Selective Detection of Dihydrogen Phosphate Anion by Fluorescence Change with Tetraamide-Based Receptors Bearing Isoquinolyl and Quinolyl Moieties

Novel fluororeceptors <b>2</b> and <b>3</b> based on tetraamide bearing 1-isoquinolyl and 2-quinolyl moieties were designed and synthesized. Highly selective and significant changes in the UV–vis and fluorescence spectra of the receptors upon the addition of H₂PO₄^– were found. In particular, receptor <b>3</b> bearing 2-quinolyl groups shows selective and nearly perfect quenching by H₂PO₄^–, whereas <b>3</b> shows small or no fluorescence changes by another anion