga13(mu3-OH) 6(mu-OH)18(H2O)24](NO3) 15 is designated as Ga13. Chapter I reviews the literature of inorganic and ligand-supported Group 13 hydroxide compounds with the aim of identifying common structural trends in metal composition and coordinating ligands. This summary is limited to clusters of aluminum, gallium, and indium. Chapter II describes in detail the synthesis and characterization of one such cluster, Al13. Following this in Chapter III is the description of the first heterometallic Group 13 hydroxide compound, Ga7In 6, which along with Ga13 was used as a precursor material for metal oxide thin films in collaboration with Professor Doug Keszler at Oregon State University. Chapter IV describes a series of six Ga/In compounds, as well as two Al/In compounds. Included in this chapter is an analysis of the heat-induced decomposition properties of the Ga/In clusters. Understanding such thermal decomposition is particularly relevant for the use of these compounds as precursor materials, as an annealing step is used to condense the films. Chapter V addresses the potential for post-synthetic modification of the compounds through metal and ligand exchange reactions, an area that also addresses the issue of solution stability of the structures

  1. Uranyl Ion Complexes with 1,1'-Biphenyl-2,2',6,6'-tetracarboxylic Acid: Structural and Spectroscopic Studies of One- to Three-Dimensional Assemblies.

    PubMed

    Thuéry, Pierre; Harrowfield, Jack

    2015-07-01

    1,1'-Biphenyl-2,2',6,6'-tetracarboxylic acid (H4L) was reacted with uranyl nitrate, either alone or in the presence of additional metal cations (Ni(2+), Cu(2+), Dy(3+)) under (solvo)-hydrothermal conditions, giving six complexes which were characterized by their crystal structure and, in all but one case, their emission spectrum in the solid state. [Ni(bipy)3][UO2(H2L)(H2O)]2(NO3)2·3H2O (1) crystallizes as a one-dimensional (1D), ribbon-like coordination polymer, while the homometallic complex [(UO2)2(L)(H2O)3]·H2O·CH3CN (2) and the heterometallic complexes [UO2Cu(L)(H2O)2]·H2O (3), [UO2Cu(L)(H2O)]·H2O (4), and [(UO2)5Cu4(HL)6(bipy)4]·2H2O (5) display two-dimensional (2D) arrangements. Lastly, the uranyl-lanthanide heterometallic complex [(UO2)8Dy(HL)6(H2O)8](I)·8H2O (6) crystallizes as a three-dimensional (3D) framework. Although these assemblies adopt different topologies, the {4(2).6} linear motif found in 1 is discernible in the structures of 2, 5, and 6, in which the higher dimensionality arises from further bridging of these subunits by uranyl (2), copper (5), or both uranyl and dysprosium (6) cations. The tetracarboxylic/ate ligands have their two aromatic rings nearly perpendicular to one another. No two of them adopt the same coordination mode in this series (except in the similar complexes 3 and 4), but chelation involving one carboxylate group from each ring is nearly ubiquitous, and the ensuing position of the cation favors the formation of planar architectures. The emission spectra of complexes 2-5 measured in the solid state show the usual uranyl vibronic fine structure, although with significant differences in the emission intensity, while complete quenching of the luminescence is observed in 1. PMID:26102315

  2. Chemistry of group 9 dimetallaborane analogues of octaborane(12).

    PubMed

    Barik, Subrat Kumar; Roy, Dipak Kumar; Ghosh, Sundargopal

    2015-01-14

    We report the synthesis, isolation and structural characterization of several moderately air stable nido-metallaboranes that represent boron rich open cage systems. The reaction of [Cp*CoCl]2, (Cp* = η(5)-C5Me5), with [BH3·thf] in toluene at ice cold temperature, followed by thermolysis in boiling toluene produced [(Cp*Co)B9H13], 1 [(Cp*Co)2B8H12], 2 and [(Cp*Co)2B6H10] 3. Building upon our earlier reactivity studies on rhodaboranes, we continue to explore the reactivity of dicobalt analogues of octaborane(12) cluster 3 with [Fe2(CO)9] and [Ru3(CO)12] at ambient conditions that yielded novel fused clusters [Fe2(CO)6(Cp*Co)2B6H10], 4 and [Ru4(CO)11(Cp*Co)2B3H3], 5 respectively. In an attempt to synthesize a heterometallic metallaborane compound we performed the reaction of [(Cp*Rh)2B6H10], 6 with [Cp*IrH4] that yielded a Ir-Ir double bonded compound [(Cp*Ir)2H3][B(OH)4], 7. All the new compounds have been characterized by IR, (1)H, (11)B, (13)C NMR spectroscopy, and the molecular structures were unambiguously established by X-ray diffraction analysis. PMID:25385503

  3. Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles

    NASA Astrophysics Data System (ADS)

    Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius; Ham, Hyung Chul

    2015-01-01

    The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt3M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.

  4. Cu(II)-Gd(III) cryogenic magnetic refrigerants and Cu8Dy9 single-molecule magnet generated by in situ reactions of picolinaldehyde and acetylpyridine: experimental and theoretical study.

    PubMed

    Liu, Jun-Liang; Lin, Wei-Quan; Chen, Yan-Cong; Gómez-Coca, Silvia; Aravena, Daniel; Ruiz, Eliseo; Leng, Ji-Dong; Tong, Ming-Liang

    2013-12-16

    A series of heterometallic [Ln(III)(x)Cu(II)(y)] complexes, [Gd2Cu2]n (1), [Gd4Cu8] (2), [Ln9Cu8] (Ln=Gd, 3·Gd; Ln=Dy, 3·Dy), were successfully synthesized by a one-pot route at room temperature with three kinds of in situ carbonyl-related reactions: Cannizzaro reaction, aldol reaction, and oxidation. This strategy led to dysprosium analogues that behaved as single-molecule magnets (SMMs) and gadolinium analogues that showed significant magnetocaloric effect (MCE). In this study a numerical DFT approach is proposed by using pseudopotentials to calculate the exchange coupling constants in three polynuclear [Gd(x)Cu(y)] complexes; with these values exact diagonalization or quantum Monte Carlo simulations have been performed to calculate the variation of the magnetic entropy involved in the MCE. For the [Dy9Cu8] complexes, local magnetic properties of the Dy(III) centers have been determined by using the CASSCF+RASSI method. PMID:24265054

  5. Synthesis and chemistry of the open-cage cobaltaheteroborane cluster [{(η(5)-C5Me5)Co}2B2H2Se2]: a combined experimental and theoretical study.

    PubMed

    Barik, Subrat Kumar; Dorcet, Vincent; Roisnel, Thierry; Halet, Jean-François; Ghosh, Sundargopal

    2015-08-28

    Reaction of [(η(5)-C5Me5)CoCl]2 with a two-fold excess of [LiBH4·thf] followed by heating with an excess of Se powder produces the dicobaltaselenaborane species [{(η(5)-C5Me5)Co}2B2H2Se2], , in good yield. The geometry of resembles a nido pentagonal [Co2B2Se2] bipyramid with a missing equatorial vertex. It can alternatively be seen as an open cage triple-decker cluster. Isolation of permits its reaction with [Fe2(CO)9] to give heterometallic diselenametallaborane [{(η(5)-C5Me5)Co}Fe(CO)3B2H2Se2], . The geometry of is similar to that of with one of the [(η(5)-C5Me5)Co] groups replaced by the isolobal, two-electron fragment [Fe(CO)3]. Both new compounds have been characterized by mass spectrometry, and by (1)H, (11)B and (13)C NMR spectroscopy. The structural architectures have been unequivocally established by crystallographic analysis. In addition, density functional theory calculations were performed to investigate the bonding and electronic properties. The large HOMO-LUMO gaps computed for both clusters are consistent with their thermodynamic stability. Natural bond order calculations predict the absence of metal-metal bonding interaction. PMID:26200318

  6. Synthesis, characterization and crystal structure of a 1D thiocyanato bridged [Cu(en)2Zn(NCS)4]ṡH2O. Comparison of the three structures with the same [Cu(en)2Zn(NCS)4] unit - different in structural terms

    NASA Astrophysics Data System (ADS)

    Wrzeszcz, Grzegorz; Muzioł, Tadeusz M.; Tereba, Natalia

    2015-03-01

    In this paper we report the synthesis method and the structure of a one-dimensional thiocyanato bridged heterometallic compound, [Cu(en)2Zn(NCS)4]ṡH2O (1). Moreover, we compare the structure of (1) with the previously described structures of [Cu(en)2Zn(NCS)4]ṡ0.5H2O (2) and [Cu(en)2Zn(NCS)4]ṡCH3CN (3) Pryma et al. (2003) [7]. The compound (1) has been characterized by thermal decomposition, IR, Vis and EPR spectra, and magnetic studies. Structure has been determined by X-ray analysis. Described coordination polymer crystallizes in the orthorhombic Cmcm space group with a = 12.414(2), b = 10.3276(14), c = 14.967(2) Å, α = β = γ = 90°, V = 1918.8(5) Å3 and Z = 4. Each distorted tetrahedral zinc(II) centre (with N-bonded NCS-) links two tetragonally distorted octahedral copper(II) centres by two end-to-end thiocyanato bridges and vice versa forming a zigzag type of CuZn chain. The structures of (1), (2) and (3) differ in crystallographic system, space group and/or CuZn chain type as well as in details. Variable temperature magnetic susceptibility measurements show very weak antiferromagnetic interactions between the paramagnetic copper(II) ions for compound (1).

  7. Regulation of charge delocalization in a heteronuclear Fe2 ru system by a stepwise photochromic process.

    PubMed

    Xu, Guang-Tao; Li, Bin; Wang, Jin-Yun; Zhang, Dao-Bin; Chen, Zhong-Ning

    2015-02-16

    Heteronuclear complexes FeCp2 -DTE-C≡C-Ru(dppe)2 Cl (1 o; dppe=1,2-bis(diphenylphosphino)ethane, Cp=cyclopentadienyl, DTE=dithienylethene) and FeCp2-DTE-C≡C-Ru(dppe)2-C≡C-DTE-FeCp2 (2 oo), with redox-active ferrocenyl and ruthenium centers separated by a photochromic DTE moiety, were prepared to achieve photoswitchable charge delocalization and Fe⋅⋅⋅Ru electronic communication. Upon UV-light irradiation of 2 oo, the Fe⋅⋅⋅Ru heterometallic electronic interaction is increasingly facilitated with stepwise photocyclization, 2 oo→2 co→2 cc; this is ascribed to the gradual increase in π-conjugated systems. The near-infrared absorptions in mixed-valence species [2 oo](+) /[2 co](+) /[2 cc](+) are gradually intensified following the conversion of [2 oo](+) →[2 co](+) →[2 cc](+) , which demonstrates that the extent of charge delocalization shows progressive enhancement with stepwise photocyclization. As revealed by electrochemical, spectroscopic, and theoretical studies, complex 2 exhibits nine switchable states through stepwise photochromic and reversible redox processes. PMID:25640650

  8. Lanthanide-to-lanthanide energy-transfer processes operating in discrete polynuclear complexes: can trivalent europium be used as a local structural probe?

    PubMed

    Zaïm, Amir; Eliseeva, Svetlana V; Guénée, Laure; Nozary, Homayoun; Petoud, Stéphane; Piguet, Claude

    2014-09-15

    This work, based on the synthesis and analysis of chemical compounds, describes a kinetic approach for identifying intramolecular intermetallic energy-transfer processes operating in discrete polynuclear lanthanide complexes, with a special emphasis on europium-containing entities. When all coordination sites are identical in a (supra)molecular complex, only heterometallic communications are experimentally accessible and a Tb → Eu energy transfer could be evidenced in [TbEu(L5)(hfac)6] (hfac = hexafluoroacetylacetonate), in which the intermetallic separation amounts to 12.6 Å. In the presence of different coordination sites, as found in the trinuclear complex [Eu3(L2)(hfac)9], homometallic communication can be induced by selective laser excitation and monitored with the help of high-resolution emission spectroscopy. The narrow and non-degenerated character of the Eu((5)D0 ↔ (7)F0) transition excludes significant spectral overlap between donor and acceptor europium cations. Intramolecular energy-transfer processes in discrete polynuclear europium complexes are therefore limited to short distances, in agreement with the Fermi golden rule and with the kinetic data collected for [Eu3(L2)(hfac)9] in the solid state and in solution. Consequently, trivalent europium can be considered as a valuable local structural probe in discrete polynuclear complexes displaying intermetallic separation in the sub-nanometric domain, a useful property for probing lanthanido-polymers. PMID:25099883

  9. Poly[[μ(2)-acetato-aquadi-μ(3)-isonicotinato-holmium(III)silver(I)] perchlorate].

    PubMed

    Feng, Sun

    2009-01-01

    In the title three-dimensional heterometallic complex, {[AgHo(C(6)H(4)NO(2))(2)(C(2)H(3)O(2))(H(2)O)]ClO(4)}(n), the Ho(III) ion is eight-coordinated by four O atoms from four different isonicotinate ligands, three O atoms from two different acetate ligands and one O atom of a water mol-ecule. The two-coordinate Ag(I) ion is bonded to two N atoms from two different isonicotinate anions. These metal coordination units are connected by bridging isonicotinate and acetate ligands, generating a three-dimensional network. The coordinated water mol-ecules link the carboxyl-ate group of the acetate ligand and the nitrate ligand by O-H⋯O hydrogen bonding. The crystal structure is further stabilized by hydrogen bonds. The perchlorate ion is disordered over two sites with site-occupancy factors 0.539 (12) and 0.461 (12), while the methyl group of the acetate ligand is disordered over two sites with site-occupancy factors 0.51 (4) and 0.49 (4). PMID:21578642

  10. Synthesis, structure and properties of the manganese-doped polyoxotitanate cage [Ti18MnO30(OEt)20(MnPhen)3] (Phen = 1,10-phenanthroline).

    PubMed

    Li, Ning; Matthews, Peter D; Leung, Jane J; King, Timothy C; Wood, Paul T; Luo, He-Kuan; Wright, Dominic S

    2015-11-28

    The novel heterometallic polyoxotitanate cage [Ti18MnO30(OEt)20(MnPhen)3] (1), obtained by solvothermal reaction of Ti(OEt)4 with Mn(AcO)3·(H2O)2 and 1,10-phenanthroline (Phen) in EtOH, has a C3 symmetric core structure containing an interstitial tetrahedral Mn(II) ion and is surrounded by three Mn(II)(Phen) fragments. The molecular structure is retained in thin film electrodes of 1 deposited by solution drop-casting onto fluorinated tin oxide (FTO). Both solid state and solution phase electrochemical measurements show dual redox couples, consistent with the two distinct Mn coordination environments in the cage structure. Sintering of 1 in air at 600 °C produces a black crystalline solid which consists of Mn-doped TiO2 (mainly in the rutile phase) together with α-Mn2O3. Such a composite semiconductor has an optical band gap of ca. 1.80 eV, similar to that of α-Mn2O3. PMID:26505462

  11. Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt3M (where M = 3d transition metals) alloy catalyst from first-principles.

    PubMed

    Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius; Ham, Hyung Chul

    2015-01-21

    The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt3M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt3M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt3M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt3M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit. PMID:25612725

  12. Smart Grafting of Lanthanides onto Silica via N,N-Dialkylcarbamato Complexes.

    PubMed

    Armelao, Lidia; Belli Dell'Amico, Daniela; Bellucci, Luca; Bottaro, Gregorio; Labella, Luca; Marchetti, Fabio; Samaritani, Simona

    2016-01-19

    The grafting and the postgrafting functionalization of lanthanide ions on commercial amorphous silica have been herein carried out by using as a precursor the terbium N,N-dibutylcarbamato derivative [Tb(O2CNBu2)3]. The reaction of the complex with the surface silanols involved only a fraction of the carbamato ligands. The following protolytic substitution of the residual carbamato ligands was carried out by exploiting the Brønsted's acidity of the β-diketone dibenzoylmethane (Hdbm), in view of the antenna effect of the β-diketonato groups, which are commonly used in lanthanide photoluminescence studies. The reaction proceeded at room temperature in a clean and easy way affording the introduction of the chosen functionality in the lanthanide coordination sphere. The same procedure has been followed by using as a precursor the X-ray characterized heterometallic N,N-dibutylcarbamato complex [NH2Bu2]2[Ln4(CO3)(O2CNBu2)12] (Ln = Eu, Tb, Tm). In both cases, X-ray photoelectron spectroscopy evidenced the chemical implantation of the lanthanide ions on the silica surface, and photoluminescence studies pointed out the potentiality of the proposed synthetic approach in the preparation of highly luminescent materials. PMID:26741027

  13. Entangled states decoherence in coupled molecular spin clusters

    NASA Astrophysics Data System (ADS)

    Troiani, Filippo; Szallas, Attila; Bellini, Valerio; Affronte, Marco

    2010-03-01

    Localized electron spins in solid-state systems are widely investigated as potential building blocks of quantum devices and computers. While most efforts in the field have been focused on semiconductor low-dimensional structures, molecular antiferromagnets were recently recognized as alternative implementations of effective few-level spin systems. Heterometallic, Cr-based spin rings behave as effective spin-1/2 systems at low temperature and show long decoherence times [1]; besides, they can be chemically linked and magnetically coupled in a controllable fascion [2]. Here, we theoretically investigate the decoherence of the Bell states in such ring dimers, resulting from hyperfine interactions with nuclear spins. Based on a microscopic description of the molecules [3], we simulate the effect of inhomogeneous broadening, spectral diffusion and electron-nuclear entanglement on the electron-spin coherence, estimating the role of the different nuclei (and of possible chemical substitutions), as well as the effect of simple spin-echo sequences. References: [1] F. Troiani, et al., Phys. Rev. Lett. 94, 207208 (2005). [2] G. A. Timco, S: Carretta, F. Troiani et al., Nature Nanotech. 4, 173 (2009). [3] F. Troiani, V. Bellini, and M. Affronte, Phys. Rev. B 77, 054428 (2008).

