Mixed-metal–organic frameworks (M′MOFs) from 1D to 3D based on the “organic” connectivity and the inorganic connectivity: syntheses, structures and magnetic properties

Abstract

Based on the IⁿO^m notion (Iⁿ = the dimensionality of the inorganic connectivity; O^m = the dimensionality of the organic connectivity; n + m ≤ 3), we obtained ten transition/alkaline earth mixed-metal–organic frameworks (M′MOFs) from 1D to 3D through a “metalloligand” strategy at room temperature. Single-crystal X-ray diffraction analyses indicate that the resulting compounds possess the square plane [M^II(pzdc)₂]²⁻ (M = Co, Ni or Cu) “organic” connectivity and the Ae–O–Ae (Ae = Ca, Sr or Ba) inorganic connectivity, which can be classified as I¹O⁰ connectivity for complexes 1, 4, 7 and 9, I¹O¹ connectivity for complexes 2, 3, 5, 6 and 8 and I¹O² connectivity for complex 10. The [M^II(pzdc)₂]²⁻ moieties acting as bis(tetradentate) polycarboxylate ligands show three types of coordination modes, namely μ₄-(η²-O,O)₂,(η¹-O′)₂, μ₆-(η²-O,O)₂,(η¹-O′)₂,(η¹-O′)₂ and μ₁₀-(η²-O,O)₂,(η²-O′,O′)₂, (η¹-O′)₂,(η¹-O′)₂,(η¹-N′)₂. Additionally, the thermal stabilities of complexes 1–10 and magnetic properties of complexes 1, 2, 4, 5 and 10 have also been investigated.