pH-value-controlled assembly of photoluminescent zinc coordination polymers

By pH-value adjustment, the reactions of zinc salt, 1,3,5-benzenetricarboxylic acid (H3btc) and 4,4′-bipyridine (bpy) yield three coordination polymers, formulated as [Zn3(btc)2(bpy)(H2O)2]n (1), [Zn(Hbtc)(bpy)(H2O)]n · 3nH2O (2) and [Zn(Hbtc)(bpy)(H2O)]n · 4nH2O (3), respectively. The structure of 1 is a 3D network containing channels filled with bpy ligands. Compound 2 consists of twofold interpenetrating (10,3)-b networks, while compound 3 is a 2D layer structure. The fluorescent studies reveal that they exhibit intense violet luminescence in solid state.