Schiff-base as highly sensitive and reversible chemosensors for HCl gas

Two optochemical sensors based on Schiff-bases doped polymethyl methacrylate (PMMA) films were obtained. The gas sensing behavior of the sensors were investigated with respect to the detection of HCl gas by absorption and fluorescence spectra at room temperature. The detection method is based on the protonation of Schiff-bases by HCl gas. It was found that two sensors exhibited good response, reversibility and stability to HCl gas. The color changes of sensors upon protonation are obvious, which can be observed with naked-eye. The changes of the spectra are likely due to increase in planarity of the molecular framework, which has been confirmed by quantum chemical calculation.