Fabrication of Langmuir–Blodgett thin films of porphyrins and investigation on their gas sensing properties

In the present study, we report about the Langmuir–Blodgett thin film fabrication and gas sensing properties of metal free 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine and its derivatives containing iron chloride, cobalt and magnesium. The isotherm graphs are recorded to investigate the optimum conditions for the thin film deposition. Gas sensing performances of these thin films for volatile organic compounds (VOCs) including chloroform, benzene, toluene and ethyl alcohol are studied using quartz crystal microbalance (QCM) technique. The experimental results showed that these materials are suitable to produce a sensing layer for VOCs compounds. The best response was recorded against toluene vapour for all thin films where the dominating effects for gas sensing mechanism was considered as interaction between the central metal atom and conjugated π electron system.