Rotational barriers in azobenzene and azonaphthalene

Area of Science:

• Computational Chemistry
• Physical Organic Chemistry
• Spectroscopy

Background:

• Theoretical predictions of rotational barriers for pi-conjugated aromatic substituents can deviate significantly from experimental values.
• Accurate prediction of these rotational barriers is crucial for understanding molecular conformation and reactivity.

Purpose of the Study:

• To investigate the accuracy of Density Functional Theory (DFT) in predicting rotational barriers for benzaldehyde, azobenzene, and azonaphthalene.
• To explore the conformational landscape of azonaphthalene and identify unique minima and their associated rotational barriers.

Main Methods:

• Utilized DFT calculations with a diverse range of exchange-correlation functionals.
• Employed various basis sets to assess their impact on rotational barrier predictions.
• Identified and characterized multiple unique minima for the azonaphthalene system.

Main Results:

• DFT calculations for benzaldehyde and azobenzene align with previously reported theoretical findings.
• Discovered 10 unique minima and their corresponding rotational barriers for azonaphthalene.
• The methodology allows for the differentiation of minima connected by rotational barriers.

Conclusions:

• DFT calculations provide a valuable tool for studying rotational barriers in aromatic systems, though accuracy can vary.
• The identification of multiple minima in azonaphthalene offers a pathway for targeted experimental validation.
• This work facilitates more precise experimental investigations into rotational barrier heights in substituted aromatics.