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Layered Network (layered + network)

Distribution by Scientific Domains

Chemistry	80%

Selected Abstracts

Linking Two Distinct Layered Networks of Nanosized {Ln18} and {Cu24} Wheels through Isonicotinate Ligands

CHEMISTRY - A EUROPEAN JOURNAL, Issue 1 2008
Jian-Wen Cheng
Abstract A new series of heterolanthanide(III)-copper(I) wheel-cluster complexes [Ln6(,3 -O)2](IN)18[Cu8(,4 -I)2(,2 -I)3],H3O (IN=isonicotinate; Ln=Y 1, Nd 2, Dy 3, Gd 4, Sm 5, Eu 6, Tb 7) were prepared by hydrothermal reaction at low pH. X-ray crystallographic studies reveal that two unusual trinuclear [Ln3(,3 -O)] and tetranuclear [Cu4(,4 -I)] cores are successfully used as secondary building units to make two different nanosized wheels [Ln18(,3 -O)6(CO2)48]6,, {Ln18}, and [Cu24(,4 -I)6(,2 -I)12]6+, {Cu24}, with 12-rings and a diameter of 26.7 and 26.4,Å, respectively. The wheels are further assembled into two-dimensional (2D) {Ln18} and {Cu24} networks, the linkages between two distinct layered networks of {Ln18} and {Cu24} wheels by IN pillars along the c axis giving a series of unprecedented three-dimensional (3D) sandwich frameworks. To our knowledge, compounds 1,7 are the first examples containing two different layered networks of nanosized Ln and transition metal (TM) wheels in wheel-cluster chemistry. The IR, UV/Vis, thermogravimetric analysis (TGA), luminescent, and magnetic properties of these complexes were also studied. [source]

Two- and Three-Dimensional Hydrogen-Bonded Networks Built from 1,3,5-[(HO)2(O)P]3C6H3 and 4-(Dimethylamino)pyridine

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2004
Michael Mehring
Abstract Crystallisation of 3,5-bis(phosphonophenyl)phosphonic acid, 1,3,5-[(HO)2(O)P]3C6H3, from MeOH/H2O in the presence of 4-(dimethylamino)pyridine, 4-(Me2N)C5H4N, gave [1-{(HO)2(O)P}-3,5-{(HO)(O)2P}2C6H3]2,[{4-(Me2N)C5H4NH}+]2 (2) and [1,3-{(HO)2(O)P}2 -5-{(HO)(O)2P}C6H3],[4-(Me2N)C5H4NH]+ (3). Single-crystal X-ray diffraction analyses revealed a two- and a three-dimensional hydrogen-bonded network for compounds 2 and 3, respectively. Compound 2 is composed of layers which are formed by hydrogen-bonded motifs of the type R2,2(8) and R4,4(16). These motifs are connected within the layer by additional hydrogen bonds and the benzene spacer. The cation [4-(Me2N)C5H4NH]+ is located between the layers and determines the interlayer separation of approximately 6.5 Å. In compound 3 a layered network of the hydrogen-bonded building units R2,3(10) was observed. These units are interconnected by four additional hydrogen bonds within the network. The benzene spacer links the adjacent layers to give a three-dimensional structure. Within this network, channels with internal dimensions of ca. 8.5 × 11.3 Å2 which are occupied by the [4-(Me2N)C5H4NH]+ cations were observed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

Tetraaquabis(d -camphor-10-sulfonato)calcium(II)

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009
Dejan Jeremi
The structure of the title compound, [Ca(C10H15O4S)2(H2O)4], is the first example in which two d -camphor-10-sulfonate anions are coordinated to a metal ion, in this case with direct Ca,O bonding. The molecule has crystallographically imposed twofold symmetry with the Ca atom on the twofold axis. Hydrogen bonds are formed between the coordinated water molecules and the O atoms of the SO3, groups of adjacent molecules, leading to the formation of a two-dimensional layered network. The compound displays sharp wavelength-selective transparency in the UV,visible spectrum, offering the potential for application as an optical filter. [source]

Remapping German-Jewish Studies: Benjamin, Cartography, Modernity

THE GERMAN QUARTERLY, Issue 3 2009
Todd Presner
By examining the entangled places of encounter, exchange, and contamination between German and Jewish, this article argues that German modernity and Jewish modernity are deeply, precariously, and indissociably intertwined. Drawing on its methodology from the field of "mobility studies" (the study of bodies moving through spaces), I argue that we must interrogate the medium in which cultural history is composed and turn our attention to the visualization of narratives of movement, dislocation, and dispersal. I look to Walter Benjamin's urban reflections, the history of modern cartography, the emergence of the railway system, and a web-based mapping project called "HyperCities" in order to show how the history of German/Jewish modernity might be mapped as layered networks and sites of encounter. [source]