1
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Weng T, Xu Z, Li K, Guo Y, Chen X, Li Z, Sun Z. 1,1'-Biolympicenyl: A Stable Non-Kekulé Diradical with a Small Singlet and Triplet Energy Gap. J Am Chem Soc 2024; 146:26454-26465. [PMID: 39254188 DOI: 10.1021/jacs.4c09627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2024]
Abstract
Dimerization of delocalized polycyclic hydrocarbon radicals is a simple and versatile method to create diradicals with tailored electronic structures and accessible high-spin states. However, the synthesis is challenging, and the stability issue of the diradicals remains a concern. In this study, we present the synthesis of a stable non-Kekulé 1,1'-biolympicenyl diradical 1 using a protection-oxidation-protection strategy. Diradical 1 demonstrated exceptional stability, with a solution half-life time exceeding 3.5 years and a solid state thermal decomposition temperature above 300 °C. X-ray crystallographic analysis revealed its intersected molecular structure and tightly bound dimer configuration. A singlet ground state with a small singlet-triplet energy gap is consistently identified using electron paramagnetic resonance (EPR) and a superconducting quantum interference device (SQUID) in a rigid matrix, and the triplet state is thermally accessible at room temperature. The solution phase properties were systematically examined through EPR, absorption spectroscopy, and cyclic voltammetry, revealing a rotational motion in the slow-motion regime and multistage redox characteristics. This study presents an efficient synthetic and stabilization strategy for organic diradicals, enabling the development of various high-spin functional materials.
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Affiliation(s)
- Taoyu Weng
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
| | - Zhuofan Xu
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
| | - Ke Li
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
| | - Yupeng Guo
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
| | - Xing Chen
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
| | - Zhaoyang Li
- School of Materials Science and Engineering, Nankai University, Tianjin 300350, China
| | - Zhe Sun
- Institute of Molecular Plus, Department of Chemistry, Tianjin University and Haihe Laboratory of Sustainable Chemical Transformations, 92 Weijin Road, Tianjin 300072, China
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2
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Sentyurin VV, Levitskiy OA, Yankova TS, Grishin YK, Lyssenko KA, Goloveshkin AS, Alabugin IV, Magdesieva TV. Double Spin with a Twist: Synthesis and Characterization of a Neutral Mixed-Valence Organic Stable Diradical. J Am Chem Soc 2024; 146:26261-26274. [PMID: 39259835 DOI: 10.1021/jacs.4c08167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/13/2024]
Abstract
A convenient design strategy opens access to neutral open-shell mixed-valence species via the redox transformation of charged stable precursors, i.e., the spiro-fused borate anions. We have implemented this strategy for the synthesis of the first neutral mixed-valence diradical: two neutral mixed-valence radical fragments were assembled via a twisted biphenyl bridge. The diradical is a crystalline solid obtained in almost quantitative yield by using a facile synthetic procedure. It is stable at room temperature in the triplet ground state with a very small singlet/triplet gap. This metal-free diradical can reversibly form five redox states. The diradical exhibits an intense IVCT band in the NIR region and can be assigned as a Class 2 Robin-Day MV (mixed valence) system with weakly interacting redox centers. Computations suggest that this diradical finds itself in a unique tug-of-war between two electron delocalization patterns, Kekulé and non-Kekulé, which gives rise to two geometric isomers that are close in energy but drastically different in spin distribution and polarity. Such bistable spin-systems should be intrinsically switchable and promising for the design of functional spin devices. The scope and limitations of the new redox-strategy for the neutral MV radicals were also tested on other types of spiro-fused borates, revealing structural factors responsible for the evolution from transient to persistent and then to stable radicals.
