Hybrid organic-anorganic 1D and 2D frameworks with ε-Keggin polyoxomolybdates as building blocks

Organic-inorganic hybrid materials based on polyoxometalate building blocks with capping La3+ ions and bidentate oxygenated ligands have been obtained by reaction at room temperature of the [epsilon-PMo12O36-(OH)(4){La(H2O)(4)}](5+) polyoxocation with glutarate (C5H6O22-) and squarate (C4O42-) organic ligands. [epsilon-PMo12O37-(OH)(3){La(H2O)(4)(C5H6O4)(0.5)}(4)].21 H2O (1) and [epsilon-PMo12O39(OH){La(H2O)(6)}(2)-{La(H2O)(5)(C4O4)(0.5)}(2)].17H(2)O (2) form unprecedented ID chains built from alternating polyoxocations and organic ligands connected through La-O links. The structures of these materials are compared to the 2D hybrid organic-inorganic framework [NC4H12](2)-[Mo22O52(OH)(18){La(H2O)(4)}(2){La- (CH3CO2)(2)}(4)].8H(2)O (3) isolated from the hydrothermal reaction of elemental precursors (MoO42-, Mo, La3+) in acetate buffer. Compound 3 is built from previously undescribed polyoxometalate units with twenty-two Mo-V centers capped by six La3+ ions, four of which are bridged by acetate ligands.