Highly sensitive and selective fluorescent probe for Ag+ based on a Eu3+ post-functionalized metal-organic framework in aqueous media

A 3D microporous compound Al(OH) (H(2)btec)center dot H2O (MIL-121) containing uncoordinated carbonyl groups is selected as a parent metal organic framework (MOF). Moreover, because the uncoordinated carbonyl groups in the channels could act as a postsynthetic modification sites, a robust luminescent lanthanide-based MOP can be constructed by encapsulating Eu3+ cations into the pores of MIL-121. The intense luminescence of Eu3+ incorporated MIL-121 products demonstrates that the framework with rigid, permanently porous structure and non-coordinated carboxyl group is an efficient scaffold for hosting and sensitizing Eu3+ cations. More significantly, the robust Eu3+@MIL-121 shows excellent selectivity, fast detection time (<5 min), and high sensitivity (detection limit, 0.1 mu M) for Ag+ ions in aqueous solution due to a great enhancement of the Eu3+-luminescence. This is a rare example of Ag+ detection in aqueous solutions based on a luminescent lanthanide MOFs.