  14. Coinage metal complexes supported by the tri- and tetraphosphine ligands.

    PubMed

    Dau, Minh Thuy; Shakirova, Julia R; Karttunen, Antti J; Grachova, Elena V; Tunik, Sergey P; Melnikov, Alexey S; Pakkanen, Tapani A; Koshevoy, Igor O

    2014-05-01

    A series of tri- and tetranuclear phosphine complexes of d(10) metal ions supported by the polydentate ligands, bis(diphenylphosphinomethyl)phenylphosphine (PPP) and tris(diphenylphosphinomethyl)phosphine (PPPP), were synthesized. All the compounds under study, [AuM2(PPP)2](3+) (M = Au (1), Cu (2), Ag (3)), [M4(PPPP)2](4+) (M = Ag (4), Au (5)), [AuAg3(PPPP)2](4+) (6), and [Au2Cu2(PPPP)2(NCMe)4](4+) (7), were characterized crystallographically. The trinuclear clusters 1-3 contain a linear metal core, while in the isostructural tetranuclear complexes 4-6 the metal framework has a plane star-shaped arrangement. Cluster 7 adopts a structural motif that involves a digold unit bridged by two arms of the PPPP phosphines and decorated two spatially separated Cu(I) ions chelated by the remaining P donors. The NMR spectroscopic investigation in DMSO solution revealed the heterometallic clusters 2, 3, and 6 are stereochemically nonrigid and undergo reversible metal ions redistribution between several species, accompanied by their solvation-desolvation. The complexes 1-3 and 5-7 exhibit room temperature luminescence in the solid state (Φem = 6-64%) in the spectral region from 450 to 563 nm. The phosphorescence observed originates from the triplet excited states, determined by the metal cluster-centered dσ* → pσ transitions. PMID:24750114

  15. Large Hexadecametallic {Mn(III) -Ln(III) } Wheels: Synthesis, Structural, Magnetic, and Theoretical Characterization.

    PubMed

    Vignesh, Kuduva R; Langley, Stuart K; Moubaraki, Boujemaa; Murray, Keith S; Rajaraman, Gopalan

    2015-11-01

    The synthesis, gas sorption studies, magnetic properties, and theoretical studies of new molecular wheels of core type {Mn(III) 8 Ln(III) 8 } (Ln=Dy, Ho, Er, Y and Yb), using the ligand mdeaH2 , in the presence of ortho-toluic or benzoic acid are reported. From the seven wheels studied the {Mn8 Dy8 } and {Mn8 Y8 } analogues exhibit SMM behavior as determined from ac susceptibility experiments in a zero static magnetic field. From DFT calculations a S=16 ground state was determined for the {Mn8 Y8 } complex due to weak ferromagnetic Mn(III) -Mn(III) interactions. Ab initio CASSCF+RASSI-SO calculations on the {Mn8 Dy8 } wheel estimated the Mn(III) -Dy(III) exchange interaction as -0.1 cm(-1) . This weak exchange along with unfavorable single-ion anisotropy of Dy(III) /Mn(III) ions, however, led to the observation of SMM behavior with fast magnetic relaxation. The orientation of the g-anisotropy of the Dy(III) ions is found to be perpendicular to the plane of the wheel and this suggests the possibility of toroidal magnetic moments in the cluster. The {Mn8 Ln8 } clusters reported here are the largest heterometallic Mn(III) Ln(III) wheels and the largest {3d-4f} wheels to exhibit SMM behavior reported to date. PMID:26403264

  16. Rare single-molecule magnets with six-coordinate Ln(III) ions exhibiting a trigonal antiprism configuration.

    PubMed

    Yao, Min-Xia; Zhu, Zhao-Xia; Lu, Xing-Yun; Deng, Xiao-Wei; Jing, Su

    2016-06-28

    Four Ni-Ln-Ni heterometallic complexes, [Ni2LnL2]NO3·3H2O (H3L = tri(((3-methoxysalicylidene)amino)ethyl)amine, Ln = Gd for , Tb for and Dy for , respectively) and [Ni2DyL2]ClO4·MTBE·0.65H2O (, MTBE = methyl tert-butyl ether) have been synthesized by diffusion of methyl tert-butyl ether vapor into the reaction solution. The X-ray analyses demonstrated that the Gd(III) ion in exhibits rare seven-coordination, the Tb(III) and Dy(III) ions in display unusual six-coordination, and two Ni(II) ions and one Ln(III) ion are bridged by six phenolato atoms to form linear Ni-Ln-Ni heterotrinuclear complexes for . All complexes exhibit weak ferromagnetic interactions between Ni(II) and Ln(III) ions. Alternating current susceptibility measurements demonstrated that compounds and behave as single-molecule magnets with the effective energy barriers of 14.17 and 11.13 K under zero direct current field. They are rare single-molecule magnets containing six-coordinate Dy(III) ions. PMID:27273165

  17. Effect of gold subsurface layer on the surface activity and segregation in Pt/Au/Pt{sub 3}M (where M = 3d transition metals) alloy catalyst from first-principles

    SciTech Connect

    Kim, Chang-Eun; Lim, Dong-Hee; Jang, Jong Hyun; Kim, Hyoung Juhn; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Hong, Seong-Ahn; Soon, Aloysius E-mail: hchahm@kist.re.kr; Ham, Hyung Chul E-mail: hchahm@kist.re.kr

    2015-01-21

    The effect of a subsurface hetero layer (thin gold) on the activity and stability of Pt skin surface in Pt{sub 3}M system (M = 3d transition metals) is investigated using the spin-polarized density functional theory calculation. First, we find that the heterometallic interaction between the Pt skin surface and the gold subsurface in Pt/Au/Pt{sub 3}M system can significantly modify the electronic structure of the Pt skin surface. In particular, the local density of states projected onto the d states of Pt skin surface near the Fermi level is drastically decreased compared to the Pt/Pt/Pt{sub 3}M case, leading to the reduction of the oxygen binding strength of the Pt skin surface. This modification is related to the increase of surface charge polarization of outmost Pt skin atoms by the electron transfer from the gold subsurface atoms. Furthermore, a subsurface gold layer is found to cast the energetic barrier to the segregation loss of metal atoms from the bulk (inside) region, which can enhance the durability of Pt{sub 3}M based catalytic system in oxygen reduction condition at fuel cell devices. This study highlights that a gold subsurface hetero layer can provide an additional mean to tune the surface activity toward oxygen species and in turn the oxygen reduction reaction, where the utilization of geometric strain already reaches its practical limit.

  18. Quantification of Site-Specific Cation Exchange in Metal-Organic Frameworks Using Multi-Wavelength Anomalous X-ray Dispersion

    SciTech Connect

    Brozek, Carl K.; Cozzolino, Anthony F.; Teat, Simon J.; Chen, Yu-Sheng; Dinc,; #259; Mircea,

    2013-09-23

    We employed multiwavelength anomalous X-ray dispersion to determine the relative cation occupation at two crystallographically distinct metal sites in Fe2+-, Cu2+-, and Zn2+-exchanged versions of the microporous metal–organic framework (MOF) known as MnMnBTT (BTT = 1,3,5-benzenetristetrazolate). By exploiting the dispersive differences between Mn, Fe, Cu, and Zn, the extent and location of cation exchange were determined from single crystal X-ray diffraction data sets collected near the K edges of Mn2+ and of the substituting metal, and at a wavelength remote from either edge as a reference. Comparing the anomalous dispersion between these measurements indicated that the extent of Mn2+ replacement depends on the identity of the substituting metal. We contrasted two unique methods to analyze this data with a conventional approach and evaluated their limitations with emphasis on the general application of this method to other heterometallic MOFs, where site-specific metal identification is fundamental to tuning catalytic and physical properties.

  19. Crystal structure of a Pd4 carbonyl tri-phenyl-phosphane cluster [Pd4(CO)5(PPh3)4]·2C4H8O, comparing solvates.

    PubMed

    Robeyns, Koen; Willocq, Christopher; Tinant, Bernard; Devillers, Michel; Hermans, Sophie

    2016-02-01

    Attempts to synthesize Au-Pd heterometallic compounds from homonuclear palladium or gold complexes, [Pd(PtBu2)2] and [Au(PPh3)Cl] in a tetra-hydro-furan (THF) solution under a CO atmosphere resulted in a homonuclear Pd cluster, namely penta-kis-(μ-carbonyl-κ(2) C:C)tetra-kis-(tri-phenyl-phosphane-κP)tetrapalladium(5 Pd-Pd) tetra-hydro-furan disolvate, [Pd4(CO)5(C18H15P)4]·2C4H8O. The complex mol-ecule lies on a twofold rotation axis. The crystal structure is described in relation to the CH2Cl2 solvate previously determined by our group [Willocq et al. (2011 ▸). Inorg. Chim. Acta, 373, 233-242], and in particular to the desolvated structure [Feltham et al. (1985 ▸). Inorg. Chem. 24, 1503-1510]. It is assumed that the title compound transforms into the latter structure, upon gradual loss of solvent mol-ecules. In the title compound, the symmetry-unique THF solvent mol-ecule is linked to the complex mol-ecule by a weak C-H⋯O hydrogen bond. Contributions of disordered solvent molecules to the diffraction intensities, most likely associated with methanol, were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] algorithm. PMID:26958368

  20. Design, Synthesis and Characterisation of New Chimeric Ruthenium(II)-Gold(I) Complexes as Improved Cytotoxic Agents

    PubMed Central

    Massai, Lara; Fernández-Gallardo, Jacob; Guerri, Annalisa; Arcangeli, Annarosa; Pillozzi, Serena

    2015-01-01

    Two heterobimetallic complexes, i.e. [RuCl2(p-cymene)(µ-dppm)AuC] (1) and [RuCl2(p-cymene)(µ-dppm)Au S(thiazoline)] (3), based on known cytotoxic [Ru(p-cymene)Cl2(PR3)] and [AuX(PR3)] (X = Cl, SR) molecular scaffolds, with the diphosphane linker 1,1-bis(diphenylphosphino) methane, dppm, were conveniently prepared and characterised. Remarkably, the new compounds manifested a more favourable in vitro pharmacological profile toward cancer cells than individual ruthenium and gold species being either more cytotoxic or more selective. The interactions of the study compounds with (pBR322) DNA and their inhibitory effects on cathepsin B were also assessed. In addition, their reactivity toward suitable models of protein targets was explored and clear evidence gained for disruption of the bimetallic motif and for protein binding of monometallic fragments. Overall, the data reported here strongly support the concept of multifunctional heterometallic compounds as “improved” candidate agents for cancer treatment. The mechanistic and pharmacological implications of the present findings are discussed. PMID:25996553

  1. Experimental and theoretical studies of structural phase transition in a novel polar perovskite-like [C2H5NH3][Na0.5Fe0.5(HCOO)3] formate.

    PubMed

    Ptak, Maciej; Mączka, Mirosław; Gągor, Anna; Sieradzki, Adam; Stroppa, Alessandro; Di Sante, Domenico; Perez-Mato, Juan Manuel; Macalik, Lucyna

    2016-02-14

    We report the synthesis, single crystal X-ray diffraction, and thermal, dielectric, Raman and infrared studies of a novel heterometallic formate [C2H5NH3][Na0.5Fe0.5(HCOO)3] (EtANaFe). The thermal studies show that EtANaFe undergoes a second-order phase transition at about 360 K. X-ray diffraction data revealed that the high-temperature structure is monoclinic, space group P2(1)/n, with dynamically disordered ethylammonium (EtA(+)) cations. EtANaFe possesses a polar low-temperature structure with the space group Pn and, in principle, is ferroelectric below 360 K. Dielectric data show that the reciprocal of the real part of dielectric permittivity above and below the phase transition temperature follows the Curie-Weiss, as expected for a ferroelectric phase transition. Based on theoretical calculations, we estimated the polarization as (0.2, 0, 0.8) μC cm(-2), i.e., lying within the ac plane. The obtained data also indicate that the driving force of the phase transition is ordering of EtA(+) cations. However, this ordering is accompanied by significant distortion of the metal formate framework. PMID:26725595

  2. Heterobimetallic hexanuclear [Mn(ΙΙΙ)4Ln(ΙΙΙ)2] clusters: a rare Mn(ΙΙΙ)4Nd(ΙΙΙ)2 example exhibiting slow relaxation of magnetization.

    PubMed

    Ke, Hongshan; Zhao, Lang; Guo, Yang; Tang, Jinkui

    2012-02-28

    Reactions of lanthanide perchlorates and manganese acetate with Schiff-base ligand (H(4)L = 2-(((2-hydroxy-3-methoxyphenyl)methylene)amino)-2-(hydroxymethyl)-1,3-propanediol) in methanol in the presence of triethylamine yielded two hexanuclear heterometallic clusters of general formula [Mn(4)(ΙΙΙ)Ln(2)(ΙΙΙ)(H(2)L)(2)(HL)(2)(CH(3)COO)(4)(CH(3)O)(2)(CH(3)OH)(4)](ClO(4))(2)·6CH(3)OH [Ln = La(ΙΙΙ) (1), Nd(ΙΙΙ) (2)]. 1 and 2 are isostructural, with the metal centres consisting of a nonplanar [Mn(4)(ΙΙΙ)Ln(2)(ΙΙΙ)(μ(2)-O)(8)(μ(3)-OR)(2)](8+) core. Variable-temperature solid state magnetic susceptibilities measurements of 1 and 2 in the temperature 2-300 K were performed, indicating dominant antiferromagnetic exchange interactions between the metal centres in both compounds. Alternating current (ac) susceptibility data for 2 displays out-of-phase signal suggesting slow relaxation of magnetization whereas no out-of-phase signal is observed in 1, highlighting the incorporation of lighter lanthanide leads to SMM property. PMID:22187017

  3. Facile Separation of Regioisomeric Compounds by a Heteronuclear Organometallic Capsule.

    PubMed

    Zhang, Wen-Ying; Lin, Yue-Jian; Han, Ying-Feng; Jin, Guo-Xin

    2016-08-24

    Owing to the often-similar physical and chemical properties of structural isomers of organic molecules, large efforts have been made to develop efficient strategies to isolate specific isomers. However, facile separation of regioisomeric compounds remains difficult. Here we demonstrate a universal organometallic capsule in which two silver centers are rigidly separated from each other by two tetranuclear [Rh4] pyramidal frustums, which selectively encapsulate a specific isomer from mixtures. Not only is the present heterometallic capsule suitable as a host for the encapsulation of a series of aromatic compounds, but also the receptor shows widely differing specificity for the various isomers. Direct experimental evidence is provided for the selective encapsulation of a series of para (p)-disubstituted benzene derivatives, such as p-xylene, p-dichlorobenzene, p-dibromobenzene, and p-diiodobenzene. The size and shape matching, as well as the Ag-π interactions, are the main forces governing the extent of molecular recognition. The encapsulated guest p-xylene can be released by using the solid-liquid solvent washing strategy, and the other guest molecules are easily liberated by using light stimulus. PMID:27463561

  4. Unexpected Interactions of the Cyanobacterial Metallothionein SmtA with Uranium.

    PubMed

    Acharya, Celin; Blindauer, Claudia A

    2016-02-15

    Molecules for remediating or recovering uranium from contaminated environmental resources are of high current interest, with protein-based ligands coming into focus recently. Metallothioneins either bind or redox-silence a range of heavy metals, conferring protection against metal stress in many organisms. Here, we report that the cyanobacterial metallothionein SmtA competes with carbonate for uranyl binding, leading to formation of heterometallic (UO2)(n)Zn4SmtA species, without thiol oxidation, zinc loss, or compromising secondary or tertiary structure of SmtA. In turn, only metalated and folded SmtA species were found to be capable of uranyl binding. (1)H NMR studies and molecular modeling identified Glu34/Asp38 and Glu12/C-terminus as likely adventitious, but surprisingly strong, bidentate binding sites. While it is unlikely that these interactions correspond to an evolved biological function of this metallothionein, their occurrence may offer new possibilities for designing novel multipurpose bacterial metallothioneins with dual ability to sequester both soft metal ions including Cu(+), Zn(2+), Cd(2+), Hg(2+), and Pb(2+) and hard, high-oxidation state heavy metals such as U(VI). The concomitant protection from the chemical toxicity of uranium may be valuable for the development of bacterial strains for bio-remediation. PMID:26808269

  5. A uranium-based UO2(+)-Mn2+ single-chain magnet assembled trough cation-cation interactions.

    PubMed

    Mougel, Victor; Chatelain, Lucile; Hermle, Johannes; Caciuffo, Roberto; Colineau, Eric; Tuna, Floriana; Magnani, Nicola; de Geyer, Arnaud; Pécaut, Jacques; Mazzanti, Marinella

    2014-01-13

    Single-chain magnets (SCMs) are materials composed of magnetically isolated one-dimensional (1D) units exhibiting slow relaxation of magnetization. The occurrence of SCM behavior requires the fulfillment of stringent conditions for exchange and anisotropy interactions. Herein, we report the synthesis, the structure, and the magnetic characterization of the first actinide-containing SCM. The 5f-3d heterometallic 1D chains [{[UO2(salen)(py)][M(py)4](NO3)}]n, (M=Cd (1) and M=Mn (2); py=pyridine) are assembled trough cation-cation interaction from the reaction of the uranyl(V) complex [UO2(salen)py][Cp*2Co] (Cp*=pentamethylcyclopentadienyl) with Cd(NO3)2 or Mn(NO3)2 in pyridine. The infinite UMn chain displays a high relaxation barrier of 134±0.8 K (93±0.5 cm(-1)), probably as a result of strong intra-chain magnetic interactions combined with the high Ising anisotropy of the uranyl(V) dioxo group. It also exhibits an open magnetic hysteresis loop at T<6 K, with an impressive coercive field of 3.4 T at 2 K. PMID:24311434

  6. Turning a "useless" ligand into a "useful" ligand: a magneto-structural study of an unusual family of Cu(II) wheels derived from functionalised phenolic oximes.

