Molecular insights into odorant recognition: Rotational and docking studies of 3-methylcyclopentane-1,2-dione and its monohydrate

The binding behavior of 3-methylcyclopentane-1,2-dione, a cyclic α-diketone with a caramel-like aroma, was investigated to elucidate molecular mechanisms of olfactory recognition. Using Fourier-transform microwave spectroscopy complemented with quantum chemical calculations, the structures of 3-methylcyclopentane-1,2-dione and its monohydrate were determined, revealing the preferred conformation of the monomer and structural changes upon complexation with water. Intramolecular hydrogen bond weakening was observed, indicating significant rearrangements, as further supported by non-covalent interaction and quantum theory analyses. Molecular docking demonstrates how these structural adaptations facilitate ligand-protein interactions, providing a microscopic framework for understanding diketone binding within odorant-binding proteins.