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A new chromene pyrazoline derivatives fluorescent probe L was designed and synthesized. The probe L appears in a 55-fold fluorescence enhancement after 5 equiv. Zn 2+ was added, and it also exhibits high sensitivity and selectivity for response to Zn 2+ in ethanol-water (V:V = 1:1) solution through “OFF-ON” type process and a possible photoinduced electron transfer (PET). Notably, the probe L distinguishes between Zn 2+ and Cd 2+ . The association constant was considered as 2.38 × 10 3  M −1 via fluorescence titration experiments. The probe L-Zn 2+ complex forms a 1:1 binding stoichiometry which was discussed by Job’s plot. The probe is very highly sensitive with fluorometric detection limit of 1.603 × 10 −10  M. It also shows good reversibility upon addition of EDTA. Furthermore, the viability of L to Zn 2+ has practical application in live cell imaging. [ABSTRACT FROM AUTHOR]

Abstract: Six lanthanide nitrato complexes [Ln=La (1), Nd (2), Eu (3), Gd (4), Tb (5), Er (6)] with a tridentate salicylamide-type ligand, 2-(2-(diisopropylamino)-2-oxoethoxy)-N-(pyridin-2-ylmethyl)benzamide (L), have been synthesized. All complexes were characterized by elemental analysis, IR, TGA and conductivity measurements. The structures of 2, 3 and 4 were determined by X-ray single-crystal diffraction and their general formulae were shown to be [LnL(NO3)3(H2O)]·CH3CN. These data indicate the tridentate salicylamide-type ligand could effectively chelate the lanthanide ions to conform to a 1:1 metal-to-ligand stoichiometry. The luminescence properties of the europium and terbium complexes were also investigated. [Copyright &y& Elsevier]