    PubMed

    Frost, Jamie M; Stirling, Robert J; Sanz, Sergio; Vyas, Nidhi; Nichol, Gary S; Rajaraman, Gopalan; Brechin, Euan K

    2015-06-14

    While the phenolic oximes (R-saoH2) are well known for producing monometallic complexes of the type [M(II)(R-saoH)2] with Cu(II) ions in near quantitative yield, their derivatisation opens the door to much more varied and interesting coordination chemistry. Here we show that combining the complimentary diethanolamine and phenolic oxime moieties into one organic framework (H4L1 and H4L2) allows for the preparation and isolation of an unusual family of [Cu(II)]n wheels, including saddle-shaped, single-stranded [Cu(II)8] wheels of general formula [Cu8(HL1)4(X)4](n)[Y] (when n = 0, X = Cl(-), NO3(-), AcO(-), N3(-); when n = 2+ X = (OAc)2/(2,2'-bpy)2 and Y = [BF4]2) and [Cu8(HL2)4(X)4] (X = Cl(-), Br(-)), a rectangular [Cu6(HL1)4] wheel, and a heterometallic [Cu4Na2(HL1)2(H2L1)2] hexagon. Magnetic studies show very strong antiferromagnetic exchange between neighbouring metal ions, leading to diamagnetic ground states in all cases. DFT studies reveal that the magnitude of the exchange constants are correlated to the Cu-N-O-Cu dihedral angles, which in turn are correlated to the planarity/puckering of the [Cu(II)]n rings. PMID:25856756

  7. Fabrication of CoTiO3-TiO2 composite films from a heterobimetallic single source precursor for electrochemical sensing of dopamine.

    PubMed

    Ehsan, Muhammad Ali; Naeem, Rabia; Khaledi, Hamid; Sohail, Manzar; Hakeem Saeed, Abbas; Mazhar, Muhammad

    2016-06-21

    Cobalt titanate-titania composite oxide films have been grown on FTO-coated glass substrates using a single-source heterometallic complex [Co2Ti4(μ-O)6(TFA)8(THF)6]·THF () which was obtained in quantitative yield from the reaction of diacetatocobalt(ii) tetrahydrate, tetraisopropoxytitanium(iv), and trifluoroacetic acid from a tetrahydrofuran solution. Physicochemical investigations of complex have been carried out by melting point, FT-IR, thermogravimetric and single-crystal X-ray diffraction analyses. CoTiO3-TiO2 films composed of spherical objects of various sizes have been grown from by aerosol-assisted chemical vapor deposition at different temperatures of 500, 550 and 600 °C. Thin films characterized by XRD, Raman and X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis have been explored for electrochemical detection of dopamine (DA). The cyclic voltammetry with the CoTiO3-TiO2 electrode showed a DA oxidation peak at +0.215 V while linear sweep voltammetry displayed a detection limit (LoD) of 0.083 μM and a linear concentration range of 20-300 μM for DA. Thus, the CoTiO3-TiO2 electrode is a potential candidate for the sensitive and selective detection of DA. PMID:27230711

  8. Metal distribution and disorder in the crystal structure of [NH2Et2][Cr7MF8((t)BuCO2)16] wheel molecules for M = Mn, Fe, Co, Ni, Cu, Zn and Cd.

    PubMed

    Larsen, Finn Krebs; Overgaard, Jacob; Christensen, Mogens; McIntyre, Garry James; Timco, Grigore; Winpenny, Richard E P

    2014-12-01

    The homometallic wheel compound [Cr8F8(O2CCMe3)16] formed with fluorine and pivalic acid ligands can be modified by introducing in the synthesis process a divalent cation M capable of octahedral coordination instead of one of the trivalent Cr centres in the ring. Heterometallic mono-anionic species [Cr7MF8(O2CCMe3)16](-) can form diethylammonium salts and be crystallized from ethylacetate solution as compounds with the general formula [NH2Et2][Cr7MF8((t)BuCO2)16][C4H8O2]0.5 for M = Mn, Fe, Co, Ni, Cu, Zn and Cd. Their structures are isomorphous, belonging to the space group P21/c. The study has determined the degree of order for the individual M heterometal over the possible metal positions of the ring in the crystal structure by modelling based on X-ray diffraction data. The model took into account disorder in tert-butyl groups of the pivalate ligands and in the position and orientation of the ethylacetate solvent molecule. The heterometal turned out to be partly ordered in the crystal structure. PMID:25449616

  9. Uranyl sensitization of samarium (III) luminescence in a two-dimensional coordination polymer

    SciTech Connect

    Knope, Karah E.; de Lill, Daniel T.; Rowland, Clare E.; Cantos, Paula M.; de Bettencourt-Dias, Ana; Cahill, Christopher L.

    2012-01-02

    Heterometallic carboxyphosphonates UO₂2+/Ln3+ have been prepared from the hydrothermal reaction of uranyl nitrate, lanthanide nitrate (Ln = Sm, Tb, Er, Yb), and phosphonoacetic acid (H₃PPA). Compound 1, (UO₂)₂(PPA)(HPPA)₂Sm(H₂O)·2H₂O (1) adopts a two-dimensional structure in which the UO₂2+ metal ions bind exclusively to the phosphonate moiety, whereas the Ln3+ ions are coordinated by both phosphonate and carboxylate functionalities. Luminescence studies of 1 show very bright visible and near-IR samarium(III)-centered emission upon direct excitation of the uranyl moiety. The Sm3+ emissive state exhibits a double-exponential decay with lifetimes of 67.2 ± 6.5 and 9.0 ± 1.3 μs as measured at 594 nm, after excitation at both 365 and 420 nm. No emission is observed in the region typical of the uranyl cation, indicating that all energy is either transferred to the Sm3+ center or lost to nonradiative processes. Herein we report the synthesis, crystal structure, and luminescent behavior of 1, as well as those of the isostructural terbium, erbium, and ytterbium analogues.

  10. Cyano-bridged coordination polymer hydrogel-derived Sn-Fe binary oxide nanohybrids with structural diversity: from 3D, 2D, to 2D/1D and enhanced lithium-storage performance

    NASA Astrophysics Data System (ADS)

    Zhang, Weiyu; Zhu, Xiaoshu; Chen, Xuguang; Zhou, Yiming; Tang, Yawen; Ding, Liangxin; Wu, Ping

    2016-05-01

    Metal oxide nanohybrids with uniform dimensions and controlled architectures possess unique compositional and structural superiorities, and thus harbor promising potential for a series of applications in energy, catalysis, and sensing systems. Herein, we propose a facile, general, and scalable cyano-bridged coordination polymer hydrogel-derived thermal-oxidation route for the construction of main-group metal and transition-metal heterometallic oxide nanohybrids with controlled constituents and architectures. The formation of Sn-Fe binary oxide nanohybrids has been demonstrated as an example by using cyano-bridged Sn(iv)-Fe(ii) bimetallic coordination polymer hydrogels (i.e., SnCl4-K4Fe(CN)6 cyanogels, Sn-Fe cyanogels) as precursors. The physicochemical properties of Sn-Fe cyanogels with different Sn/Fe ratios have been systematically examined, and it is found that perfect Sn-Fe cyanogels without unbridged Sn(iv) or Fe(ii) can be formed with Sn/Fe ratios from 2 : 1 to 1 : 2. More importantly, the simple adjustment of Sn/Fe ratios in the Sn-Fe cyanogel precursors can realize flexible dimensional control of the Sn-Fe binary oxide nanohybrids, and 2D/1D SnO2-Fe2O3 hierarchitectures, 2D SnO2-Fe2O3 nanosheets, and 3D SnO2-Fe2O3 networks have been synthesized using the Sn-Fe 1 : 2, Sn-Fe 1 : 1, and Sn-Fe 2 : 1 cyanogels as precursors, respectively. To demonstrate their compositional/structural superiorities and potential applications, the lithium-storage utilization of the Sn-Fe binary oxide nanohybrids has been selected as an objective application, and the nanohybrids exhibit Sn/Fe ratio-dependent lithium-storage performance. As a representative example, the 2D/1D SnO2-Fe2O3 hierarchitectures manifest markedly enhanced Li-storage performance in terms of reversible capacities and cycling stability in comparison with their constituent units, i.e., bare SnO2 nanosheets and Fe2O3 nanorods. The proposed cyanogel-derived thermal-oxidation strategy could open up new

  11. Crystal structure of a Pd4 carbonyl tri­phenyl­phosphane cluster [Pd4(CO)5(PPh3)4]·2C4H8O, comparing solvates

    PubMed Central

    Robeyns, Koen; Willocq, Christopher; Tinant, Bernard; Devillers, Michel; Hermans, Sophie

    2016-01-01

    Attempts to synthesize Au–Pd heterometallic compounds from homonuclear palladium or gold complexes, [Pd(PtBu2)2] and [Au(PPh3)Cl] in a tetra­hydro­furan (THF) solution under a CO atmosphere resulted in a homonuclear Pd cluster, namely penta­kis­(μ-carbonyl-κ2 C:C)tetra­kis­(tri­phenyl­phosphane-κP)tetrapalladium(5 Pd—Pd) tetra­hydro­furan disolvate, [Pd4(CO)5(C18H15P)4]·2C4H8O. The complex mol­ecule lies on a twofold rotation axis. The crystal structure is described in relation to the CH2Cl2 solvate previously determined by our group [Willocq et al. (2011 ▸). Inorg. Chim. Acta, 373, 233–242], and in particular to the desolvated structure [Feltham et al. (1985 ▸). Inorg. Chem. 24, 1503–1510]. It is assumed that the title compound transforms into the latter structure, upon gradual loss of solvent mol­ecules. In the title compound, the symmetry-unique THF solvent mol­ecule is linked to the complex mol­ecule by a weak C—H⋯O hydrogen bond. Contributions of disordered solvent molecules to the diffraction intensities, most likely associated with methanol, were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] algorithm. PMID:26958368

  12. Synthesis, reaction and structure of a series of chromium(III) complexes containing oxalate ligand

    NASA Astrophysics Data System (ADS)

    Chen, Xu-Fang; Liu, Li; Ma, Jian-Gong; Yi, Long; Cheng, Peng; Liao, Dai-Zheng; Yan, Shi-Ping; Jiang, Zong-Hui

    2005-08-01

    A series of chromium(III) complexes [Cr(bipy)(HC2O4)2]Cl·3H2O (1), [Cr(phen)(HC2O4)2]Cl·3H2O (2), [Cr(phen)2(C2O4)]ClO4 (3), [Cr2(bipy)4(C2O4)](SO4)·(bipy)0.5·H2O (4) and [Mn(phen)2(H2O)2]2[Cr(phen)(C2O4)2]3ClO4·14H2O (5) were synthesized (bipy=4,4‧-bipyridine, phen=1,10-phenanthroline), while the crystal structures of 1 and 3-5 have been determined by X-ray analysis. 1 and 3 are mononuclear complexes, 4 contains binuclear chromium(III) ions and 5 is a 3D supromolecule formed by complicated hydrogen bonding. 1-3 are potential molecular bricks of chromium(III) building blocks for synthesis heterometallic complexes. When we use these molecular bricks as ligands to react with other metal salts, unexpected complexes 4 and 5 are isolated in water solution. The synthesis conditions and reaction results are also discussed.

  13. Novel bimetallic dispersed catalysts for temperature-programmed coal liquefaction. Technical progress report, April--June 1993

    SciTech Connect

    Song, Chunshan; Parfitt, D.P.; Schobert, H.H.

    1993-08-01

    The ultimate goal of the present research is to develop novel catalytic hydroliquefaction process using highly active dispersed catalysts. The primary objective of this research is to develop novel bimetallic dispersed catalysts from organometallic molecular precursors, that can be used in low concentrations (heterometallic complexes consisting of two transition metals, Mo and Co, and sulfur in a single molecule were synthesized and tested as precursors of bimetallic dispersed catalysts for liquefaction of a Montana subbituminous coal (DECS-9) at the loading level of 0.5 wt% Mo on dmmf coal. It was found that the structure of the precursors, in particular the ligands to the metal species, affect the activity of the resulting catalyst significantly. Among the M-M` type precursors tested, Mo-Co thiocubane, Mo{sub 2}Co{sub 2}S{sub 4}(Cp){sub 2}(CO){sub 2} [Cp = cyclopentadiene], designated as MoCo-TC2, produced in-situ the best catalyst The performance of the Mo-Co bimetallic catalyst was further enhanced by using temperature programmed (TPL) conditions consisting of a low temperature soaking at 200{degrees}C, programmed heat-up to 400 or 425{degrees}C followed by a 30 minutes hold. The pro ed heat-up serves as an in-situ activation of catalyst and coal pretreatment, which contributes to more effective hydrogenation of reactive fragments at high temperature.

  14. Synthesis and characterization of heterotrinuclear bis(μ2-chlorido)dicopper (II) mono zinc(II) complexes derived from succinoyldihydrazones

    NASA Astrophysics Data System (ADS)

    Borthakur, Rosmita; Kumar, Arvind; Lal, R. A.

    2014-01-01

    Three new zinc (II)-copper (II) heterometallic trinuclear complexes of the composition [ZnCu2(Ln)(μ2-Cl)2(H2O)6]ṡ2H2O (H4Ln = H4L1, H4L2, H4L3) have been synthesized from substituted succinoyldihydrazones (H4Ln) in methanol medium. The composition of the complexes has been established on the basis of data obtained from analytical, mass spectral studies and molecular weight determinations in DMSO. The structure of the ligand H4L2 has been established by X-ray crystallography. The structure of the complexes has been discussed in the light of molar conductance, magnetic moment, electronic, EPR, IR and FT-IR spectral studies. The molar conductance values for the complexes fall in the region 1.2-1.7 ohm-1 cm2 mol-1 in DMSO solution indicating that all of these are non-electrolyte. The magnetic moment values suggest weak M-M interaction in the structural unit of the complexes. The dihydrazone ligand is present in enol form in all of the complexes. Copper centre has tetragonally distorted octahedral stereochemistry. The EPR parameters of the complexes indicate that the copper centre has doublet state as the ground state. The electron transfer reactions of the complexes have been investigated by cyclic voltammetry.

  15. Supramolecular control over molecular magnetic materials: γ-cyclodextrin-templated grid of cobalt(II) single-ion magnets.

