Citation: Xu, Hui-Ling; Zeng, Xiao-Shan; Li, Jie; Xu, Yu-Ci; Qiu, Hai-Jiang; Xiao, Dong-Rong (2018). The impact of metal ions on photoinduced electron-transfer properties: four photochromic metal--organic frameworks based on a naphthalenediimide chromophore. CrystEngComm, 20, pp. 2430-.