Three-dimensional mesomeric networks assembled from helix-linked sheets: syntheses, structures, and magnetisms

Abstract

Two new three-dimensional nickel coordination polymers, [Ni₃(BTC)₂(4,4′-bpy)₂(H₂O)₅]·1.5H₂O (1) and [Ni(PDB)(4,4′-bpy)]·0.5H₂O (2) (4,4′-bpy = bipyridine, BTC = 1,2,4-benzenetricarboxylate, PDB = pyridine-3,4-dicarboxylate), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TGA, and single crystal X-ray diffraction. Both compounds contain 2D scaffolding motifs, and most interestingly adjacent scaffolds are connected by infinite helical chains into unique three-dimensional mesomeric networks. Moreover, temperature-dependent magnetic susceptibilities for the two compounds were studied, and ferromagnetic interactions through syn-anti carboxylate bridges between Ni sites have been observed.