Study on the binding ability of cobalt-porphyrin with small volatile organic compounds based on density functional theory

Abstract

A colorimetric sensor array is a rapid and high sensitivity sensor for the detection and identification of volatile organic compounds. Theoretical investigations are performed to study the binding ability of the colorimetric sensor array with volatile organic compounds. Cobalt-porphyrin is selected to investigate the binding ability of the colorimetric sensor array with small volatile organic compounds. The binding energy of cobalt-porphyrin with small volatile organic compounds, such as O₂, N₂, H₂S, trimethylamine, propanol, propane, ethyl acetate, butanone and so on, is investigated using density functional theory (DFT) methods at three different spin multiplicities: low-spin (singlet), intermediate-spin (triplet) and high-spin (quintet) states. The relative and absolute binding energies of all the complexes are obtained at the optimized geometries. The triplet state is found to have the lowest energy for the CoP–O₂ complex, whereas the singlet state has the lowest energy for the other complexes. The binding energies for the complexes considered are in order starting from the lowest energy state: H₂S < propane < O₂ < N₂ < ethyl acetate < butanone < propanol < trimethylamine. This theoretical result can be used to optimize the sensor to increase the detection ability of the colorimetric sensor array.