Zinc is one of the most common metal ions in biological systems. Small molecule sensors for it include:
*ZX1, a compound comprizing a dipicolylamine (DPA) Zinc binding subunit that has greater affinity for Zinc than other species found in solution such as Ca and Mg. 
*Zinpyr-1 (ZP1), a compound containing a dichlorofluorescein fluorescent compound bound to two 2-picolamine (DPA) species that bind Zn(II). ZP1 is part of a family of zinc sensors known as the Zinpyr series, the members of which are variants on ZP1 to enable specific affinities and fluorescence profiles.
*ZnAF-1 sensors that comprise an aryl donor and a xanthenone acceptor and have a large change in fluorescence upon binding Zn(II). They have been used to study uptake of Zn(II) in CA3 pyramidal neurons.