Hazrah AS, Insausti A, Ma J, Al-Jabiri MH, Jäger W, Xu Y. Wetting vs Droplet Aggregation: A Broadband Rotational Spectroscopic Study of 3-Methylcatechol⋅⋅⋅Water Clusters.
Angew Chem Int Ed Engl 2023;
62:e202310610. [PMID:
37697450 DOI:
10.1002/anie.202310610]
[Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/13/2023]
Abstract
Two competing solvation pathways of 3-methylcatechol (MC), an atmospherically relevant aromatic molecule, with up to five water molecules were explored in detail by using a combination of broadband rotational spectroscopy and computational chemistry. Theoretically, two different pathways of solvation emerge: the commonly observed droplet pathway which involves preferential binding among the water molecules while the solute serves as an anchor point for the formation of a water cluster, and an unexpected wetting pathway which involves interactions between the water molecules and the aromatic face of MC, i.e., a wetting of the π-surface. Conclusive identification of the MC hydrate structures, and therefore the wetting pathway, was facilitated by rotational spectra of the parent MC hydrates and several H2 18 O and 13 C isotopologues which exhibit splittings associated with methyl internal rotation and/or water tunneling motions. Theoretical modelling and analyses offer insights into the tunneling and conversion barriers associated with the observed hydrate conformers and the nature of the non-covalent interactions involved in choosing the unusual wetting pathway.
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