Influence of substitution patterns on isomer preference in 1 : 1 chromone-methanol complexes.

The cluster formed by chromone and methanol serves as an excellent model for studying the various contributions to intermolecular interaction energy. The asymmetric ketone motif of chromone provides distinct hydrogen-bonding sites, enabling differentiation between an "inside" and an "outside" isomer using infrared spectroscopy. We employ DFT simulations to assess how functional groups influence the balance between the two isomers and to identify derivatives that switch their isomer preference upon electronic excitation. We identify three mono-substituted and four doubly substituted chromone derivatives that meet these criteria. Additionally, the contributions to intermolecular interactions are examined using the local energy decomposition method.