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

Abstract

Three hybrid materials based on Keggin-type polyoxometalates, [Cu^I₃(fsa)₄(PMo₁₂O₄₀)] (1), [Ag₅(fsa)₄H(PMo₁₂O₄₀)₂] (2), and [Ag₆(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 [Cu₃(fsa)₄]³⁺ (3-MOS), which could be regarded as a quasi-sinusoid-like unit. Compound 2 contains a pentametal–organic segment [Ag₅(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.