Supramolecular assembly based on a heteropolyanion: synthesis and crystal structure of Na<SUB>3</SUB>(H<SUB>2</SUB>O)<SUB>6</SUB>[Al(OH)<SUB>6</SUB>Mo<SUB>6</SUB>O<SUB>18</SUB>]&#183;2H<SUB>2</SUB>O

Synthesis and structural characterization of a polyoxometalate compound Na3(H2O)6 [Al(OH)6Mo6O18]&#183;2H2O (1) have been described. Compound1 exhibits three-dimensional network structure in the solid state, which is assembled by Anderson-type heteropolyanions, [Al(OH)6Mo6O18]n3n- , as building blocks sharing sodium cations.1 possesses "sinuous" channels occupied by supramolecular water dimers as guests. Anderson anions, sodium-coordinated water and crystal water are additionally involved in an intricate hydrogen-bonding network in the crystal of 1

A chiral Mn(IV) complex and its supramolecular assembly: synthesis, characterization and properties

The open air reaction of the chiral Schiff base ligand H2L, prepared by the condensation of L-phenylalaninol and 5-bromosalicylaldehyde, with MnII(CH3COO)2·4H2O yielded dark brown complex [MnIVL2]·0·5 DMF (1). Compound 1 was characterized by elemental analysis, IR, UV-visible, CD and EPR spectroscopy, cyclic voltammetry and room temperature magnetic moment determination. Single-crystal X-ray analysis revealed that compound 1 crystallises in the monoclinic P21 space group with six mononuclear [MnIV L2] units in the asymmetric unit along with three solvent DMF molecules. In the crystal structure, each Mn(IV) complex, acting as the building unit, undergoes supramolecular linking through C-H···0 bonds leading to an intricate hydrogen bonding network

Two different zinc(II)-aqua complexes held up by a metal-oxide based support: synthesis, crystal structure and catalytic activity of [HMTAH]<SUB>2</SUB>[{Zn(H<SUB>2</SUB>O)<SUB>5</SUB>}{Zn(H<SUB>2</SUB>O)<SUB>4</SUB>}{Mo<SUB>7</SUB>O<SUB>24</SUB>}]&#183;2H<SUB>2</SUB>O (HMTAH = protonated hexamethylenetetramine)

An inorganic-organic hybrid material, [HMTAH]2[{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}]&#183;2H2O (1) (where HMTAH = protonated hxamethylenetetramine) has been synthesized and structurally characterized. The compound 1 crystallizes in a monoclinic space group C2/c. The crystal data of 1: &#945; = 43&#183;12(3), b = 12&#183;399(10), c = 16&#183;285(13), &#946; = 111&#183;131(11), Z = 8. Its crystal structure shows that two different Zn(II)-aqua complexes, [Zn(H2O)5]2+ and [Zn(H2O)4]2+ are covalently coordinated to a heptamolybdate anion [Mo7O24]6- resulting in an anionic species of polyoxometalate supported zinc-aqua complexes, [{Zn(H2O)5}{Zn(H2O)4}{Mo7O24}]2-, that is stabilized with two protonated hexamethylenetetramine cations in the title compound 1. In the crystal structure, both lattice water molecules are found to interact with the heptamolybdate cluster anion and the protonated hexamethylenetetramine cation resulting in an intricate three-dimensional hydrogen bonding network. Interestingly, compound 1 exhibits catalytic activity towards oxidation of some primary alcohols

Polyoxometalates: toward new materials

This article describes an account of some of our polyoxometalate (POM)-based research, we have been doing in our laboratory last several years. There are several well-defined POM cluster anions, that are structurally characterized. We have chosen Anderson-type of heteropolyanion [Al(OH)6Mo6O18]3- and explored its linking propensity in different dimensions using 's', 'd' and 'f' block elements as linkers.We have demonstrated how a lanthanide linker provides a new pathway in forming a two-dimensional linked {As8V14} system [{Ln(H2O)6}2As8V14O42(SO3)]n · 8nH2O, that is derived from discrete {As8V14} cluster containing compound (NH4)6[As8V14O42(SO3)]. A polyoxometalate compound has been described in which a reduced tungstovanadate-heteropolyanion clusters get linked via capped V = O groups into one-dimensional chains. All these systems have already been reported elsewhere. The last portion of this article will be described by a new system [3-ampH]6[V10O28] · 2H2O having discrete molecular structure and extended supramolecular structure

A Versatile Polyoxovanadate in Diverse Cation Matrices: A Supramolecular Perspective

A series of decavanadate based compounds, formulated as [Co(H2O)6][{Na4(H2O)14}{V10O28}]·4H2O (1), [Zn(H2O)6][Na3(H2O)14] [HV10O28]·4H2O (2), [HMTAH]2 [{Zn(H2O)4}2{V10O28}]·2H2O (3), [{Co(3-amp)(H2O)5}]2 [3-ampH]2 [V10O28] · 6H2O (4), [4-ampH]10[{Na(H2O)6}{HV10O28}][V10O28]·15H2O (5), [{4-ampH}6 {Co(H2O)6}3][V10O28]2·14H2O (6), and [{4-ampH}10{Zn(H2O)6}][V10O28]2·10H2O (7), have been synthesized (where HMTAH = mono-protonated hexamethylenetetramine, 3-ampH = protonated 3-amino pyridine and 4-ampH= protonated 4-aminopyridine) from the relevant aqueous sodium-vanadate solution, by varying the pH of the solution and amino pyridine/hexamine derivatives as well as transition metal salts (Co(II)- and Zn(II)-salts). In this series of compounds 1–7, the polyoxovanadate (POV) cluster [V10O28]6− is the common cluster anion, stabilized by diverse cations. The diverse supramolecular patterns around the decavanadate cluster anion in different cationic matrices have been described to understand the microenvironment in the decavanadate-based minerals. All of these compounds have solvent water molecules in their respective crystal lattices. Since water can interact directly with cations and anions, providing an additional stability and structural diversity, we have analyzed supramolecular water structures in all these compounds to comprehend the role of the lattice water in the formation of natural decavanadate containing minerals. Compounds 1–7, that are isolated at an ambient condition from aqueous solution, are characterized by routine spectral analysis, elemental analyses and finally unambiguously by single crystal X-ray crystallography

