Fluorescent asymmetric bis-ureas for pyrophosphate recognition in pure water

Abstract

Three fluorescent asymmetric bis-urea receptors (L1–L3) have been synthesised. The binding properties of L1–L3 towards different anions (fluoride, acetate, hydrogencarbonate, dihydrogen phosphate, and hydrogen pyrophosphate HPpi³⁻) have been studied by means of ¹H-NMR, UV-Vis and fluorescence spectroscopy, single crystal X-ray diffraction, and theoretical calculations. In particular, a remarkable affinity for HPpi³⁻ has been observed in the case L1 (DMSO-d₆/0.5% H₂O) which also acts as a fluorimetric chemosensor for this anion. Interestingly, when L1 is included in cetyltrimethylammonium (CTAB) micelles, hydrogen pyrophosphate recognition can also be achieved in pure water.