فهرست نشریات علمی دسترسی آزاد ایران

The effects of some structural changes on the anion-chalcogen interaction in dithieno[3,2-b;2′ ,3′-d]thiophenes (DTTs) as synthetic anion transporters were investigated using quantum-mechanical calculations in the gas phase and in CCl4, DMSO, and water. The σ-holes on the sulfur atoms of DTTs are responsible for enabling ion transport. The σ-hole depth of DTTs is significantly influenced by the type of bridge and the presence and positioning of electron-withdrawing substituents near the sulfur atoms. Compounds featuring an SO₂ bridge exhibit the strongest chalcogen interaction, while those with an NCH₃ bridge show the weakest. Moreover, the close arrangement of N and S atoms in DTTs reduces the electron density on the external surfaces of the sulfur atoms, thereby generating deeper σ-holes. Reducing the charge and aromaticity of the central ring, together with increasing the local minimum electrostatic potential on the bridge, leads to a deeper σ-hole and consequently a stronger chalcogen interaction. According to the energy decomposition analysis, stronger interactions are primarily electrostatic, while weaker interactions are governed mainly by exchange.