Spectroscopic and theoretical studies of some 2-(2′-ethylsulfanyl)acetyl-5-substituted furans and thiophenes

•Calculations for 1-5 predict three antiperiplanar and three synperiplanar conformers.•IR doublets of 1-5 in solution indicate at least two conformers.•The antiperiplanar conformers are more stable for compounds 1 and 2.•The synperiplanar conformers are more stable for compounds 3-5.•Molecular dynamics and PCM were employed to simulate solvent effects.•Conformer stability is controlled by electrostatic and orbital interactions.