A multi-descriptor analysis of substituent effects on the structure and aromaticity of benzene derivatives: π-Conjugation versus charge effects

Autor(es)

Chagas, Julio C. V. ; Milanez, Bruno D. ; Oliveira, Vytor P. ; Pinheiro Jr, Max ; Ferrao, Luiz F. A. ; Aquino, Adelia J. A. ; Lischka, Hans ; Machado, Franciso B. C.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Computational Chemistry; v. 45, n. 12, p. 15-pg., 2023-12-28.

Resumo

This work provides a detailed multi-component analysis of aromaticity in monosubstituted (X = CH3, CH2-$$ {\mathrm{H}}_2<^>{-} $$, CH2+$$ {\mathrm{H}}_2<^>{+} $$, NH2, NH-, NH+, OH, O-, and O+) and para-homodisubstituted (X = CH3, CH2, NH2, NH, OH, and O) benzene derivatives. We investigate the effects of substituents using single-reference (B3LYP/DFT) and multireference (CASSCF/MRCI) methods, focusing on structural (HOMA), vibrational (AI(vib)), topological (ELF pi), electronic (MCI), magnetic (NICS), and stability (S0-T1 splitting) properties. The findings reveal that appropriate pi-electron-donating and pi-electron-accepting substituents with suitable size and symmetry can interact with the pi-system of the ring, significantly influencing pi-electron delocalization. While the charge factor has a minimal impact on pi-electron delocalization, the presence of a pz orbital capable of interacting with the pi-electron delocalization is the primary factor leading to a deviation from the typical aromaticity characteristics observed in benzene. One can manipulate the electronic structure properties of a specific molecule to attain desired properties through the strategic introduction of substituent effects. This study offers insights into how substituents impact pi-electron delocalization. While charge effects primarily play a role in the sigma domain of electrons, pi-electron conjugation resulting from substituent effects significantly influences the aromaticity of the benzene ring moiety.image (AU)

• Processo FAPESP: 22/16385-8 - Dispositivos orgânicos emissores de luz, conversores de energia via fissão singleto e materiais híbridos 0D/0D para produção de hidrogênio: abordagem da química computacional
• Beneficiário: Francisco Bolivar Correto Machado
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 19/03729-8 - Desenvolvimento teórico-experimental de materiais energéticos aplicados à propulsão química
• Beneficiário: Luiz Fernando de Araújo Ferrão
• Modalidade de apoio: Auxílio à Pesquisa - Regular