Seven novel Sr^II–Sm^III and Sr^II–Dy^III coordination polymers: Construction of five classes of structural topologies using different amounts of imidazole

The employment of pyridine-2,6-dicarboxylic acid (H₂pda) and imidazole (im) in the synthesis of Sr^II–Sm^III and Sr^II–Dy^III coordination polymers has been reported. Seven novel heterometallic coordination polymers of compositions, [Dy₃Sr₃(pda)₇(Hpda)(H₂O)₉]·6H₂O (1), [LnSr(pda)₃(H₂O)₅]·Him·H₂O (Ln = Sm(2), Dy(3)), [Ln₂Sr(pda)₆(H₂O)₅]·4Him·C₂H₅OH·nH₂O (Ln = Sm(4), n = 4; Dy(5), n = 5), [Sm₂Sr₂(pda)₅(H₂O)₉]·2H₂O (6) and [DySr(pda)₃(H₂O)₄]·Him·3H₂O (7), have been prepared and characterized. Complexes 1, 2–3, and 6 display three varieties of 2-D structures. 4–5 and 7 exhibit two types of 1-D chain structures. The structures of the complexes could be controlled via choosing appropriate starting materials and tuning the amount of imidazole. The photo-luminescent properties of these complexes have been investigated. The results show the exclusive luminescence emission bands being characteristic of Sm^III and Dy^III.