Conformational Landscape of Oxygen-Containing Naphthalene Derivatives

TL;DR

This study explores the conformational preferences of oxygen-containing naphthalene derivatives relevant to atmospheric chemistry using spectroscopy and quantum calculations, revealing how substitution position influences reactivity.

Contribution

It provides detailed conformational analysis of specific PACs, highlighting the effects of substitution location on molecular structure and reactivity, advancing understanding of atmospheric pollutants.

Findings

Intramolecular hydrogen bonding influences conformations.

Substitution position affects conformational energies.

Charge distribution explains conformational preferences.

Abstract

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.