Infrared Spectroscopy of Neutral and Cationic Benzonitrile-Methanol Binary Clusters in Supersonic Jets

The formation of nitrogen-containing organic interstellar molecules is of great importance to reveal chemical processes and the origin of life on Earth. Benzonitrile (BN) is one of the simplest nitrogen-containing aromatic molecules in the interstellar medium (ISM) that has been detected in recent years. Methanol (CH₃OH) exists widely in interstellar space with high reactivity. Herein, we measured the infrared (IR) spectra of neutral and cationic BN-CH₃OH clusters by vacuum ultraviolet (VUV) photoionization combined with time-of-flight mass spectrometry. Combining IR spectra with the density functional theory calculations, we reveal that the BN-CH₃OH intends to form a cyclic H-bonded structure in neutral clusters. However, after the ionization of BN-CH₃OH clusters, proton-shared N···H···O and N···H···C structures are confirmed to form between BN and CH₃OH, with the minor coexistence of H-bond and O-π structures. The formation of the proton-shared structure expands our knowledge of the evolution of the life-related nitrogen-containing molecules in the universe and provides a possible pathway to the further study of biorelevant aromatic organic macromolecules.