New [PbBi 2 O 4 ][Bi 2 O 2 ]Cl 2 and [Pb n Bi 10-n O 13 ][Bi 2 O 2 ] n Cl 4+ n Series by Association of Sizable Subunits: Relationship with Arppe’s Compound Bi 24 O 31 Cl 10 and Luminescence Properties

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Bonding Scheme and Optical Properties in BiM 2 O 2 (PO 4 ) (M=Cd, Mg, Zn); Experimental and Theoretical Analysis

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New [PbBi₂O₄][Bi₂O₂]Cl₂ and [Pb_nBi_10‑nO₁₃][Bi₂O₂]_<i>n</i>Cl_4+<i>n</i> Series by Association of Sizable Subunits: Relationship with Arppe’s Compound Bi₂₄O₃₁Cl₁₀ and Luminescence Properties

Four new mixed lead–bismuth oxychloride compounds have been prepared and characterized by single crystal X-ray diffraction. Their crystal structures are described on the basis of the association of distinct building units found in parent Pb or Bi oxychlorides. The new compound PbBi₄O₆Cl₂ is formed of the stacking of 2D positive [Bi₂O₂]²⁺ layers and neutral [PbBi₂O₄]⁰ double layers separated by Cl^– anions. Similar motifs with finite lengths are combined together in the new series [Pb_<i>n</i>Bi_{10‑<i>n</i>}O₁₃]­[Bi₂O₂]<i>_n</i>Cl_4+<i>n</i>. From the structural viewpoint, it is striking that this family of homologous phases is strongly related to Bi₂₄O₃₁Cl₁₀ well-known as Arppe’s compound in which the fluorite-like [Bi₂O₂]<i>_n</i> subunit was increased from <i>n</i> = 1 (mixed Bi/Pb Arppe’s compound) to <i>n</i> = 2, 3, and 4 new members. The preparation of the respective powders shows the predominant stability of the <i>n</i> = 2 term which was prepared as a single-phase, while other terms have not been obtained in absence of secondary phases. For <i>n</i> = 2, the impedance spectroscopy shows a conductivity value σ ∼ 10^–3 S cm^–1 at 650 °C and suggests a contribution of Cl^– in the diffusion process. Most remarkable, PbBi₄O₆Cl₂ as well as [Pb₂Bi₈O₁₃]­[Bi₂O₂]₂Cl₆ show very bright red emission at low temperature, which could be assigned to Bi³⁺ transitions by comparison to BaBi₄O₆Cl₂. The different shapes of the excitation spectra lead to the assumption of a complete Pb–Bi energy transfer

Increasing Complexity in the Uranyl Ion − Kemp’s Triacid System: From One- and Two-Dimensional Polymers to Uranyl − Copper(II) Dodeca- and Hexadecanuclear Species

International audienceKemp’s triacid (cis,cis-1,3,5-trimethylcyclohexane-1,3,5-tricarboxylic acid, LH3) has recently been shown to be a versatile ligand for the uranyl ion, with the presence of additional nickel(II) cations allowing isolation of nanotubular and cage species in particular. The high sensitivity of the uranyl−LH3 system to variations in the experimental conditions was the incentive for the present investigation of different solvents as organic components in solvo-hydrothermal synthesis methods and of different additional species (metal cations, 2,2′-bipyridine). Reaction of LH3 with uranyl ions under purely hydrothermal conditions gives [UO2(LH2)2(H2O)2]·2H2O (1), an unremarkable mononuclear complex. In the presence of manganese nitrate and in water−THF or water−methanol, respectively, the complexes [Hbipy][UO2(L)]·0.5H2O·0.25THF (2) and [(UO2)3(MeL)2(OH)2(H2O)]·8MeOH (3) were obtained; 2 is a two-dimensional (2D) species, while 3 is one-dimensional (1D) and contains the monoester derivative of LH3, formed in situ. Another 2D compound, [UO2Tb(L)2H(H2O)2] (4), crystallizes in the presence of terbium(III) nitrate. The three complexes [(UO2)8(L)6H2(H2O)6]·H2O (5), [(UO2)8(L)6H2(H2O)6]·3H2O (6), and [Cu2(C2O4)(bipy)2(THF)2][(UO2)8(L)6H- (H2O)6]2·4H2O·7THF (7), which were obtained in the presence of copper(II) or nickel(II) cations, all contain homometallic octanuclear cage-like species analogous to that previously reported. The most interesting complexes in this series, [(UO2)8Cu4(L)8(H2O)16]·9H2O (8) and [(UO2)10Cu6(L)10(OH)2(H2O)7] (9), were obtained together in water−THF and in the presence of copper(II) cations. Compound 8 is a dodecanuclear metallacycle comprising four (UO2)2Cu trinuclear subunits, in which the central copper atom is bound to two uranyl oxo groups, arranged in helical geometry. Compound 9 is a large, hexadecanuclear cage-like species devoid of any crystallographic symmetry. In both 8 and 9, uranyl ions are topologically sufficient for the formation of the cyclic or cage molecules, and the hydrated copper ions are located inside. The curved shape of the three-pronged Kemp’s tricarboxylate ligand appears well suited to the formation of closed species (nanotubes, rings, and cages), which are in all cases coated on the outside by the hydrophobic parts of the ligands