    PubMed

    Nedelko, Natalia; Kornowicz, Arkadiusz; Justyniak, Iwona; Aleshkevych, Pavlo; Prochowicz, Daniel; Krupiński, Piotr; Dorosh, Orest; Ślawska-Waniewska, Anna; Lewiński, Janusz

    2014-12-15

    Single-ion magnets (SIMs) are potential building blocks of novel quantum computing devices. Unique magnetic properties of SIMs require effective separation of magnetic ions and can be tuned by even slight changes in their coordination sphere geometry. We show that an additional level of tailorability in the design of SIMs can be achieved by organizing magnetic ions into supramolecular architectures, resulting in gaining control over magnetic ion packing. Here, γ-cyclodextrin was used to template magnetic Co(II) and nonmagnetic auxiliary Li(+) ions to form a heterometallic {Co, Li, Li}4 ring. In the sandwich-type complex [(γ-CD)2Co4Li8(H2O)12] spatially separated Co(II) ions are prevented from superexchange magnetic coupling. Ac/dc magnetic and EPR studies demonstrated that individual Co(II) ions with positive zero-field splitting exhibit field-induced slow magnetic relaxation consistent with the SIMs' behavior, which is exceptional in complexes with easy-plane magnetic anisotropy. PMID:25494948

  16. Heterodimetallic [LnLn′] Lanthanide Complexes: Toward a Chemical Design of Two-Qubit Molecular Spin Quantum Gates

    PubMed Central

    2015-01-01

    A major challenge for realizing quantum computation is finding suitable systems to embody quantum bits (qubits) and quantum gates (qugates) in a robust and scalable architecture. An emerging bottom-up approach uses the electronic spins of lanthanides. Universal qugates may then be engineered by arranging in a molecule two interacting and different lanthanide ions. Preparing heterometallic lanthanide species is, however, extremely challenging. We have discovered a method to obtain [LnLn′] complexes with the appropriate requirements. Compound [CeEr] is deemed to represent an ideal situation. Both ions have a doubly degenerate magnetic ground state and can be addressed individually. Their isotopes have mainly zero nuclear spin, which enhances the electronic spin coherence. The analogues [Ce2], [Er2], [CeY], and [LaEr] have also been prepared to assist in showing that [CeEr] meets the qugate requirements, as revealed through magnetic susceptibility, specific heat, and EPR. Molecules could now be used for quantum information processing. PMID:25203521

  17. CS2 activation at uranium(III) siloxide ate complexes: the effect of a Lewis acidic site.

    PubMed

    Camp, Clément; Cooper, Oliver; Andrez, Julie; Pécaut, Jacques; Mazzanti, Marinella

    2015-02-14

    Multimetallic cooperative binding of heteroallenes provides an attractive route to their activation, but the reduction of CS(2) at heterobimetallic sites, associating an electron-rich metal with a main group Lewis acid has not been explored. Here we show that the presence of a heterometallic U, K site plays an important role in the CS(2) reduction by uranium(iii) complexes of the electron-rich and the sterically demanding tris(tert-butoxy)siloxide ligand. Specifically, the ion-pair complex [K(18c6)][U(OSi(O(t)Bu)(3))(4)], 1, leads preferentially to the reductive disproportionation of CS(2) to K(2)CS(3) and CS. The crystal structure of the thiocarbonate intermediate complex [U(OSi(O(t)Bu(3)(4) (μ(3)-κ(2):κ(2):κ(2-)CS(3))K(2)(18c6)(2)], 2, isolated from the toluene reaction mixture has been determined. In contrast, the heterobimetallic complex [U(OSi(O(t)Bu(3)(4)K], 3, promotes preferentially the reductive dimerization of CS(2) to K(2)C(2)S(4) and K(2)C(3)S(5). The [K(2)C(2)S(4)(DMSO)(3)](n), 5, and [U(OSi(O(t)Bu)(3))(4)K(2)(C(3)S(5))](n), 6, polymeric compounds were isolated from this reaction and structurally characterized. PMID:25436831

  18. Efficient Ni(II)2Ln(III)2 Electrocyclization Catalysts for the Synthesis of trans-4,5-Diaminocyclopent-2-enones from 2-Furaldehyde and Primary or Secondary Amines.

    PubMed

    Griffiths, Kieran; Kumar, Prashant; Mattock, James D; Abdul-Sada, Alaa; Pitak, Mateusz B; Coles, Simon J; Navarro, Oscar; Vargas, Alfredo; Kostakis, George E

    2016-07-18

    A series of heterometallic coordination clusters (CCs) [Ni(II)2Ln(III)2(L1)4Cl2(CH3CN)2] 2CH3CN [Ln = Y (1Y), Sm (1Sm), Eu (1Eu), Gd (1Gd), or Tb (1Tb)] were synthesized by the reaction of (E)-2-(2-hydroxy-3-methoxybenzylidene-amino)phenol) (H2L1) with NiCl2·6(H2O) and LnCl3·x(H2O) in the presence of Et3N at room temperature. These air-stable CCs can be obtained in very high yields from commercially available materials and are efficient catalysts for the room-temperature domino ring-opening electrocyclization synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. Structural modification of the catalyst to achieve immobilization or photosensitivity is possible without deterioration in catalytic activity. PMID:27355452

  19. Bis(1,1,1,5,5,5-hexafluoropentane-2,4-dionato)tetrakis(μ4-1,1,1,5,5,5-hexafluoropentane-2,2,4,4-tetraolato)copper(II)octatin(II): a prospective precursor for Cu-doped SnO2 films.

    PubMed

    Lieberman, Craig M; Filatov, Alexander S; Vreshch, Volodimir D; Dikarev, Evgeny V

    2013-12-15

    The crystal structure of a tin-rich heterometallic supramolecular product, [CuSn8(C5HF6O2)2(C5H2F6O4)4] or [Sn4(hfpt)2-Cu(hfac)2-Sn4(hfpt)2], (I), is reported (hfpt is the tetraanion of 1,1,1,5,5,5-hexafluoropentane-2,2,4,4-tetraol and hfac is the anion of 1,1,1,5,5,5-hexafluoropentane-2,4-dione). Reaction between tin(II) tetraolate, [Sn4(hfpt)2], and copper(II) β-diketonate, [Cu(hfac)2], was utilized for the preparation of (I). The asymmetric unit consists of the whole [Sn4(hfpt)2] unit and half of a [Cu(hfac)2] unit, with the Cu atom lying on an inversion center. Intermolecular Cu···O interactions from the axial positions of copper in [Cu(hfac)2] and O atoms of the hfpt ligand in [Sn4(hfpt)2] mediate the formation of a sandwich-type structure for (I). Additional intermolecular Sn···O interactions between neighbouring [Sn4(hfpt)2] units complete a two-dimensional network. PMID:24311485

  20. Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures

    PubMed Central

    Manshina, A. A.; Grachova, E. V.; Povolotskiy, A. V.; Povolotckaia, A. V.; Petrov, Y. V.; Koshevoy, I. O.; Makarova, A. A.; Vyalikh, D. V.; Tunik, S. P.

    2015-01-01

    In the present work an efficient approach of the controlled formation of hybrid Au–Ag–C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles’ dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

  1. Laser-induced transformation of supramolecular complexes: approach to controlled formation of hybrid multi-yolk-shell Au-Ag@a-C:H nanostructures.

    PubMed

    Manshina, A A; Grachova, E V; Povolotskiy, A V; Povolotckaia, A V; Petrov, Y V; Koshevoy, I O; Makarova, A A; Vyalikh, D V; Tunik, S P

    2015-01-01

    In the present work an efficient approach of the controlled formation of hybrid Au-Ag-C nanostructures based on laser-induced transformation of organometallic supramolecular cluster compound is suggested. Herein the one-step process of the laser-induced synthesis of hybrid multi-yolk-shell Au-Ag@a-C:H nanoparticles which are bimetallic gold-silver subnanoclusters dispersed in nanospheres of amorphous hydrogenated a-C:H carbon is reported in details. It has been demonstrated that variation of the experimental parameters such as type of the organometallic precursor, solvent, deposition geometry and duration of laser irradiation allows directed control of nanoparticles' dimension and morphology. The mechanism of Au-Ag@a-C:H nanoparticles formation is suggested: the photo-excitation of the precursor molecule through metal-to-ligand charge transfer followed by rupture of metallophilic bonds, transformation of the cluster core including red-ox intramolecular reaction and aggregation of heterometallic species that results in the hybrid metal/carbon nanoparticles with multi-yolk-shell architecture formation. It has been found that the nanoparticles obtained can be efficiently used for the Surface-Enhanced Raman Spectroscopy label-free detection of human serum albumin in low concentration solution. PMID:26153347

  2. Configuring bonds between first-row transition metals.

    PubMed

    Eisenhart, Reed J; Clouston, Laura J; Lu, Connie C

    2015-11-17

    Alfred Werner, who pioneered the field of coordination chemistry, envisioned coordination complexes as a single, transition metal atom at the epicenter of a vast ligand space. The idea that the locus of a coordination complex could be shared by multiple metals held together with covalent bonds would eventually lead to the discovery of the quadruple and quintuple bond, which have no analogues outside of the transition metal block. Metal-metal bonding can be classified into homometallic and heterometallic groups. Although the former is dominant, the latter is arguably more intriguing because of the inherently larger chemical space in which metal-metal bonding can be explored. In 2013, Lu and Thomas independently reported the isolation of heterometallic multiple bonds with exclusively first-row transition metals. Structural and theoretical data supported triply bonded Fe-Cr and Fe-V cores. This Account describes our continued efforts to configure bonds between first-row transition metals from titanium to copper. Double-decker ligands, or binucleating platforms that brace two transition metals in proximity, have enabled the modular synthesis of diverse metal-metal complexes. The resulting complexes are also ideal for investigating the effects of an "ancillary" metal on the properties and reactivities of an "active" metal center. A total of 38 bimetallic complexes have been compiled comprising 18 unique metal-metal pairings. Twenty-one of these bimetallics are strictly isostructural, allowing for a systematic comparison of metal-metal bonding. The nature of the chemical bond between first-row metals is remarkably variable and depends on two primary factors: the total d-electron count, and the metals' relative d-orbital energies. Showcasing the range of covalent bonding are a quintuply bonded (d-d)(10) Mn-Cr heterobimetallic and the singly bonded late-late pairings, e.g., Fe-Co, which adopt unusually high spin states. A long-term goal is to rationally tailor the

  3. Lanthanide-Potassium Biphenyl-3,3'-disulfonyl-4,4'-dicarboxylate Frameworks: Gas Sorption, Proton Conductivity, and Luminescent Sensing of Metal Ions.

    PubMed

    Zhou, Li-Juan; Deng, Wei-Hua; Wang, Yu-Ling; Xu, Gang; Yin, Shun-Gao; Liu, Qing-Yan

    2016-06-20

    A novel sulfonate-carboxylate ligand of biphenyl-3,3'-disulfonyl-4,4'-dicarboxylic acid (H4-BPDSDC) and its lanthanide-organic frameworks {[LnK(BPDSDC)(DMF)(H2O)]·x(solvent)}n (JXNU-2, where JXNU denotes Jiangxi Normal University, DMF indicates dimethylformamide, and Ln = Sm(3+), Eu(3+), and Pr(3+)) were synthesized and structurally characterized. The three isomorphous lanthanide compounds feature three-dimensional frameworks constructed from one-dimensional (1D) rod-shaped heterometallic Ln-K secondary building units and are an illustration of a Kagome-like lattice with large 1D hexagonal channels and small 1D trigonal channels. The porous material of the representive JXNU-2(Sm) has an affinity to quadrupolar molecules such as CO2 and C2H2. In addition, the JXNU-2(Sm) compound exhibits humidity- and temperature-dependent proton conductivity with a large value of 1.11 × 10(-3) S cm(-1) at 80 °C and 98% relative humidity. The hydrophilic sulfonate group on the surface of channels facilitates enrichment of the solvate water molecules in the channels, which enhances the proton conductivity of this material. Moreover, the JXNU-2(Eu) material with the characteristic bright red color shows the potential for recognition of K(+) and Fe(3+) ions. The enhancing Eu(3+) luminescence with the K(+) ion and quenching Eu(3+) luminescence with the Fe(3+) ion can be associated with the functional groups of the organic ligand. PMID:27267985

  4. Solvent-templated supramolecular isomerism in 2D coordination polymer constructed by Ni(II)2Co(II) nodes and dicyanamido spacers: drastic change in magnetic behaviours.

    PubMed

    Ghosh, Soumavo; Mukherjee, Sandip; Seth, Piya; Mukherjee, Partha Sarathi; Ghosh, Ashutosh

    2013-10-01

    Two heterometallic coordination polymers (CPs) have been prepared using [Ni(II)L]2Co(II) (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine) as nodes and dicyanamido spacers by varying the solvent for synthesis. Structural characterizations revealed that methanol assisted the formation of a two-dimensional (4,4) connected rhombic grid network of [(NiL)2Co(NCNCN)2]∞ (1a) whereas relatively less polar acetonitrile afforded a different superstructure {[(NiL)2Co(NCNCN)2]·CH3CN}∞ (1b) with a two-dimensional (4,4) connected square grid network. The presence of acetonitrile molecules in the structure of 1b seems to change the spatial orientation of the terminal metalloligands [NiL] from pseudo-eclipsed in 1a to staggered-like in 1b around the central Co(II). These structural changes in the nodes together with the conformationally flexible dicyanamido spacers, which are cis coordinated to the Co(II) in both trinuclear units, led to the differences in the final 2D network. Variable-temperature magnetic susceptibility measurements revealed that this supramolecular isomerism led to a drastic transition from spin-frustrated antiferromagnetism for 1a to a dominant ferromagnetic behaviour for 1b. The geometrical differences in Ni2Co coordination clusters (CCs) which are scalene triangular in 1a but nearly linear in 1b, are held responsible for the changes of the magnetic properties. The DFT calculations of exchange interactions between metal centres provide a clear evidence of the role played by the fundamental geometrical factors on the nature and magnitude of the magnetic coupling in these pseudo-polymorphic CPs. PMID:23900267

  5. Redox potential tuning by redox-inactive cations in nature's water oxidizing catalyst and synthetic analogues.

    PubMed

    Krewald, Vera; Neese, Frank; Pantazis, Dimitrios A

    2016-04-20

    The redox potential of synthetic oligonuclear transition metal complexes has been shown to correlate with the Lewis acidity of a redox-inactive cation connected to the redox-active transition metals of the cluster via oxo or hydroxo bridges. Such heterometallic clusters are important cofactors in many metalloenzymes, where it is speculated that the redox-inactive constituent ion of the cluster serves to optimize its redox potential for electron transfer or catalysis. A principal example is the oxygen-evolving complex in photosystem II of natural photosynthesis, a Mn4CaO5 cofactor that oxidizes water into dioxygen, protons and electrons. Calcium is critical for catalytic function, but its precise role is not yet established. In analogy to synthetic complexes it has been suggested that Ca(2+) fine-tunes the redox potential of the manganese cluster. Here we evaluate this hypothesis by computing the relative redox potentials of substituted derivatives of the oxygen-evolving complex with the cations Sr(2+), Gd(3+), Cd(2+), Zn(2+), Mg(2+), Sc(3+), Na(+) and Y(3+) for two sequential transitions of its catalytic cycle. The theoretical approach is validated with a series of experimentally well-characterized Mn3AO4 cubane complexes that are structural mimics of the enzymatic cluster. Our results reproduce perfectly the experimentally observed correlation between the redox potential and the Lewis acidities of redox-inactive cations for the synthetic complexes. However, it is conclusively demonstrated that this correlation does not hold for the oxygen evolving complex. In the enzyme the redox potential of the cluster only responds to the charge of the redox-inactive cations and remains otherwise insensitive to their precise identity, precluding redox-tuning of the metal cluster as a primary role for Ca(2+) in biological water oxidation. PMID:26762578

  6. First-row transition-metal-diborane and -borylene complexes.

    PubMed

    Sharmila, Dudekula; Mondal, Bijan; Ramalakshmi, Rongala; Kundu, Sangita; Varghese, Babu; Ghosh, Sundargopal

    2015-03-23

    A combined experimental and quantum chemical study of Group 7 borane, trimetallic triply bridged borylene and boride complexes has been undertaken. Treatment of [{Cp*CoCl}2 ] (Cp*=1,2,3,4,5-pentamethylcyclopentadienyl) with LiBH4 ⋅thf at -78 °C, followed by room-temperature reaction with three equivalents of [Mn2 (CO)10 ] yielded a manganese hexahydridodiborate compound [{(OC)4 Mn}(η(6) -B2 H6 ){Mn(CO)3 }2 (μ-H)] (1) and a triply bridged borylene complex [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 MnH(CO)3 ] (2). In a similar fashion, [Re2 (CO)10 ] generated [(μ3 -BH)(Cp*Co)2 (μ-CO)(μ-H)2 ReH(CO)3 ] (3) and [(μ3 -BH)(Cp*Co)2 (μ-CO)2 (μ-H)Co(CO)3 ] (4) in modest yields. In contrast, [Ru3 (CO)12 ] under similar reaction conditions yielded a heterometallic semi-interstitial boride cluster [(Cp*Co)(μ-H)3 Ru3 (CO)9 B] (5). The solid-state X-ray structure of compound 1 shows a significantly shorter boron-boron bond length. The detailed spectroscopic data of 1 and the unusual structural and bonding features have been described. All the complexes have been characterized by using (1) H, (11) B, (13) C NMR spectroscopy, mass spectrometry, and X-ray diffraction analysis. The DFT computations were used to shed light on the bonding and electronic structures of these new compounds. The study reveals a dominant B-H-Mn, a weak B-B-Mn interaction, and an enhanced B-B bonding in 1. PMID:25689833

