Four Cu–Ln coordination polymers [Cu₂Ln(tda)₂N₃(H₂O)₄·2H₂O] (Ln = Gd (1), Tb (2), Dy (3), Sm (4), tda = 1,2,3-triazole-4,5-dicarboxylate) have been synthesized by employing H₃tda and azido as co-ligands. Complexes 1–4 exhibit the hydrogen bonded three-dimensional (3D) network and intriguing magnetic properties. Among them, 1, 3 and 4 involve antiferromagnetic interaction between metal ions, while 2 exhibits ferromagnetic behavior, demonstrating that magnetic properties could be mediated by a variety of rare earth metal ions.