One-pot preparation of pyrazole “turn on” and “turn off” fluorescent sensors for Zn2+ and Cd2+ directly from chalcones via in situ aromatisation

Abstract

A direct chalcone to pyrazole synthetic route to “turn on” and “turn off” fluorescent sensors for Cd²⁺ and Zn²⁺ was developed using CuCl₂ as an in situ oxidant. This one-pot approach produced eight novel pyridine based pyrazole fluorescent sensors displaying both “turn on” and “turn off” properties dependent on the substutient on the aryl ring (4-F, 4-Cl, 4-Br, 4-I, 4-CN, 4-NO₂, 4-OMe and 3,4-OMe). The results within provide valuable insight for future pyrazole sensor design.