In this work, a new imidazole-based sensitive and selective sensor was synthesized. It was observed that the synthesized new fluorescent sensor had high selectivity and sensitivity to Fe3+ ions. The association constant of the sensor was found by using Stern Volmer Plot as 14,318 M-1. Binding stoichiometry between sensor and Fe3+ ions was found by using Job's plot as 1:1. The synthesized chemical sensor was found to exhibit a large Stokes' shift (107 nm). The proposed turn-OFF mechanism regarding bonding between sensor and Fe+3 ions was discussed by NMR data and DFT calculations. Furthermore, it was revealed that planarity and functional groups such as methoxy and carbonyl affected the quantum yield. These results were confirmed by plotting of Frontier orbitals and calculated dihedral angles.