1
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Fowler PW, Anstöter CS. Tuning (Anti)Aromaticity: Variations on the [8]-Circulene Framework. Chemphyschem 2024; 25:e202300791. [PMID: 38279875 DOI: 10.1002/cphc.202300791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/10/2024] [Accepted: 01/22/2024] [Indexed: 01/29/2024]
Abstract
Optoelectronic properties of organic molecules are underpinned by delocalisation and delocalisability of π-electrons. These properties are sensitive to small changes in electron count, whether achieved by heteroatom substitution or redox chemistry. One measure of the delocalisability of π-electrons is the current induced by an external magnetic field, which is diagnostic of (anti)aromaticity. The ab initio ipsocentric method is used here to model diverse ring-current patterns in the family of [8]-circulenes based on tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), in different charge states, with disjoint hetero-atom substitution, and with CC units systematically replaced by BN pairs. Maps calculated at the CHF/CTOCD-DZ2/6-31G** level reveal that these modifications of the TCPTP framework access the full range of possibilities for current from concentric global circulations (typically counter rotating) to full (non-aromatic) localisation. In the ipsocentric approach, induced current density is partitioned into robust orbital contributions that obey selection rules based on orbital symmetry, energy and nodal character. The selection rules are applied here to interpret current-density and exploit insights gained from simpler models to suggest design strategies for fine-tuning of π-delocalisability (aromaticity and antiaromaticity) in macrocyclic frameworks.
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Affiliation(s)
- Patrick W Fowler
- Department of Chemistry, University of Sheffield, Sheffield, United Kingdom
| | - Cate S Anstöter
- School of Chemistry, University of Edinburgh, Edinburgh, Edinburgh, United Kingdom
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2
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Radenković S, Tomović Ž. Tuning the structure and properties of N-doped positively charged polycyclic aromatic hydrocarbons. Chemphyschem 2022; 23:e202200125. [PMID: 35404503 DOI: 10.1002/cphc.202200125] [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: 02/23/2022] [Revised: 04/07/2022] [Indexed: 11/11/2022]
Abstract
A detailed study of the geometry, aromatic character, electronic and magnetic properties for a series of positively charged N-doped PAHs was performed. Magnetic properties of the examined molecules were analyzed by means of the magnetically induced current density calculated using the diamagnetic-zero version of the continuous transformation of origin of current density (CTOCD-DZ) method. The comparative study of the local aromaticity of the studied molecules was performed using several different indices: energy effect (ef), harmonic oscillator model of aromaticity (HOMA) index, six centre delocalization index (SCI) and nucleus independent chemical shifts (NICS). The presence of N-atoms in the inner rings was found to cause a planarity distortion in the studied N-doped systems. The geometric changes and charged nature of the studied N-doped systems do not significantly influence the current density and the local aromaticity distribution in comparison with the corresponding parent benzenoid hydrocarbons. The present study demonstrates how quantum chemical calculations can be used for rational design of novel PAHs and fine tuning of their properties.
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Affiliation(s)
- Slavko Radenković
- University of Kragujevac: Univerzitet u Kragujevcu, Department of Chemistry, 12 Radoja Domanovića, P.O. Box 60, 34000, Kragujevac, SERBIA
| | - Željko Tomović
- Eindhoven University of Technology: Technische Universiteit Eindhoven, Department of Chemical Engineering & Chemistry and Institute for Complex Molecular Systems, NETHERLANDS
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3
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Fuhrer TJ, Houck M, Iacono ST. Fluoromaticity: The Molecular Orbital Contributions of Fluorine Substituents to the π-Systems of Aromatic Rings. ACS OMEGA 2021; 6:32607-32617. [PMID: 34901609 PMCID: PMC8655763 DOI: 10.1021/acsomega.1c04175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 11/10/2021] [Indexed: 06/14/2023]
Abstract
The addition of fluorine atoms to an aromatic ring brings about an additional set of π-bonding and antibonding orbitals culminating after the addition of the sixth fluorine with a new set of π-aromatic-like orbitals that affect the molecule in a way that we will refer to hereafter as "fluoromaticity". Depending on the number and position of the fluorine atoms, the contributed π-orbitals can even further stabilize the ring leading to smaller bond lengths within the ring and higher resistance to addition reactions. This added ring stability partially explains the high thermostability and chemical resistance found in polymers containing fluorinated aromatics in their architecture. A similar molecular orbital effect is seen with the addition of other halogen atoms to aromatic rings, though to a much smaller degree and not resulting in the additional ring stability.
