A new Hg2+ colorimetric chemosensor: the synthesis of chromeno[d]pyrimidine-2,5-dione/thione derivatives using Fe3O4@SiO2@(BuSO3H)3

The synthesis of chromeno[ d ]pyrimidine-2,5-dione/thione derivatives has been described by the reaction of aryl aldehydes, urea/thiourea, and 4-hydroxycoumarin using Fe 3 O 4 @SiO 2 @(BuSO 3 H) 3 as catalyst under microwave irradiation (MWI) in H 2 O. The sensing application of 4-(4-chlorophenyl)-3,4-dihydro-1 H -chromeno[4,3- d ]pyrimidine-2,5-dione 4b was examined upon addition of different cations by UV–Vis spectroscopy and exhibited excellent sensitivity towards Hg 2+ ions by increasing the absorption. The UV–visible absorption spectral data showed good linearity between the UV–Vis absorption of chemosensor 4b and the concentration of Hg 2+ with a detection limit of 3.76 × 10 –7 M. Furthermore, the chemosensor 4b exhibited an obvious color change from white to light pink in the presence of Hg 2+ in EtOH solution. Graphic abstract