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Wang D, Shi C, Baumgarten M, Wang W, Liu J. Nonalternating π-System Mediated Spin Coupling in Azulene Nitronyl Nitroxide Diradicals. J Org Chem 2024. [PMID: 39137948 DOI: 10.1021/acs.joc.4c01206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
To explore the distinctions in spin coupling between the molecular bridges of alternating and nonalternating π-systems, we synthesized a pair of isoelectronic compounds, namely, 2,6-Na-NN and 2,6-Az-NN, by utilizing naphthalene and azulene (naphthalene = Na and azulene = Az) as the bridges, respectively. Moreover, we conducted assessments to predict the coupling paths for nonalternating azulene. Variable-temperature EPR (VT-EPR) and SQUID results consistently reveal that both 2,6-Na-NN and 2,6-Az-NN exhibit antiferromagnetic coupling interactions, with coupling constants of J(2,6-Na-NN) = -22.3 cm-1 and J(2,6-Az-NN) = -30.1 cm-1, respectively. Density functional theory computations support these discoveries by revealing negative coupling constants (J < 0) and the spin densities population of the diradicals are observed to delocalize into the molecular bridges. This work suggests the most suitable coupling path for 2,6-Az-NN. In addition, we have investigated the potential spatial resistance of the diradicals in conjunction with single-crystal data. Theoretical calculations underestimating the torsion angle of the diradicals and overestimating the value of the magnetic coupling provide an explanation for this phenomenon. The final experimental results and theoretical calculations show that the 2,6-Az-NN coupling path prefers short paths.
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Affiliation(s)
- Di Wang
- Anhui Key Laboratory of Advanced Building Materials, School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
| | - Chengfang Shi
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China
| | - Martin Baumgarten
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
| | - Wenping Wang
- School of Chemistry and Chemical Engineering, Hefei University of Technology, Hefei 230009, China
| | - Jin Liu
- Anhui Key Laboratory of Advanced Building Materials, School of Materials Science and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China
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Zhang D, Zhu Z, Xiao X, Fang YH, Xiao T, Wang X, Jiang SD, Zhao D. An Air-Stable Carbon-Centered Triradical with a Well-Addressable Quartet Ground State. J Am Chem Soc 2024; 146:21752-21761. [PMID: 39056815 DOI: 10.1021/jacs.4c05898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2024]
Abstract
Organic polyradicals with a high-spin ground state and quantum magnetic properties suitable for spin manipulation are valuable materials for diverse innovative technologies, including quantum devices. However, the typically high reactivity and low stability of conventional polyradicals present a major obstacle to such applications. In this study, a highly stable carbon-centered triradical TR with a quartet ground state and excellent stability (τ1/2 of ∼90 days in air-saturated toluene at room temperature) is achieved, which shows apposite magnetic anisotropy and Zeeman splitting partition with favorable addressability. By virtue of the optimal stability, thorough structural and magnetic characterizations are realized. With X-ray crystallography unambiguously proving the molecular structure, the quartet ground state (ΔED-Q = 0.78 kcal/mol) is confirmed by the SQUID measurements, while the cw- and pulsed EPR techniques offer additional supportive evidence for the high-spin nature. Remarkably, owing to the easily attained magnetic anisotropy, selective excitations between different Zeeman splitting levels are successfully demonstrated with TR in its frozen toluene solution without the requirement for special alignment, which is unprecedented for organic polyradicals. Along with the millisecond spin-lattice relaxation and microsecond coherence time manifested by TR, this triradical is promising for potential coherent spin manipulation applications as a multienergy-level quantum information carrier.
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Affiliation(s)
- Di Zhang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Ziqi Zhu
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Xiao Xiao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Yu-Hui Fang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Tongtong Xiao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Xiaoge Wang
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
| | - Shang-Da Jiang
- Spin-X Institute, School of Chemistry and Chemical Engineering, State Key Laboratory of Luminescent Materials and Devices, Guangdong-Hong Kong-Macao Joint Laboratory of Optoelectronic and Magnetic Functional Materials, South China University of Technology, Guangzhou 510641, China
| | - Dahui Zhao
- Beijing National Laboratory for Molecular Sciences, Centre for the Soft Matter Science and Engineering, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry, Peking University, Beijing 100871, China
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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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Fabri B, Funaioli T, Frédéric L, Elsner C, Bordignon E, Zinna F, Di Bari L, Pescitelli G, Lacour J. Triple para-Functionalized Cations and Neutral Radicals of Enantiopure Diaza[4]helicenes. J Am Chem Soc 2024; 146:8308-8319. [PMID: 38483324 DOI: 10.1021/jacs.3c13487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
Modulation of absorbance and emission is key for the design of chiral chromophores. Accessing a series of compounds absorbing and emitting (circularly polarized) light over a wide spectral window and often toward near-infrared is of practical value in (chir)optical applications. Herein, by late-stage functionalization on derivatives bridging triaryl methyl and helicene domains, we have achieved the regioselective triple introduction of para electron-donating or electron-withdrawing substituents. Extended tuning of electronic (e.g., E1/2red -1.50 V → -0.68 V) and optical (e.g., emission covering from 550 to 850 nm) properties is achieved for the cations and neutral radicals; the latter compounds being easily prepared by mono electron reductions under electrochemical or chemical conditions. While luminescence quantum yields can be increased up to 70% in the cationic series, strong Cotton effects are obtained for certain radicals at low energies (λabs ∼ 700-900 nm) with gabs values above 10-3. The open-shell electronic nature of the radicals was further characterized by electron paramagnetic resonance revealing an important spin density delocalization that contributes to their persistence.
