Construction of Multifunctional Luminescent Lanthanide MOFs by Hydrogen Bond Functionalization for Picric Acid Detection and Fluorescent Dyes Encapsulation

From the perspective of efficient and economical utilization of materials, it is very meaningful to achieve multifunctional performance in its assembly process, and this is also the future development trend of metal–organic framework (MOF) materials. As an important type of intermolecular interaction, hydrogen bonding is widely used in supramolecular self-assembly, molecular recognition, and catalytic organic reactions. Following the hydrogen bond functionalization construction strategy, we introduced urea–hydrogen bonding sites into the ligands and then introduced functionalized ligands into the MOF frameworks, which efficiently realized the construction of multifunctional lanthanide MOFs. Structural analysis indicated that the MOF consists of 2D layers with parallelogram holes and stacking into 3D frameworks through the N–H···O hydrogen bonding interactions. Interestingly, a functionalization ligand in the MOF frameworks plays three different roles: support, recognition, and both support and recognition. Thanks to the pores rich in urea sites and the excellent luminescent properties of lanthanide ions, the MOF can be used as a regenerable luminescent sensor for the efficient detection of picric acid. Moreover, two fluorescent dyes, such as perylene and fluorescein, can be encapsulated into the functionalized pores and show excellent dual-emitting performance, which proved that we have successfully adjusted the luminescent properties of Ln-MOF by introducing guest luminescent molecules. More importantly, the hydrogen bond functionalization construction strategy will provide some experimental reference for the construction of multifunctional MOF materials.