Fabrication and DFT Calculation of Amine-Functionalized Metal-Organic Framework as a Turn-On Fluorescence Sensor for Fe 3+ and Al 3+ Ions.

Due to their important role in biological systems, it is urgent to develop a material that can rapidly and sensitively detect the concentration of Fe and Al ions. In this work, a brand-new Cd-based metal-organic framework [Cd(BTBD)(AIC)] (, BTBD = 4,7-bis(1-1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole and HAIC = 5-aminoisophthalic acid) with a 4-connected topology was designed and synthesized. The symmetrical Cd centers are linked by AIC ligands with μ-η:η:η:η coordination mode to form a [Cd(COO)] secondary building unit (SBU). The contiguous SBUs are further connected by BTBD ligands to form a two-dimensional (2D) layer structure. can remain stable in aqueous solutions with pH values of 3-12 or in boiling water. Luminescent experiments suggest that displays more than eightfold fluorescence enhancement in the presence of Fe and Al ions, and the detection limits for Fe and Al ions are 0.196 and 0.184 μM, respectively. Furthermore, the change in luminescence color is uncomplicatedly distinguishable with the naked eye under ultraviolet light at 365 nm. In addition, a series of devices based on including fluorescence test strips, lamp beads, and composite films were developed to detect metal ions visual changes in luminescence color. Significantly, is a rare MOF-based turn-on fluorescence sensor for the detection of Fe ions. The theoretical calculation suggests that the complexation of Fe/Al ions and the -NH group contributes to fluorescence enhancement.