Light-controlled efficient photoluminescence based on an europium β-diketonate complex with single-crystal-to-single-crystal [2+2] cycloaddition

A brand new europium( iii ) β-diketonate complex undergoes a single-crystal-to-single-crystal transformation via [2+2] cycloaddition after UV irradiation, triggering strong Eu( iii ) red emission turn-on, which is highly photostable even after 50 hours of irradiation. A photo-patterning process is successfully conducted for security printing application in materials science. An europium β-diketonate complex is first reported with enhanced luminescence by single-crystal-to-single-crystal [2+2] cycloaddition, which is useful for security photo.