Leveraging Crystalline and Amorphous States of a Metal‐Organic Complex for Transformation of the Photosalient Effect and Positive‐Negative Photochromism

Abstract Uncovering differences between crystalline and amorphous states in molecular solids would both promote the understanding of their structure–property relationships, as well as inform development of multi‐functional materials based on the same compound. Herein, for the first time, we report an approach to leverage crystalline and amorphous states of a zero‐dimensional metal‐organic complex, which exhibited negative and positive photochromism, due to the competitive chemical routes between photocycloaddition and photogenerated radicals. Furthermore, different polymorphs lead to the on/off toggling of photo‐burst movement (photosalient effect), indicating the controllable light‐mechanical conversion. Three demos were further constructed to support their application in information encryption and anti‐counterfeiting. This work provides the proof‐of‐concept of a state‐ and polymorph‐dependent photochemical route, paving an effective way for the design of new dynamically responsive systems.