Perimedine-linked rhodamine dye in visual sensing of Al<sup>3+</sup>, Fe<sup>3+</sup> and Fe<sup>2+</sup> ions in aqueous organic medium under different experimental conditions MondalSubhendu GhoshKumaresh 2019 <p>Perimedine labelled rhodamine dye <b>1</b> has been designed and synthesised. Metal ion binding studies of <b>1</b> have been performed in CH<sub>3</sub>CN/H<sub>2</sub>O (3:1, v/v, 10 mM Tris-HCl buffer, pH = 6.90). Compound <b>1</b> senses multiple metal ions such as Al<sup>3+</sup>, Fe<sup>3+</sup> and Fe<sup>2+</sup> by exhibiting <i>turn on</i> fluorescence and colour change (colourless to pink) under different experimental conditions. Concentration variation distinguishes Al<sup>3+</sup> from Fe<sup>3+</sup> ion. At low concentration (<i>c</i> = 1 x 10<sup>−4</sup> M), only Al<sup>3+</sup> ion can exhibit <i>turn on</i> fluorescence with sharp colour change. Sensing of Fe<sup>2+</sup> ion through <i>turn on</i> fluorescence and colour change has been possible <i>via</i> in situ oxidation by following Fenton’s reaction.</p>