2026-04-17T07:46:36Zhttps://recercat.cat/oai/request

oai:recercat.cat:10256/268982025-06-13T00:10:45Zcom_2072_452955com_2072_2054col_2072_453073

Effect of size, charge, and spin state on Hückel and Baird aromaticity in [N]annulenes Van Nyvel, Louis Alonso, Mercedes Solà i Puig, Miquel Agencia Estatal de Investigación Aromaticitat (Química) Aromaticity (Chemistry) Hückel, Regla de Hückel's rule Baird, Regla de Baird's rule Química orgànica Chemistry, Organic The Hückel and Baird rules provide a framework to understand the aromaticity of monocyclic π-conjugated molecules in their singlet ground state and lowest-lying triplet state, respectively, particularly in the context of [N]annulenes. According to Hückel's rule, a molecule in the ground state is aromatic if it contains 4n+2 π-electrons, while Baird's rule states that a molecule in the lowest-lying triplet state is aromatic if it contains 4n π-electrons, where n = 0, 1, 2, and so on. A previous study (J. Am. Chem. Soc. 2021, 143, 2403) examined the changes in the aromaticity of singlet ground-state [N]annulenes as the ring size increased from N = 12 to 66. However, no systematic investigation has yet been conducted for the lowest-lying triplet state of [N]annulenes or charged [N]annulenes. In this work, we address this gap by performing DFT calculations across several aromaticity descriptors, including structural, electronic, magnetic, and energetic indicators of aromaticity, with a particular focus on aromatic stabilization energies (ASEs). Our findings reveal that both neutral and charged [N]annulenes adhere to the Hückel and Baird rules. Nevertheless, for larger ring sizes, these rules diminish in significance, and the distinction between ASEs (and other indices of aromaticity) of [N]annulenes with 4n and 4n+2 π-electrons becomes less and less pronounced M. S. is grateful for the financial support from the Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/50110001103, Projects PID2023-147424NB-I00 and PID2020-113711GB-I00) and the Generalitat de Catalunya (Project 2021-SGR-623 and ICREA Academia prize 2024) 2025-04-07 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion peer-reviewed http://hdl.handle.net/10256/26898 40028624 PMC11869322 http://hdl.handle.net/10256/26898 eng info:eu-repo/semantics/altIdentifier/doi/10.1039/D4SC08225G info:eu-repo/semantics/altIdentifier/issn/2041-6520 info:eu-repo/semantics/altIdentifier/eissn/2041-6539 PID2023-147424NB-I00 PID2020-113711GB-I00 info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2021-2023/PID2023-147424NB-I00/ES/DISEÑO COMPUTACIONAL DE COMPUESTOS ORGANICOS PI-CONJUGADOS PARA APLICACIONES FOTOVOLTAICAS Y OPTOELECTRONICAS/ info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020/PID2020-113711GB-I00/ES/DISEÑO Y SINTESIS DE FULLERENOS PARA LA CONSTRUCCION DE CELDAS SOLARES HIBRIDAS DE PEROVSKITA Y FULERENOS D ALTO RENDIMIENTO. UN ENFOQUE EXPERIMENTAL Y COMPUTACIONAL SINERGICO/ Reconeixement-NoComercial 4.0 Internacional http://creativecommons.org/licenses/by-nc/4.0 info:eu-repo/semantics/openAccess 10 p. application/pdf Royal Society of Chemistry (RSC) Chemical Science, 2025, vol. 16, núm. 13, p. 5613-5622 Articles publicats (D-Q) Van Nyvel, Louis Alonso, Mercedes Solà i Puig, Miquel 2025 Effect of size, charge, and spin state on Hückel and Baird aromaticity in [N]annulenes Chemical Science 16 5613 5622