Computational investigation on the molecular and electronic structure of the interaction of thiophene with various toxic gases

Abstract

Density functional theory calculations were used to examine adsorption of carbonyl fluoride (COF₂), cyanogen chloride (CNCl), and boron trifluoride (BF₃) on thiophene using B3LYP/6-31+G(d) and ωB97XD/6-31+G(d). All complexes exhibit weak exothermic adsorption consistent with physisorption. Counterpoise-corrected interaction energies at B3LYP are −2.259, −3.389, and −4.730 kJ/mol for COF₂, CNCl, and BF₃, respectively; corresponding ωB97XD values are −11.970, −10.042, and −16.736 kJ/mol. Adsorption changes the dipole moment of thiophene from 0.5469 D to 1.2527, 3.4267, and 0.6534 D, respectively. COF₂ reduces the calculated HOMO–LUMO gap from 5.97 to 5.131 eV, whereas CNCl and BF₃ yield gaps of 5.972 and 6.00 eV. Mulliken and natural bond orbital analyses indicate small intermolecular charge transfers, and the calculated desorption times are short under the assumed conditions. BF₃ has the strongest calculated binding, while COF₂ produces the largest orbital-gap response. These molecular-level predictions support further investigation of thiophene-based materials for toxic-gas sensing, although device performance requires experimental validation.

KEY WORDS: Thiophene, Toxic gases, Density functional theory, Interaction energy, Charge transfer, Molecular orbitals

Bull. Chem. Soc. Ethiop. 2027, 41(1), 219-238.                                                                                       

DOI: https://dx.doi.org/10.4314/bcse.v41i1.15