Low PH Hydrothermal Synthesis and Properties of Lanthanide-organic Frameworks with (4(10),6(5))(4(9),6(6)) Topology Constructed from Ln-Hbptc Building Blocks

Two novel lanthanide-organic frameworks (LnOFs) with (4(10),6(5))(4(9),6(6)) topology, [Ln(Hbptc)(H(2)O)](n) (Ln = Eu(1), Gd(2); H(4)bptc = 3,3',4,4'-biphenyltetracarboxylic acid) were synthesized via the hydrothermal in situ reaction between lanthanide salts and 3,3',4,4'-biphenyltetracarboxylic dianhydride (bpta) under low pH conditions. In complexes 1 and 2, homohelix bundles with opposite chirality are assembled alternately and result in pillar-like 3D extended networks incorporated with coordinated water molecules, which show high thermal stability. The luminescence properties are illustrated by the Eu(III) complex (1) and its Gd-doped compound, which are intensive red emitters. The magnetic properties of complexes 1 and 2 are also investigated.