for the transformation from ground state to defected state. Whereas pyrene retains some of its symmetry due to the symmetry exhibited by the Stone-Wales defect itself, coronene loses much more of its symmetry. The formation of these (5,7)-ring defects in PAHs may be well supported in asymptotic giant branch stars or planetary nebulae. Those environments strongly enable the transition from the ground state to the defect state. Therefore the knowledge of the IR spectra of these molecules will support future investigations aiming for a thorough understanding of the unidentified IR emission bands. ]{}

Introduction
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Polycyclic aromatic hydrocarbons (PAHs) are one of the most interesting components of the interstellar medium (ISM). The infrared (IR) spectra of different astronomical objects like HII regions, photodissociation regions (PDRs) or asymptotic giant branch (AGB) stars and planetary nebulae (PNe) are dominated by emission features in the region between 3.3 - 18${\mu}$m (Peeters [@peeters], Draine & Li [@draine]). It is thought that PAHs are also carriers of these diffuse interstellar bands, the so called DIBs (Tielens [@tielens]). But different from laboratory - the isolation of a single species is not possible. The spectra contain a superposition of many different molecules. Therefore a sophisticated understanding of 