A novel urea-based “turn-on” fluorescent sensor for detection of Fe3+/F− ions with high selectivity and sensitivity

A novel urea-based “turn-on” fluorescent sensor 1,3-bis(4-(tert-butyldimethylsilyloxy)phenyl)urea (TBSU) has been synthesized and its sensing properties are explored. This sensor exhibited highly selective and sensitive detection of Fe3+ and F− ions in aqueous DMSO solution (DMSO/H2O, 95/5, v/v) with a significant fluorescence and absorption enhancement. The 1:1 stoichiometric structure between TBSU and Fe3+ was adequately supported by Job-plot evaluation, optical titration and FT-IR analysis. The recognition process of the chemosensor TBSU for Fe3+ is chemically reversible on the addition of CN− anion. The Fe3+/F− detection was not affected by the coexistence of other competitive ions. In addition, the detection limit was found to be as low as 5.87 × 10−8 M for Fe3+ and 4.84 × 10−8 M for F−, respectively. Thus, TBSU could be a highly promising fluorescent sensor for the direct determination of Fe3+/F− ions in aqueous DMSO medium.