Fluorescence Fluoride Ion Sensor Utilizing Desilylation of N-Silylated 9- Aminoanthracene

Abstract

N,N-Bis(trimethylsilyl)-9-aminoanthracene (Si9AA) was synthesized by deprotonation of 9-aminoanthracne (9AA) with n-BuLi followed by the addition of trimethylsilyl chloride (TMSCl). Under ultraviolet, Si9AA showed blue fluorescence originated from the anthracene skeleton due to orthogonal relation between anthracene skeleton and bis(trimethylsilyl)amino group, which was determined by X-ray crystallographic analysis, while 9AA, in which conjugation exists between the anthracene and the amino group, showed green fluorescence. In a THF solution, Si9AA was converted to 9AA by desilylation of bis(trimethylsilyl)amino group with fluoride ion, which was contained in tetrabutylammonium fluoride (TBAF) or KF-18-crown-6 complex, resulting in fluorescence color change from blue to green. Si9AA was found to utilize as a sensor to detect fluoride ion in THF solution or on a thin layer chromatography (TLC) via the fluorescence color change without any metals, regarding a metal free fluorescence fluoride sensor in green chemistry.