A New Sensitive and Selective Off-On Fluorescent Zn2+ Chemosensor Based on 3,3',5,5'-Tetraphenylsubstituted Dipyrromethene

A New «off-on» Fluorescence Zinc Ion Sensors Based on Iodo- and Bromosubstituted Dipyrromethenes

Monoiodo- and dibromsubstituted dipyrromethenes HL¹ - HL³ were described as a highly sensitive and selective «Off-On» fluorescent chemosensor for Zn²⁺ based on the chelation-enhanced fluorescence (CHEF) effect. Сoordination reactions of HL¹ - HL³ with Zn²⁺ cations are accompanied by a significant (124 to 215-fold) increase in fluorescence intensity against the background of other metal ions in the binary propanol-1/cyclohexane mixture (1:30). The fluorometric detection limit of Zn²⁺ ions using HL¹ - HL³ sensors is from 3.0∙10^-8 to 3.3·10^-9 mol/L. The presence of Na⁺, K⁺, Ca²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Co²⁺, Pb²⁺ cations does not interfere with the detection of Zn²⁺. Complexation reactions are accompanied by a visual change in the color of the solution from yellow-orange to pink-raspberry so that the HL¹ - HL³ ligands can also be used as a «naked-eye» indicators of the presence of Zn²⁺ ions.

A new 1,2,3-triazole-decorated imino-phenol: selective sensing of Zn2+, Cu2+ and picric acid under different experimental conditions

A new 1,2,3-triazole-based imino-phenol 1 is synthesized. It selectively senses Zn²⁺ in CH₃CN–H₂O with a detection limit of 1.8 × 10⁻⁶ M. Further, the selective sensing of Cu²⁺ and picric acid is achieved by the ensemble 1.Zn²⁺ in CH₃CN–H₂O.

A ‘turn-on’ fluorescent chemosensor for the detection of Zn2+ ion based on 2-(quinolin-2-yl)quinazolin-4(3H)-one

2-(Quinolin-2-yl)quinazolin-4(3H)-one (Q) was synthesized via the Brønsted acid-promoted tandem cyclization/dehydrogenation reaction with a good yield. Compound Q is a selective ‘turn-on’ fluorescent sensor for Zn2+ ion without interference by Cd2+. The 1:1 binding model of Q to Zn2+ was confirmed by the Benesi-Hildebrand analysis, Job’s plot analysis and a ultraviolet-visible (UV-Vis) titration experiment. Furthermore, the light-on fluorescent response can be observed by the naked eye under UV-lamp irradiation (365 nm).