Luminescence investigation of Fe (III) – rhodamine B complexes obtained by solvent extraction

Optical properties of complexes of rhodamine B (RB) and Fe3+ ions have been investigated using optical spectroscopy. The ionic-association coordination compounds of rhodamine B and iron ions (FeRB) were prepared in the acid environment by means of solvent extraction to chloroform phase. Emission and excitation spectra and luminescence decay curves were analyzed as a function of metal ion concentration. It was found that Fe3+ ions at such conditions were effective in quenching fluorescence and that the intensity of luminescence clearly depended on the metal ion concentration. The emission decrease was observed in the concentration range from 1 to 60 μg Fe/mL solution. Similar relationship was also recorded for the luminescence lifetimes of the investigated systems. Basis on the lifetime and fluorescence intensity measurements and the Stern-Volmer relation the values of quenching rate constant kq and Ksv constant for the investigated system at chloroform phase were also determined. -- Highlights: ► The complexes of rhodamine B and Fe3+ were prepared by extraction to chloroform phase. ► Optical properties of FeRB complexes were studied as a function of Fe3+ concentration. ► The emission intensities and lifetimes decrease with increasing of quencher content. ► The quenching rate constant kq and Ksv constant for the study systems were determined