Multicolour barcoding in one MOF crystal through rational postsynthetic transmetalation

Multicolour photoluminescence has attracted extensive interest in the past decades due to its potential applications in anticounterfeiting and colour barcoding. However, it remains a great challenge to heterogeneously tune the luminescence colour in a single metal-organic framework (MOF) crystal/particle at bulk scale. Here, macroscopic colour multiplexing showing discernable emissions to naked eyes, has been first achieved on a new non-luminescent Ce³⁺-MOF crystal via efficient step-by-step postsynthetic transmetalation. The presence of a clear demarcation line between dual emissions has been validated by the luminescence lifetimes. Furthermore, multiplex emission can be selectively and rapidly turned-off via an easily performed post synthetic chemical treatment.