Novel polycyclic "turn-on" and "turn-off" pyrazoline and pyrazole fluorescent sensors for selective real-world monitoring of Fe/Fe in aqueous environments.

Seven novel polycyclic pyrazoline and pyrazole sensors were synthesised and screened for useful photophysical properties with pyrazoline 2 and pyrazole 7, displaying an Fe "turn-off" response in aqueous environments with Fe limits of detection (LoD) of 2.12 μM and 3.41 μM, respectively.

Novel pyrazoline and pyrazole "turn on" fluorescent sensors selective for Zn/Cd at 480 nm and Fe/Fe at 465 nm in MeCN.

A small series of simple pyrazoline and pyrazole based sensors, all derived from the same chalcone precursors, were synthesised, characterised and screened for their fluorescence "turn on" properties in the presence of multiple metals. Pyrazole 8 displayed an excellent fluorescence profile with approx. 20× fold increase in 480 nm with Zn compared to a 2.