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Affiliation(s)
- Vyacheslav V Sentyurin
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
| | - Oleg A Levitskiy
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
| | - Tatiana S Yankova
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
| | - Yuri K Grishin
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
| | - Konstantin A Lyssenko
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
| | - Alexander S Goloveshkin
- A.N.Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, Vavilova St. 28, Moscow 119934, Russia
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Tatiana V Magdesieva
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russia
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3
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Chatterjee S, Jana P, Mahato S, Bandyopadhyay S. Light-induced reversible switching of generation and extinction of an organic radical anion. Phys Chem Chem Phys 2024; 26:22472-22478. [PMID: 39145399 DOI: 10.1039/d4cp02810d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
Radicals play a crucial role across various domains, ranging from serving as catalysts in chemical reactions to materials for spintronic applications. Currently, a major challenge for the chemists is the development of the next generation of organic radicals controllable by photons. To tackle this challenge, here we introduce a dyad system that combines a dimethyldihydropyrene (DHP) photochromic unit with a naphthalene diimide (NDI) moiety. This system forms a stable organic NDI-based radical-anion upon exposure to light in a solvent containing a small amount of an amine that acts as an electron donor. The radical anion formation has also been demonstrated with a chemical reductant. The photoisomerization of this photochromic system converts it into a less-conjugated and less-electron-rich form, affecting the generation of the radical as well as its stability. Consequently, light-induced isomerization effectively quenches the radical. Thus, the formation and existence of the radical can be adjusted by manipulating the photoisomerization of the photochromic unit under diverse light sources. Additionally, the system exhibits significant differences in emission in the radical and the closed-shell state, thereby offering a dual readout of the state of the molecule.
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Affiliation(s)
- Sheelbhadra Chatterjee
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal, 741246, India.
| | - Palash Jana
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal, 741246, India.
| | - Samyadeb Mahato
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal, 741246, India.
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, West Bengal, 741246, India
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Subhajit Bandyopadhyay
- Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Kolkata, Mohanpur, Nadia, West Bengal, 741246, India.
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4
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Chang X, Arnold ME, Blinder R, Zolg J, Wischnat J, van Slageren J, Jelezko F, Kuehne AJC, von Delius M. A Stable Chichibabin Diradicaloid with Near-Infrared Emission. Angew Chem Int Ed Engl 2024; 63:e202404853. [PMID: 38695271 DOI: 10.1002/anie.202404853] [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: 03/11/2024] [Indexed: 06/21/2024]
Abstract
Conjugated molecules with multiple radical centers such as the iconic Chichibabin diradicaloid hold promise as building blocks in materials for quantum sensing and quantum information processing. However, it is a considerable challenge to design simple analogues of the Chichibabin hydrocarbon that are chemically inert, exhibit high diradical character and emit light at a distinct wavelength that may offer an optical readout of the spin state in functional ensembles. Here we describe the serendipitous discovery of the stable TTM-TTM diradicaloid, which exhibits high diradical character, a striking sky-blue color and near-infrared (NIR) emission (in solution). This combination of properties is unique among related diradicaloids and is due to the presence of hydrogen and chlorine atoms in "just the right positions", allowing a perfectly planar, yet predominantly benzenoid bridge to connect the two sterically stabilized radical centers. In-depth studies of the optical and magnetic properties suggest that this structural motif could become a mainstay building block of organic spin materials.
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Affiliation(s)
- Xingmao Chang
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Mona E Arnold
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Rémi Blinder
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Julia Zolg
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Jonathan Wischnat
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Joris van Slageren
- Institut für Physikalische Chemie and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Fedor Jelezko
- Institute of Quantum Optics and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Alexander J C Kuehne
- Institute of Macromolecular and Organic Chemistry and Center for Integrated Quantum Science and Technology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Max von Delius
- Institute of Organic Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
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5
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Hu C, Kuhn L, Makurvet FD, Knorr ES, Lin X, Kawade RK, Mentink-Vigier F, Hanson K, Alabugin IV. Tethering Three Radical Cascades for Controlled Termination of Radical Alkyne peri-Annulations: Making Phenalenyl Ketones without Oxidants. J Am Chem Soc 2024; 146:4187-4211. [PMID: 38316011 DOI: 10.1021/jacs.3c13371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Although Bu3Sn-mediated radical alkyne peri-annulations allow access to phenalenyl ring systems, the oxidative termination of these cascades provides only a limited selection of the possible isomeric phenalenone products with product selectivity controlled by the intrinsic properties of the new cyclic systems. In this work, we report an oxidant-free termination strategy that can overcome this limitation and enable selective access to the full set of isomerically functionalized phenalenones. The key to preferential termination is the preinstallation of a "weak link" that undergoes C-O fragmentation in the final cascade step. Breaking a C-O bond is assisted by entropy, gain of conjugation in the product, and release of stabilized radical fragments. This strategy is expanded to radical exo-dig cyclization cascades of oligoalkynes, which provide access to isomeric π-extended phenalenones. Conveniently, these cascades introduce functionalities (i.e., Bu3Sn and iodide moieties) amenable to further cross-coupling reactions. Consequently, a variety of polyaromatic diones, which could serve as phenalenyl-based open-shell precursors, can be synthesized.
