1
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Badri Z, Nourigheimasi F, Foroutan-Nejad C. Tetraquinolines; four linked quinoline units or porphyrinoids. Org Biomol Chem 2024; 22:2284-2291. [PMID: 38407320 DOI: 10.1039/d3ob01616a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Tetraquinolines (TEQs) have been recently synthesized and proposed to be a new member of the porphyrinoid family with highly distorted, nonplanar, geometries. In this contribution by studying several molecules, closely related to TEQs, we have suggested that the origin of the nonplanarity of TEQs and their counterparts is a combination of steric strain and the propensity of the molecules to avoid antiaromaticity. The tendency of TEQs to coordinate with doubly charged metal ions can be interpreted in terms of their transition from potential antiaromaticity to nonaromaticity. Even metal-coordinated TEQs do not sustain diatropic ring currents. Although full planarization is not possible because of steric strain, doubly oxidized TEQs and their counterparts sustain moderate global diatropic ring currents and partially planarize. The nature of current density in the molecules is studied in the light of Steiner-Fowler selection rules.
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Affiliation(s)
- Zahra Badri
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
| | - Farnoush Nourigheimasi
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260, USA
| | - Cina Foroutan-Nejad
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
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2
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Pavlak I, Matasović L, Buchanan EA, Michl J, Rončević I. Electronic Structure of Metalloporphenes, Antiaromatic Analogues of Graphene. J Am Chem Soc 2024; 146:3992-4000. [PMID: 38294407 PMCID: PMC10870706 DOI: 10.1021/jacs.3c12079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2023] [Revised: 01/13/2024] [Accepted: 01/17/2024] [Indexed: 02/01/2024]
Abstract
Zinc porphene is a two-dimensional material made of fully fused zinc porphyrins in a tetragonal lattice. It has a fully conjugated π-system, making it similar to graphene. Zinc porphene has recently been synthesized, and a combination of rough conductivity measurements and infrared and Raman spectroscopies all suggested that it is a semiconductor (Magnera, T.F. et al. Porphene and Porphite as Porphyrin Analogs of Graphene and Graphite, Nat. Commun.2023, 14, 6308). This is in contrast with all previous predictions of its electronic structure, which indicated metallic conductivity. We show that the gap-opening in zinc porphene is caused by a Peierls distortion of its unit cell from square to rectangular, thus giving the first account of its electronic structure in agreement with the experiment. Accounting for this distortion requires proper treatment of electron delocalization, which can be done using hybrid functionals with a substantial amount of exact exchange. Such a functional, PBE38, is then applied to predict the properties of many first transition row metalloporphenes, some of which have already been prepared. We find that changing the metal strongly affects the electronic structure of metalloporphenes, resulting in a rich variety of both metallic conductors and semiconductors, which may be of great interest to molecular electronics and spintronics. Properties of these materials are mostly governed by the extent of the Peierls distortion and the number of electrons in their π-system, analogous to changes in aromaticity observed in cyclic conjugated molecules upon oxidation or reduction. These results give an account of how the concept of antiaromaticity can be extended to periodic systems.
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Affiliation(s)
- Ivan Pavlak
- Department
of Chemistry, Faculty of Science, University
of Zagreb, Horvatovac 102A, Zagreb 10000, Croatia
| | - Lujo Matasović
- Cavendish
Laboratory, Department of Physics, University
of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, U.K.
| | - Eric A. Buchanan
- Department
of Chemistry and Biochemistry, University
of Colorado, Boulder, Colorado 80309-0215, United States
| | - Josef Michl
- Department
of Chemistry and Biochemistry, University
of Colorado, Boulder, Colorado 80309-0215, United States
- Institute
of Organic Chemistry and Biochemistry of the CAS, Flemingovo nám. 2, Prague 6 16610, Czech Republic
| | - Igor Rončević
- Institute
of Organic Chemistry and Biochemistry of the CAS, Flemingovo nám. 2, Prague 6 16610, Czech Republic
- Department
of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, U.K.