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Affiliation(s)
- Timothy J. Fuhrer
- Department
of Chemistry, Radford University, Box 6949 Radford, Virginia 24142, United States
| | - Matthew Houck
- Department
of Chemistry & Chemistry Research Center, United States Air Force Academy, Colorado Springs, Colorado 80840, United States
| | - Scott T. Iacono
- Department
of Chemistry & Chemistry Research Center, United States Air Force Academy, Colorado Springs, Colorado 80840, United States
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4
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Forse AC, Merlet C, Grey CP, Griffin JM. NMR studies of adsorption and diffusion in porous carbonaceous materials. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 124-125:57-84. [PMID: 34479711 DOI: 10.1016/j.pnmrs.2021.03.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 03/24/2021] [Accepted: 03/26/2021] [Indexed: 06/13/2023]
Abstract
Porous carbonaceous materials have many important industrial applications including energy storage, water purification, and adsorption of volatile organic compounds. Most of their applications rely upon the adsorption of molecules or ions within the interior pore volume of the carbon particles. Understanding the behaviour and properties of adsorbate species on the molecular level is therefore key for optimising porous carbon materials, but this is very challenging owing to the complexity of the disordered carbon structure and the presence of multiple phases in the system. In recent years, NMR spectroscopy has emerged as one of the few experimental techniques that can resolve adsorbed species from those outside the pore network. Adsorbed, or "in-pore" species are shielded with respect to their free (or "ex-pore") counterparts. This shielding effect arises primarily due to ring currents in the carbon structure in the presence of a magnetic field, such that the observed chemical shift differences upon adsorption are independent of the observed nucleus to a first approximation. Theoretical modelling has played an important role in rationalising and explaining these experimental observations. Together, experiments and simulations have enabled a large amount of information to be gained on the adsorption and diffusion of adsorbed species, as well as on the structural and magnetic properties of the porous carbon adsorbent. Here, we review the methodological developments and applications of NMR spectroscopy and related modelling in this field, and provide perspectives on possible future applications and research directions.
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Affiliation(s)
- Alexander C Forse
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - Céline Merlet
- CIRIMAT, Université de Toulouse, CNRS, Université Toulouse 3 - Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse cedex 9, France; Réseau sur le Stockage Électrochimique de l'Énergie (RS2E), Fédération de Recherche CNRS 3459, HUB de l'Énergie, Rue Baudelocque, 80039 Amiens, France
| | - Clare P Grey
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
| | - John M Griffin
- Department of Chemistry, Lancaster University, Lancaster LA1 4YB, UK
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5
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Radenković S, Đorđević S. Relating nucleus independent chemical shifts with integrated current density strengths. Phys Chem Chem Phys 2021; 23:11240-11250. [PMID: 33949527 DOI: 10.1039/d1cp00784j] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Indices based on the nucleus independent chemical shift (NICS) are the most frequently used in analysis of magnetic aromaticity. The magnetically induced current density, on the other hand, is a key concept in defining magnetic aromaticity. The integrated current strength (current strength susceptibility) was found to be a very useful tool in aromaticity studies. There is widely accepted notion that the properly chosen NICS-based index can provide information on the current density strength and direction in a molecule of interest. In this work, a detailed numerical testing of the relationship between the integrated bond current strength and the most employed NICS indices was performed for a set of 43 monocyclic aromatic molecules. Based on the statistical data analysis, the relationship between the bond current strength and its π and σ electron components, on one side, and the isotropic NICS (NICSiso and NICSπ,iso) and zz-component of the NICS tensor (NICSzz and NICSπ,zz), on the other side, was examined. It was found that between the NICSπ,zz(1) and π-electron bond current strenghts there is very good linear correlation. Quite surprisingly, it was revealed that the NICSiso(1) and NICSzz(1) are not correlated with the π electron bond current strengths. On the other hand, a reasonably good linear correlation was found between the NICSzz(1) and total bond current strengths.
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Affiliation(s)
- Slavko Radenković
- Faculty of Science, University of Kragujevac, P. O. Box 60, 34000 Kragujevac, Serbia.
| | - Slađana Đorđević
- Faculty of Science, University of Kragujevac, P. O. Box 60, 34000 Kragujevac, Serbia.
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Prokopiou G, Autschbach J, Kronik L. Assessment of the Performance of Optimally Tuned Range‐Separated Hybrid Functionals for Nuclear Magnetic Shielding Calculations. ADVANCED THEORY AND SIMULATIONS 2020. [DOI: 10.1002/adts.202000083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Georgia Prokopiou
- Department of Materials and InterfacesWeizmann Institute of ScienceRehovot 76100 Israel
| | - Jochen Autschbach
- Department of ChemistryState University of New York at BuffaloBuffalo NY 14260‐3000 USA
| | - Leeor Kronik
- Department of Materials and InterfacesWeizmann Institute of ScienceRehovot 76100 Israel
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7
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Anstöter CS, Gibson CM, Fowler PW. Modelling aromatisation of (BN) nH 2n azabora-annulenes. Phys Chem Chem Phys 2020; 22:15919-15925. [DOI: 10.1039/d0cp02284e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Although borazine, the ‘inorganic benzene’, is non-aromatic, ab initio calculation, guided by symmetry and electron-counting arguments, indicates that charging up the higher homologue borazocine to the dianionic state gives an aromatic monocycle.
