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Báez-Grez R, Rios RP. Is azulene's local aromaticity and relative stability driven by the Glidewell-Lloyd rule? Phys Chem Chem Phys 2024; 26:12162-12167. [PMID: 38590242 DOI: 10.1039/d4cp00091a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The local aromaticity of azulene has been studied to understand their electronic properties. For this purpose, we have used the magnetic criterion through magnetically induced current density maps, ring current strengths, NICSzz(1), and the bifurcation value of three-dimensional surfaces of NICSzz. On the other hand, the delocalization criterion was used by calculating the MCI and ELFπ. The results show that the five-membered ring (5-MR) is more aromatic than the seven-membered ring (7-MR) and more aromatic than the free C5H5- ring. The opposite case is seen for the seven-membered ring, which is less aromatic than the free C7H7+. The local aromatic rings in azulene are formed due to an intramolecular electron transfer from the 7-MR to the 5-MR. In addition, the proposed resonance structures that allow explaining the properties of azulene, such as the dipole moment or the relative stability (in comparison to other isomers), show a preference for the formation of 5-MRs; for this reason, it is possible to conclude that the aromaticity and relative stability of azulene is driven by the Glidewell-Lloyd rule.
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Affiliation(s)
- Rodrigo Báez-Grez
- Facultad de Ciencias, Universidad Arturo Prat, Casilla 121, Iquique 1100000, Chile
| | - Ricardo Pino Rios
- Centro de Investigación Medicina de Altura - CEIMA, Universidad Arturo Prat. Casilla 121, Iquique 1100000, Chile.
- Química y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Casilla 121, Iquique 1100000, Chile
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2
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Leyva-Parra L, Pino-Rios R. Update for Isomerization Stabilization Energies: The Fulvenization Approach. ACS OMEGA 2024; 9:1436-1442. [PMID: 38222592 PMCID: PMC10785285 DOI: 10.1021/acsomega.3c07881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/28/2023] [Accepted: 12/04/2023] [Indexed: 01/16/2024]
Abstract
An alternative approach for calculating aromatic stabilization energies is proposed based on transforming an (anti)aromatic ring into a fulvene isomer. This fulvenization process gives a value of 34.05 kcal·mol-1 for benzene in the singlet state and a value of -17.85 kcal·mol-1 in the triplet state. Additionally, it is possible to use experimental values (as long as they exist) for the calculation as the gas-phase formation enthalpies of benzene and fulvene, whose difference is 33.72 kcal·mol-1. On the other hand, this same approach has been evaluated on several six-membered rings, including those persubstituted, biradicals, azines, and inorganic analogues, giving results in agreement with those reported in the literature using different criteria. Additionally, it is possible to differentiate the aromaticity of the rings in polycyclic aromatic hydrocarbons according to Clar's rules. Assigning the (anti)aromatic character in various nonbenzenoid rings (neutral and charged), except for five- and seven-membered rings, is also possible. The construction of the fulvene isomers in PAHs is set such that nonaromaticity-related effects are not considered. The results show that the fulvenization approach is an effective and efficient approach that can serve as an alternative or complement to existing tools.
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Affiliation(s)
- Luis Leyva-Parra
- Departamento
de Ciencias Químicas, Centro de Química Teórica
& Computacional (CQT&C), Universidad
Andrés Bello, Facultad de Ciencias Exactas, Avenida República 275, 8370146 Santiago de Chile, Chile
| | - Ricardo Pino-Rios
- Instituto
de Estudios de la Salud, Universidad Arturo
Prat, 1100000 Iquique, Chile
- Química
y Farmacia, Facultad de Ciencias de la Salud, Universidad Arturo Prat, Casilla 121, 1100000 Iquique, Chile
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3
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Ding W, Zhang Z, Chen X, Zhan CG. Assessment of the performance of six indices in predicating the aromaticity of planar porphyrinoids. J Mol Model 2023; 29:83. [PMID: 36862263 DOI: 10.1007/s00894-023-05485-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 02/21/2023] [Indexed: 03/03/2023]
Abstract
CONTEXT AND RESULTS Aromaticity is a fundamental chemical concept that has been widely used in explaining the reactivity, stability, structure, and magnetic properties of many molecules such as conjugated macrocycles, metal heterocyclic compounds, and certain metal clusters. Porphyrinoids (including porphyrin) are of particular interest in terms of diverse aromaticity. Various indices therefore have been used to predict the aromaticity of porphyrin-like macrocycles. However, the reliability of these indices for porphyinoids is always questionable. In order to assess the performance of the indices, we have selected six representative indices to predict the aromaticity of 35 porphyrinoids. The calculated values were then compared with the corresponding results obtained from experiments. Our studies suggest that the theoretical prediction by nucleus independent chemical shifts (NICS), topology of the induced magnetic field (TIMF), anisotropy of the induced current density (AICD), and gauge including magnetically induced current method (GIMIC) are essentially consistent with experimental evidence in all 35 cases and thus are preferred indices. COMPUTATIONAL AND THEORETICAL TECHNIQUES Based on density functional theory, the performance of the NICS, TIMF, AICD, GIMIC, harmonic oscillator model of aromaticity (HOMA), and multicenter bond order (MCBO) indices were evaluated theoretically. Molecular geometries were optimized at the M06-2X/6-311G** level. NMR calculations using GIAO or CGST method were performed at the M06-2X/6-311G** level. The above calculations were carried out using Gaussian16 suite. The TIMF, GIMIC, HOMA, and MCBO indices were obtained using the Multiwfn program. The AICD outputs were visualized using the POV-Ray software.
