Fluorescence quenching of 6-methoxyquinoline: an indicator for sensing chloride ion in aqueous media

The quenching of fluorescence intensity and decay time of protonated form of 6-methoxyquinoline (6MQ+) with chloride ion (Cl−) in aqueous solution at ambient temperatures have been investigated. The quenching follows linear Stern–Volmer relation. The values of Stern–Volmer quenching constant/quenching efficiency (Ksv) and quenching rate constant (Kq) for the Cl− ion are close to 75 M−1 and 3.21×109 M−1 S−1, respectively. The quenching is found to be collisional or dynamical in nature. The study reveals that the system can be used as a sensor for the detection of chloride ion.