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Affiliation(s)
- Chaowei Hu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Leah Kuhn
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Favour D Makurvet
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Erica S Knorr
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Xinsong Lin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Rahul K Kawade
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Kenneth Hanson
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
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6
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Saha HK, Mallick D, Das S. Dibenzoheterole-Fused s-Indacenes. J Org Chem 2023; 88:16248-16258. [PMID: 37943573 DOI: 10.1021/acs.joc.3c01719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023]
Abstract
Heterole (pyrrole, thiophene, furan, thiophene-S,S-dioxide)-fused s-indacenes are known for their enhanced paratropic ring-current strength. However, the outcome of the antiaromatic properties for dibenzoheterole-fused s-indacene antiaromatics remained underexplored. Carbazole-, dibenzothiophene-, dibenzofuran-, and dibenzo[b,d]thiophene-5,5-dioxide-fused s-indacenes 1-4, respectively, were synthesized and characterized by experimental (NMR, single-crystal, UV-vis, CV) and computational (DFT) approaches to study the ground-state antiaromatic properties. Sulfone-containing 4 showed the weakest paratropic ring-current strength for the s-indacene unit, while 1-3 showed a relatively greater paratropicity for the s-indacene unit, as evidenced by the changes in 1H NMR chemical shifts of s-indacene protons. Such observation was explained by the electron-withdrawing effect of the sulfone group and loss of 4n + 2 aromaticity of the heterole unit for 4 reducing its s-indacene paratropicity strength as the nonaromaticity of the heterole unit reduces the π-bond character at the dibenzo[b,d]thiophene-5,5-dioxide/s-indacene fusion site to avoid antiaromatic s-indacene ring formation. The modulation of the paratropic ring-current strength of s-indacene for 1-4 was further supported by the NICS(1)zz and ring-current (ACID) calculations.
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Affiliation(s)
- Hemonta Kumar Saha
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
| | - Dibyendu Mallick
- Department of Chemistry, Presidency University, Kolkata 700073, West Bengal, India
| | - Soumyajit Das
- Department of Chemistry, Indian Institute of Technology Ropar, Rupnagar 140001, Punjab, India
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7
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Moriyasu R, Quintero SM, Gómez-García CJ, Suzuki K, Kitamura C, Murata M, Alonso M, Casado J, Kato SI. Isomerism tunes the diradical character of difluorenopyrroles at constant Hückel-level anti-aromaticity. Chem Sci 2023; 14:13468-13474. [PMID: 38033889 PMCID: PMC10685319 DOI: 10.1039/d3sc03297c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 10/22/2023] [Indexed: 12/02/2023] Open
Abstract
A new diradical based on diindenocarbazole or difluorenopyrrole was synthesized and experimentally characterized by optical, electrochemical, and magnetic techniques, as well as quantum chemical calculations. The isomerism of these structures tunes the diradical character and the associated properties, representing a unique case of such important modulation. A full study of the electronic structure was carried out considering the perturbative interactions between different canonical forms as well as the anti-aromatic character of the molecular cores. Such a study reveals how we can tune diradical character simply by reorganizing the bonding patterns at constant chemical costs (composition).
