TSQ

6-Methoxy-(8-p-toluenesulfonamido)quinoline (TSQ) is one of the most efficient fluorescent stains for zinc (II). It was introduced by Russian biochemists Toroptsev and Eshchenko in the early 1970's. The popularity of TSQ as physiological stain rose after seminal works by Christopher Frederickson two decades later. TSQ forms a 2:1 (Ligand-Metal) complex with zinc and emits blue light upon excitation at 365 nanometers (or 3.65 × 10-7 meters). TSQ has been extensively applied to study Zn(II) in mossy fibers of the hippocampus.