An halogen anions sensor based on the hydrophobic entrapment of a fluorescent proble in silica sol-gel thin film

A halogen anion (Cl−, Br−, I−) sensor has been designed, based on the entrapment of a fluorescent molecule in a sol-gel silica film deposited on a glass substrate. A key factor is the use of the newly synthesized hydrophobic fluorophore, N-dodecyl-6-methoxyquinolinium, so as to avoid the problem of leaching. This probe allows detection and measurement of chloride concentrations in the physiological range (100 mM) coupled with a response time less than 1 s. The fluorescence quenching data are fitted to a model which assumes two quenching sites.