Dual chemosensing properties of new ferrocene-based receptors towards fluoride and copper(II) ions

The new ferrocene based receptors N-[4-ferrocenyl-2-methyl-4-oxobut-1-enyl]-N′-phenylthiourea (1), N-[4-ferrocenyl-2-methyl-4-oxobut-1-enyl]-N′-[4-nitrophenyl]thiourea (2) were synthesized and characterized. Fluorescence titrations of receptors 1 and 2 with various transition metal ions showed selective response to Cu2+ ions and the emission intensities quenched significantly. Electrochemical titrations with anions revealed that receptors 1 and 2 sensed the F− anion in high selectivity with a cathodic shift of 100 mV.

Two new colorimetric chemosensors 1 and 2 have been synthesized and characterized by different spectroscopic techniques like IR, Mass and NMR. Anion binding studies carried out using UV–visible spectrophotometric titrations revealed that these receptors exhibit selective recognition towards F− over other halide anions. Chromogenic receptors 1 and 2 undergo distinct color changes from yellow to green (1) and red to dark green (2) on gradual addition of Cu(II) and can be used as colorimetric probes for spectrophotometric and visual analysis of Cu(II) in the presence of other transition metal ions such as Mg2+, Ca2+, Cd2+, Ni2+, Co2+, Mn2+ and Zn2+. Fluorescence titrations of receptors 1 and 2 with various transition metal ions showed selective response to Cu2+ ions and the emission intensities quenched significantly. Electrochemical titrations with anions revealed that receptors 1 and 2 sensed the F− anion in high selectivity with a cathodic shift of 100 mV.Figure optionsDownload as PowerPoint slideHighlights
► Easy to synthesize 1 and 2.
► Detectable by using colorimetric, optical (UV–vis and fluorescence) and electrochemical methods.
► Both sensors highly sensitive at low analyte concentration.
► These receptors can also be used to detect copper ions.