A dendrimer-based highly sensitive and selective fluorescence-quenching sensor for Fe(3+) both in solution and as film.

A novel fluorescent dendrimer PYTPAG2, with pyrene as the interior core and triphenylamine (TPA) as the exterior periphery, is studied as a fluorescence-quenching sensor for iron (ш) ions (Fe(3+)), both in solution and as a film. This dendrimer-based sensor possesses preferential detection of Fe(3+) by a very strong fluorescence quenching not found for other metal ions. The fluorescent detection limits of this PYTPAG2 sensor for Fe(3+) in solution and thin-film are 6.5×10(-7)M and 5.0×10(-7)M, respectively. The possible mechanism of this process is explained by the complexation between the peripheral TPA units of PYTPAG2 and Fe(3+) ions, which may disrupt the fluorescence resonance energy transfer (FRET) from the TPA groups to the pyrene core (intramolecular of PYTPAG2) and results in the fluorescence quenching. Moreover, this striking performance could not be disturbed by pH, the interference with other metal ions, counter anions, or surrounding environment. In addition, biological fluorescence imaging studies of Fe(3+) in living roundworms demonstrate its valuable practical application.