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Affiliation(s)
- Ryotaro Moriyasu
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
| | - Sergio Moles Quintero
- Departament of Physical Chemistry, University of Málaga Campus de Teatinos s/n Málaga 29071 Spain
| | - Carlos J Gómez-García
- Departament of Inorganic Chemsitry, University of Valencia C/ DR. Moliner, 50, 46100 Brujassot Valencia Spain
| | - Kazumasa Suzuki
- Department of Material Chemistry, Graduate School of Engineering, Nagoya university Furo-cho, Chikusa-ku Nagoya 464-8603 Japan
| | - Chitoshi Kitamura
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
| | - Michihisa Murata
- Department of Applied Chemistry, Faculty of Engineering, Osaka Institute of Technology 5-16-1 Ohmiya, Asahi-ku Osaka 535-8585 Japan
| | - Mercedes Alonso
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB)Plei nlaan 2 1050 Brussels Belgium
| | - Juan Casado
- Departament of Physical Chemistry, University of Málaga Campus de Teatinos s/n Málaga 29071 Spain
| | - Shin-Ichiro Kato
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
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8
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Sirianni D, Song X, Wairegi S, Wang EB, Mendoza-Gomez SA, Luxon A, Zimmerley M, Nussdorf A, Filatov M, Hoffmann R, Parish CA. Variations on the Bergman Cyclization Theme: Electrocyclizations of Ionic Penta-, Hepta-, and Octadiynes. J Am Chem Soc 2023; 145:21408-21418. [PMID: 37747784 PMCID: PMC10557144 DOI: 10.1021/jacs.3c06691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2023] [Indexed: 09/26/2023]
Abstract
The Bergman cyclization of (Z)-hexa-3-ene-1,5-diyne to form the aromatic diradical p-benzyne has garnered attention as a potential antitumor agent due to its relatively low cyclization barrier and the stability of the resulting diradical. Here, we present a theoretical investigation of several ionic extensions of the fundamental Bergman cyclization: electrocyclizations of the penta-1,4-diyne anion, hepta-1,6-diyne cation, and octa-1,7-diyne dication, leveraging the spin-flip formulation of the equation-of-motion coupled cluster theory with single and double substitutions (EOM-SF-CCSD). Though the penta-1,4-diyne anion exhibits a large cyclization barrier of +66 kcal mol-1, cyclization of both the hepta-1,6-diyne cation and octa-1,7-diyne dication along a previously unreported triplet pathway requires relatively low energy. We also identified the presence of significant aromaticity in the triplet diradical products of these two cationic cyclizations.
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Affiliation(s)
- Dominic
A. Sirianni
- Department
of Natural Sciences, Daemen University, Amherst, New York 14226, United States
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Xinli Song
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Salmika Wairegi
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Evan B. Wang
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | | | - Adam Luxon
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Maxwell Zimmerley
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Ariana Nussdorf
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
| | - Michael Filatov
- Department
of Chemistry, Southern Methodist University, Dallas, Texas 75275, United States
| | - Roald Hoffmann
- Department
of Chemistry, Cornell University, Ithaca, New York 14853, United States
| | - Carol A. Parish
- Department
of Chemistry, University of Richmond, Richmond, Virginia 23173, United States
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9
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Mizuno Y, Nogata A, Suzuki M, Nakayama KI, Hisaki I, Kishi R, Konishi A, Yasuda M. Synthesis and Characterization of Dibenzothieno[ a, f]pentalenes Enabling Large Antiaromaticity and Moderate Open-Shell Character through a Small Energy Barrier for Bond-Shift Valence Tautomerization. J Am Chem Soc 2023; 145:20595-20609. [PMID: 37695346 DOI: 10.1021/jacs.3c07356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Experimental and theoretical rationalization of bond-shift valence tautomerization, characterized by double-well potential surfaces, is one of the most challenging topics of study among the rich electronic properties of antiaromatic molecules. Although the pseudo-Jahn-Teller effect (PJTE) is an essential effect to provide attractive characteristics of 4nπ systems, an understanding of the