Stability and Reactivity of the Phenalene and Olympicene Isomers

Author(s)

Ferrao, Luiz F. A. ; Pontes, Marcelo A. P. ; Fernandes, Gabriel F. S. ; Bettanin, Fernanda ; Aquino, Adelia J. A. ; Lischka, Hans ; Nachtigallova, Dana ; Machado, Francisco B. C.

• Document type: Journal article
• Source: Journal of Physical Chemistry A; v. 127, n. 45, p. 12-pg., 2023-11-03.

Abstract

The phenalene (triangulene) and olympicene molecules belong to the polycyclic aromatic hydrocarbon class, which have attracted substantial technological interest due to their unique electronic properties. Electronic structure calculations serve as a valuable tool in investigating the stability and reactivity of these molecular systems. In the present work, the multireference calculations, namely, the complete active space second-order perturbation theory and multireference averaged quadratic coupled cluster (MR-AQCC), were employed to study the reactivity and stability of phenalene and olympicene isomers, as well as their modified structures where the sp(3)-carbon at the borders were removed. The harmonic oscillator model of aromaticity (HOMA) and the nucleus-independent chemical shift as geometric and magnetic indexes calculated with density functional theory were utilized to assess the aromaticity of the studied molecules. These indexes were compared with properties such as the excitation energy and natural orbitals occupation. The reactivity analyzed using the HOMA index combined with MR-AQCC revealed the radical character of certain structures as well as the weakening of their aromaticity. Moreover, the results suggest that the removal of sp(3)-carbon atoms and the addition of hydrogen atoms did not alter the pi network and the excitation energies of the phenalene molecules. (AU)

• FAPESP's process: 22/16385-8 - Organic light emitting devices, energy converters via singlet fission and 0D/0D hybrid materials for hydrogen production: computational chemistry approach
• Grantee: Francisco Bolivar Correto Machado
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/22669-3 - Electronic Structural Engineering in the design of catalysts applied to hybrid propulsion rocket engines
• Grantee: Gabriel Freire Sanzovo Fernandes
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 19/03729-8 - Theoretical and experimental development of energetic materials applied to chemical propulsion
• Grantee: Luiz Fernando de Araújo Ferrão
• Support Opportunities: Regular Research Grants