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Affiliation(s)
- Wenjing Ding
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, 430074, China
| | - Zhan Zhang
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, 430074, China.
| | - Xi Chen
- Key Laboratory of Catalysis and Energy Materials Chemistry of Ministry of Education & Hubei Key Laboratory of Catalysis and Materials Science, South-Central Minzu University, Wuhan, 430074, China.
| | - Chang-Guo Zhan
- College of Pharmacy, University of Kentucky, Lexington, KY, 40536, USA
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4
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Inostroza D, García V, Yañez O, Torres-Vega JJ, Vásquez-Espinal A, Pino-Rios R, Báez-Grez R, Tiznado W. On the NICS limitations to predict local and global current pathways in polycyclic systems. NEW J CHEM 2021. [DOI: 10.1039/d1nj01510a] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Here, we analyze the possibility of predicting local and global current densities in a series of bicyclic hydrocarbons with 4n and 4n + 2 π-electrons from the nucleus-independent chemical shifts (NICS) computations.
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Affiliation(s)
- Diego Inostroza
- Computational and Theoretical Chemistry Group
- Departamento de Ciencias Químicas
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- Santiago
| | - Victor García
- Departamento Académico de Fisicoquímica - Facultad de Química e Ingeniería Química
- Universidad Nacional Mayor de San Marcos
- Lima
- Peru
| | - Osvaldo Yañez
- Center of New Drugs for Hypertension (CENDHY)
- Santiago
- Chile
- Department of Pharmaceutical Science and Technology
- School of Chemical and Pharmaceutical Sciences
| | - Juan J. Torres-Vega
- Centro de Investigaciones Tecnológicas
- Biomédicas y Medioambientales
- Callao
- Peru
| | - Alejandro Vásquez-Espinal
- Computational and Theoretical Chemistry Group
- Departamento de Ciencias Químicas
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- Santiago
| | - Ricardo Pino-Rios
- Laboratorio de Química Teórica
- Facultad de Química y Biología. Universidad de Santiago de Chile (USACH)
- Santiago
- Chile
| | - Rodrigo Báez-Grez
- Computational and Theoretical Chemistry Group
- Departamento de Ciencias Químicas
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- Santiago
| | - William Tiznado
- Computational and Theoretical Chemistry Group
- Departamento de Ciencias Químicas
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- Santiago
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5
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Pino-Rios R, Solà M. The Relative Stability of Indole Isomers Is a Consequence of the Glidewell-Lloyd Rule. J Phys Chem A 2020; 125:230-234. [DOI: 10.1021/acs.jpca.0c09549] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ricardo Pino-Rios
- Laboratorio de Química teórica, Facultad de Química y Biología. Universidad de Santiago de Chile (USACH), Región Metropolitana, 8320000, Chile
| | - Miquel Solà
- Institute of Computational Chemistry and Catalysis, University of Girona, Girona, Catalonia 17003, Spain
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Pino-Rios R, Cárdenas-Jirón G, Tiznado W. Local and macrocyclic (anti)aromaticity of porphyrinoids revealed by the topology of the induced magnetic field. Phys Chem Chem Phys 2020; 22:21267-21274. [PMID: 32935691 DOI: 10.1039/d0cp03272g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The aromaticity in porphyrinoids results from the π conjugation through two different annular perimeters: the macrocyclic ring and the local heterocyclic rings appended to it. Analyses, based on aromatic stabilization energies (ASE), indicate that the local circuits (6π) are responsible for the significant aromatic stabilization of these systems. This local aromaticity can be coupled with the one from 4n + 2π macrocyclic circuit. It can either compensate for the destabilization due to a 4n π macrocyclic circuit, or be the only source of aromatic stabilization in porphyrinoids with macrocycles without π-conjugated bonds. This "multifaceted" aromatic character of porphyrinoids makes it challenging to analyze their aromaticity using magnetic descriptors because of the intricate interaction of local versus macro-cyclic circulation. In this contribution, we show that the analysis of the bifurcation of the induced magnetic field, Bind, allows clear identification and quantification of both local, and macrocyclic aromaticity, in a representative group of porphyrinioids. In porphyrin, bifurcation values accurately predict the local and macrocyclic contribution rate to overall aromatic stabilization determined by ASE.
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Affiliation(s)
- Ricardo Pino-Rios
- Laboratorio de Química teórica, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Av. Libertador Bernardo O'Higgins 3363, Santiago, Estación Central, Región Metropolitana, Chile.
| | - Gloria Cárdenas-Jirón
- Laboratorio de Química teórica, Facultad de Química y Biología, Universidad de Santiago de Chile (USACH), Av. Libertador Bernardo O'Higgins 3363, Santiago, Estación Central, Región Metropolitana, Chile.
| | - William Tiznado
- Departamento de Química, Facultad de Ciencias Exactas, Universidad Andres Bello (UNAB), Av. República 275, Santiago, Región Metropolitana, Chile.
