Stabilization of Tetravalent Cerium upon Coordination of Unsaturated Heteropolytungstate Anions

Abstract

P, Si, Ge, B) and a monovacant Dawson derivative anion P2W1706i10-were adopted as the ligand for cerium(III). The formation of the complexes [CeL]lm-3)-and [CeL2]<2m-3>-was confirmed by means of absorption spectroscopy, where Lm~denotes an unsaturated heteropolytungstate anion of P, Si, or Ge, while clear evidence for the complexation of BW11O399-was not obtained. Electrochemical behaviors of heteropolytungstocerates(III) were studied by cyclic and differential pulse voltammetry in aqueous solution. The redox potential of the cerium(IV/III) couple was considerably lowered (below +1 V vs Ag/AgCl) upon coordination of heteropolytungstate in aqueous solution at pH 4.5. The magnitude of the potential shift for [CeL]lm"3>" increased in the order PWnOgg7-, P2W1706i10-, GeWnOag8-, and SiWuOag8-. A similar trend was observed for [CeL2]12m-3>-with larger potential shift than those of [CeL]lm-3>-. The shift of the redox potential for cerium(IV/III) is caused primarily by the large negative charge of the unsaturated heteropolytungstate.

Luminescent Polyoxotungstoeuropate Anion‐Pillared Layered Double Hydroxides

“…Literature methods were used to prepare sodium or potassium salts of the polyoxotungstoeuropate anions [EuW 10 O 36 ] 9-, [49] [Eu-(BW 11 O 39 )(H 2 O) 3 ] 6-, [31] and [Eu(PW 11 O 39 ) 2 ] 11-. [50] The Zn-Al LDH starting material, ZnAl[NO 3 -], was prepared as described previously. [12] Synthesis of Polyoxotungstoeuropate Anion-Pillared Layered Double Hydroxides: Anion-exchange reactions with a series of europiumcontaining polyoxotungstate anions were carried out on an aqueous slurry of ZnAl[NO 3 -], using the method described by Evans et al (Table 1).…”

Inorganic-organic hybrids constructed of bis(undecatungstogermanate)lanthanates polyoxoanions and oxalate-bridged dinuclear copper complexes and their magnetic properties

“…They can form expansive structures by a combination of donors containing N or carboxyl groups (such as acetates and oxalates) [8,9] or by bridging Cl atoms to obtain highly nuclear magnetic clusters [10,11]. More attention has recently been given to the POM-based hybrids that have been modified by dinuclear copper com- Gd; n = 19,17,22,20,19; m = 4,4,4,9,2) by introducing dinuclear copper (II)-oxalate into the bis(undecatungstogermanate)lanthanates cluster. X-ray structural analyses show…”

“…The compound K 8−x Na x GeW 11 O 39 ·9H 2 O was prepared as previously described [19]. All the chemicals were used as purchased without further purification.…”

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A series of inorganic-organic hybrids K 2 Na m H 9−m [{Ln(GeW 11 O 39 ) 2 }{Cu 2 (bpy) 2 (μ-ox)}]·nH 2 O (bpy = 2,2-bipyridine and ox = oxalate; Ln = La, Nd, Sm, Eu, Gd; n = 19,17,22,20,19; m = 4,4,4,9,2) were isolated after reacting in a potassium acetate buffer. X-ray structural analyses show that compounds 1-5 are isomorphic and consist of [Ln(GeW 11 O 39 ) 2 ] 13− polyoxoanion building blocks and oxalate-bridged dinuclear copper metalorganic complex with a 1D chain structure.

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“…Only our group has reported a similar building block based on bis(undecatungstophosphate) lanthanates polyoxoanion inorganic-organic hybrids. Herein, we successfully isolated 5 inorganic-organic hybrids K 2 Na m H 9−m [{Ln(GeW 11 O 39 ) 2 }{Cu 2 (bpy) 2 (μ-ox)}]·nH 2 O (bpy = 2,2-bipyridine and ox=oxalate; Ln=La, Nd, Sm, Eu, Gd; n = 19,17,22,20,19; m = 4, 4, 4, 9, 2) by introducing dinuclear copper (II)-oxalate into the bis(undecatungstogermanate)lanthanates cluster. X-ray structural analyses show that compounds 1-5 are isomorphic and consist of [Ln(GeW 11 O 39 ) 2 ] 13− polyoxoanion building blocks and oxalate-bridged dinuclear copper metalorganic complex with a 1D chain structure.…”