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3
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Bradley D, Hillier BK, Peeks MD. Electronic delocalization in charged macrocycles is associated with global aromaticity. Chem Commun (Camb) 2023; 59:13438-13441. [PMID: 37860973 DOI: 10.1039/d3cc03464j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
When oxidized, cycloparaphenylenes and porphyrin nanorings can exhibit macrocyclic ring currents which have been used to assign these molecules as (anti)aromatic. These assignments have been controversial because the presence of ring currents does not always imply cyclic electronic delocalization, which is essential to the definition of aromaticity. Here, we show that the emergence of macrocyclic ring currents in these molecules is correlated with increased electronic delocalization, supporting assignments of these molecules as (anti)aromatic.
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Affiliation(s)
- David Bradley
- School of Chemistry, UNSW Sydney, NSW 2052, Australia.
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4
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Mahmood A, Dimitrova M, Sundholm D. Current-Density Calculations on Zn-Porphyrin 40 Nanorings. J Phys Chem A 2023; 127:7452-7459. [PMID: 37665662 PMCID: PMC10510378 DOI: 10.1021/acs.jpca.3c03564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 08/04/2023] [Indexed: 09/06/2023]
Abstract
Two porphyrinoid nanorings have been studied computationally. They were built by linking 40 Zn-porphyrin units with butadiyne bridges. The molecular structures belonging to the D40h point group were fully optimized with the Turbomole program at the density functional theory (DFT) level using the B3LYP functional and the def2-SVP basis sets. The aromatic character was studied at the DFT level by calculating the magnetically induced current-density (MICD) susceptibility using the GIMIC program. The neutral molecules are globally non-aromatic with aromatic Zn-porphyrin units. Charged nanorings could not be studied because almost degenerate frontier orbitals led to vanishing optical gaps for the cations. Since DFT calculations of the MICD are computationally expensive, we also calculated the MICD using three pseudo-π models. Appropriate pseudo-π models were constructed by removing the outer hydrogen atoms and replacing all carbon and nitrogen atoms with hydrogen atoms. The central Zn atom was either replaced with a beryllium atom or with two inner hydrogen atoms. Calculations with the computationally inexpensive pseudo-π models yielded qualitatively the same magnetic response as obtained in the all-electron calculations.
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Affiliation(s)
- Atif Mahmood
- Department of Chemistry, University
of Helsinki, P.O. Box 55, A. I. Virtasen Aukio 1, FIN-00014 Helsinki, Finland
| | - Maria Dimitrova
- Department of Chemistry, University
of Helsinki, P.O. Box 55, A. I. Virtasen Aukio 1, FIN-00014 Helsinki, Finland
| | - Dage Sundholm
- Department of Chemistry, University
of Helsinki, P.O. Box 55, A. I. Virtasen Aukio 1, FIN-00014 Helsinki, Finland
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5
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Karas LJ, Jalife S, Viesser RV, Soares JV, Haley MM, Wu JI. Tetra-tert-butyl-s-indacene is a Bond-Localized C 2h Structure and a Challenge for Computational Chemistry. Angew Chem Int Ed Engl 2023; 62:e202307379. [PMID: 37467313 PMCID: PMC10528983 DOI: 10.1002/anie.202307379] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/18/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Whether tetra-tert-butyl-s-indacene is a symmetric D2h structure or a bond-alternating C2h structure remains a standing puzzle. Close agreement between experimental and computed proton chemical shifts based on minima structures optimized at the M06-2X, ωB97X-D, and M11 levels confirm a bond-localized C2h symmetry, which is consistent with the expected strong antiaromaticity of TtB-s-indacene.
