1
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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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Euringer L, Holzapfel M, Krummenacher I, Franz M, Richert S, Braunschweig H, Lambert C. Tuning Electron Transfer Coupling and Exchange Interaction in Bis-triarylamine Radical Cations and Dications by Bridge Electron Density. J Am Chem Soc 2024. [PMID: 39316417 DOI: 10.1021/jacs.4c09221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
The influence of the electron density of a bridge connecting two redox centers on both the intervalence hole transfer and the magnetic superexchange was investigated in a series of bridged bis-triarylamine mono- and dications. In this series, the bridge was 2,7-fluorenyl, where the bridge electron density was modified by substituents at the 9-position. For the mixed-valence monocations, the observation of both an intervalence charge transfer (IVCT) band and an absorption band associated with an electron transfer from the bridging fluorene to the triarylamine radical cation centers allowed determination of the electron transfer couplings in the framework of the three-state generalized Mulliken-Hush theory. Comparison of the derived couplings with those obtained from a classical two-state approach demonstrates an enhancement of the electronic coupling which increases with decreasing bridge state energy. For the dicationic diradical counterparts, the singlet-triplet gap (exchange interaction) was determined both experimentally and by quantum chemical methods. Hereby, an increase of antiferromagnetic coupling with a lowering of the bridge state energy by electron donating substituents was observed. Analysis of the involved molecular orbitals suggests that the ferromagnetic coupling is inversely proportional to the square of the bridge energy, which is also supported by the experimental findings. This influence of the bridge state energy on both types of interactions, electron transfer and magnetic exchange, provides a design guideline for fine-tuning the properties of electronically coupled organic redox dyads by variation of the bridge electron density.
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Affiliation(s)
- Leon Euringer
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Marco Holzapfel
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Ivo Krummenacher
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Michael Franz
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
| | - Sabine Richert
- Institute of Physical Chemistry, University of Freiburg, Albertstraße 21, 79104 Freiburg, Germany
| | - Holger Braunschweig
- Institut für Anorganische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Christoph Lambert
- Institut für Organische Chemie, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
- Center für Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany
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3
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Khalilian MH, DiLabio GA. Non-Aufbau electronic structure in radical enzymes and control of the highly reactive intermediates. Chem Sci 2024; 15:11865-11874. [PMID: 39092113 PMCID: PMC11290419 DOI: 10.1039/d4sc01785d] [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: 03/16/2024] [Accepted: 06/07/2024] [Indexed: 08/04/2024] Open
Abstract
Radicals are highly reactive, short-lived chemical species that normally react indiscriminately with biological materials, and yet, nature has evolved thousands of enzymes that employ radicals to catalyze thermodynamically challenging chemistry. How these enzymes harness highly reactive radical intermediates to steer the catalysis to the correct outcome is a topic of intense investigation. Here, the results of detailed QM/MM calculations on archetype radical B12-enzymes are presented that provide new insights into how these enzymes control the reactivity of radicals within their active sites. The catalytic cycle in B12-enzymes is initiated through the formation of the 5'-deoxyadenosyl (Ado˙) moiety, a primary carbon-centred radical, which must migrate up to 8 Å to reach the target substrate to engage in the next step of the catalytic process, a hydrogen atom abstraction. Our calculations reveal that Ado˙ within the protein environment exhibits an unusual non-Aufbau electronic structure in which the singly occupied molecular orbital is lower in energy than the doubly occupied orbitals, an uncommon phenomenon known as SOMO-HOMO inversion (SHI). We find that the magnitude of SHI in the initially formed Ado˙ is larger compared to when the Ado˙ is near the intended substrate, leading to the former being relatively less reactive. The modulation of the SHI originates from Coulombic interactions of a quantum nature between a negative charge on a conserved glutamate residue and the spin on the Ado˙. Our findings support a novel hypothesis that these enzymes utilize this quantum Coulombic effect as a means of maintaining exquisite control over the chemistry of highly reactive radical intermediates in enzyme active sites.
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Affiliation(s)
- M Hossein Khalilian
- Department of Chemistry, The University of British Columbia 3247 University Way Kelowna British Columbia V1V 1V7 Canada +1-250-807-6617
| | - Gino A DiLabio
- Department of Chemistry, The University of British Columbia 3247 University Way Kelowna British Columbia V1V 1V7 Canada +1-250-807-6617
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4
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Wei L, Kushwaha R, Sadhukhan T, Wu H, Dao A, Zhang Z, Zhu H, Gong Q, Ru J, Liang C, Zhang P, Banerjee S, Huang H. Dinuclear Tridentate Ru(II) Complex with Strong Near-Infrared Light-Triggered Anticancer Activity. J Med Chem 2024; 67:11125-11137. [PMID: 38905437 DOI: 10.1021/acs.jmedchem.4c00624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2024]
Abstract
The design of the dinuclear Ru(II) complex (Ru2) with strong near-infrared (NIR) absorption properties has been reported for efficient anticancer phototherapy. Under 700 nm LED light excitation, Ru2 exhibited remarkable synergistic type I/II photosensitization ability and photocatalytic activity toward intracellular biomolecules. Ru2 showed impressive 700 nm light-triggered anticancer activity under normoxia and hypoxia compared with the clinically used photosensitizer Chlorin e6. The mechanistic studies showed that Ru2 induced intracellular redox imbalance and perturbed the energy metabolism and biosynthesis in A549 cancer cells. Overall, this work provides a new strategy for developing efficient metal-based complexes for anticancer phototherapy under NIR light.
