Distinct color change of a Ho(III)-based metal-organic framework upon varying incident light sources

Abstract

Lanthanide metal–organic frameworks (Ln-MOFs) have gained significant attention in recent years due to their diverse characteristics ranging from material science to biomedical applications. Although Ln-MOFs possess properties that are common to all MOF categories, they can exhibit unique structural combinations owing to their high coordination numbers and distinctive optical properties. Herein, we report the Ho(III)-based zwitterionic MOF H1 which crystallizes in the monoclinic space group C2/c. The nine-coordinate Ho(III) ion presents a configuration related to the gek2 topology. Remarkably, H1 features unique optical properties, namely, the physical change of color from white to pink upon changing the incident light source from sunlight to fluorescent light. A literature review through the Cambridge crystallographic data center (CCDC) reveals this being the first report of a Ho(III)-MOF showing such optical behavior.