Continuous and precise recognition of N2H4 and Cu2+ has been achieved using chalcone derivatives as a D-A-D΄-type fluorescent chemical sensor

[Display omitted] •Applying the ICT mechanism to enhance the sensitivity of probe FZ in detecting N2H4.•FZN could be further developed into a novel Cu2+ fluorescence probe.•The LOD was down to 3.39 × 10-8 M for N2H4 and 1.47 × 10-8 M for Cu2+.•The probe had been successfully developed into a TLC test plate for practical detection of Cu2+. A fluorescent probe, FZ, based on the ESIPT and ICT mechanisms was designed. It transformed from a ratio probe to a fluorescence turn-on probe using the properties of the ICT mechanism, enhancing the sensitivity for detecting N2H4. The calculated detection limit was 3.39 × 10-8 M. The existence of intramolecular hydrogen bonds between O–H and C = O was confirmed through single crystal structure analysis. Additionally, taking advantage of the structural features of FZN generated from the reaction of FZ with N2H4, it was developed into a new quenching-type Cu2+ fluorescent probe with a detection limit of 1.47 × 10-8 M, achieving high sensitivity and selectivity for Cu2+ detection. Furthermore, it was adapted into a fluorescence TLC testing plate for detecting trace amounts of Cu2+ in the environment, demonstrating its potential applicability in Cu2+ detection.