Hydrothermal syntheses and structures of first examples of lanthanide 7,8,4′-tricarboxymethoxyisoflavone coordination polymers

Two novel isostructure open frameworks of Ln(III), [Ln(L)(H2O)·1.5H2O]n, [Ln = Pr(1), Eu(2)], have been successfully synthesized using multifunctional organic compound 7,8,4′-tricarboxymethoxyisoflavone (L) as a linker through hydrothermal technique. Compounds 1 and 2 consist of 2D networks, which are further assembled into 3D architecture with 1D channels constructed by coordination bonds and the lattice water molecules array in lines occupying these voids via hydrogen bonds. In these compounds, L only exhibit one coordination mode coordinating to Ln(III), and four oxygen atoms from two carboxylate groups and two carboxymethoxy groups of one L coordinate to one Ln(III), simultaneously. The thermogravimetric analyses of these compounds show that the coordinated water and lattice water are lost in two steps, and the final residues are lanthanide oxides.