Perimidine Derivative as a Colorimetric/fluorescence turn-on Sensor for Fe³⁺: Smartphone-assisted Sensing and...

A novel perimidine derivative: 2-(isoquinolin-1-yl)-1H-perimidine (sensor 1) was synthesized via a facile, one-step reaction between DAN (1,8 diaminonaphthalene) and 2- quinolinecarboxaldehyde. The as-synthesised sensor 1 was found to be stable under a wide pH range of 2-12, and it behaved as a colorimetric as well as fluorescence turn-on sensor for Fe³⁺ with a response range varying from 0 to 200 µM. The fluorescence titration profile was used to calculate the binding constant as 1.3 × 10⁴ M^-1 and the LOD was as low as 7.4 nM. Additionally, the interference studies revealed the capability of 1.Fe³⁺ complex to sense Cu²⁺, which was accompanied by the fluorescence turn-off response. The binding constant and detection limit of 1.Fe³⁺ complex for Cu²⁺ were calculated to be 1.44 × 10³ M and 1.13 × 10^-7 M, respectively. The Fe³⁺ induced fluorescence enhancement at different concentrations was also recognized via smartphone, which could benefit in resource-limited areas and could be used as an alternative for complex instrumentation.