Chlorophyll a and pheophytin a as gas sensors of CO2 and O2 molecules

The electronic and structural properties of porphyrin derivatives, such as chlorophyll a and pheophytin a, in pristine form and interacting with molecules of CO2 and O2 are investigated through ab initio calculations. Both chlorophyll a and pheophytin a can adsorb molecules of CO2 and O2 with binding energies around 0.2 eV indicating a physisorption regime. Modifications in the electronic properties of the resulting systems have been observed. These results are a consequence of the molecular levels of hybridization between the gases and the porphyrin molecules. Thus, these results open some possibilities to use those pigments as gas sensors.