Hg2+-selective ratiometric and "off-on" chemosensor based on the azadiene-pyrene derivative.

A new pyrene-based derivative bearing an azadiene group was synthesized as a ratiometric chemosensor for Hg(2+) in aqueous acetonitrile solution. The "off-on" type signaling behavior of the fluoroionophore is due to the metal ion induced conformational changes from the weak pyrene monomer emissions to strong pyrene excimer emission.

4'-[4-(Pyridin-2-yl)phen-yl]-2,2':6',2''-terpyridine.

In the title compound, C(26)H(18)N(4), each ring is almost planar with maximum deviation of 0.012 (5) Å. In the crystal, mol-ecules are stacked by weak C-H⋯π inter-actions, forming a three-dimensional framework.