Simple pyrazoline and pyrazole turn on fluorescent sensors selective for Cd2+ and Zn2+ in MeCN

An efficient two-step synthesis of pyrazoline ligand 1 is described which is an effective turn on fluorescent sensor for Cd2+ in MeCN. Oxidation to the corresponding pyrazole ligand 2 creates a turn on fluorescent sensor now selective for Zn2+ and able to distinguish it from Cd2+.