  7. Heterobimetallic cerium(iv) oxo clusters supported by a tripodal oxygen ligand.

    PubMed

    Wong, Kang-Long; So, Yat-Ming; Wang, Guo-Cang; Sung, Herman H-Y; Williams, Ian D; Leung, Wa-Hung

    2016-06-01

    Heterometallic Ce(IV)/M (M = Mo(VI), Re(VII), V(V)) oxo clusters supported by the Kläui tripodal oxygen ligand [(η(5)-C5H5)Co{P(O)(OEt)2}3](-) (LOEt(-)) have been synthesized and structurally characterized, and the catalytic activity of the Ce(IV)/V(V) oxo cluster in the oxidation of thioanisoles has been studied. Treatment of [Ce(LOEt)Cl3] (1) with [Ag2MoO4] afforded the reported Ce(IV)/Mo(VI) cluster [H4(CeLOEt)6Mo9O38] (2), whereas that with [AgReO4] yielded the Ce(IV)/Re(VII) cluster [{LOEtCe(ReO4)2(H2O)(μ-ReO4)}2] (3) that contains an 8-membered Ce2Re2O4 ring. Treatment of 1 with [Ag3VO4] afforded the Ce(IV)/V(V) cluster [H2(CeLOEt)4(V[double bond, length as m-dash]O)4(μ4-O)(μ3-O)12] (4) containing a {Ce4V4O13} oxo-metallic core. The solid-state structure of 4 consists of four {VO4}(3-) units bridged by four {LOEtCe(3+)} moieties and a μ4-oxo ligand. Each Ce atom in 4 is 9-coordinated, whereas the geometry around each V atom is pseudo square pyramidal with a terminal oxo at the apical position. Cluster 4 is an active catalyst for the oxidation of substituted thioanisoles with tert-butyl hydroperoxide. For example, the oxidation of thioanisole with tert-butyl hydroperoxide in the presence of 0.01 mol% of 4 gave a ca. 30 : 1 mixture of the sulfoxide and sulfone products in 96% yield. PMID:27142892

  8. DFT modelling of the [M-Pd-M] 6+ metal atom chains (M = Ni, Pd): Structural, electronic and magnetic issues

    NASA Astrophysics Data System (ADS)

    López, Xavier; Rohmer, Marie-Madeleine; Bénard, Marc

    2008-11-01

    Following the recent findings on heterometallic string complexes, we extend the recently published work on NiPdNi(dpa) 4Cl 2 to discuss the Ni-Pd-Ni and Pd 3 chains with equatorial ligands (L) being dipyridylamide (dpa), 2,6-bis(phenylamido)pyridine (BPAP) and N, N'-bis-( p-toluenesulfonyl)-pyridyldiamide (Lpts), using the DFT formalism. The analysis of such a hypothetical series of linear trimetallics anticipates that, for NiPdNi(dpa) 4Cl 2, the extended valence shell of palladium strengthens the antiferromagnetic coupling between high-spin terminal nickel atoms. For L = BPAP the system, as expected, becomes diamagnetic, and antiferromagnetism reappears for L = Lpts. The theoretical modelling of the coupling following the Heisenberg Hamiltonian applied to two magnetic centres (H^=-2JS·S) gives -2 J = 320 and 497 cm -1 for L = dpa and Lpts, respectively. Pd 3 chains display an enhanced tendency to be diamagnetic with various ligands. More specifically with dpa, Pd 3(dpa) 4Cl 2—should it be synthesized—could be magnetically inactive since the strongly antiferromagnetic state generated by the coupling of two terminal, high-spin Pd atoms (-2 J = 1393 cm -1) is computed to be in close competition with the diamagnetic, closed-shell state. For L = Lpts as for BPAP, the hypothetic [Pd 3] 6+ chain is predicted to be diamagnetic, resulting from the high energy of the antibonding d(Pd)-p(N) orbital. The shift toward diamagnetism induced by the replacement of Ni by Pd in terminal position is therefore assigned to a stronger N → M donation interaction with M = Pd.

  9. Homo- and Heterobimetallic Ruthenium(II) and Osmium(II) Complexes Based on a Pyrene-Biimidazolate Spacer as Efficient DNA-Binding Probes in the Near-Infrared Domain.

    PubMed

    Mardanya, Sourav; Karmakar, Srikanta; Mondal, Debiprasad; Baitalik, Sujoy

    2016-04-01

    We report in this work a new family of homo- and heterobimetallic complexes of the type [(bpy)2M(Py-Biimz)M'(II)(bpy)2](2+) (M = M' = Ru(II) or Os(II); M = Ru(II) and M' = Os(II)) derived from a pyrenyl-biimidazole-based bridge, 2-imidazolylpyreno[4,5-d]imidazole (Py-BiimzH2). The homobimetallic Ru(II) and Os(II) complexes were found to crystallize in monoclinic form with space group P21/n. All the complexes exhibit strong absorptions throughout the entire UV-vis region and also exhibit luminescence at room temperature. For osmium-containing complexes (2 and 3) both the absorption and emission band stretched up to the NIR region and thus afford more biofriendly conditions for probable applications in infrared imaging and phototherapeutic studies. Detailed luminescence studies indicate that the emission originates from the respective (3)MLCT excited state mainly centered in the [M(bpy)2](2+) moiety of the complexes and is only slightly affected by the pyrene moiety. The bimetallic complexes show two successive one-electron reversible metal-centered oxidations in the positive potential window and several reduction processes in the negative potential window. An efficient intramolecular electronic energy transfer is found to occur from the Ru center to the Os-based component in the heterometallic dyad. The binding studies of the complexes with DNA were thoroughly studied through different spectroscopic techniques such as UV-vis absorption, steady-state and time-resolved emission, circular dichroism, and relative DNA binding study using ethidium bromide. The intercalative mode of binding was suggested to be operative in all cases. Finally, computational studies employing DFT and TD-DFT were also carried out to interpret the experimentally observed absorption and emission bands of the complexes. PMID:27011117

  10. The influence of H-bonding on the 'ambidentate' coordination behaviour of the thiocyanate ion to Cd(II): a combined experimental and theoretical study.

    PubMed

    Hazari, Alokesh; Das, Lakshmi Kanta; Bauzá, Antonio; Frontera, Antonio; Ghosh, Ashutosh

    2014-06-01

    Two new trinuclear hetero-metallic copper(II)-cadmium(II) complexes [(CuL)2Cd(NCS)2] (1) and [(CuL(R))2Cd(SCN)2] (2) have been synthesized using [CuL] and [CuL(R)] as "metalloligands" (where H2L = N,N'-bis(salicylidene)-1,4-butanediamine and H2L(R) = N,N'-bis(2-hydroxybenzyl)-1,4-butanediamine) respectively. Both the complexes were characterized by elemental analysis, various spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligands" [CuL] are coordinated to a central Cd(II) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal thiocyanate ions. In complex 2, which is linear, in addition to the double phenoxido bridge, two SCN(-) coordinate to the trans positions of the central octahedral Cd(II) via S atoms. Theoretical calculations on the energetic difference between the two possible coordination modes of the thiocyanate anion to the Cd atom reveal that N-coordination is preferred over S-coordination in agreement with the much greater abundance of the reported N-bonded structures. In 2, there is a strong N-H···NCS-Cd H-bonding interaction, the binding energy of which is computed to be approximately -9.3 kcal mol(-1), which is sufficient to compensate the 9.0 kcal mol(-1) of energetic cost due to the unusual Cd-SCN coordination mode. PMID:24715108

  11. Magnetic order in a novel 3D oxalate-based coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n.

    PubMed

    Jurić, Marijana; Pajić, Damir; Žilić, Dijana; Rakvin, Boris; Molčanov, Krešimir; Popović, Jasminka

    2015-12-21

    A heterometallic coordination polymer {[Cu(bpy)3][Mn2(C2O4)3]·H2O}n (1; bpy = 2,2'-bipyridine) was synthesized using a building-block approach and characterized by IR spectroscopy, single-crystal X-ray diffraction, magnetization measurement, and X-band ESR spectroscopy both on a single crystal and a polycrystalline sample. The molecular structure of 1 is made of a three-dimensional (3D) anionic network [Mn2(C2O4)3]n(2n-) and tris-chelated cations [Cu(bpy)3](2+) occupying the vacancies of the framework. In compound 1 magnetic order is confirmed below 12.8 K - magnetization measurements reveal an antiferromagnetic-like network of canted Mn(2+) spins with incorporated paramagnetic Cu(2+) centres. The ESR spectroscopy distinctly shows the phase transition; above T≈ 13 K, single isotropic Lorentzian lines of Mn(2+) ions in the high spin state S = 5/2 were observed, while below this temperature, only characteristic Cu(2+) signals from cations were detected. Thermal decomposition residues of 1 at different temperatures (800-1000 °C) were analyzed by powder X-ray diffraction; by heating the sample up to 1000 °C the spinel oxide CuMn2O4 [94.1(2) wt%] was formed. From the refined structural parameters, it could be seen that the obtained spinel is characterized by the inversion parameter δ∼ 0.8, and therefore the structural formula at room temperature can be written as (tet)[Cu0.17Mn0.83](oct)[Mn1.17Cu0.83]O4. PMID:26564382

  12. Optical absorption engineering in stacked plasmonic Au-SiO₂-Pd nanoantennas.

    PubMed

    Wadell, Carl; Antosiewicz, Tomasz J; Langhammer, Christoph

    2012-09-12

    The nonradiative decay of a localized surface plasmon through absorption of a captured photon and excitation of an energetic electron-hole pair is a potentially very effective way to enhance chemical reactions on metal nanoparticle surfaces, so far limited to Ag (and Au). Here we explore the possibility of efficient and spectrally widely tunable optical absorption engineering based on heterometallic optical nanoantennas. They consist of an optimized antenna element made of Au (or Ag) and a catalytically active second metallic element separated by a thin SiO(2) layer. Specifically, we find that stacked Au-SiO(2)-Pd nanodisk antennas exhibit pronounced local absorption enhancement in the catalytic Pd particle. The effect is caused by efficient power transfer from the Au disk, exhibiting a narrow low-loss resonance and acting as an antenna collecting photons, to the Pd disk due to strong coupling between the two. The Pd element thus acts as receiver that efficiently dissipates energy into electron-hole pairs owing to efficient coupling to intra and interband transitions. In fact, the energy transfer is found to be so effective that the absorption efficiency at a given wavelength can be enhanced up to 6 to 9 times, and the total absorption integrated over a wide spectral range (400-900 nm) up to 2-fold, depending on the antenna dimensions. This finding suggests a novel route toward highly efficient plasmon-enhanced catalysis on widely selectable catalytic metal particle surfaces not limited to the "classic" plasmonic metals Au and Ag. PMID:22916998

  13. The small iron-sulfur protein from the ORP operon binds a [2Fe-2S] cluster.

    PubMed

    Maiti, Biplab K; Moura, Isabel; Moura, José J G; Pauleta, Sofia R

    2016-09-01

    A linear cluster formulated as [S2MoS2CuS2MoS2](3-), a unique heterometallic cluster found in biological systems, was identified in a small monomeric protein (named as Orange Protein). The gene coding for this protein is part of an operon mainly present in strict anaerobic bacteria, which is composed (in its core) by genes coding for the Orange Protein and two ATPase proposed to contain Fe-S clusters. In Desulfovibrio desulfuricans G20, there is an ORF, Dde_3197 that encodes a small protein containing several cysteine residues in its primary sequence. The heterologously produced Dde_3197 aggregates mostly in inclusion bodies and was isolated by unfolding with a chaotropic agent and refolding by dialysis. The refolded protein contained sub-stoichiometric amounts of iron atoms/protein (0.5±0.2), but after reconstitution with iron and sulfide, high iron load contents were detected (1.8±0.1 or 3.4±0.2) using 2- and 4-fold iron excess. The visible absorption spectral features of the iron-sulfur clusters in refolded and reconstituted Dde_3197 are similar and resemble the ones of [2Fe-2S] cluster containing proteins. The refolded and reconstituted [2Fe-2S] Dde_3197 are EPR silent, but after reduction with dithionite, a rhombic signal is observed with gmax=2.00, gmed=1.95 and gmin=1.92, consistent with a one-electron reduction of a [2Fe-2S](2+) cluster into a [2Fe-2S](1+) state, with an electron spin of S=½. The data suggests that Dde_3197 can harbor one or two [2Fe-2S] clusters, one being stable and the other labile, with quite identical spectroscopic properties, but stable to oxygen. PMID:27240719

  14. Retrosynthetic approach to the design of molybdenum-magnesium oxoalkoxides.

    PubMed

    Kuznetsov, Denis A; Fedyanin, Ivan V; Lyssenko, Konstantin A; Bazhenova, Tamara A

    2014-09-14

    The reaction of MoCl5 methanolysis in the presence of magnesium ions was shown to produce an extensive row of heterobimetallic Mg-Mo(V, VI) oxomethoxides of different nuclearity ranging from 4 for [Mg2(CH3OH)4Mo2O2(OCH3)10] (1) to 26 for [Mg(DMF)3(CH3OH)3]2[Mo22Mg4O48(OCH3)28(DMF)6] (2) with the latter possessing a ring morphology. Examination of [Mo6O12(OCH3)16Mg4(CH3OH)6] (3), [Mo6O12(OCH3)12Mg2(DMF)4] (4a), and [Mo6O16(OCH3)4Mg2(DMF)8] (5a) X-ray structures revealed the presence of the well known tetranuclear core {Mo4O8(OCH3)2}(2+) thus similar reactivity patterns leading to their formation were assumed. For convenient synthesis of such heterobimetallic oxoalkoxides, the retrosynthetic approach based on speculative deconstruction of a target molecule onto simpler fragments was suggested and successfully employed. Namely, the reaction of the stoichiometric amounts of appropriately chosen Mo(V), Mo(VI) and Mg(2+) synthons led to their assembling resulting in the formation of heterometallic clusters 3, 5a and [Mo6O12(OCH3)12Mg2(CH3OH)4]·2CH3OH (4b) characterized by means of elemental analysis, UV-Vis, IR spectroscopy, and X-ray crystallography. PMID:25019529

  15. Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

    SciTech Connect

    Zhang, Sheng; Qu, Xiao-Ni; Xie, Gang; Wei, Qing; Chen, San-Ping

    2014-02-15

    Four alkaline-earth coordination polymers, [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba{sub 2}O{sub 11}N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2.

  16. Spirobifluorene bridged Ir(III) and Os(II) polypyridyl arrays: synthesis, photophysical characterization, and energy transfer dynamics.

    PubMed

    Ventura, Barbara; Barbieri, Andrea; Degli Esposti, Alessandra; Seneclauze, Julie Batcha; Ziessel, Raymond

    2012-03-01

    The synthesis, characterization, photophysics, and time-dependent density functional theory (TD-DFT) calculations of spirobifluorene-bipyridine based iridium(III), osmium(II), and mixed Ir/Os complexes are presented. The preparation of the reference and mixed complexes proceeded step-by-step and microwave irradiation facilitated the complexation of osmium. The absorption of the target heterobimetallic derivative, Ir-L-Os, is described by linear combination of half of the absorption spectra of the homobimetallic analogues, Ir-L-Ir and Os-L-Os, due to the occurrence of mixed ligand and metal based transitions when the spirobifluorene-(bpy)(2) bridging ligand L is linked to the metal, confirming a negligible interaction between the substituted metallic chromophores. TD-DFT calculations on monometallic, homo- and hetero-bimetallic complexes fully disentangled the origin of the absorption features. Noticeably, in the mixed Ir-L-Os complex an almost quantitative energy transfer from the (3)Ir to the (3)Os MLCT state is occurring, with a rate constant of 4.1 × 10(8) s(-1) and nearly exclusively via a Dexter-type mechanism mediated by the orbitals of the spiroconjugated ligand. This result, together with the outcomes of the TD-DFT calculations, supports the existence of spiroconjugation and evidences the interesting role of this kind of bridge in the energy transfer dynamics of the arrays. In all the complexes, moreover, the ligand fluorescence is heavily quenched by energy transfer processes toward the metallic appended units; the rate constant is estimated in the order of 10(10) s(-1) for Ir-L-Os and higher than 10(12) s(-1) for the other complexes. In the heterometallic array, both at room temperature and at 77 K, all photons are thus funneled to the emissive Os (3)MLCT state, which acts as energy trap for the antenna cascade. PMID:22356478

  17. Structural characterization of environmentally relevant ternary uranyl citrate complexes present in aqueous solutions and solid state materials.