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Affiliation(s)
- Lucas J Karas
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Said Jalife
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Renan V Viesser
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - João V Soares
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
| | - Michael M Haley
- Department of Chemistry & Biochemistry and the Materials Science Institute, University of Oregon, Eugene, OR 97403-1253, USA
| | - Judy I Wu
- Department of Chemistry, University of Houston, Houston, TX 77204, USA
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6
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Han Y, Zhu J, Dong S, Eng Y, Tao T, Gopalakrishna TY, Chi C. Bisazapentalene Dication: Global Aromaticity and Open-Shell Singlet Ground State. Org Lett 2023; 25:3380-3385. [PMID: 37162270 DOI: 10.1021/acs.orglett.3c00870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Antiaromatic moieties fused in polycyclic π-conjugated molecules usually exhibit strong localized antiaromaticiy. Herein, we reported the synthesis and properties of a bisazapentalene dication (BAP2+) obtained from in situ two-electron oxidation of neutral species 8. Noteworthily, it possesses global aromaticity and an open-shell singlet ground state. This study underlines the importance of heteroatoms in determining the delocalization of π-electrons and the aromaticity of molecules in their oxidized states.
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Affiliation(s)
- Yi Han
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Jun Zhu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Shaoqiang Dong
- Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, PR China
| | - Yijie Eng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Tao Tao
- School of Environmental Science and Engineering, Nanjing University of Information Science & Technology, Nanjing 210044, PR China
| | - Tullimilli Y Gopalakrishna
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
| | - Chunyan Chi
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore
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7
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Casademont‐Reig I, Soriano‐Agueda L, Ramos‐Cordoba E, Torrent‐Sucarrat M, Matito E. Reply to the Correspondence on “How Aromatic Are Molecular Nanorings? The Case of a Six‐Porphyrin Nanoring”**. Angew Chem Int Ed Engl 2022; 61:e202206836. [DOI: 10.1002/anie.202206836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Indexed: 11/08/2022]
Affiliation(s)
- Irene Casademont‐Reig
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Department of General Chemistry (ALGC) Vrije Universiteit Brussel (VUB) Pleinlaan 2 1050 Brussels Belgium
| | | | - Eloy Ramos‐Cordoba
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia Kimika Fakultatea Euskal Herriko Unibertsitatea UPV/EHU P.K. 1072 20080 Donostia Euskadi Spain
| | - Miquel Torrent‐Sucarrat
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Ikerbasque, Basque Foundation for Science Plaza Euskadi 5 48009 Bilbao Euskadi Spain
- Department of Organic Chemistry I Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU) 20018 Donostia Euskadi Spain
| | - Eduard Matito
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Ikerbasque, Basque Foundation for Science Plaza Euskadi 5 48009 Bilbao Euskadi Spain
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8
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Casademont‐Reig I, Soriano‐Agueda L, Ramos‐Cordoba E, Torrent‐Sucarrat M, Matito E. Reply to the Correspondence on “How Aromatic Are Molecular Nanorings? The Case of a Six‐Porphyrin Nanoring”**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Irene Casademont‐Reig
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Department of General Chemistry (ALGC) Vrije Universiteit Brussel (VUB) Pleinlaan 2 1050 Brussels Belgium
| | | | - Eloy Ramos‐Cordoba
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Polimero eta Material Aurreratuak: Fisika, Kimika eta Teknologia Kimika Fakultatea Euskal Herriko Unibertsitatea UPV/EHU P.K. 1072 20080 Donostia Euskadi Spain
| | - Miquel Torrent‐Sucarrat
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Ikerbasque, Basque Foundation for Science Plaza Euskadi 5 48009 Bilbao Euskadi Spain
- Department of Organic Chemistry I Universidad del Pais Vasco/Euskal Herriko Unibertsitatea (UPV/EHU) 20018 Donostia Euskadi Spain
| | - Eduard Matito
- Donostia International Physics Center (DIPC) 20018 Donostia Euskadi Spain
- Ikerbasque, Basque Foundation for Science Plaza Euskadi 5 48009 Bilbao Euskadi Spain
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