structure-property relationship derived from the PJTE for planar 4nπ electron systems is still in its infancy. Herein, we describe the synthesis and characterization of two regioisomers of the thiophene-fused diareno[a,f]pentalenes 6 and 7. The magnetic and optoelectronic properties characterize these sulfur-doped diareno[a,f]pentalenes as open-shell antiaromatic molecules, in sharp contrast to the closed-shell antiaromatic systems of 3 and 5, in which these main cores consist of the same number of π electrons as 6 and 7. Notably, thiophene-fused 6b and 7b showed pronounced antiaromaticity, the strongest among the previous systems, as well as moderate open-shell characteristics. Our experimental and theoretical investigations concluded that these properties of 6b and 7b are derived from the small energy barrier Ea‡ for the bond-shift valence tautomerization. The energy profile of the single crystal of 6b showed the temperature-dependent structural variations assigned to the dynamic mutual exchange between the two Cs-symmetric structures, which was also supported by changes in the chemical shifts of variable-temperature 1H NMR spectra in the solution phase. Both experimental and computational results revealed the importance of introducing heteroaromatic rings into 4nπ systems for controlling the PJTE and manifesting the antiaromatic and open-shell natures originating from the high-symmetric structure. The findings of this study advance the understanding of antiaromaticity characterized by the PJTE by controlling the energy barrier for bond-shift valence tautomerizations, potentially leading to the rational design of optoelectronic devices based on novel antiaromatic molecules possessing the strong contributions of their high-symmetric geometries.
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Affiliation(s)
- Yusuke Mizuno
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Akira Nogata
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Mitsuharu Suzuki
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ken-Ichi Nakayama
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Ichiro Hisaki
- Division of Chemistry, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
| | - Ryohei Kishi
- Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531, Japan
- Center for Quantum Information and Quantum Biology (QIQB), Osaka University, Toyonaka, Osaka 560-8531, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Akihito Konishi
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
| | - Makoto Yasuda
- Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
- Innovative Catalysis Science Division, Institute for Open and Transdisciplinary Research Initiatives (ICS-OTRI), Osaka University, Suita, Osaka 565-0871, Japan
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10
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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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11
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Tabata N, Uchino T, Kitamura C, Yoshizawa K, Shiota Y, Kato SI. Site-selective radical reactions of kinetically stable open-shell singlet diradicaloid difluorenoheteroles with tributyltin hydride and azo-based radical initiators. Chem Sci 2023; 14:5974-5982. [PMID: 37293653 PMCID: PMC10246680 DOI: 10.1039/d3sc00381g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Accepted: 04/20/2023] [Indexed: 06/10/2023] Open
Abstract
We have demonstrated site-selective radical reactions of the kinetically stable open-shell singlet diradicaloids difluoreno[3,4-b:4',3'-d]thiophene (DFTh) and difluoreno[3,4-b:4',3'-d]furan (DFFu) with tributyltin hydride (HSn(n-Bu)3) and azo-based radical initiators. Treatment of these diradicaloids with HSn(n-Bu)3 induces hydrogenation at the ipso-carbon in the five-membered rings, while treatment with 2,2'-azobis(isobutyronitrile) (AIBN) induces substitution at the carbon atoms in the peripheral six-membered rings. We have also developed one-pot substitution/hydrogenation reactions of DFTh/DFFu with various azo-based radical initiators and HSn(n-Bu)3. The resulting products can be converted into substituted DFTh/DFFu derivatives via dehydrogenation. Theoretical calculations unveiled a detailed mechanism of the radical reactions of DFTh/DFFu with HSn(n-Bu)3 and with AIBN, and that the site-selectivity of these radical reactions is controlled by the balance of the spin density and the steric hindrance in DFTh/DFFu.
