Gas sensors made from Langmuir-Blodgett films of porphyrins

Langmuir-Blodgett multilayer films of porphyrins have been produced and in-plane conductivity measurements performed on the samples when exposed to the toxic gases NO2, CO and H2S. A number of porphyrins showed a large and rapid increase in conductivity when exposed to NO2. The response of the samples varied with film thickness, the partial pressure of the gas, the central metal ion of the porphyrin and also with the peripheral substituents on the porphyrin ring.