Research of a highly selective fluorescent chemosensor for aluminum(III) ions based on photoinduced electron transfer

A highly selective fluorescent chemosensor for aluminum(III) ions, N,N′-bis(2-hydroxy-1-naphthaldehyde)-l,2-phenylenediamine (H2L) was synthesized and characterized. When aluminum(III) ions are added to H2L solution in DMF, the solution exhibits two remarkably enhanced emissions at 517 and 540 nm, which could not be observed with other metal ions. The results of 1H NMR titration, MALDI-TOF-MS and DFT studies indicate that H2L and aluminum(III) ions form a 1:1 complex. The association constant Ka was determined to be 2.67 × 106 and the limit of detection (LOD) was calculated to be 10−6 M. The sensing mechanism can be explained by the photoinduced electron transfer (PET).