A highly selective ratiometric bifunctional fluorescence probe for Hg2+ and F- ions

A triarylborane derivative BN-S, which contains a Hg2+-responsive dithioacetal group and a F--responsive boryl group, has been designed and synthesized via the functionalization of 2-dimesitylboryl-2'-( N, N-dimethylamino) biphenyl core skeleton with a dithioacetal substituent. This compound displays intense intramolecular charge transfer fluorescence, even for its nano-aggregates in water. The Hg2+-promoted deprotection of the dithioacetal group and complexation of F- with the tri-coordinate boron center cause hypochromism of fluorescence to different extents. And thus BN-S behaves as a promising ratiometric bifunctional fluorescence probe to detect Hg2+ and F- simultaneously. In addition, the detection of Hg2+ is performable in aqueous medium using its nano-aggregates.