Effects of fluorination in the ring of zinc tetraphenylporphyrin on its gas-response to volatiles at room temperature

Comparative tests were carried out on the gas-sensing properties of the evaporation films of zinc tetraphenylporphyrin and its fluorinated derivative [zinc-meso-tetra (2,3,4,5,6-pentafluorophenyl)-porphyrin] to some volatiles (ammonia, trimethylamine, triethylamine, methanol, ethanol, and formaldehyde) at room temperature. Experimental results indicated that the gas responses and the response rates of the films strongly depended upon the species of volatiles and the fluorination modification. Although the fluorination affected the response to trimethylamine slightly, the response magnitude and speed to ammonia increased dramatically after the fluorination. The response magnitude could increase by four orders of magnitude within 1 min, and the response speed was enhanced by more than 30 folds. On the contrary, the responses to triethylamine, ethanol, methanol, and formaldehyde decreased. Moreover, the fluorinated films showed good reversibility even at room temperature by the purge with highly pure N2.