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A colorimetric and fluorescent 'on-off' chemosensor 1 was developed for the selective and sensitive detection of Cu2+ over the other examined metal ions. Upon addition of Cu2+, sensor 1 exhibits moderate enhancement in the absorbance intensity with a naked-eye detectable colour change from colourless to yellow in DMSO/H2O (50:50, v/v). Also, the emission of 1 was selectively quenched in the presence Cu2+ with fast response and the detection limit was found to be 50 nM. [ABSTRACT FROM AUTHOR]

A new fluoride selective fluorescent receptor (13E,19E)-N1',N3'-bis[4-(diethylamino)-2-hydroxybenzylidene]malonohydrazide (1) was designed and synthesized. Receptor 1 showed a highly selective fluorescent 'turn-on' response towards F- among the various tested anions such as F-, Cl-, Br-, I-, HSO4-, H2PO4-, NO2- and CN- in CH3OH:H2O (50:50, v/v), due to the formation of hydrogen bonding host-guest complex in 1:1 stoichiometry with a detection limit of 45.7 nM and association constant of 1.0 x 104 M-1. The nature of interactions between the receptor 1 and F- was investigated by ¹H NMR and the probable structure of the 1⋅F- complex was predicted by B3LYP/6-31G** method. [ABSTRACT FROM AUTHOR]