pH-Driven Fluorescent Switch Behavior of Azometine Dyes in Solid Matrix Materials

Photoinduced switch behaviors of two dimethylamino-bearing azometine derivatives (AZM-I and AZM-II) were investigated in conventional solvents, polyvinyl chloride (PVC) and ethyl cellulose (EC) by means of absorption and emission spectroscopy. The fluorescence modulation of the molecular switches arises from increasing response of the exploited molecules to pH between pH=6.00 and 11.00 in emission intensity at 590 and 582nm. In the employed systems optical or chemical inputs are transduced into detectable spectroscopic outputs after the controlled exchange of protons between solution and membrane phases. In immobilized phases the attained reversible relative signal changes were very good; 97% and 99% for AZM-I and AZM-II respectively. Sensitivities of the molecular switches to most abundant anions and metal cations were also investigated. Except that of bicarbonate, Hg2+ and Ag+, presence of anions and metal cations in test medium did not restrict the proton sensing ability of the molecules.