Terthiophene as a model sensor for some atmospheric gases: theoretical study

ABSTRACT

We use density functional theory (DFT) to assess the ability of terthiophene (as a simplest model of polythiophene, denoted as TTP) for detecting of atmospheric gases. Specifically, at the ωB97XD/6-31G(d,p) level of theory, the sensitivity of TTP towards CO, CO₂, SO₂ and CH₃OH is investigated. To better understand the electronic properties of interacting TTP, natural-bond-orbital (NBO) and density-of-states (DOSs) analyses are performed for TPP in free mode and interacted form with the above molecules. The types of interactions between these species with TTP were studied in terms of the HOMO and LUMO energies. UV-Vis spectra are calculated for all systems and the data shows that the λ_max values are red or blue shifted depending on the analyte, which are proving for successfully interaction. The calculated interaction energies are ?16.7, ?14.3, ?8.2 and ?5.3 kJ/mol for TTP-CH₃OH, TTP-SO₂, TTP-CO₂ and TTP-CO, respectively.