The design and synthesis of artificial receptors capable of binding and sensing anions have been widely explored in the field of host-guest chemistry. Herein, a series of acyclic ferrocene-based imidazolium receptors 3a~3e were designed and synthesized. All the receptors were prepared by reactions of 1-(ferrocenylmethylene)imidazole 1 with corresponding dibromides in solvent under refluxing, followed by anion exchanges with NH 4 PF 6 . The structures of all the products were determined by IR, 1 H NMR, 13 C NMR, MS and elemental analysis. The crystal structure 3e was confirmed by X-ray crystallography, and it was clear that molecules were linked by C-H…F hydrogen bonds interactions. The interaction between these receptors and various anions was studied by electrochemical measurements and 1 H NMR spectroscopy. The receptors 3a~3e were proven to be highly selective and sensitive to F -. 1 H NMR titrations demonstrated that the receptors and anions form 1∶ 1 complex, and the receptors displayed a strong (C-H) + …X -in anion recognition. Receptor 3c was the most effective receptor to bind with fluoride ion compared to the others.
and the effect of reaction time of 5 min and 10 min respectively. However, there is no selectively responds to other anions. Using NMR titration and theoretical (B3LYP/6-31G (d, p)) methods further confirmed the hydrogen bond acceptor molecules and anions.
In this work, we reported a simple coumarin-boronic acid ester fluorescent probe 1, which displayed very high "ON-OFF" fluorescence response for Hg 2+ in an aqueous environment (H 2 O/CH 3 CN = 1:1, v/v) or in a PBS solution (pH = 7.4). With the addition of Hg 2+ to the solution of probe, a color change from light yellow to orange could be observed by naked eye. The detection limits were lower than Scheme 1. The synthesis procedure of probe 1.
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