  Polycyclic aromatic compounds (PACs) constitute an important class of
molecules found in various environments and are considered important pollutants
of the Earth's atmosphere. In particular, functionalization of PACs modify the
ring aromaticity, which greatly influences the chemical reactivity of these
species. In this work we studied several oxygen-containing PACs, relevant to
atmospheric chemistry. We investigated the conformational landscape of four
naphthalene-derivative molecules -- namely ,1- and 2-hydroxynaphthalene and 1-
and 2-naphthaldehyde -- by means of rotational and vibrational spectroscopy
supported by quantum chemical calculations. For 1-hydroxynaphthalene and
1-naphthaldehyde, intramolecular hydrogen bonding and steric effects drive the
conformational preferences while for 2-hydroxynaphthalene and 2-naphthaldehyde,
the charge distributions allow us to understand the conformational landscape.
This work not only demonstrates how the localization of the substitution group
in the ring influences the conformational relative energies and but also
constitutes a step toward a better understanding of the different chemical
reactivity of such functionalized PACs.
