Synthesis of Thiostannates, Oxo-Thiostannates and Tin-Sulfides Applying Transition Metal Complexes Containing Macrocyclic Amine Molecules: Development of new synthetic routes to synthesize Sn-S and S-Sn-O compounds and investigation of their properties

The aims of the present work were the synthesis and characterization of new thiostannates, oxo-thiostannates and tin-sulfide compounds. The salt Na4SnS414H2O was used as precursor, which was reacted with transition metal complexes containing macrocyclic amine ligands. The advantage of macrocyclic amine ligands is on the one hand they form very stable complexes and on the other hand they provide one or two free coordination sites so that a bond formation between thiostannate anion and transition metal cation is possible, if the transition metal cation prefers an octahedral environment. The formation of Na4SnS4·14H2O was investigated demonstrating that Na4SnS4·14H2O could be prepared through a new simple procedure reacting Na2S9H2O with SnCl45H2O in H2O at room temperature. For the precipitation of the product dried acetone was added to the aqueous solution. Furthermore, the stability of Na4SnS4·14H2O was investigated indicating that Na4SnS4·14H2O transforms slowly to the new compound Na4Sn2S6·5H2O in the solid state. The formation of Na4Sn2S6·5H2O probably requires a protonation of the terminal S2- anions and condensation of the protonated species under release of H2S. In addition, the stability of Na4SnS4·14H2O in H2O was investigated by 119Sn-NMR spectroscopy demonstrating that the [Sn2S6]4- anions were formed very fast in aqueous solution. Na4SnS414H2O was reacted with the complexes [Ni(cyclen)](ClO4)2 and [Ni(cyclen)(H2O)2](ClO4)2H2O under hydrothermal conditions leading to the generation of new oxo-thiostannate compounds: {[Ni(cyclen)]6[Sn6S12O2(OH)6]}2(ClO4)19H2O and [Ni(cyclen)(H2O)2]4[Sn10S20O4]~13H2O (cyclen = 1,4,7,10-tetraazacyclododecane). The crystal structure of {[Ni(cyclen)]6[Sn6S12O2(OH)6]}2(ClO4)19H2O is constructed by the rare cluster [Sn6S12O2(OH)6]10- and six Ni2+ centered complexes which are covalently bonded to the cluster via Ni–S und Ni–OH bonds. In [Ni(cyclen)(H2O)2]4[Sn10S20O4] ~13H2O only isolated cations and anions are observed. Both compounds display good photocatalytic activity for H2 generation. Investigations of the thermal properties of both compounds indicate that the water molecules of [Ni(cyclen)(H2O)2]4[Sn10S20O4]~13H2O can be reversibly removed and incorporated without structural collapse. However, the crystal water of {[Ni(cyclen)]6[Sn6S12O2(OH)6]}2(ClO4)19H2O cannot be reversibly removed and treatment with small amounts of water was required leading to the generation of the pristine material and an unidentified phase. Using the [Cu(cyclam](ClO4)2 complex (cyclam = 1,4,8,11-tetraazacyclotetradecane) the new layered compound {[Cu(cyclam)]2[Sn2S6]}n2nH2O could be obtained, which is the first thiostannate compound containing Cu(II) cations. {[Cu(cyclam)]2[Sn2S6]}n2nH2O was synthesized at room temperature using H2O as solvent. In the crystal structure distorted CuN4S2 octahedra are observed. The distortion of the octahedra was confirmed by EPR spectroscopy. The sample can be dehydrated and rehydrated without changing the crystallinity of the material. Similar to the synthesis of {[Cu(cyclam)]2[Sn2S6]}n2nH2O, syntheses were performed using the complexes [Ni(L1)](ClO4)2 and [Ni(L2)](ClO4)2 (L1 = 1,8-dimethyl- 1,3,6,8,10,13-hexaazacyclotetradecane and L2 = 1,8-diethyl-1,3,6,8,10,13- hexaazacyclotetradecane) at room temperature leading to crystallization of new compounds: [Ni(L1)][Ni(L1)Sn2S6]n∙2H2O and [Ni(L2)]2[Sn2S6]∙4H2O. Since the complexes [Ni(L1)](ClO4)2 and [Ni(L2)](ClO4)2 are poorly soluble in water but exhibit a good solubility in organic solvents like acetonitrile or dimethylsulfoxide, syntheses were carried out by overlaying an aqueous solution of Na4SnS4∙14H2O with the [Ni(L1)](ClO4)2 complex dissolved in acetonitrile or by overlaying a solution of the [Ni(L2)](ClO4)2 complex dissolved in dimethylsulfoxid with an aqueous solution of Na4SnS4∙14H2O

La nouvelle économie: qu’y a-t-il de nouveau?

