Solvothermal Syntheses, Crystal Structures, and Luminescent Properties of Two New Cadmium(II) Coordination Polymers Based on Rigid / Flexible Dicarboxylate and N, N′‐Bis(4‐pyridyl)‐1, 4, 5, 8‐naphthalenetetracarboxydiimide1. Issue 5 (25th February 2015)