Fluorescent asymmetric bis-ureas for pyrophosphate recognition in pure water

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 HPpi 3− ) have been studied by means of 1 H-NMR, UV-Vis and fluorescence spectroscopy, single crystal X-ray diffraction, and theoretical calculations. In particular, a remarkable affinity for HPpi 3− has been observed in the case L1 (DMSO- d 6 /0.5% H 2 O) 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. Fluorescent asymmetric bis-ureas are able to recognize HPpi 3− in water.