Communication lors d'une conférence internationaleVoilà un nouveau concept qui a conquis le monde ces derniers temps, que tout lemonde en parle sans exception : « la nouvelle économie ». Mais de quoi s’agit-il aujuste ? Qu’y a-t-il de nouveau ? A vrai dire, le terme en lui-même donne vraiment àréfléchir ; S’agit-il d’une course économique plus rapide que la traditionnelle dont safinalité est certainement l’ors ? Ou alors d’un mot-valise, parmi d’autres, quimarquent essentiellement le discours économique où la rhétorique a certes unefonction argumentaire, dont les économistes y font recours afin de manipuler àvolonté les leviers pour accélérer ou freiner l’activité économique

Lateralization of eye use in cuttlefish : opposite direction for anti-predatory and predatory behaviors

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Physiology 7 (2016): 620, doi:10.3389/fphys.2016.00620.Vertebrates with laterally placed eyes typically exhibit preferential eye use for ecological activities such as scanning for predators or prey. Processing visual information predominately through the left or right visual field has been associated with specialized function of the left and right brain. Lateralized vertebrates often share a general pattern of lateralized brain function at the population level, whereby the left hemisphere controls routine behaviors and the right hemisphere controls emergency responses. Recent studies have shown evidence of preferential eye use in some invertebrates, but whether the visual fields are predominately associated with specific ecological activities remains untested. We used the European common cuttlefish, Sepia officinalis, to investigate whether the visual field they use is the same, or different, during anti-predatory, and predatory behavior. To test for lateralization of anti-predatory behavior, individual cuttlefish were placed in a new environment with opaque walls, thereby obliging them to choose which eye to orient away from the opaque wall to scan for potential predators (i.e., vigilant scanning). To test for lateralization of predatory behavior, individual cuttlefish were placed in the apex of an isosceles triangular arena and presented with two shrimp in opposite vertexes, thus requiring the cuttlefish to choose between attacking a prey item to the left or to the right of them. Cuttlefish were significantly more likely to favor the left visual field to scan for potential predators and the right visual field for prey attack. Moreover, individual cuttlefish that were leftward directed for vigilant scanning were predominately rightward directed for prey attack. Lateralized individuals also showed faster decision-making when presented with prey simultaneously. Cuttlefish appear to have opposite directions of lateralization for anti-predatory and predatory behavior, suggesting that there is functional specialization of each optic lobe (i.e., brain structures implicated in visual processing). These results are discussed in relation to the role of lateralized brain function and the evolution of population level lateralization.This work was supported by a post-doctoral study grant from the Fyssen Foundation to AS, and by a research grant “Sélavie” from the Fyssen Foundation to CJ-A. The Sholley Foundation provided partial support for the research in Woods Hole

Directed Dehydration of Na 4 Sn 2 S 6 ⋅ 5H 2 O Generates the New Compound Na 4 Sn 2 S 6: Crystal Structure and Selected Properties

The new thiostannate Na4Sn2S6 was prepared by directed crystal water removal from the hydrate Na4Sn2S6 ⋅ 5H2O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn2S6]4− anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn2S6]4− anion, movements of the fragments of the opened [Sn2S6]4− anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS5 polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na4Sn2S6 ⋅ 5H2O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na+ ion conductivity of 0.31 μS cm−1 and an activation energy for ionic transport of Ea=0.75 eV

Directed Dehydration of Na4_4Sn2_2S6_6 ⋅ 5H2_2O Generates the New Compound Na4_4Sn2_2S6_6: Crystal Structure and Selected Properties

The new thiostannate Na$_4$Sn$_2$S$_6$ was prepared by directed crystal water removal from the hydrate Na$_4$Sn$_2$S$_6$ ⋅ 5H$_2$O at moderate temperatures. While the structure of the hydrate comprises isolated [Sn$_2$S$_6$]$^{4−}$ anions, that of the anhydrate contains linear chains composed of corner-sharing SnS4 tetrahedra, a structural motif not known in thiostannate chemistry. This structural rearrangement requires bond-breakage in the [Sn2S6]4− anion, movements of the fragments of the opened [Sn2S6]4− anion and Sn−S−Sn bond formation. Simultaneously, the coordination environment of the Na+ cations is significantly altered and the in situ formed NaS$_5$ polyhedra are joined by corner- and edge-sharing to form a six-membered ring. Time-dependent in situ X-ray powder diffraction evidences very fast rehydration into Na$_4$Sn$_2$S$_6$ ⋅ 5H$_2$O during storage in air atmosphere, but recovery of the initial crystallinity requires several days. Impedance spectroscopy demonstrates a mediocre room-temperature Na$^+$ ion conductivity of 0.31 μS cm$^{−1}$ and an activation energy for ionic transport of E$_a$=0.75 eV

