Two zinc(II) complexes, namely [Zn(tmphen) 2 (H 2 odpa)]· 0.88H 2 O (1) and [Zn(tmphen) 2 (H 2 odpa)] n (2) (tmphen = 3,4,7,8-tetramethyl-1,10-phenanthroline, H 4 odpa = 4,4 -oxydiphthalic acid), have been successfully synthesized at different pH values under hydrothermal conditions. In complex 1, the mononuclear [Zn(tmphen) 2 (H 2 odpa)]·0.88H 2 O units are bridged by hydrogen bonds and C-H···π interactions. In 2, H 2 odpa 2− ligands act as bridges between neighboring Zn atoms to form a one-dimensional chain. The structural diversities of 1 and 2 reveal that the pH value of the reaction system plays a crucial role in the assembly of coordination polymer solids.