Highly Selective Colorimetric Chemosensor for Co²⁺

A new highly selective colorimetric chemosensor for Co²⁺ was developed based on coumarin-conjugated thiocarbanohydrazone. The ligand senses Co²⁺ in solution by changing its color from light yellow to deep pink. The sensor has been used in the development of practically viable colorimetric kits and as a staining agent for Co²⁺ in microorganisms.