Inkjet-printed phosphorescent Iridium(III) complex based paper sensor for highly selective detection of Hg2+

Abstract First of its kind inkjet-printed phosphorescent Iridium(III) complex [Ir(TPQ) 2 (4-EO 2 -pic)] paper based chemosensor has been developed for Hg 2+ ions. The probe is highly selective towards mercury analyte over other metal ions (Cu 2+ , Ca 2+ , Co 2+ , Cd 2+ , Pb 2+ , Zn 2+ , Ni 2+ , Mg 2+ , Mn 2+ , Al 3+ , Fe 3+ , La 3+ , Ag + , K + , Na + and Li + ). [Ir(TPQ) 2 (4-EO 2 -pic)] complex solution gave a visible color change from orange to yellow and significant phosphorescence quenching. Upon addition of aqueous Hg 2+ , the [Ir(TPQ) 2 (4-EO 2 -pic)] inkjet-printed paper gave a significant color change in both normal and UV light. The detection limit was found out as 1.78 × 10 −8  M. Cyclic voltammetry (CV) studies were conducted to explore the further utility of [Ir(TPQ) 2 (4-EO 2 -pic)] as electrochemical sensor for Hg 2+ ions in CH 3 CN/H 2 O (v/v = 1/1). The oxidation wave intensity of [Ir(TPQ) 2 (4-EO 2 -pic)] at 0.98  V decreased and new reversible oxidation wave was appeared at 0.91  V The binding ratio of the [Ir(TPQ) 2 (4-EO 2 -pic)]-Hg 2+ complex was determined to be 1:1 according to the Job's Plot. The probable binding modes of these [Ir(TPQ) 2 (4-EO 2 -pic)] with Hg 2+ have also been suggested on the basis of the 1 H NMR titration, absorption and luminescence studies.