Development of highly selective fluorescent ferrocenyl-iminopyridine chemosensor for biologically relevant Fe3+

Design, synthesis, characterization, and ion detection studies of two ferrocene-appended Schiff bases namely N-(2-ferrocenylamino]ethyl)-5-nitropyridin-2-amine ( 1 ) and ferrocenylamino-1H-imidazole-4-carboxamide ( 2 ) been reported. Both the chemosensors have been thoroughly characterized using Fourier transfer infrared, ¹H and ¹³C nuclear magnetic resonance, high resolution mass spectrometry, and ultraviolet/visible (UV/visible) and fluorescence spectral techniques. Probes 1 and 2 were designed with the aim of appending the ferrocenyl group with pyridine ring having an amine substitution (for 1 ) and imidazole ring with an amide substitution (for 2 ). Interaction of these probes with a series of cations and anions was examined through UV/vis and fluorescence spectral techniques. Probe 2 exhibited an insignificant response towards anions and loss of selectivity for cations, whereas 1 displayed highly selective detection towards biologically important Fe³⁺ in 2:1 (probe:cation) stoichiometry. Notably, none of the cations and anions could interfere the selectivity of Fe³⁺ ensured by 1 in aqueous medium. The limit of detection for Fe³⁺ detection using 1 was determined to be 0.2 ppm. The results strongly suggest that 1 could find promising future application as a chemosensor for Fe³⁺ in biological systems for quantification and qualitative analysis.