In previous work, the facile method to prepare perylene diimide radical anion salt by alkali treatment was reported. However, the effects of structure on synthetic process of perylene diimide radical anion salt, and the difference of response to Cu 2+ are not thoroughly understood. In this work, two bay-substituted perylene diimide derivatives radical anion salts have been synthesized and characterized in order to study the influence of the bay-substituted groups on the formation condition of the corresponding radical anion salt, and the sensitivity to Cu 2+. The result indicates that the perylene diimide with electron-donating groups (-O-Ph) at bay position was much easier to get the air-stable radical anion salts and had higher sensitivity to Cu 2+ compared to the perylene diimide with electron-withdrawing groups (-Br) at bay position.