Metal-organic segment-induced dimensionality evolution in polyoxometalate-based hybrids

Three hybrid materials based on Keggin-type polyoxometalates, [Cu-3(I)(fsa)(4)(PMo12O40)] (1), [Ag-5(fsa)(4)H(PMo12O40)(2)] (2), and [Ag-6(fsa)(6)(PMo12O40)(2)] (3), (fsa = 1-((bis(4-fluorophenyl)methylsilyl)methyl)-1H-1,2,4-triazole), have been hydrothermally synthesized. A series of unique and fascinating metal-organic segments ( named MOSs) assembled from M-I (Cu-I/Ag-I) metals have been observed. Compound 1 contains a kind of trimetal-organic segment [Cu-3(fsa)(4)](3+) (3-MOS), which could be regarded as a quasi-sinusoid-like unit. Compound 2 contains a pentametal-organic segment [Ag-5(fsa)(4)](5+) (5-MOS), which exhibits a saturated sinusoid-like unit compared with 3-MOS. In 3, in addition to a saturated 5-MOS similar to that in 2, a new monometal-organic segment [Ag(fsa)(2)](+) (1-MOS) was assembled as a result of increasing the molar ratio of Ag/fsa. Evolution of such unique MOSs induces the ascension of dimensionality in a step-by-step manner, from a 1D chain to a 2D layer, and finally a 3D framework for 1, 2 and 3, respectively.