Hybridization of quinacridone and synthetic hectorite and the photoluminescence quenching by metal ions

Quinacridone, a red pigment, was hybridized with a synthetic hectorite by a mechanochemical reaction. Though quinacridone was not photoluminescent , the products were photoluminescent and the photoluminescence quantum yield was 0.89 when the dye loading was 0.00009 g dye/g clay. The product was dispersed in water to give stable suspensions with varied viscosities depending on the concentration of the hybrids. The photoluminescence of the aqueous suspension was quenched by Cr 3+ , Co 2+ , Cu 2+ , Fe 2+ , Ni 2+ and Pb 2+ as described by linear Stern-Volmer plots at the concentration of 1–600 ppm. Among the tested metal ions , Cr 3+ gave the most efficient quenching (the K SV value of 0.0125). The quenching of the photoluminescence of the quinacridone-synthetic hectorite hybrid was applicable to detect Cu 2+ and Cr 3+ at ppb level.