Alcohol gas sensors based on magnesium tetraphenyl porphyrins

Metallo-porphyrins thin films have been demonstrated as optical gas sensors for detecting various kinds of gases. In this work, magnesium 5,10,15,20-tetraphenyl porphyrin (MgTPP) thin films were prepared by spinning the solution using chloroform as solvent onto clean glass substrates, then subjected to a thermal annealing at 280°C in the argon atmosphere. These MgTPP optical gas sensors have higher responses with methyl alcohol than ethyl alcohol based on dynamic flow of alcohol vapors at 25°C. Quantum mechanical calculation based on density functional theory has found that the interaction energy between MgTPP with methyl alcohol is higher than ethyl alcohol. Principal component analysis (PCA) was used to classify the data from the optical absorbance spectra into three groups of alcohols, which are MeOH (100%), EtOH (100%) and a mixture of MeOH (50%) and EtOH (50%). From these results, MgTPP thin film can be an efficient sensing material to discriminate alcohols.