Sulfur Centered Hydrogen Bonding in Thioglycolic Acid and Its Clusters: A Computational Exploration

The conformational landscape of thioglycolic acid (TGA) was investigated by using the CCSD/cc-pVTZ level of theory. The GGC conformer was identified as the global minimum, followed by the GAC conformer. The calculated rotational constant for the GGC conformer exhibited good agreement with the previously reported experimental results. Subsequently, the study delved into the exploration of sulfur-centered hydrogen bonding in TGA's dimer and trimer clusters, employing the CCSD/cc-pVDZ level of theory. These clusters revealed the participation of both oxygen and sulfur atoms in noncovalent H-bonding, contributing to their stability. The presence of these noncovalent interactions in TGA clusters was elucidated through Atoms in Molecule (AIM), reduced density gradient (RDG), and natural bond order (NBO) analysis, while electrostatic potential (ESP) charge and vibrational mode analysis further supported these findings.