Schiff base thin film materials for chloroform vapor detection

Abstract

Two novel Schiff base compounds, (E)-4-((4-(dimethylamino)benzylidene)amino)benzoic acid (DMPABA) and (E)-4-(2-(4-(dimethylamino)benzylidene)hydrazinyl)benzoic acid (DMPHBA), were synthesized to investigate for the vapor sensor behavior against chloroform vapor. DMPABA and DMPHBA thin films were fabricated using the spin coating method. A surface plasmon resonance system was employed to study the sensor response and the adsorption behavior. The Elovich model was chosen to determine the initial adsorption rate (a) and the Elovich desorption constant (b). Sensor response rates of DMPHBA and DMPABA thin films were determined to be 8.38 and 6.93, respectively. The a values of the DMPHBA and DMPABA thin films were calculated as 2775.97 and 1728.51 ppm mm-2, respectively. The b value (0.0373 mm2s ppm-1) of the DMPHBA thin film was lower than the b value (0.0602 mm2s ppm-1) of the DMPABA thin film. The DMPHBA film against chloroform vapor yielded a better performance than the DMPABA thin film. The chemical difference between the two materials is an & horbar;NH & horbar; group, which improved the sensor response and adsorption behavior.