A highly selective and fast-response fluorescent probe based on Cd-MOF for the visual detection of Al3+ ion and quantitative detection of Fe3+ ion

A new luminescent Cd(II)-based metal-organic framework, [Cd(PAM)(4-bpdb)(1.5)]center dot DMF (Cd-MOF, PAM = 4,4'-methylenebis(3-hydroxy-2-naphthalene-carboxylic acid) and 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-buta-diene) was successfully synthesized by solvothermal synthesis method. The Cd-MOF reveals excellent luminescence property which can selectively detect Al3+ and Fe3+ ions among other interfering metal ions. The detection limit is 0.56 mu M for Al3+ ion in aqueous solutions, and it is obvious lower than the maximum standard of Al3+ ion in drinking water of 7.41 mu M which is defined by the WHO. More importantly, the Cd-MOF shows an obvious luminescent color change from yellow to blue under the UV lamp irradiation at 365 nm with the dropping of Al3+ ion, which can make it apply to the visual detection. And, the detection based on the test paper was explored for the first time. In addition, the Cd-MOF can also be used for quantitative detecting Fe3+ ion, and the LOD for Fe3+ ion can be as low as 0.3 mu M which is lower than most reported MOFs. It is worth noting that Fe3+ and Al3+ ions can not interfere with each other. These properties make it become an excellent luminescence sensor for the detection of Al3+ and Fe3+ ions.