Synthesis And Property Of New Supramolecular Assembly Based On Polyoxometalate

Polyoxometalates (POMs) have been widely studied for their structural versatility and potential application in many kinds of fields, such as catalysis, medicine, sorption and materials science. In this paper, eight new POM-based compounds on the basis of molybdate or tungstate polyoxoanion clusters have been hydrothermally synthesized and characterized, which are decorated or bridged by various transition metal ions and organic N-containing ligands. The thermal stabilities and fluorescent activity of these compounds have also been studied.(1) Two novel POM polymers have been gained based on V–Mo Keggin polyoxoanion cluster bicapped by antimony and M-phen (M = Ni, Co) subunits:[Co(phen)₃]₂[(VO₄)Mo₈V₄Sb₂O₃₆]·6H₂O (1)[Ni(phen)₂(H₂O)]₂[(VO₄)Mo₈V₄Sb₂O₃₆]·2H₂O (2)Both compound 1 and 2 exhibit similar structures. The difference is that 1 is a neutral bi-supporting POMs, while in 2 the inorganic and organic subunits are connected via hydrogen bonds.(2) Three new POM-based supramolecular compounds have been synthesized via based on V-centered Keggin-type polyoxoanions and M-phen (M = Ni, Co, Ag,) subunits:[Ni(mbpy)₃]₂[VW₁₂O₄₀] (3)[Co(mbpy)₃]₂[H₂VW₁₂O₄₀][W₆O₁₉]·4H₂O (4)[Ag(phen)₃][ Ag(phen)₂]₃[VW₁₂O₄₀]·4H₂O (5)(mbpy = 4,4'-Dimethyl-2,2'-bipyridyl)Compounds 3-5 are all have [VW₁₂O₄₀]^n- polyoxoanion as inorganic subunit. It is interesting that the structural unit of compound 4 contains both a hetero- and an isopolyoxoanion, and the environment of Ag in compound 5 is unusual. (3) An inorganic-organic supramolecular assembly has been synthesized based onsandwich-type POM cluster:(Hbpe)₃(H₂tpy)H[(VO)₆(SbW₉O₃₃)₂]·2H₂O (6)The three-dimensional hybrid supramolecular framework of 6 is fabricated via extensively intermolecular interactions between/among inorganic anions and organic cations. (4) Based on isopoly-molybdate or -tungstate, two new POM supramolecular compounds have been hydrothermally synthesized and structurally characterized:(H₂bpe)[Mo₄O₁₃] (7)[Co(mbpy)₃][W₆O₁₉] (8)Compound 7 is constructed from 1D {Mo₄O₁₃} inorganic chains integrated by protonated bpe ligands, and compound 8 contains a Lindqvist polyoxoanion [W₆O₁₉]^2- decorated by a [Co(mbpy)₃]²⁺ fragment.