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Affiliation(s)
- Bibiana Fabri
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, Geneva 4 1211, Switzerland
| | - Tiziana Funaioli
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Lucas Frédéric
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, Geneva 4 1211, Switzerland
| | - Christina Elsner
- Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, Geneva 4 1211, Switzerland
| | - Enrica Bordignon
- Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, Geneva 4 1211, Switzerland
| | - Francesco Zinna
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Lorenzo Di Bari
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Gennaro Pescitelli
- Dipartimento di Chimica e Chimica Industriale, University of Pisa, Via G. Moruzzi 13, Pisa 56124, Italy
| | - Jérôme Lacour
- Department of Organic Chemistry, University of Geneva, Quai Ernest Ansermet 30, Geneva 4 1211, Switzerland
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Yang K, Li Z, Huang Y, Zeng Z. bay/ ortho-Octa-substituted Perylene: A Versatile Building Block toward Novel Polycyclic (Hetero)Aromatic Hydrocarbons. Acc Chem Res 2024; 57:763-775. [PMID: 38386871 DOI: 10.1021/acs.accounts.3c00793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2024]
Abstract
ConspectusPolycyclic (hetero)aromatic hydrocarbons (PAHs) have emerged as a focal point in current interdisciplinary research, spanning the realms of chemistry, physics, and materials science. Possessing distinctive optical, electronic, and magnetic properties, these π-functional materials exhibit significant potential across diverse applications, including molecular electronic devices, organic spintronics, and biomedical functions, among others. Despite the extensive documentation of various PAHs over the decades, the efficient and precise synthesis of π-extended PAHs remains a formidable challenge, hindering their broader application. This challenge is primarily attributed to the intricate and often elusive nature of their synthesis, compounded by issues related to low solubility and unfavored stability.The development of π-building blocks that can be facilely and modularly transformed into diverse π-frameworks constitutes a potent strategy for the creation of novel PAH materials. For instance, based on the classic perylene diimide (PDI) unit, researchers such as Würthner, Wang, and Nuckolls have successfully synthesized a plethora of structurally diverse PAHs, as well as numerous other π-functional materials. However, until now the availability of such versatile building blocks is still severely limited, especially for those simultaneously having a facile preparation process, adequate solubilizing groups, favored material stability, and critically, rich possibilities for structural extension spaces.In this Account, we present an overview of our invention of a highly versatile bay-/ortho-octa-substituted perylene building block, designated as Per-4Br, for the construction of a series of novel PAH scaffolds with tailor-made structures and rich optoelectronic and magnetic properties. First, starting with a brief discussion of current challenges associated with the bottom-up synthesis of π-extended PAHs, we rationalize the key features of Per-4Br that enable facile access to new PAH molecules including its ease of large-scale preparation, favored material stability and solubility, and multiple flexible reaction sites, with a comparison to the PDI motif. Then, we showcase our rational design and sophisticated synthesis of a body of neutral or charged, closed- or open-shell, curved, or planar PAHs via controlled annulative π-extensions in different directions such as peripheral, diagonal, or multiple dimensions of the Per-4Br skeleton. In this part, the fundamental structure-property relationships between molecular conformations, electronic structures, and self-assembly behaviors of these PAHs and their unique physiochemical properties such as unusual open-shell ground states, global aromaticity, state-associated/stimuli-responsive magnetic activity, and charge transport characteristics will be emphatically elaborated. Finally, we offer our perspective on the continued advancement of π-functional materials based on Per-4Br, which, we posit, may stimulate heightened research interest in the versatile structural motifs typified by Per-4Br, consequently catalyzing further progress in the realm of organic π-functional materials.
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Affiliation(s)
- Kun Yang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Zuhao Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Yulin Huang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
| | - Zebing Zeng
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, Hunan 410082, China
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