To further probe the nature of quenching mechanism, the Tb-SA films contacted with Cu2+ solution were dried and examined by powder XRD. As illustrated in Fig. S3, the results indicated that BLZ945 Tb-SA film retained some of its structural characters after interacted with Cu2+ ions. The original peaks of Tb-SA remained observable, while the appearance of several new peaks indicated that Cu2+ ions were affected the structure of the film thus dramatically decreased the luminescence of Tb3+. In contrast, the XRD pattern of Tb-SA films contacted with other ions were still matched with the original pattern of as-prepared film. Also, after several times of washing by deionized water and DMF, the luminescence of Cu2+ treated Tb-SA film still retained at a very low level. However, these quenched films can recover most of its original luminescence back via treated with Na2EDTA weak solution (see SI for details). These results suggested that partial ion-exchange might occur in the framework according to previously reported literatures  and . Since static quenching is commonly originated from the formation of non-luminescent complex between the fluorophore and quencher. The luminescent lifetime experiments also suggested partial ion-exchange might occur in the framework, forming the non-luminescent complex of Cu2+ and succinic acid and also diminishes the energy transfer process of surrounding Tb-SA complex, thus significantly diminished the luminescence of the film.