Amine-functionalized titanium metal-organic framework (NH2-MIL-125(Ti)): A novel fluorescent sensor for the highly selective sensing of copper ions

Herein, titanium based metal organic framework (MOF) i.e. NH2-MIL-125(Ti) has been successfully fabricated via solvothermal route using titanium isopropoxide and 2-aminoterephthalic acid as starting materials. The characterization and evaluation of structural, morphological and compositional analysis were done using several analytical techniques such as XRD, FTIR, BET surface area, XPS, FE-SEM and HR-TEM. Furthermore, the synthesized MOF's performance was explored as an efficient fluorescent probe for the quantification of transition metal ions. The results revealed that NH2-MIL-125(Ti) was strongly specific and sensitive to Cu(II) ions. Remarkably, the fluorescence intensity of NH2-MIL-125(Ti) decreased proportionally towards the concentration of Cu(II) ions. The sensor provides a useful platform for the detection of Cu(II) ions in the linear range 0–72 μM with a detection limit of 0.72 μM, besides, the value of Stern-Volmer constant was found to be 3.2 × 104 M−1. Moreover, NH2-MIL-125(Ti) as a Cu(II) sensor can be simply recycled affirming its high stability, which reveals NH2-MIL-125(Ti) as a prospective fluorescent probe. The prepared sensor was also applied for the determination of Cu(II) ions in real water samples to test its practical utility.