Energetics of the rotational isomers of thiophenecarboxaldehydes in the ground state

► Infrared spectra of thiophenaldehydes have been measured in Ar matrices at 7 K. ► Utilizing photo-induced rotational isomerism, the two rotamers have been identified. ► Energy differences between the two rotamers of thiophenecarboxaldehydes were determined. ► The results are in excellent agreement with those obtained by Coupled Cluster calculation.