    PubMed

    Basile, Madeline; Unruh, Daniel K; Flores, Erin; Johns, Adam; Forbes, Tori Z

    2015-02-14

    Organic acids are important metal chelators in environmental systems and tend to form soluble complexes in aqueous solutions, ultimately influencing the transport and bioavailability of contaminants in surface and subsurface waters. This is particularly true for the formation of uranyl citrate complexes, which have been utilized in advanced photo- and bioremediation strategies for soils contaminated with nuclear materials. Given the complexity of environmental systems, the formation of ternary or heterometallic uranyl species in aqueous solutions are also expected, particularly with Al(iii) and Fe(iii) cations. These ternary forms are reported to be more stable in aqueous solutions, potentially enhancing contaminant mobility and uptake by organisms, but the exact coordination geometries of these soluble molecular complexes have not been elucidated. To provide insight into the nature of these species, we have developed a series of geochemical model compounds ([(UO(2))(2)Al(2)(C(6)H(4)O(7))(4)](6-) (U(2)Al(2)), [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)](6-) (U(2)Fe(2)-1) and [(UO(2))(2)Fe(2)(C(6)H(4)O(7))(4)(H(2)O)(2)](6-) (U(2)Fe(2)-2) and [(UO(2))(2)Fe(4)(OH)(4)(C(6)H(4)O(7))(4)](8-) (U(2)Fe(4))) that were characterized by single-crystal X-ray diffraction and vibrational spectroscopy. Mass spectroscopy was then employed to compare the model compounds to species present in aqueous solutions to provide an enhanced understanding of the ternary uranyl citrate complexes that could be relevant in natural systems. PMID:25372632

  18. Synthesis, structures, and magnetic properties of a family of 3d-4f [Na2Fe6Ln2] complexes (Ln = Y, Gd and Dy): effect of ligands on the connection of inorganic subunits.

    PubMed

    Zhou, Qi; Yang, Fen; Liu, Dan; Peng, Yu; Li, Guanghua; Shi, Zhan; Feng, Shouhua

    2013-01-28

    A family of 3d-4f heterometallic compounds [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(HL)(4)(CH(3)O)(4)(PhCO(2))(6)] (1, H(4)L = 2-{[(2-hydroxy-3-methoxyphenyl)methylene]amino}-2-(hydroxymethyl)-1,3-propanediol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (2, H(3)L' = (E)-2-ethyl-2-(2-hydroxy-3-methoxybenzylideneamino)propane-1,3-diol), [Na(2)Fe(III)(6)Dy(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(Bu(t)CO(2))(6)] (3) [Na(2)Fe(III)(6)Y(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(H(2)O)] (4), and [Na(2)Fe(III)(6)Gd(III)(2)(N(3))(4)(L')(4)(CH(3)O)(4)(PhCO(2))(6)(CH(3)OH)(2)] (5) have been prepared using Schiff-base ligands, trinuclear iron precursor complexes, azides and lanthanide nitrates as reactants. In compounds 1 and 2, the structure of the [Na(2)Fe(III)(6)Dy(III)(2)] cluster forms a couple of cis,trans-isomers with substitution of methyl for a free hydroxyl group which belongs to the Schiff-base ligand. When the pivalates are employed instead of bulkier benzoates, the trans-[Na(2)Fe(III)(6)Dy(III)(2)] clusters act as network nodes in the formation of rhombic grid-like layered structures in compound 2. Compounds 2, 4 and 5 have similar metallic cores, only with different crystal solvent molecules. The magnetic measurements on all the compounds indicate dominant antiferromagnetic interactions between the metal centers. PMID:23114511

  19. Advanced thermally stable jet fuels. Technical progress report, August 1992--October 1992

    SciTech Connect

    Schobert, H.H.; Eser, S.; Song, C.; Hatcher, P.G.; Walsh, P.M.; Coleman, M.M.; Bortiatynski, J.; Burgess, C.; Dutta, R.; Gergova, K.; Lai, W.C.; Li, J.; McKinney, D.; Parfitt, D.; Peng, Y.; Sanghani, P.; Yoon, E.

    1993-02-01

    The Penn State program in advanced thermally stable coal-based jet fuels has five borad objectives: (1) development of mechanisms of degradation and solids formation; (2) quantitative measurement of growth of sub-micrometer and miocrometer-sized particles suspended in fuels during thermal stressing; (3) characterization of carbonaceous deposits by various instrumental and microscopic methods; (4) elucidation of the role of additives in retarding the formation of carbonaceous solids; and (5) assessment of the potential of production of high yields of cycloalkanes by direct liquefaction of coal. Pyrolysis of four isomers of butylbenzene was investigated in static microautoclave reactors at 450{degrees}C under 0.69 MPa of UHP N{sub 2}. Thee rates of disappearance of substrates were found to depend upon the bonding energy of C{alpha}-C{beta} bond in the side chain in the initial period of pyrolysis reactions. Possible catalytic effects of metal surfaces on thermal degradation and deposit formation at temperatures >400{degrees}C have been studied. Carbon deposition depends on the composition of the metal surfaces, and also depends on the chemical compositions of the reactants. Thermal stressing of JP-8 was conducted in the presence of alumina, carbonaceous deposits recovered from earlier stressing experiments, activated carbon, carbon black, and graphite. The addition of different solid carbons during thermal stressing leads to different reaction mechanisms. {sup 13}C NMR spectroscopy, along with {sup 13}C-labeling techniques, have been used to examine the thermal stability of a jet fuel sample mixed with 5% benzyl alcohol. Several heterometallic complexes consisting of two transition metals and sulfur in a single molecule were synthesized and tested as precursors of bimetallic dispersed catalysts for liquefaction of a Montana subbituminous and Pittsburgh No. 8 bituminous coals.

  20. Structures and standard molar enthalpies of formation of a series of Ln(III)–Cu(II) heteronuclear compounds with pyrazine-2,3-dicarboxylic acid

    SciTech Connect

    Yang, Qi; Xie, Gang; Wei, Qing; Chen, Sanping Gao, Shengli

    2014-07-01

    Fifteen lanthanide–copper heteronuclear compounds, formulated as [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 6}]·xH{sub 2}O (1–6(x=2), 8(x=3), 9–10(x=4)); [CuLn{sub 2}(pzdc){sub 4}(H{sub 2}O){sub 4}]·xH{sub 2}O (7, 12–13, 15(x=4), 14(x=5), 11(x=8)) (Ln(III)=La(1); Ce(2); Pr(3); Nd(4); Sm(5); Eu(6); Gd(7); Tb(8); Dy(9); Ho(10); Er(11); Tm(12); Yb(13); Lu(14); Y(15); H{sub 2}pzdc (C{sub 6}H{sub 4}N{sub 2}O{sub 4})=pyrazine-2,3-dicarboxylic acid) have been hydrothermally synthesized. All compounds were characterized by element analysis, IR spectroscopy, single-crystal X-ray diffraction and thermal analysis. X-ray diffraction analyses confirm that all compounds are isostructural and feature a 3D brick-like framework structure with (4.6{sup 2}){sub 2}(4{sup 2}.6{sup 2}.8{sup 2})(6{sup 3}){sup 2}(6{sup 5}.8){sub 2} topology. Using 1 mol cm{sup −3} HCl(aq) as calorimetric solvent, with an isoperibol solution–reaction calorimeter, the standard molar enthalpies of formation of all compounds were determined by a designed thermochemical cycle. In addition, solid state luminescence properties of compounds 5, 6, 8 and 9 were studied in the solid state. - Graphical abstract: According to Hess' rule, the standard molar enthalpies of formation of Ln–Cu heterometallic coordination compounds were determined by a designed thermochemical cycle. - Highlights: • Fifteen lanthanide–copper heteronuclear isostructural compounds. • Structurally characterization by IR, X-ray diffraction and thermal analysis. • The standard molar enthalpy of formation. • Isoperibol solution–reaction calorimetry.

  1. Novel Di- and Trinuclear Palladium Complexes Supported by N,N'-Diphosphanyl NHC Ligands and N,N'-Diphosphanylimidazolium Palladium, Gold, and Mixed-Metal Copper-Gold Complexes.

    PubMed

    Ai, Pengfei; Gourlaouen, Christophe; Danopoulos, Andreas A; Braunstein, Pierre

    2016-02-01

    The reaction of the trinuclear complex [Ag3(μ3-PC(NHC)P,κP,κC(NHC),κP)2](OTf)3 (Ag3; PC(NHC)P = N,N'-bis(di-tert-butylphosphanyl)imidazol-2-ylidene) with [Pd(dba)2] afforded the trinuclear palladium complex [Pd3(μ3-PC(NHC)P,κP,κC(NHC),κP)2](OTf)2 (Pd3) and the dinuclear palladium(I) complex [Pd2(μ2-PC(NHC)P,κP,κC(NHC),κP)2](OTf)2 (Pd2). The assignment of the oxidation state of the metals in the mixed-valence Pd3 chain as Pd(0)-Pd(II)-Pd(0) was based on the reactivity of the complex with 2,6-dimethylphenyl isocyanide and density functional theory calculations. Reaction of PCNHCP with [PdMe2(tmeda)] afforded the palladium(II) complex [PdMe2(PC(NHC)P,κP,κC(NHC))] (Pd-Me2), with PC(NHC)P acting as a bidentate ligand. The reaction of PC(NHC)P with [Pd(dba)2] led to a dinuclear palladium(0) complex [Pd2(μ2-PC(NHC)P,κP,κC(NHC),κP)](dba) (Pd2-dba); attempted replacement of the remaining dba by PC(NHC)P failed. The imidazolium triflate PCHP, precursor to PC(NHC)P, was reacted with [Pd2(dba)3]·CHCl3 to give the (2 + 2) metalla-mesocyclic cationic palladium(0) complex [Pd2(μ2-PCHP,κP,κP)2] (PCHP-Pd2), which resisted further deprotonation of the imidazolium cation. In contrast, PCHP reacted with [AuCl(tht)] to give [Au2Cl2(μ2-PCHP,κP,κP)] (PCHP-Au2), in which one Au-Cl moiety is bound to each P donor. Further reaction of PCHP-Au2 with [Au{N(SiMe3)2}(PPh3)] afforded a mixture of the trinuclear [Au3(μ3-PC(NHC)P,κP,κC(NHC),κP)2](OTf)3 (Au3) and [AuCl(PPh3)], while reaction with [CuMes]5, where Mes = 2,4,6-trimethylphenyl, resulted in a novel, centrosymmetric, heterometallic complex [Au2Mes2(Cu4Cl4)(PCHP,κP,κP)2] (PCHP-AuCu) featuring a new PCHP-AuMes metalloligand bridging a Cu···Cu diagonal of a Cu4Cl4 cubane via the P and AuMes functionalities. PMID:26790035

  2. Emissive {Mn4(III)Ca} clusters with square pyramidal topologies: syntheses and structural, spectroscopic, and physicochemical characterization.

    PubMed

    Alaimo, Alysha A; Takahashi, Daisuke; Cunha-Silva, Luís; Christou, George; Stamatatos, Theocharis C

    2015-03-01

    The one-pot reactions between Mn(ClO4)2·6H2O, Ca(ClO4)2·4H2O, and the potentially tetradentate (N,O,O,O) chelating/bridging ligand salicylhydroxime (shiH3), resulting from the in situ metal ion-assisted amide-iminol tautomerism of salicylhydroxamic acid in the presence of various fluorescence carboxylate groups and base NEt3, afford a family of structurally similar {Mn4Ca} clusters with distorted square pyramidal topology. The reported complexes (NHEt3)2[Mn4Ca(L1)4(shi)4] (1), (NHEt3)2[Mn4Ca(L2)4(shi)4] (2), (NHEt3)5[Mn4Ca(L2)4(shi)4(shiH2)2](ClO4) (3), and (NHEt3)2[Mn4Ca(L3)4(shi)4] (4) contain a similar [Mn4Ca(μ-NO)4](10+) core of four Mn(III) atoms at the square base and a Ca(II) atom occupying the apical site. Peripheral ligation about the core is provided by four η(1):η(1):μ carboxylate groups of the anions of 2-naphthoic acid (L1(-)), 9-anthracenecarboxylic acid (L2(-)), and 1-pyrenecarboxylic acid (L3(-)). Solid-state direct current magnetic susceptibility studies revealed the presence of predominant antiferromagnetic exchange interactions between the 4 Mn(III) centers, which were primarily quantified by using a simple 1-J fit model to give S = 0 spin ground states with low-lying excited states close in energy to the ground state. Solution studies in solvent MeCN were carried out on all complexes and confirmed their structural integrity. Cyclic voltammetry studies showed a similar well-defined reversible oxidation and an irreversible reduction for all complexes, thus establishing their redox potency and electrochemical efficiency. Emission studies in solution proved the optical activity of all compounds, with the observed "blue" emission peaks attributed to the π-rich chromophores of the organic fluorescence ligands. The combined results demonstrate the ability of shiH3 and fluorescence carboxylates to yield new heterometallic Mn/Ca clusters with (i) the same Mn/Ca ratio as the oxygen-evolving complex of Photosystem II, (ii) structural stability in

  3. Vanadium oxide based materials: Synthesis, characterization and gas sensing properties

    NASA Astrophysics Data System (ADS)

    Ayesh, Samar I.

    In recent years, the demand for gas sensors based on safety and process control requirements has been expanding. The reason for such demand sterns from environmental and safety concerns since the toxic gases released from automobile exhausts and chemical plants can directly or indirectly pollute our environment and affect our health. Among the chemicals studied, nitrogen oxide (NOx) gases are among the most dangerous air pollutants. Transition metal oxide clusters (or polyoxometalates) provide an exciting opportunity for the design and synthesis of a new generation of materials for efficient NOx sensing. Polyoxometalates are an important and fast emerging class of compounds that exhibit many remarkable properties. Chapter 1 provides introduction and background of chemical sensors. It describes the need for gas sensors and the current status of research in the area of NOx gas sensors in particular. A description of polyoxmetalates and their relevance as potential novel gas sensor materials is also given. Chapter 2 describes the synthesis and characterization by FTIR spectroscopy, elemental analysis, thermogravimetric analysis, manganometric titration, bond valence sum calculation, temperature dependent magnetic properties studies, electron paramagnetic resonance, and complete single crystal X-ray diffraction analysis of newly prepared vanadium oxide based-systems that have been discovered during the course of this work. First, the system containing arrays of decavanadates networked by extensive hydrogen bonding with cyclic nitrogen bases are described. This is followed by the mixed-valence vanadium oxide cluster, [VV 13VIV3O42(Cl)]-7, containing a hitherto unknown vanadium oxide framework structure. Finally the synthesis of 3D-framework materials is described. These compounds have highly symmetrical closely related three-dimensional framework structures consisting vanadium oxide shells {V18O42(XO4)} linked via heterometallic atoms {M' = Cd, Zn} into three

  4. Hydride, gold(i) and related derivatives of the unsaturated ditungsten anion [W2Cp2(μ-PCy2)(μ-CO)2](-).

    PubMed

    Alvarez, M Angeles; García, M Esther; García-Vivó, Daniel; Ruiz, Miguel A; Vega, M Fernanda

    2014-11-14

    Protonation of the title anion with [NH4]PF6 gave [W2Cp2(H)(μ-PCy2)(CO)2] (), which in solution exists as an equilibrium mixture of two isomers having either bridging (major) or terminal (minor) hydrides. Both molecules retain short intermetallic distances (ca. 2.54 Å), with the H-bridged isomer being almost 15 kJ mol(-1) more stable than the terminal one, according to density functional theory calculations. Further protonation with acids having weakly coordinating anions (BF4(-) or BAr'4(-); Ar' = 3,5-C6H3(CF3)2) yielded isomeric cations also displaying bridging and terminal hydride ligands ([W2Cp2(μ-H)(H)(μ-PCy2)(CO)2](+) and [W2Cp2(H)2(μ-PCy2)(CO)2](+)), with the latter being only slightly more energetic (by ca. 4 kJ mol(-1)). In contrast, protonation of with carboxylic acids yielded carboxylate-bridged derivatives [W2Cp2(μ-PCy2)(μ-O:O'-O2CR)(CO)2] [R = Ph, CF3] following from dihydrogen elimination. The title anion also reacted readily with metal-based electrophiles such as ClSnPh3 and [AuCl(PR3)] (R = (i)Pr, p-tol) to give the corresponding heterometallic clusters [W2Cp2(μ-PCy2)(μ-SnPh3)(CO)2] and [AuW2Cp2(μ-PCy2)(CO)2(PR3)], these having the added electrophile placed at the bridging position and formally retaining triple W-W bonds. The gold complexes, however, were rather unstable species decomposing spontaneously to give the tetranuclear clusters [Au2W2Cp2(μ-PCy2)(CO)2(PR3)2]X (W-W = 2.5803(6) Å and Au-Au = 2.8050(6) Å when R = (i)Pr and X = PF6), which could be prepared more conveniently by adding two equivalents of [AuCl(PR3)] to the anion, as expected. In contrast, reaction of the title anion with ClPbPh3 led to the formation of the phenyl-bridged complex [W2Cp2(μ-PCy2)(μ-Ph)(CO)2], following from the formal loss of PbPh2. PMID:25238551