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Affiliation(s)
- Naoki Tabata
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
| | - Takumi Uchino
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
| | - Chitoshi Kitamura
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
| | - Kazunari Yoshizawa
- Institute for Materials Chemistry and Engineering (IMCE), Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Yoshihito Shiota
- Institute for Materials Chemistry and Engineering (IMCE), Kyushu University 744 Motooka Nishi-ku Fukuoka 819-0395 Japan
| | - Shin-Ichiro Kato
- Department of Materials Chemistry, School of Engineering, The University of Shiga Prefecture 2500 Hassaka-cho Hikone Shiga 522-8533 Japan
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12
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Guo J, Tian X, Wang Y, Dou C. Progress of Indeno-type Organic Diradicaloids. Chem Res Chin Univ 2023. [DOI: 10.1007/s40242-023-2363-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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13
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Closed-shell and open-shell dual nature of singlet diradical compounds. PURE APPL CHEM 2023. [DOI: 10.1515/pac-2023-0114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/09/2023]
Abstract
Abstract
Unlike triplet diradicals, singlet diradicals can vary in diradical character from 0 % to 100 % depending on linker units that allow two formally unpaired electrons to couple covalently. In principle, the electronic structure of singlet diradicals can be described as a quantum superposition of closed-shell and open-shell structures. This means that, depending on the external environment, singlet diradicals can behave as either closed-shell or open-shell species. This paper summarizes our progress in understanding the electronic structure of π-conjugated singlet diradical molecules in terms of closed-shell and open-shell dual nature. We first discuss the coexistence of intra- and intermolecular covalent bonding interactions in the π-dimer of a singlet diradical molecule. The intra- and intermolecular coupling of two formally unpaired electrons are related to closed-shell and open-shell nature of singlet diradical, respectively. Then we demonstrate the coexistence of the covalent bonding interactions in the one-dimensional stack of singlet diradical molecules having different diradical character. The relative strength of the interactions is varied with the magnitude of singlet diradical index y
0. Finally, we show the dual reactivity of a singlet diradical molecule, which undergoes rapid [4 + 2] and [4 + 4] cycloaddition reactions in the dark at room temperature. Closed-shell and open-shell nature endow the singlet diradical molecule with the reaction manner as diene and diradical species, respectively.
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14
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Kuriakose F, Commodore M, Hu C, Fabiano CJ, Sen D, Li RR, Bisht S, Üngör Ö, Lin X, Strouse GF, DePrince AE, Lazenby RA, Mentink-Vigier F, Shatruk M, Alabugin IV. Design and Synthesis of Kekulè and Non-Kekulè Diradicaloids via the Radical Periannulation Strategy: The Power of Seven Clar's Sextets. J Am Chem Soc 2022; 144:23448-23464. [PMID: 36516873 DOI: 10.1021/jacs.2c09637] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This work introduces an approach to uncoupling electrons via maximum utilization of localized aromatic units, i.e., the Clar's π-sextets. To illustrate the utility of this concept to the design of Kekulé diradicaloids, we have synthesized a tridecacyclic polyaromatic system where a gain of five Clar's sextets in the open-shell form overcomes electron pairing and leads to the emergence of a high degree of diradical character. According to unrestricted symmetry-broken UCAM-B3LYP calculations, the singlet diradical character in this core system is characterized by the y0 value of 0.98 (y0 = 0 for a closed-shell molecule, y0 = 1 for pure diradical). The efficiency of the new design strategy was evaluated by comparing the Kekulé system with an isomeric non-Kekulé diradical of identical size, i.e., a system where the radical centers cannot couple via resonance. The calculated singlet-triplet gap, i.e., the ΔEST values, in both of these systems approaches zero: -0.3 kcal/mol for the Kekulé and +0.2 kcal/mol for the non-Kekulé diradicaloids. The target isomeric Kekulé and non-Kekulé systems were assembled using a sequence of radical periannulations, cross-coupling, and C-H activation. The diradicals are kinetically stabilized by six tert-butyl substituents and (triisopropylsilyl)acetylene groups. Both molecules are NMR-inactive but electron paramagnetic resonance (EPR)-active at room temperature. Cyclic voltammetry revealed quasi-reversible oxidation and reduction processes, consistent with the presence of two nearly degenerate partially occupied molecular orbitals. The experimentally measured ΔEST value of -0.14 kcal/mol confirms that K is, indeed, a nearly perfect singlet diradical.
