Quantum Tunneling Fingerprints of Chirality-Induced Symmetry Preferences in Methyl Lactate Dimer

Methyl lactate, a chiral molecule with multiple functional groups, has played a pivotal role in advancing experimental and theoretical chiroptical methods. Leveraging conformer-specific jet-cooled rotational spectroscopy in tandem with extensive conformational searches and quantum chemical calculations, we investigated chirality self-recognition in the methyl lactate dimer. The experimental fingerprint-like spectral patterns, including methyl rotor tunneling splittings, allowed the definite identification of one heterochiral and two homochiral binary conformers from a large number of low-energy candidates. Nuclear spin statistics analyses and methyl internal rotor parameters reveal different nuclear tunneling dynamics in the homochiral versus heterochiral environments and highlight the associated chirality-driven symmetry preference in the observed conformers. The results provide comprehensive experimental data for benchmarking quantum chemical calculations of chiral properties and pave the way for the exploration of this prototypical dimer across different frequency ranges using other spectroscopic tools.