  5. Versatile N2S2 nickel-dithiolates as mono- and bridging bidentate, S-donor ligands to gold(I).

    PubMed

    Pinder, Tiffany A; Montalvo, Steven K; Lunsford, Allen M; Hsieh, Chung-Hung; Reibenspies, Joseph H; Darensbourg, Marcetta Y

    2014-01-01

    Development of square planar cis-dithiolate nickel complexes as metallo S-donor ligands focuses on the synthesis and structures of gold(I) heterometallic clusters derived from assemblage with three NiN2S2 complexes: Ni(bme-daco), Ni(bme-dach) and Ni(ema)(2-) (bme-daco = (bismercaptoethanediazacyclooctane); bme-dach = bismercaptoethanediazacycloheptane; and ema = N,N'-ethylenebis-2-mercaptoacetamide). With Ph3PAuCl as the gold source, examples of simple S-aurolation retaining the PPh3 on Au(+) were obtained for [{Ni(bme-daco)}AuPPh3](+)Cl(-) and [{Ni(ema)}2Au4(PPh3)4], where the latter complex demonstrated unsupported aurophilic interactions between [{Ni(ema)}Au2(PPh3)2] units in its X-ray crystal structure (Au-Au = 3.054 and 3.127 Å). Three compounds containing fully-supported digold units with Au-Au distances in the aurophilic range of 3.11 to 3.13 Å were found as stair-step structures in which planar NiN2S2 step treads are connected by planar S2Au2S2 risers at ca. 90°: [{Ni(bme-daco)}2Au2](2+)(Cl(-))2; [{Ni(bme-dach)}2Au2](2+)(Cl(-))2; and (Et4N(+))2[{Ni(ema)}2Au2](2-). Electrochemical data from cyclic voltammograms demonstrated a positive shift in Ni(II/I) couples for the [{NiN2S2}xAuy] complexes as compared to the NiN2S2 precursors and a ca. 700 mV decrease in communication between multiple NiN2S2 units as compared to [{NiN2S2}2Ni](2+) analogues in slant chair conformation. The analogy between NiN2S2 metallodithiolate ligands and diphosphine ligands holds here as in other examples of inorganic and organometallic complexes. PMID:24108061

  6. Theoretical Modeling of the Magnetic Behavior of Thiacalix[4]arene Tetranuclear Mn(II)2Gd(III)2 and Co(II)2Eu(III)2 Complexes.

    PubMed

    Aldoshin, Sergey M; Sanina, Nataliya A; Palii, Andrew V; Tsukerblat, Boris S

    2016-04-01

    In view of a wide perspective of 3d-4f complexes in single-molecule magnetism, here we propose an explanation of the magnetic behavior of the two thiacalix[4]arene tetranuclear heterometallic complexes Mn(II)2Gd(III)2 and Co(II)2Eu(III)2. The energy pattern of the Mn(II)2Gd(III)2 complex evaluated in the framework of the isotropic exchange model exhibits a rotational band of the low-lying spin excitations within which the Landé intervals are affected by the biquadratic spin-spin interactions. The nonmonotonic temperature dependence of the χT product observed for the Mn(II)2Gd(III)2 complex is attributed to the competitive influence of the ferromagnetic Mn-Gd and antiferromagnetic Mn-Mn exchange interactions, the latter being stronger (J(Mn, Mn) = -1.6 cm(-1), Js(Mn, Gd) = 0.8 cm(-1), g = 1.97). The model for the Co(II)2Eu(III)2 complex includes uniaxial anisotropy of the seven-coordinate Co(II) ions and an isotropic exchange interaction in the Co(II)2 pair, while the Eu(III) ions are diamagnetic in their ground states. Best-fit analysis of χT versus T showed that the anisotropic contribution (arising from a large zero-field splitting in Co(II) ions) dominates (weak-exchange limit) in the Co(II)2Eu(III)2 complex (D = 20.5 cm(-1), J = -0.4 cm(-1), gCo = 2.22). This complex is concluded to exhibit an easy plane of magnetization (arising from the Co(II) pair). It is shown that the low-lying part of the spectrum can be described by a highly anisotropic effective spin-(1)/2 Hamiltonian that is deduced for the Co(II)2 pair in the weak-exchange limit. PMID:26974224

  7. Supramolecular architectures of novel chromium(III) oxalate complexes: steric effects of the ligand size and building-blocks approach.

    PubMed

    Androš, Lidija; Jurić, Marijana; Molčanov, Krešimir; Planinić, Pavica

    2012-12-28

    Five new oxalate complexes of chromium(III), [Hphen][Cr(phen)(C(2)O(4))(2)]·2H(2)O (1), [Cr(phen)(2)(C(2)O(4))][Cr(phen)(C(2)O(4))(2)]·3H(2)O (2), [Cr(phen)(2)(C(2)O(4))]NO(3)·H(2)C(2)O(4)·H(2)O (3), [Cr(bpy)(2)(C(2)O(4))][Cr(bpy)(C(2)O(4))(2)]·3H(2)O (4) and [Cr(bpy)(2)(C(2)O(4))]NO(3)·1/2H(2)C(2)O(4)·4H(2)O (5) (phen = 1,10-phenanthroline, bpy = 2,2'-bipyridine), were prepared by using an (oxalato)tantalate(V) solution as a source of oxalate ligands. The compounds contain either the discrete mononuclear [Cr(L)(2)(C(2)O(4))](+) cation [L = phen (3); L = bpy (5)] or the discrete mononuclear [Cr(L)(C(2)O(4))(2)](-) anion [L = phen (1)], or both types of mononuclear ions [L = phen (2); L = bpy (4)]. The crystal structures are dominated by the hydrogen-bonding and π···π-stacking interactions that give rise to the overall two- (compounds 1, 2, 4, 5) or three-dimensional (compound 3) architectures. Compounds 2 and 4 represent a borderline case between isostructurality and non-isostructurality; they exhibit an analogous packing of the cation and the anion units, but the crystallization water molecules occupy different positions - due to a difference in size between the phen and bpy ligands. The influence of steric factors is evident also in the case of 3 and 5, which, despite very similar chemical formulae, exert a completely different packing of the constituents. By the self-assembling of 1 and 4, used as building blocks in the reaction with calcium(II) cations, the heterobimetallic polymeric compounds {[CaCr(2)(phen)(2)(C(2)O(4))(4)]·5H(2)O}(n) (6) and {[CaCr(2)(bpy)(2)(C(2)O(4))(4)]·0.83H(2)O}(n) (7) were obtained. The crystal structure of 7 is reported: the [Cr(bpy)(C(2)O(4))(2)](-) unit, through the two oxalate groups, acts as a chelating ligand towards Ca cations, resulting in heterometallic one-dimensional double zigzag chains, formed of diamond-shaped units. The characterization of the compounds obtained was accomplished by the spectroscopy and

  8. Crystal structure of an unknown solvate of dodecakis-(μ2-alaninato-1:2κ(2) O:N,O)cerium(III)hexa-nickel(II) aqua-tris-(hydroxido-κO)tris-(nitrato-κ(2) O,O')cerate(III).

    PubMed

    Bezzubov, Stanislav I; Doljenko, Vladimir D; Churakov, Andrei V; Zharinova, Irina S; Kiselev, Yuri M

    2015-10-01

    The chiral title compound, [CeNi6(C3H6NO2)12][Ce(NO3)3(OH)3(H2O)], comprises a complex heterometallic Ni/Ce cation and a homonuclear Ce anion. Both the cation and anion exhibit point group symmetry 3. with the Ce(III) atom situated on the threefold rotation axis. The cation metal core consists of six Ni(II) atoms coordinated in a slightly distorted octa-hedral N2O4 configuration by N and O atoms of 12 deprotonated l-alaninate ligands exhibiting both bridging and chelating modes. This metal-organic coordination motif encapsulates one Ce(III) atom that shows an icosa-hedral coordination by the O-donor atoms of the l-alaninate ligands, with Ce-O distances varying in the range 2.455 (5)-2.675 (3) Å. In the anion, the central Ce(III) ion is bound to three bidentate nitrate ligands, to three hydroxide ligands and to one water mol-ecule, with Ce-O distances in the range 2.6808 (19)-2.741 (2) Å. The H atoms of the coordinating water mol-ecule are disordered over three positions due to its location on a threefold rotation axis. Disorder is also observed in fragments of two l-alaninate ligands, with occupancy ratios of 0.608 (14):0.392 (14) and 0.669 (8):0.331 (8), respectively, for the two sets of sites. In the crystal, the complex cations and anions assemble through O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional network with large voids of approximately 1020 Å(3). The contributions of highly disordered ethanol and water solvent mol-ecules to the diffraction data were removed with the SQUEEZE procedure [Spek (2015 ▸). Acta Cryst. C71, 9-18]. The given chemical formula and other crystal data do not take into account the unknown amount of these solvent mol-ecules. PMID:26594427

  9. Exploring the coordinative adaptation and molecular shapes of trinuclear CuM(II) (M = Zn/Cd) complexes derived from salen type Schiff bases: structural and theoretical studies.

    PubMed

    Hazari, Alokesh; Das, Lakshmi Kanta; Bauzá, Antonio; Frontera, Antonio; Ghosh, Ashutosh

    2016-04-01

    Three new trinuclear hetero-metallic complexes [(CuL)2Zn(NCS)2] (1), [(CuL(R))2Zn(NCS)(μ1,1-NCS)] (2) and [(CuL(R))2Cd(μ1,3-NCS)2] (4) have been synthesized using [CuL] and [CuL(R)] as "metalloligands" (where H2L = N,N'-bis(salicylidene)-1,3-propanediamine and H2L(R) = N,N'-bis(2-hydroxybenzyl)-1,3-propanediamine). All three complexes are characterized by elemental analysis, spectroscopic methods and single crystal XRD. Complex 1 is an angular trinuclear species, in which two terminal four-coordinate square planar "metalloligands" [CuL] are coordinated to a central Zn(ii) through double phenoxido bridges along with two mutually cis nitrogen atoms of terminal isothiocyanate ions as is usually found in such complexes. In contrast, in complex 2, the two terminal "metalloligands" [CuL(R)] are square pyramidal, as one of the SCN(-) ions makes an unusual μ1,1-NCS bridge between copper centers while the other one coordinates to Zn(ii) through a N atom in a usual fashion making its geometry also square pyramidal. For 4 which possesses an angular trinuclear structure, in addition to double phenoxido bridges from two terminal [CuL(R)], both the SCN(-) ions are S-bonded to Cd(ii) and form a bridge (cis-μ1,3-SCN) between Cd(ii) and each of the terminal Cu(ii) ions. This structure is different from its unreduced analogue in which NCS(-) was N-terminal coordinated to Cd(ii) (3/3'). All the structures have been optimized using density functional theory (DFT) calculations. It has been found that for H2L, optimized structures like 1 and 2 differ only by 0.4 kcal mol(-1) but the H2L(R) structure 2 is more stable by 5.5 kcal mol(-1) than the structure resembling 1. For Cd(ii) complexes also, H2L optimized structures such as 3 and 4 do not differ significantly in energy (1.0 kcal mol(-1)) but the H2L(R) structure 4 is more stable than that of 3 by 4.6 kcal mol(-1). In fact, structure 4 has been found to be the most stable one among the other possible isomers of H2L(R). PMID

  10. Bipolar mass spectrometry of labile coordination complexes, redox active inorganic compounds, and proteins using a glass nebulizer for sonic-spray ionization.

    PubMed

    Antonakis, Manolis M; Tsirigotaki, Alexandra; Kanaki, Katerina; Milios, Constantinos J; Pergantis, Spiros A

    2013-08-01

    In this study, we report on the development of a novel nebulizer configuration for sonic-spray ionization (SSI) mass spectrometry (MS), more specifically for a version of SSI that is referred to as Venturi easy ambient sonic-spray ionization (V-EASI) MS. The developed nebulizer configuration is based on a commercially available pneumatic glass nebulizer that has been used extensively for aerosol formation in atomic spectrometry. In the present study, the nebulizer was modified in order to achieve efficient V-EASI-MS operation. Upon evaluating this system, it has been demonstrated that V-EASI-MS offers some distinct advantages for the analysis of coordination compounds and redox active inorganic compounds over the predominantly used electrospray ionization (ESI) technique. Such advantages, for this type of compounds, are demonstrated here for the first time. More specifically, a series of labile heptanuclear heterometallic [Cu(II) 6Ln(III)] clusters held together with artificial amino acid ligands, in addition to easily oxidized inorganic oxyanions of selenium and arsenic, were analyzed. The observed advantages pertain to V-EASI appearing to be a "milder" ionization source than ESI, not requiring electrical potentials for gas phase ion formation, thus eliminating the possibility of unwanted redox transformations, allowing for the "simultaneous" detection of negative and positive ions (bipolar analysis) without the need to change source ionization conditions, and also not requiring the use of syringes and delivery pumps. Because of such features, especially because of the absence of ionization potentials, EASI can be operated with minimal requirements for source parameter optimization. We observed that source temperature and accelerating voltage do not seem to affect labile compounds to the extent they do in ESI-MS. In addition, bipolar analysis of proteins was demonstrated here by acquiring both positive and negative ion mass spectra from the same protein solutions

  11. Temperature-dependent self-assembly of near-infrared (NIR) luminescent Zn2Ln and Zn2Ln3 (Ln=Nd, Yb or Er) complexes from the flexible Salen-type Schiff-base ligand.

    PubMed

    Miao, Tiezheng; Zhang, Zhao; Feng, Weixu; Su, Peiyang; Feng, Heini; Lü, Xingqiang; Fan, Daidi; Wong, Wai-Kwok; Jones, Richard A; Su, Chengyong

    2014-11-11

    Through the self-assembly of the precursor [Zn(L)(MeCN)] (H2L=N,N'-bis(3-methoxy-salicylidene)cyclohexane-1,2-diamine) with LnCl3·6H2O (Ln=La, Nd, Yb, Er or Gd) and NaN3 in alcohol-containing solutions, two series of mixed anions-induced Zn2Ln-arrayed complexes [Zn2(L)2(MeOH)ClLn(N3)]·Cl (Ln=La, 1; Ln=Nd, 2; Ln=Yb, 3; Ln=Er, 4 or Ln=Gd, 5) and Zn2Ln3-arrayed complexes [Zn2(L)3Cl2(μ2-OH)(μ3-OH)2Ln3(N3)2] (Ln=La, 6; Ln=Nd, 7; Ln=Yb, 8; Ln=Er, 9 or Ln=Gd, 10) are obtained at room temperature or under reflux, respectively. In contrast to Zn2Ln-arrayed complexes with the two Zn2+ ions in the inner cis-N2O2 cores and one Ln3+ ion in the outer O2O2 moieties, the demetalation of partial precursors leads to the selective exchange of Zn2+ centers for the Ln3+ ions for the formation of novel heterometallic Zn2Ln3-arrayed complexes with the Ln3+ ions in both the inner cis-N2O2 core and the outer O2O2 moieties of the ligands. The result of their photophysical properties shows that the characteristic near-infrared (NIR) luminescence of Nd3+ or Yb3+ ion has been sensitized from the excited state (both 1LC and 3LC) of the ligand H2L, while relatively lower quantum yields for Zn2Ln3-arrayed complexes than those for Zn2Ln-arrayed complexes, correspondingly, should be due to the luminescent quenching with the involvement of OH- oscillators around the Ln3+ ions. PMID:24866087

  12. Synthesis of mono-amidinate-ligated rare-earth-metal bis(silylamide) complexes and their reactivity with [Ph3C][B(C6F5)4], AlMe3 and isoprene.