Sur la presence de l’algue marine Caulerpa racemosa (Forsskal) J. Agardh (Caulerpales, Chlorophyta) devant la côte Mostaganemoise (ouest Algerie)

Sobre la presencia de Caulerpa racemosa (Forsskal) J. Agardh (Caulerpales, Chlorophyta) en la costa de Mostaganemoise (O de Argelia

Directed Dehydration as Synthetic Tool for Generation of a New Na4_{4}SnS4_{4} Polymorph: Crystal Structure, Na+^{+} Conductivity, and Influence of Sb‐Substitution

We present the convenient synthesis and characterization of the new ternary thiostannate Na$_{4}$SnS$_{4}$4 (space group I4$_{1}$/acd ) by directed removal of crystal water molecules from Na$_{4}$SnS$_{4}$⋅14 H$_{2}$O. The compound represents a new kinetically stable polymorph of Na$_{4}$SnS$_{4}$, which is transformed into the known, thermodynamically stable form (space group P$\overline{4}$2$_{1}$c) at elevated temperatures. Thermal co-decomposition of mixtures with Na$_{3}$SbS$_{4}$⋅9 H$_{2}$O generates solid solution products Na$_{4}-x$Sn$_{1-x}$Sb$_{x}$S$_{4}$ (x=0.01, 0.10) isostructural to the new polymorph (x=0). Incorporation of Sb$^{5+}$ affects the bonding and local structural situation noticeably evidenced by X-ray diffraction, $_{119}$Sn and $_{23}$Na NMR, and $_{119}$Sn Mössbauer spectroscopy. Electrochemical impedance spectroscopy demonstrates an enormous improvement of the ionic conductivity with increasing Sb content for the solid solution (σ$_{25°}$C=2×10$_{-3}$, 2×10$_{-2}$, and 0.1 mS cm$_{-1}$ for x=0, 0.01, and 0.10), being several orders of magnitude higher than for the known Na$_{4}$SnS$_{4}$ polymorph

Directed Dehydration as Synthetic Tool for Generation of a New Na4 SnS4 Polymorph: Crystal Structure, Na+ Conductivity, and Influence of Sb-Substitution

We present the convenient synthesis and characterization of the new ternary thiostannate Na4 SnS4 (space group I41/acd ) by directed removal of crystal water molecules from Na4 SnS4 ⋅14 H2 O. The compound represents a new kinetically stable polymorph of Na4 SnS4 , which is transformed into the known, thermodynamically stable form (space group P4‾21c ) at elevated temperatures. Thermal co-decomposition of mixtures with Na3 SbS4 ⋅9 H2 O generates solid solution products Na4-x Sn1-x Sbx S4 (x=0.01, 0.10) isostructural to the new polymorph (x=0). Incorporation of Sb5+ affects the bonding and local structural situation noticeably evidenced by X-ray diffraction, 119 Sn and 23 Na NMR, and 119 Sn Mössbauer spectroscopy. Electrochemical impedance spectroscopy demonstrates an enormous improvement of the ionic conductivity with increasing Sb content for the solid solution (σ25°C =2×10-3 , 2×10-2 , and 0.1 mS cm-1 for x=0, 0.01, and 0.10), being several orders of magnitude higher than for the known Na4 SnS4 polymorph

Some more properties and remarks about keys for relation scheme

In this paper we prove some additional properties of keys and  superkeys for relation schemes. Basing on these  properties, some algorithms finding keys for relation schemes are improved and their complexities are estimated. Finally, some remarks on the translations of relation schemes are given

Room-Temperature Solid-State Transformation of Na4 SnS4 ⋅ 14H2 O into Na4 Sn2 S6 ⋅ 5H2 O: An Unusual Epitaxial Reaction Including Bond Formation, Mass Transport, and Ionic Conductivity

A highly unusual solid-state epitaxy-induced phase transformation of Na4 SnS4  ⋅ 14H2 O (I) into Na4 Sn2 S6  ⋅ 5H2 O (II) occurs at room temperature. Ab initio molecular dynamics (AIMD) simulations indicate an internal acid-base reaction to form [SnS3 SH]3- which condensates to [Sn2 S6 ]4- . The reaction involves a complex sequence of O-H bond cleavage, S2- protonation, Sn-S bond formation and diffusion of various species while preserving the crystal morphology. In situ Raman and IR spectroscopy evidence the formation of [Sn2 S6 ]4- . DFT calculations allowed assignment of all bands appearing during the transformation. X-ray diffraction and in situ 1 H NMR demonstrate a transformation within several days and yield a reaction turnover of ≈0.38 %/h. AIMD and experimental ionic conductivity data closely follow a Vogel-Fulcher-Tammann type T dependence with D(Na)=6×10-14  m2  s-1 at T=300 K with values increasing by three orders of magnitude from -20 to +25 °C