New fluorescent zinc complexes: towards specific sensors for hydrogen sulfide in solution.

Two new fluorescent zinc complexes 1 and 2 have been synthesized by reaction of the complex Tp(Ph,Me)Zn(OH) with 7-hydroxy-4-methylcoumarin (MUH) or 7-mercapto-4-methylcoumarin (MUSH). While the alcoholato derivative Tp(Ph,Me)Zn(MU) 1 is not efficient for sensing hydrogen sulfide, the thiolato complex Tp(Ph,Me)Zn(MUS) 2 is a colorimetric "turn-on" and fluorescence "turn-off" sensor which shows high selectivity for hydrogen sulfide in the presence of additional thiols like cysteine or glutathione.