    PubMed

    Luo, Yunjie; Lei, Yinlin; Fan, Shimin; Wang, Yibin; Chen, Jue

    2013-03-21

    Amine elimination of rare-earth-metal tris(silylamide) complexes Ln[N(SiHMe(2))(2)](3)(THF)(x) (Ln = Sc, x = 1; Ln = Y, x = 2) with 1 equiv. of the amidines [PhC(N-2,6-R(2)C(6)H(3))(2)]H afforded a series of neutral mono(amidinate) rare-earth-metal bis(silylamide) complexes [PhC(N-2,6-R(2)C(6)H(3))(2)]Ln[N(SiHMe(2))(2)](2)(THF)(y) (R = Me, Ln = Sc, y = 0 (1); R = Me, Ln = Y, y = 1 (2); R = (i)Pr, Ln = Y, y = 1 (3)). Treatment of 1-3 with 1 equiv. of [Ph(3)C][B(C(6)F(5))(4)] in THF generated the corresponding cationic amidinate rare-earth-metal mono(silylamide) complexes [{PhC(N-2,6-R(2)C(6)H(3))(2)}Ln{N(SiHMe(2))(2)}(THF)(3)][B(C(6)F(5))(4)] (R = Me, Ln = Sc (4), Y (5); R = (i)Pr, Ln = Y (6)). When 1-3 were first activated with 1 equiv. of [Ph(3)C][B(C(6)F(5))(4)] in toluene, then treatment with THF gave the unexpected cationic amidinate rare-earth-metal amide complexes [{PhC(N-2,6-R(2)C(6)H(3))(2)}LnN{SiHMe(2)}{SiMe(2)N(SiHMe(2))(2)}(THF)(n)][B(C(6)F(5))(4)] (R = Me, Ln = Sc, n = 2 (7); R = Me, Ln = Y, n = 4 (8); R = (i)Pr, Ln = Y, n = 2 (9)). The reaction of 1-3 with excess AlMe(3) produced the heterometallic Ln/Al methyl complexes [PhC(N-2,6-R(2)C(6)H(3))(2)]Ln[(μ-Me)(2)AlMe(2)](2) (R = Me, Ln = Sc (10), Y (11); R = (i)Pr, Ln = Y (12)). All these complexes were well-characterized by elemental analysis, NMR spectroscopy and FT-IR spectroscopy. 2, 6 and 11 were further structurally authenticated by X-ray crystallography. The binary catalyst system of 1/[Ph(3)C][B(C(6)F(5))(4)] in toluene showed activity toward 3,4-selective polymerization of isoprene, whilst the tertiary catalyst systems of 1-3/[Ph(3)C][B(C(6)F(5))(4)]/AlMe(3) were highly active for cis-1,4-selective polymerization of isoprene. PMID:23340682

  13. Mixed-metal molecular complexes: Single-molecule nanomagnets and bioinorganic models of the water oxidizing complex of photosystem II

    NASA Astrophysics Data System (ADS)

    Mishra, Abhudaya

    2006-12-01

    methods have been developed to prepare a variety of heterometallic MnCa(Sr) complexes, namely, Mn13Ca2, Mn11Ca4, Mn8Ca and Mn14Sr; these are the first of their kind. X-ray absorption spectroscopy has been performed on all of these complexes and the results compared with analogous data on the WOC of PS II. In particular, Ca, Sr, and Mn, EXAFS and XANES reveal a distinct similarity between the sub-units within these complexes and the Mn 4CaOx site of the WOC. The data strongly suggest that a single-atom O bridge exists between the Mn atoms and the Ca atom of the WOC.

  14. Two types of novel tetra-iron substituted sandwich-type arsenotungastates with supporting lanthanide pendants.

    PubMed

    Chen, Lijuan; Zhang, Fang; Ma, Xing; Luo, Jie; Zhao, Junwei

    2015-07-28

    Two classes of novel tetra-iron substituted sandwich-type arsenotungastates (ATs) with supporting lanthanide (Ln) pendants KNa2 [Ln(H2O)7][Fe4(H2O)10(B-β-AsW9O33)2]·21H2O [Ln = La(III) (1), Pr(III) (2), Nd(III) ()3, Sm(III) (4)] and [Ln(H2O)8]2[Fe4(H2O)8(l-thr)2(B-β-AsW9O33)2]·20H2O [Ln = La(III) (5), Pr(III) ()6, Nd(III) (7), Sm(III) (8), Eu(III) (9), Gd(III) (10), Tb(III) (11), Dy(III) (12), Er(III) (13)] (l-thr = l-threonine) have been synthesized by the hydrothermal reaction of the [As2W19O67(H2O)](14-) precursor with Fe(3+) cations and Ln(3+) cations in the presence of l-thr or l-leucine and l-alanine, and further characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Structural analyses indicate that 1-4 display the inorganic 2-D sheet architecture constructed from tetra-iron sandwiched AT [Fe4(H2O)10(B-β-AsW9O33)2](6-) fragments by bridging [Ln(H2O)7](3+) cations whereas the molecular structures of the isostructural 5-13 consist of an organic-inorganic hybrid tetra-iron substituted sandwich-type AT [Fe4(H2O)8(l-thr)2(B-β-AsW9O33)2](6-) fragment and two pendant [Ln(H2O)8](3+) cations. As far as we know, 1-4 represent the rare inorganic 2-D extended ATs based on transition-metal substituted sandwich-type polyoxometalate units and Ln linkers and 5-13 are the first Fe-Ln heterometallic ATs with amino acid ligands. The solid state photoluminescence (PL) measurements of 9 and 11 have been performed at room temperature. The PL emission of 9 is mainly derived from the characteristic (5)D0 → (7)F2 (J = 4-0) transitions of the Eu(III) cations whereas the PL behavior of 11 stems from the common contribution of the (5)D4 → (7)FJ (J = 5-3) transitions of the Tb(III) ions and oxygen-to-metal (O → W) charge-transfer transitions of AT segments. The thermogravimetric (TG) analyses of 1-4 and 6-12 have been investigated. PMID:26066321

  15. Low-dimensional copper(II) complexes with the trinucleating ligand 2,4,6-tris(di-2-pyridylamine)-1,3,5-triazine: synthesis, crystal structures, and magnetic properties.

    PubMed

    Yuste, Consuelo; Cañadillas-Delgado, Laura; Labrador, Ana; Delgado, Fernando S; Ruiz-Pérez, Catalina; Lloret, Francesc; Julve, Miguel

    2009-07-20

    oxalato) and 7.476(2)-8.098(2) A (through dipyatriz). Magnetic susceptibility measurements of polycrystalline samples of 1-3 in the temperature range 1.9-295 K show the occurrence of a weak antiferromagnetic interaction across dipyatriz in 1 [J = -0.08(1) cm(-1), the Hamiltonian being defined as (wedge)H = -J ((wedge)S(1).(wedge)S(2) + (wedge)S(1) x (wedge)S(3) + (wedge)S(2) x (wedge)S(3))] and weak ferro- (2) and strong antiferromagnetic (3) interactions through the oxalato bridge in 2 [J = +0.45(2) cm(-1)] and 3 [J = -390(1) cm(-1)]. The use of the dipyatriz-containing copper(II) species as a building block to design homo- and heterometallic magnetic compounds is analyzed and discussed. PMID:20507110

  16. Strong ferromagnetic exchange interactions in hinge-like Dy(O2Cu)2 complexes involving double oxygen bridges.

    PubMed

    Ida, Yumi; Ghosh, Soumavo; Ghosh, Ashutosh; Nojiri, Hiroyuki; Ishida, Takayuki

    2015-10-01

    lanthanide and transition metal ions. We found that the exchange coupling strength is sensitive to the structural parameters such as bond angles, bond lengths, and butterfly angles. Precise determination of the exchange parameters would contribute to development of exchange-coupled 4f-3d heterometallic complexes. PMID:26381465

  17. Single-molecule magnetism in a family of {Co(III)2Dy(III)2} butterfly complexes: effects of ligand replacement on the dynamics of magnetic relaxation.

    PubMed

    Langley, Stuart K; Ungur, Liviu; Chilton, Nicholas F; Moubaraki, Boujemaa; Chibotaru, Liviu F; Murray, Keith S

    2014-05-01

    The synthesis and structural characterization of four related heterometallic complexes of formulas [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)4](NO3)2·MeOH·H2O (1a) and [Dy(III)2Co(III)2(OMe)2(teaH)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·H2O (1b), [Dy(III)2Co(III)2(OMe)2(dea)2(O2CPh)4(MeOH)4](NO3)2 (2), [Dy(III)2Co(III)2(OMe)2(mdea)2(O2CPh)4(NO3)2] (3), and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)4](NO3)2·0.5MeOH·H2O (4a) and [Dy(III)2Co(III)2(OMe)2(bdea)2(O2CPh)4(MeOH)2(NO3)2]·MeOH·1.5H2O (4b) are reported (teaH3 = triethanolamine, deaH2 = diethanolamine, mdeaH2 = N-methyldiethanolamine, and bdeaH2 = N-n-butyldiethanolamine). Compounds 1 (≡ 1a and 1b) and 4 (≡ 4a and 4b) both display two unique molecules within the same crystal and all compounds display a butterfly type core, with the Dy(III) ions occupying the central body positions and the diamagnetic Co(III) ions the outer wing-tip sites. Compounds 1-4 were investigated via direct current and alternating current magnetic susceptibility measurements, and it was found that each complex displayed single-molecule magnet (SMM) behavior. All four compounds display unique coordination and geometric environments around the Dy(III) ions and it was found that each displays a different anisotropy barrier. Ab initio calculations were performed on 1-4 and these determined the low lying electronic structure of each Dy(III) ion and the magnetic interactions for each cluster. It was found that there was a strong correlation between the calculated energy gap between the ground and first excited states of the single-ion ligand-field split Dy(III) levels and the experimentally observed anisotropy barrier. Furthermore, the transverse g factors found for the Dy(III) ions, defining the tunnelling rates within the ground Kramers doublets, are largest for 1, which agrees with the experimental observation of the shortest relaxation time in the high-temperature domain for this complex. The magnetic exchange between the Dy

  18. An Extended Chain and Trinuclear Complexes Based on Pt(II)-M (M = Tl(I), Pb(II)) Bonds: Contrasting Photophysical Behavior.

    PubMed

    Forniés, Juan; Giménez, Nora; Ibáñez, Susana; Lalinde, Elena; Martín, Antonio; Moreno, M Teresa

    2015-05-01

    The syntheses and structural characterizations of a Pt-Tl chain [{Pt(bzq)(C6F5)2}Tl(Me2CO)]n 1 and two trinuclear Pt2M clusters (NBu4)[{Pt(bzq)(C6F5)2}2Tl] 2 and [{Pt(bzq)(C6F5)2}2Pb] 3 (bzq = 7,8-benzoquinolinyl), stabilized by donor-acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain 1 is formed by alternate "Pt(bzq)(C6F5)2" and "Tl(Me2CO)" fragments, with Pt-Tl bond separations in the range of 2.961(1)-3.067(1) Å. The isoelectronic trinuclear complexes 2 (which crystallizes in three forms, namely, 2a, 2b, and 2c) and 3 present a sandwich structure in which the Tl(I) or Pb(II) is located between two "Pt(bzq)(C6F5)2" subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt-M bonds. The lowest-lying absorption band in the UV-vis spectra in CH2Cl2 and tetrahydrofuran (THF) of 1, associated with (1)MLCT/(1)L'LCT (1)[5dπ(Pt) → π*(bzq)]/(1)[(C6F5) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt-Tl fragments in solution, also supported by NMR spectroscopy. In 2 and 3, it shows a blue shift in THF and a red shift in CH2Cl2, supporting a more extensive cleavage of the Pt-M bonds in THF solutions than in CH2Cl2, where the trinuclear entities are predominant. The Pt-Tl chain 1 displays in solid state a bright orange-red emission ascribed to (3)MM'CT (M' = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et2O), related to the coordination/decoordination of the guest molecule to the Tl(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt-Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH2Cl2) 1 shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt2Tl complex 2 shows an emission close to 1, ascribed to

  19. Coordination modes, spectral, thermal and biological evaluation of hetero-metal copper containing 2-thiouracil complexes

    NASA Astrophysics Data System (ADS)

    Masoud, Mamdouh S.; Soayed, Amina A.; El-Husseiny, Amel F.

    2012-12-01

    Mononuclear copper complex [CuL(NH3)4]Cl2·0.5H2O and three new hetero-metallic complexes: [Cu2Ni(L)2(NH3)2Cl2·6H2O] 2H2O, [Cu3Co(L)4·8H2O]Cl·4·5H2O, and [Cu4Co2Ni(L)3(OH)4(NH3)Cl4·3H2O]4H2O where L is 2-thiouracil, were prepared and characterized by elemental analyses, molar conductance, room-temperature magnetic susceptibility, spectral (IR, UV-Vis and ESR) studies and thermal analyses techniques (TG, DTG and DTA). The molar conductance data revealed that [CuL(NH3)4]Cl2·0.5H2O and [Cu3Co(L)4·8H2O]Cl·4.5H2O are electrolytes, while, [Cu2Ni(L)2(NH3)2Cl2·6H2O]·2H2O and [Cu4Co2Ni(L)3(OH)4(NH3)Cl4·3H2O]4H2O are non-electrolytes. IR spectra showed, that 2-thiouracil ligand behaves as a bidentate or tetradentate ligand. The geometry around the metal atoms is octahedral in all the prepared complexes except in [Cu4Co2Ni(L)3(OH)4(NH3)Cl4·3H2O]4H2O complex where square planar environment around Co(II), Ni(II) and Cu(II) were suggested. Thermal decomposition study of the prepared complexes was monitored by TG, DTG and DTA analyses under N2 atmosphere. The decomposition course and steps were analyzed. The order of chemical reactions (n) was calculated via the peak symmetry method and the activation parameters of the non- isothermal decomposition were computed from the thermal decomposition data. The negative values of ΔS∗ deduced the ordered structures of the prepared complexes compared to their starting reactants. The antimicrobial activity of the prepared complexes were screened in vitro against a Gram positive, a Gram negative bacteria, a filamentous fungi and a yeast. The antimicrobial screening data showed that the studied compounds exhibited a good level of activity against Escherichia coli, Staphylococcus aureus and Candida albicans but have no efficacy against Aspergillus flavus. It was observed that [Cu4Co2Ni(L)3(OH)4(NH3)Cl4·3H2O]4H2O complex showed the most intensive activity against the tested microorganisms. Trials to prepare single crystals from

  20. Modulation of the Structure and Properties of Uranyl Ion Coordination Polymers Derived from 1,3,5-Benzenetriacetate by Incorporation of Ag(I) or Pb(II).

    PubMed

    Thuéry, Pierre; Harrowfield, Jack

    2016-07-01

    Reaction of uranyl nitrate with 1,3,5-benzenetriacetic acid (H3BTA) in the presence of additional species, either organic bases or their conjugate acids or metal cations, has provided 12 new crystalline complexes, all but one obtained under solvo-hydrothermal conditions. The complexes [C(NH2)3][UO2(BTA)]·H2O (1) and [H2NMe2][UO2(BTA)] (2) crystallize as one- or two-dimensional (1D or 2D) assemblies, respectively, both with uranyl tris-chelation by carboxylate groups and hydrogen-bonded counterions but different ligand conformations. One of the bound carboxylate units is replaced by chelating 1,10-phenanthroline (phen) or 3,4,7,8-tetramethyl-1,10-phenanthroline (Me4phen) in the complexes [(UO2)3(BTA)2(phen)3]·4H2O (3) and [(UO2)3(BTA)2(Me4phen)3]·NMP·3H2O (4) (NMP = N-methyl-2-pyrrolidone), which are a 2D network with honeycomb topology and a 1D polymer, respectively. With silver(I) cations, [UO2Ag(BTA)] (5), a three-dimensional (3D) framework in which the ligand assumes various chelating/bridging coordination modes, and the aromatic ring is involved in Ag(I) bonding, is obtained. A series of seven heterometallic complexes results when lead(II) cations and N-chelating molecules are both present. The complexes [UO2Pb(BTA)(NO3)(bipy)] (6) and [UO2Pb2(BTA)2(bipy)2]·3H2O (7), where bipy is 2,2'-bipyridine, crystallize from the one solution, as 1D and 2D assemblies, respectively. The two 1D coordination polymers [UO2Pb(BTA)(HCOO)(phen)] (8 and 9), again obtained from the one synthesis, provide an example of coordination isomerism, with the formate anion bound either to lead(II) or to uranyl cations. Another 2D architecture is found in [(UO2)2Pb2(BTA)2(HBTA)(H2O)2(phen)2]·2H2O (10), which provides a possible example of a Pb-oxo(uranyl) "cation-cation" interaction. While [UO2Pb(BTA)(HCOO)0.5(NO3)0.5(Me2phen)] (11), where Me2phen is 5,6-dimethyl-1,10-phenanthroline, is a 1D assembly close to those in 6 and 8, [UO2Pb2(BTA)2(Me4phen)2] (12), obtained together with