Hydrothermal Preparation of Five Rare-Earth (Re = Dy, Gd, Ho, Pr, and Sm) Luminescent Cluster-Based Coordination Materials: The First MOFs-based Ratiometric Fluorescent Sensor for Lysine and Bifunctional Sensing Platform for Insulin and Al3+

Through the powerful hydrothermal method, five rare-earth (Re = Dy, Gd, Ho, Pr, and Sm) three-dimensional (3D) cluster-based metal–organic frameworks (MOFs) have been synthesized, namely, [Dy(L)(H2O)(DMF)]n (1), {[Gd(L)(H2O)(DMF)]·DMF}n (2), {[Ho(L)(H2O)(DMF)]·0.5DMF}n (3), {[Pr(L)(H2O)(DMF)]·0.5DMF}n (4), and {[Sm(L)(H2O)1.55(DMF)0.45]·DMF}n (5; H3L = terphenyl-3,4″,5-tricarboxylic acid), which have been determined by single crystal X-ray analyses and PXRD characterization. Structural analyses reveal that, in 1–5, these L3– ligands are linked by five different rare-earth centers, forming the iso-structural nanoporous frameworks. PXRD patterns of bulky samples 1–5 also are consistent with theoretical PXRD patterns confirming their purity. Solid state photoluminesce of free H3L and 1–5 at room temperature also has been investigated indicating strong ligand-based emissions. Besides these, fluorescent dye Rhodamine B (RhB) can be introduced into MOF1 forming the composite material RhB@MOF1 with a high quantu...