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8
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Pla P, Wang Y, Martín F, Alcamí M. Hydrogenated polycyclic aromatic hydrocarbons: isomerism and aromaticity. Phys Chem Chem Phys 2020; 22:21968-21976. [DOI: 10.1039/d0cp04177g] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A simple model based on adjacency matrices is introduced to study the stability of hydrogenated polycyclic aromatic hydrocarbons. Aromaticity governs their relative stability having the most stable isomers the higher number of non-hydrogenated rings.
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Affiliation(s)
- Paula Pla
- Departamento de Química
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
| | - Yang Wang
- School of Chemistry and Chemical Engineering
- Yangzhou University
- Yangzhou
- China
| | - Fernando Martín
- Departamento de Química
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
| | - Manuel Alcamí
- Departamento de Química
- Universidad Autónoma de Madrid
- 28049 Madrid
- Spain
- Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia)
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9
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Orozco‐Ic M, Barroso J, Charistos ND, Muñoz‐Castro A, Merino G. Consequences of Curvature on Induced Magnetic Field: The Case of Helicenes. Chemistry 2019; 26:326-330. [DOI: 10.1002/chem.201904390] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Mesías Orozco‐Ic
- Departamento de Física Aplicada Centro de Investigación y, de Estudios Avanzados, Unidad Mérida Mérida Yucatán México
| | - Jorge Barroso
- Departamento de Física Aplicada Centro de Investigación y, de Estudios Avanzados, Unidad Mérida Mérida Yucatán México
| | - Nickolas D. Charistos
- Department of Chemistry, Laboratory of Quantum and Computational Chemistry Aristotle University of Thessaloniki Thessaloniki 54 124 Greece
| | - Alvaro Muñoz‐Castro
- Laboratorio de Química Inorgánica y Materiales Moleculares Facultad de Ingeniería Universidad Autónoma de Chile Santiago Chile
| | - Gabriel Merino
- Departamento de Física Aplicada Centro de Investigación y, de Estudios Avanzados, Unidad Mérida Mérida Yucatán México
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10
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Charistos ND, Muñoz-Castro A, Sigalas MP. The pseudo-π model of the induced magnetic field: fast and accurate visualization of shielding and deshielding cones in planar conjugated hydrocarbons and spherical fullerenes. Phys Chem Chem Phys 2019; 21:6150-6159. [DOI: 10.1039/c9cp00836e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen skeletal models accurately reproduce the π-induced magnetic field of planar PAHs and spherical fullerenes.
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Affiliation(s)
- Nickolas D. Charistos
- Laboratory of Quantum and Computational Chemistry
- Department of Chemistry
- Aristotle University of Thessaloniki
- Thessaloniki
- Greece
| | - Alvaro Muñoz-Castro
- Laboratorio de Química Inorgánica y Materiales Moleculares
- Facultad de Ingeniería
- Universidad Autonoma de Chile
- Santiago
- Chile
| | - Michael P. Sigalas
- Laboratory of Quantum and Computational Chemistry
- Department of Chemistry
- Aristotle University of Thessaloniki
- Thessaloniki
- Greece
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11
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Strauss V, Schäfer RA, Hauke F, Hirsch A, Guldi DM. Polyhydrogenated Graphene: Excited State Dynamics in Photo- and Electroactive Two-Dimensional Domains. J Am Chem Soc 2015; 137:13079-86. [DOI: 10.1021/jacs.5b07896] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Volker Strauss
- Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander University of Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
| | - Ricarda A. Schäfer
- Department
of Chemistry and Pharmacy and Joint Institute of Advanced Materials
and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen, Germany
| | - Frank Hauke
- Department
of Chemistry and Pharmacy and Joint Institute of Advanced Materials
and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen, Germany
| | - Andreas Hirsch
- Department
of Chemistry and Pharmacy and Joint Institute of Advanced Materials
and Processes (ZMP), Friedrich-Alexander University of Erlangen-Nürnberg, Henkestr. 42, 91054 Erlangen, Germany
| | - Dirk M. Guldi
- Department of Chemistry and Pharmacy & Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander University of Erlangen-Nürnberg, Egerlandstr. 3, 91058 Erlangen, Germany
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