Luminescence-based spectroelectrochemical sensor for [Tc(dmpe)3]2+/+ (dmpe = 1,2-bis(dimethylphosphino)ethane) within a charge-selective polymer film.

A spectroelectrochemical sensor consisting of an indium tin oxide (ITO) optically transparent electrode (OTE) coated with a thin film of partially sulfonated polystyrene-blockpoly(ethylene-ran-butylene)-block-polystyrene (SSEBS) was developed for Tc(dmpe)(3) (dmpe = 1,2-bis(dimethylphosphino)ethane). Tc(dmpe)(3) was preconcentrated by ion-exchange into the SSEBS film after a 20 min exposure to aqueous Tc(dmpe)(3) solution, resulting in a 14-fold increase in cathodic peak current compared to a bare OTE. Colorless Tc(dmpe)(3) was reversibly oxidized to colored Tc(dmpe)(3) by cyclic voltammetry. Detection of Tc(dmpe)(3) was accomplished through emission spectroscopy by electrochemically oxidizing the complex from nonemissive Tc(dmpe)(3) to emissive Tc(dmpe)(3). The working principle of the sensor consisted of electrochemically cycling between nonemissive Tc(dmpe)(3) and emissive Tc(dmpe)(3) and monitoring the modulated emission (λ(exc) = 532 nm; λ(em) = 660 nm). The sensor gave a linear response over the concentration range of 0.16-340.0 μM of Tc(dmpe)(3) in aqueous phase with a detection limit of 24 nM.