New Heteropolycyclic Structures for Fluoride Anion Sensing by Naked-Eye Visualization

Fluoride anion (F-) plays an important and fundamental role in chemical, biological, pathological, and environmental processes. It is highly desired to develop new methods for facial and efficient F- detection. Herein we present the synthesis and characterization of two effective fluoride ion probes and their selective F- sensing by naked-eye visualization. A N-heteroannelated anthraquinone derivative, compound I, was prepared by a cyclocondensation reaction of 1,2-diaminoanthraquinone with 1,6-bis(triisopropylsilyl)-hexa-l,5-diyne-3,4-dione. Compound I was treated with malononitrile in the presence of Lehnert reagent to afford an HCl adduct, compound II, and an aza-polycyclic aromatic compound III. All three compounds were characterized crystallographically and were studied photochemically. Similarly, 2,3-diamino-1,4-anthraquinone reacted with 1,6-bis(triisopropylsilyl)-hexa-l,5-diyne-3,4-dione to afford compound IV, which reacted with malononitrile in the presence of Lehnert reagent to yield compound V. Compounds III and V are sensitive and selective probes for the detection of F- with significant color changes. The detection by naked eye visualization is rapid and facile, showing both compounds are potential probes for fluoride ion sensing.