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Báez-Grez R, Inostroza D, García V, Vásquez-Espinal A, Donald KJ, Tiznado W. Aromatic ouroboroi: heterocycles involving a σ-donor-acceptor bond and 4n + 2 π-electrons. Phys Chem Chem Phys 2020; 22:1826-1832. [PMID: 31829390 DOI: 10.1039/c9cp05071j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The aromaticity and dynamics of a set of recently proposed neutral 5- and 6-membered heterocycles that are closed by dative (donor-acceptor) or multi-center σ bonds, and have resonance forms with a Hückel number of π-electrons, are examined. The donors and acceptors in the rings include N, O, and F, and B, Be, and Mg, respectively. The planar geometry of the rings, coupled with evidence from different measures of aromaticity, namely the NICSzz, and NICSπzz components of the conventional nucleus independent chemical shifts (NICS), and ring current strengths (RCS), indicate non-trivial degrees of aromaticity in certain cases, including the cyclic C3B2OH6 and C3BOH5 isomers, both with three bonds to the O site in the ring. The former is lower in energy by at least 17.6 kcal mol-1 relative to linear alternatives obtained from molecular dynamics simulations in this work. Some of the other systems examined are best described as non-aromatic. Ring opening, closing, and isomerization are observed in molecular dynamics simulations for some of the systems studied. In a few cases, the ring indeed persists.
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Affiliation(s)
- Rodrigo Báez-Grez
- Computational and Theoretical Chemistry Group, Departamento de Ciencias Químicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 498, Santiago, Chile.
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Báez-Grez R, Pino-Rios R. Borataalkene or boratabenzene? Understanding the aromaticity of 9-borataphenanthrene anions and its central ring. NEW J CHEM 2020. [DOI: 10.1039/d0nj03942j] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The recently isolated 1 is isoelectronic to 2 and shows reactivity in central ring that resembles both (cyclo)alkene and aromatic ring. Evaluation of local aromaticity reveal that central ring is best described as a non-aromatic following Clar’s rules.
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Affiliation(s)
- Rodrigo Báez-Grez
- Computational and Theoretical Chemistry Group
- Departamento de Ciencias Química
- Facultad de Ciencias Exactas
- Universidad Andres Bello
- República 498
| | - Ricardo Pino-Rios
- Laboratorio de Química teórica
- Facultad de Química y Biología
- Universidad de Santiago de Chile (USACH) Av. Libertador Bernardo O’Higgins 3363
- Estación Central
- Chile
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Pino‐Rios R, Cárdenas‐Jirón G, Ruiz L, Tiznado W. Interpreting Aromaticity and Antiaromaticity through Bifurcation Analysis of the Induced Magnetic Field. ChemistryOpen 2019; 8:321-326. [PMID: 30906684 PMCID: PMC6414146 DOI: 10.1002/open.201800238] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/09/2019] [Indexed: 11/29/2022] Open
Abstract
In all molecules, a current density is induced when the molecule is subjected to an external magnetic field. In turn, this current density creates a particular magnetic field. In this work, the bifurcation value of the induced magnetic field is analyzed in a representative set of aromatic, non-aromatic and antiaromatic monocycles, as well as a set of polycyclic hydrocarbons. The results show that the bifurcation value of the ring-shaped domain adequately classifies the studied molecules according to their aromatic character. For aromatic and nonaromatic molecules, it is possible to analyze two ring-shaped domains, one diatropic (inside the molecular ring) and one paratropic (outside the molecular ring). Meanwhile, for antiaromatic rings, only a diatropic ring-shaped domain (outside the molecular ring) is possible to analyze, since the paratropic domain (inside the molecular ring) is irreducible with the maximum value (attractor) at the center of the molecular ring. In some of the studied cases, i. e., in heteroatomic species, bifurcation values do not follow aromaticity trends and present some inconsistencies in comparison to ring currents strengths, showing that this approximation provides only a qualitative estimation about (anti)aromaticity.
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Affiliation(s)
- Ricardo Pino‐Rios
- Laboratorio de Química Teórica, Facultad de Química y BiologíaUniversidad de Santiago de Chile (USACH)Av. Libertador Bernardo O'Higgins 3363Santiago, Estación Central, Región MetropolitanaChile
| | - Gloria Cárdenas‐Jirón
- Laboratorio de Química Teórica, Facultad de Química y BiologíaUniversidad de Santiago de Chile (USACH)Av. Libertador Bernardo O'Higgins 3363Santiago, Estación Central, Región MetropolitanaChile
| | - Lina Ruiz
- Instituto de Ciencias Biomédicas, Facultad Ciencias de la SaludUniversidad Autónoma de ChileSantiagoChile
| | - William Tiznado
- Departamento de Química, Facultad de Ciencias Exactas, Computational and Theoretical Chemistry GroupUniversidad Andres Bello (UNAB)Av. República 275Santiago, Región MetropolitanaChile
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