LAUSR

For the first time, we have reported the metal ion sensing behaviour of a fluorescent probe APAP (derivative of 4-amino/4-formyl antipyrine) along with its precursors (AAP-4-Aminoantipyrine, FAP-4-Formylantipyrine) and explained the tuning of precursors resulted in difference in the sensing behaviour. The two antipyrine precursors (4-amino/4-formyl antipyrine) were condensed together to form a new host molecule APAP, which acts an effective fluorescent chemosensor for detection of Fe3+ ions. The precursors AAP and FAP would able to detect Al3+ and Cr3+ ions respectively. The antipyrine precursors as well as the antipyrine derivative showed fluorescence response towards trivalent cations when treated with various metal ions in CH3OH:H2O (1:9, v/v) medium. Binding stoichiometry between APAP and Fe3+ ion was 1:1 from Jobs’ plot and the binding constant value was calculated as 5.3 × 105 M−1 by Benesi–Hildebrand plot. Addition of Na2EDTA to the [APAP-Fe3+] complex solution quenched the fluorescence emission, indicating the reversible nature of the probe. The binding of APAP with Fe3+ was based on restricted PET with CHEF process. Quantum mechanical studies using time dependent density functional theory (TDDFT) have also been carried out to understand the mechanism of Fe3+ binding mode with APAP probe. With respect to various pH, the probe APAP exhibited an AND molecular logic gate behaviour when H+ and Fe3+ ions were given as inputs.Graphical abstractFor the first time, the metal recognition property of a fluorescent probe along with its precursors was studied.