Organic–inorganic one-dimensional hybrid aggregates constructed from aromatic-bisphosphonate-functionalized polyoxomolybdates

Abstract

Five novel lanthanide-substituted polyoxomolybdates (NH₄)₅Na₃H₂[{Ln(H₂O)₇}₂{Mo₅O₁₅(1,4-O₃PCH₂C₆H₄CH₂PO₃)}₄]·nH₂O [Ln = Tb³⁺ (1), Ho³⁺ (2), Er³⁺ (3), Tm³⁺ (4), Yb³⁺ (5); n = 33, 32, 41, 30, 47] have been prepared in a conventional aqueous solution reaction of ammonium molybdate with Ln³⁺ ions and p-xylyenediphosphonic acid. Crystal structure analyses reveal that 1–5 are isomorphic. The prominent architecture characteristic is that their structural units consist of a tetrameric cyclic-shaped [{Mo₅O₁₅(1,4-O₃PCH₂C₆H₄CH₂PO₃)}₄]¹⁶⁻ segment stabilized by two [Ln(H₂O)₇]³⁺ cations, which are connected to propagate one-dimensional chain by Ln³⁺ ions. As is known, compounds 1–5 stand for the first Ln-substituted aromatic-bisphosphonate-functionalized polyoxomolybdates. The solid-state photoluminescence measurement of 1 has been performed at ambient temperature, and it displayed the characteristic emissions of Tb ions based on its 4f–4f transitions. In addition, the magnetic properties of 1–5 compounds show that they all exhibit anti-ferromagnetic interactions.