A polymorphic lanthanide complex as selective Co2+ sensor and luminescent timer

A rarely reported polymorphic lanthanide complex is prepared by acetylacetone (acac) tuning method. Luminescence properties of 1 are studied. Interestingly, 1 is proved to be a multifunctional material. It is a highly selective and sensitive Co 2+ sensor, among 24 species, only Co 2+ quenching the Tb 3+ centered luminescence. The possible sensing mechanism is the decomposition of 1 which induced by Co 2+ . The limit of detection (LOD) for sensing Co 2+ is as low as 330   nM, which is lower than the standard of Chinese environmental protection department. Mechanism study confirmed the luminescence quenching can be ascribed to the decomposition of 1 which induced by Co 2+ . Further investigations find 1 -Co 2+ can be applied as tunable luminescent timer, by tuning the ratio of 1 /Co 2+ . CIE coordinates of 1 -Co 2+ change regularly (has excellent linearity) from green to violet with the time increasing.