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Affiliation(s)
- Febin Kuriakose
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Michael Commodore
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Chaowei Hu
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Catherine J Fabiano
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Debashis Sen
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Run R Li
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Shubham Bisht
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Ökten Üngör
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Xinsong Lin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Geoffrey F Strouse
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - A Eugene DePrince
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Robert A Lazenby
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Frederic Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida32310, United States
| | - Michael Shatruk
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida32306-4390, United States
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15
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Kalapos P, Mayer PJ, Gazdag T, Demeter A, Oruganti B, Durbeej B, London G. Photoswitching of Local (Anti)Aromaticity in Biphenylene-Based Diarylethene Molecular Switches. J Org Chem 2022; 87:9532-9542. [PMID: 35849785 PMCID: PMC9361354 DOI: 10.1021/acs.joc.2c00504] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Indexed: 02/02/2023]
Abstract
Photoinduced tuning of (anti)aromaticity and associated molecular properties is currently in the focus of attention for both tailoring photochemical reactivity and designing new materials. Here, we report on the synthesis and spectroscopic characterization of diarylethene-based molecular switches embedded in a biphenylene structure composed of rings with different levels of local (anti)aromaticity. We show that it is possible to modulate and control the (anti)aromatic character of each ring through reversible photoswitching of the aryl units of the system between open and closed forms. Remarkably, it is shown that the irreversible formation of an annulated bis(dihydro-thiopyran) side-product that hampers the photoswitching can be efficiently suppressed when the aryl core formed by thienyl groups in one switch is replaced by thiazolyl groups in another.
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Affiliation(s)
- Péter
Pál Kalapos
- MTA
TTK Lendület Functional Organic Materials Research Group, Institute
of Organic Chemistry, Research Centre for
Natural Sciences, Magyar tudósok krt. 2, 1117 Budapest, Hungary
| | - Péter J. Mayer
- MTA
TTK Lendület Functional Organic Materials Research Group, Institute
of Organic Chemistry, Research Centre for
Natural Sciences, Magyar tudósok krt. 2, 1117 Budapest, Hungary
- Institute
of Chemistry, University of Szeged, Rerrich tér 1, 6720 Szeged, Hungary
| | - Tamás Gazdag
- MTA
TTK Lendület Functional Organic Materials Research Group, Institute
of Organic Chemistry, Research Centre for
Natural Sciences, Magyar tudósok krt. 2, 1117 Budapest, Hungary
- Hevesy
György PhD School of Chemistry, Eötvös
Loránd University, Pázmány Péter sétány 1/a, Budapest 1117, Hungary
| | - Attila Demeter
- Institute
of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Magyar tudósok krt. 2, 1117 Budapest, Hungary
| | - Baswanth Oruganti
- Department
of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, SE-45041 Kalmar, Sweden
| | - Bo Durbeej
- Division
of Theoretical Chemistry, IFM, Linköping
University, SE-58183 Linköping, Sweden
| | - Gábor London
- MTA
TTK Lendület Functional Organic Materials Research Group, Institute
of Organic Chemistry, Research Centre for
Natural Sciences, Magyar tudósok krt. 2, 1117 Budapest, Hungary
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16
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Saha HK, Mallick D, Das S. Unveiling two antiaromatic s-indacenodicarbazole isomers with tuneable paratropicity. Chem Commun (Camb) 2022; 58:8492-8495. [DOI: 10.1039/d2cc02318k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Linear and curved antiaromatic s-indacenodicarbazole isomers were synthesized and characterized to show tuneable strength of s-indacene paratropicity, as analyzed by NICS(1)zz and ACID (ring-current) calculations. The curved isomer showed a...
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