Linear-light-controlled reverse electron transfer in a 3-D pyromelliticdiimide-based photo-/thermochromic cadmium( <scp>ii</scp> ) coordination polymer

The implementation of linear-light-controlled reverse electron transfer (ET) of photo-/thermo-induced chromic materials is of great importance for practical applications but remains challenging. In this work, a novel three-dimensional (3-D) bifunctional photo-/thermochromic cadmium(II) coordination polymer (CP) was developed, in which the reverse ET can be triggered by conventional linear visible light. The switching between the forward and reverse ET reactions involving photochromism and thermochromism could be repeated more than 120 times and 20 times, respectively. The present work has overcome a traditional concept that reverse ET reactions of bifunctional photo-/thermochromic materials can only be realized by applying heat/dark treatments and hence has provided an effective strategy for constructing bifunctional chromic materials with linear-light-induced reversibility and excellent fatigue resistance.