Investigation of Yb(III)–PVC membrane interfacial interaction by semiempirical PM6/SPARKLE method based on 1,10-phenanthroline-5,6-dione as a suitable neutral ionophore

To predict the selectivity of Yb(III)–PVC membrane, the semiempirical PM6/SPARKLE method was used to investigate the binding of Yb(III) and other cations to 1,10-phenanthroline-5,6-dione (PDO). The study has shown that the chelating ligand, PDO, is selectively coordinated to Yb(III) at two coordination sites involving the pyridylic nitrogen atoms in the interface of membrane/solution. The membrane was used as a potentiometric Yb sensor, based on PDO as an ionophore, sodium tetraphenyl borate (NaTBP) as a lipophilic ionic additive, and tributyl phosphate (TBP) as a plasticizer. The electrode had a good Nernstian response for Yb(III) ions over a wide concentration range from 5 × 10−6 to 1 × 10−2 M and a detection limit of 5.7 × 10−7 M with a slope of 19.7 ± 0.2 mV/decade in a pH range of 4.0–12.0. The sensor had a very fast response time of less than 5 s over the whole concentration range and can be used over a period of 6 wk without any significant divergence in potentials.

Semiempirical PM6/SPARKLE method used to model the binding of Yb(III)-1,10-phenanthroline-5,6-dione. These studies shown that the chelating ligand selectively attaches to Yb(III) at two points in the membrane–solution interface.Figure optionsDownload high-quality image (52 K)Download as PowerPoint slideResearch highlights
► The results of the Mopac2009 calculations show selective complexation of Yb(III) by PDO ligand that correlate quite well with experimental data.
► The proposed sensor has a very fast response time.
► This electrode was applied as an indicator electrode in potentiometric titration for determination of Yb(III) and also for fluoride ions.
► The empirical selectivity coefficients are in agreement with the PM6/SPARKLE calculations.
► Among different cations, Yb(III) has the lowest ΔHr with PDO ligand.