A highly selective ratiometric bifunctional fluorescence probe for Hg(2+) and F(-) ions

A triarylborane derivative BN-S, which contains a Hg(2+)-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 Hg(2+)-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 Hg(2+) and F(-) simultaneously. In addition, the detection of Hg(2+) is performable in aqueous medium using its nano-aggregates.