A novel highly selective FRET sensor for Fe(III) and DFT mechanistic evaluation.

A novel FRET-based sensor has been designed and developed through the conjugation of naphthyl and rhodamine via propylamine spacer, Naph-Rh. The naphthyl moiety serves as a FRET donor due to its emission spectrum overlapping with the rhodamine B absorption band. Naph-Rh exhibited a selectivity for sensing Fe3+ over other metal ions with a visual color change and fluorescent enhancement. The ratio of the Naph-Rh and Fe3+ was determined to be 1:1 based on Job's plot analysis with a detection limit of 83 nM. The probe exhibited a linear response to Fe3+ in the range of 0-120 µM. Furthermore, the density functional theory (DFT) calculations of Naph-Rh were carried out to rationalize the design and portray the plausible Fe3+ sensing mechanism.