Reversible Multistimuli Switching of a Spiropyran-Functionalized Organic Cage in Solid and Solution.

A spiropyran-decorated covalent organic cage (PC2) has been designed, employing dynamic imine chemistry followed by imine bond reduction. The molecule is capable of altering its color upon exposure to external stimuli such as heat and light. Construction of a 3D organic cage introduces a new piece to the system by swapping the closed form with the open form in the solid state with diverse color change. Moreover, this material has high chemical stability and is capable of reversible stimuli-responsive color change without any degradation for an extended period.