6,7,6′,7′-Tetra­phenyl-2,2′-bi[1,3-dithia-5,8-diaza­cyclo­penta­[b]naphthalenyl­idene] chloro­form disolvate

The title compound, C42H24N4S4·2CHCl3, a symmetrical tetra­thia­fulvalene (TTF) derivative, was prepared by a tri­ethyl­phos­phite-mediated self-coupling reaction of 6,7-diphenyl-1,3-dithia-5,8-diaza­cyclo­penta­[b]napthalen-2-one. The asymmetric unit contains two TTF mol­ecules and four chloro­form solvent mol­ecules. Cl⋯Cl inter­actions [contact distances = 3.263 (1)–3.395 (2) Å] are present between the solvent mol­ecules, resulting in a tape along the bc plane. The crystal packing features weak C—H⋯Cl and C—H⋯N hydrogen bonds, resulting in the formation of a two-dimensional supramolecular network

2-Amino­anilinium 2-chloro­acetate

In the crystal structure of the title compound, C6H9N2 +·ClCH2COO−, prepared by the reaction of OPDA (orthophenelynediamine) with chloro­acetic ­acid, N—H⋯O hydrogen bonds generate ladder-like chains and very weak inter­molecular C—H⋯Cl hydrogen-bonding inter­actions between the anions and cations lead to a supra­molecular network. C—H⋯O inter­actions also occur

Stepwise reduction of electron-precise, six-electron, triangular, [Mo<SUB>3</SUB><SUP>IV</SUP>S<SUB>4</SUB>(CN)<SUB>9</SUB>]<SUP>5-</SUP> to electron-rich seven, eight and unstable nine-electron species resulting in core expansion to electron-precise, twelvee-lectron, tetrahedral, [Mo<SUB>4</SUB><SUP>III</SUP>S<SUB>4</SUB>(CN)<SUB>12</SUB>]<SUP>8-</SUP>

Facile reduction of the triangular {Mo3IV }6-core containing [Mo3S4 (CN)9]5- derivative is achieved in aqueous medium, containing the KOH-KCN-K2 [Zn(CN)4] ternary system as supporting electrolyte, in a two-step one-electron reduction reaction followed by an irreversible one. The diamagnetic species containing the {Mo3}8 core, obtained by chemical reduction of [Mo3S4(CN)9]5- with zinc in aqueous medium containing KOH-KCN, is oxidized by air in two steps. The partially oxidized species with {Mo3}7 core in the first step exhibits characteristic ESR signals which on further oxidation quantitatively reverts to the original compound with {Mo3}6 core displaying distinctly separate isosbestic points in the stepwise conversion of {Mo3}8 to {Mo3}7 and {Mo3}7 to {Mo3}6 cores. Under drastic reduction conditions with aluminium in 40% aqueous KOH solution the {Mo3}6 core is reduced to unstable trinuclear {Mo3III }9 core which expands to tetrahedral {Mo4III }12-core containing [Mo4S4(CN)12]8- derivative according to electron-precise cluster rule

Effect of Subband Landau Level Coupling to the Linearly Dispersing Collective Mode in a Quantum Hall Ferromagnet

In a recent experiment (Phys. Rev. Lett. {\bf 87}, 036903 (2001)), Spielman et al observed a linearly dispersing collective mode in quantum Hall ferromagnet. While it qualitatively agrees with the Goldstone mode dispersion at small wave vector, the experimental mode velocity is slower than that calculated by previous theories by a factor about 0.55. A better agreement with the experimental data may possibly be achieved by taking the subband Landau level coupling into account due to the finiteness of the layer thickness. A novel coupling of quantum fluctuation to the tunneling is briefly discussed.Comment: 4 pages; published versio

"The fruits of independence": Satyajit Ray, Indian nationhood and the spectre of empire

Challenging the longstanding consensus that Satyajit Ray's work is largely free of ideological concerns and notable only for its humanistic richness, this article shows with reference to representations of British colonialism and Indian nationhood that Ray's films and stories are marked deeply and consistently by a distinctively Bengali variety of liberalism. Drawn from an ongoing biographical project, it commences with an overview of the nationalist milieu in which Ray grew up and emphasizes the preoccupation with colonialism and nationalism that marked his earliest unfilmed scripts. It then shows with case studies of Kanchanjangha (1962), Charulata (1964), First Class Kamra (First-Class Compartment, 1981), Pratidwandi (The Adversary, 1970), Shatranj ke Khilari (The Chess Players, 1977), Agantuk (The Stranger, 1991) and Robertsoner Ruby (Robertson's Ruby, 1992) how Ray's mature work continued to combine a strongly anti-colonial viewpoint with a shifting perspective on Indian nationhood and an unequivocal commitment to cultural cosmopolitanism. Analysing how Ray articulated his ideological positions through the quintessentially liberal device of complexly staged debates that were apparently free, but in fact closed by the scenarist/director on ideologically specific notes, this article concludes that Ray's reputation as an all-forgiving, ‘everybody-has-his-reasons’ humanist is based on simplistic or even tendentious readings of his work