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-EO2-pic)] paper based chemosensor has been developed for Hg2+ ions. The probe is highly selective towards mercury analyte over other metal ions (Cu2+, Ca2+, Co2+, Cd2+, Pb2+, Zn2+, Ni2+, Mg2+, Mn2+, Al3+, Fe3+, La3+, Ag+, K+, Na+ and Li+). [Ir(TPQ)2(4-EO2-pic)] complex solution gave a visible color change from orange to yellow and significant phosphorescence quenching. Upon addition of aqueous Hg2+, the [Ir(TPQ)2(4-EO2-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-EO2-pic)] as electrochemical sensor for Hg2+ ions in CH3CN/H2O (v/v = 1/1). The oxidation wave intensity of [Ir(TPQ)2(4-EO2-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-EO2-pic)]-Hg2+ complex was determined to be 1:1 according to the Job's Plot. The probable binding modes of these [Ir(TPQ)2(4-EO2-pic)] with Hg2+ have also been suggested on the basis of the 1H NMR titration, absorption and luminescence studies.