A novel luminescent microporous lanthanide metal-organic framework (Ln-MOF) based on a urea-containing ligand has been successfully assembled. Structural analysis revealed that the framework features two types of 1D channels, with urea N-H bonds projecting into the pores. Luminescence studies have revealed that the Ln-MOF exhibits high sensitivity, good selectivity, and a fast luminescence quenching response towards Fe , Cr anions, and picric acid. In particular, in the detection of Cr O and picric acid, the Ln-MOF can be simply and quickly regenerated, thus exhibiting excellent recyclability. To the best of our knowledge, this is the first example of a multi-responsive luminescent Ln-MOF sensor for Fe , Cr anions, and picric acid based on a urea derivative. This Ln-MOF may potentially be used as a multi-responsive regenerable luminescent sensor for the quantitative detection of toxic and harmful substances.

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Two novel lanthanide metal–organic framework (Ln‐MOF) luminescent sensors for the detection of picric acid have been successfully assembled. Following a function‐oriented strategy, urea hydrogen‐bonding functional sites were introduced into two MOF frameworks. A structural analysis indicated that the two MOFs have the exact same structure, namely 2D layers with diamond‐shaped holes that are accumulated into a 3D framework through the hydrogen‐bonding interactions between urea and carboxylate groups. Interestingly, only half of the urea units are involved in supporting the MOF framework through N−H⋅⋅⋅O hydrogen‐bonding interactions, whereas the other half are located in the pore channel and act as empty recognition sites. Abundant N−H urea bonds are present in the inner walls of three types of interpenetrating 1D channels. Luminescence studies revealed that the two Ln‐MOFs exhibit high sensitivity, good selectivity, and a fast luminescence quenching response towards picric acid. In particular, the two Ln‐MOFs can be simply and quickly regenerated, and exhibit excellent recyclability. In summary, we have successfully used a function‐oriented strategy to achieve multiple functions in a ligand to construct lanthanide MOF luminescent sensors for the detection of picric acid, thereby providing a potential strategy for the future development of MOF luminescent sensors with a specific target.

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