A family of lanthanide-zinc coordination polymers with two different types of three-dimensional (3-D) frameworks based on 4,5-imidazoledicarboxylic acid and oxalic acid, namely,2), Sm (3), Eu (4), and H 3 ImDC = 4,5-imidazoledicarboxylic acid, H 2 ox = oxalic acid) and 5), Dy (6), Ho (7), Er (8), Yb (9), and Lu (10)), were successfully constructed under certain conditions and characterized by elemental analysis, IR, thermogravimetric (TG), and single-crystal X-ray diffraction. The results reveal that compounds 1À4 (I structure) are isomorphous 3-D coordination frameworks containing two-dimensional (2-D) [Zn 2 (ImDC) 2 ] layers and one-dimensional (1-D) Ln 2 (μ 2 -O) 2 (ox) sine wave-like chains with 1-D square channels, while 4 0 À10 coordination polymers (II structure) are also isomorphous and feature 3-D pillar-layered coordination frameworks constructed from 2-D Zn-carboxylate [Zn 2 (ImDC) 2 ] layers and Ln 2 (ox) pillars with 1-D flat channels. The structural variation from I to II with the europium ion as a critical point, in which two types of europium complexes 4 and 4 0 can reversibly transform into each other, may be attributed to the lanthanide contraction effect. Meanwhile, the adsorption and photoluminescent properties of the partial compounds are also investigated.

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