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Affiliation(s)
- Li Wei
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong 518060, P.R. China
| | - Rajesh Kushwaha
- Department of Chemistry, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh 221005, India
| | - Tumpa Sadhukhan
- Department of Chemistry, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu 603203, India
| | - Haorui Wu
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China
| | - Anyi Dao
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China
| | - Zhishang Zhang
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China
| | - Haotu Zhu
- Department of Oncology, Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong 518107, P.R. China
| | - Qiufang Gong
- Institute for Advanced Research, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, Zhejinag 325035, P.R. China
| | - Jiaxi Ru
- Institute for Advanced Research, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, Zhejinag 325035, P.R. China
| | - Chao Liang
- Institute for Advanced Research, Cixi Biomedical Research Institute, Wenzhou Medical University, Wenzhou, Zhejinag 325035, P.R. China
| | - Pingyu Zhang
- College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen, Guangdong 518060, P.R. China
| | - Samya Banerjee
- Department of Chemistry, Indian Institute of Technology (BHU), Varanasi, Uttar Pradesh 221005, India
| | - Huaiyi Huang
- School of Pharmaceutical Sciences (Shenzhen), Shenzhen Campus of Sun Yat-sen University, Shenzhen, Guangdong 518107, P.R. China
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5
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Sakamaki T, Zhang Y, Fukuma S, Cruz CM, Valdivia AC, Campaña AG, Casado J, Shang R, Nakamura E. Doubly Spiro-Conjugated Chiral Carbocycles Exhibiting SOMO-HOMO Inversion in Persistent Radical Cations. J Am Chem Soc 2024; 146:12712-12722. [PMID: 38655573 DOI: 10.1021/jacs.4c02404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Persistent chiral organic open-shell systems have captured growing interest due to their potential applications in organic spintronic and optoelectronic devices. Nevertheless, the integration of configurationally stable chirality into an organic open-shell system continues to pose challenges in molecular design. The π-extended skeleton incorporated in spiro-conjugated carbocycles can provide robust chiroptical properties and a significant stabilization of the excited and ionic radical states. However, this approach has been relatively less explored in the design of persistent organic open-shell systems. We report here the (S,S)-, (R,R)-, and meso-isomers of doubly spiro-conjugated carbocycles featuring flat and rigid carbon-bridged para-phenylenevinylene (CPV) of different conjugation lengths connected by two spiro-carbon centers, which we denote D-spiro-CPV for its quasi-dimeric structure. Our synthetic method based on a double lithiation cyclization approach enables facile production of D-spiro-CPV. D-spiro-CPVs exhibit circularly polarized luminescence (CPL) with high fluorescence quantum yields (ΦFL) resulting in a high CPL brightness of 21 M-1 cm-1 and also exhibit high thermal and photostability. The monoradical cation of D-spiro-CPV absorbing near-infrared light is notably persistent, exhibiting a half-life of 570 h under ambient conditions due to doubly spiro-conjugative stabilization. Theoretical and electrochemical studies indicate the radical cation of D-spiro-CPVs presents a non-Aufbau electron filling, exhibiting inversion of the energy level of the singly occupied molecular orbital (SOMO) and the highest (doubly) occupied molecular orbitals with the SOMO level even below the HOMO-1 level (double SHI effect). Our discoveries provide valuable insights into non-Aufbau molecules and the development of configurationally stable, optically active persistent radicals.
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Affiliation(s)
- Takumi Sakamaki
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Yan Zhang
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Shota Fukuma
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Carlos M Cruz
- Departamento de Química Orgánica, Facultad de Ciencias, Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada (UGR), Avenida Fuente Nueva s/n, 18071 Granada, Spain
| | - Abel Cárdenas Valdivia
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
| | - Araceli G Campaña
- Departamento de Química Orgánica, Facultad de Ciencias, Unidad de Excelencia de Química Aplicada a Biomedicina y Medioambiente (UEQ), Universidad de Granada (UGR), Avenida Fuente Nueva s/n, 18071 Granada, Spain
| | - Juan Casado
- Department of Physical Chemistry, Faculty of Science, University of Málaga, Campus de Teatinos, s/n, 29071 Málaga, Spain
| | - Rui Shang
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
| | - Eiichi Nakamura
- Department of Chemistry, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan
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6
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Nain S, Mukhopadhyaya A, Ali ME. Unravelling the Highest Magnetic Anisotropy Among all the nd-Shells in [WCp2]0 Metallocene. Inorg Chem 2024; 63:7401-7411. [PMID: 38578709 DOI: 10.1021/acs.inorgchem.4c00437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
Single-molecule magnets (SMMs) with a large magnetization reversal barrier are predominated by the lanthanide systems due to their strong spin-orbit coupling (SOC). However, the transition metals have also emerged as potential contenders and the largest magnetic anisotropy has been identified for a cobalt system among any d-series-based SMMs (Bunting et al. Science 2018, 362, eaat7319). In this work, we have explored the magnetic anisotropy in highly axial ligand field systems of metallocene, having different d-subshell (3d4, 4d4, and 5d4). The wave function-based multireference methods including static and dynamic electron correlations have been employed to investigate the zero-field splitting (ZFS) parameters. Here, we report exceptionally large magnetic anisotropy for a 5d complex of [WCp2]0 with the highest energy barrier that is nearly twice as high as the previous record value for the Co complex. We have also observed that the axial ZFS parameter (D) is increasing down the group in the order of 3d < 4d < 5d, pertaining to a large SOC.
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Affiliation(s)
- Sakshi Nain
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Aritra Mukhopadhyaya
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
| | - Md Ehesan Ali
- Institute of Nano Science and Technology, Sector-81, Mohali, Punjab 140306, India
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7
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Guo H, Lovell JB, Shu C, Pink M, Morton M, Rajca S, Rajca A. Chiral π-Conjugated Double Helical Aminyl Diradical with the Triplet Ground State. J Am Chem Soc 2024; 146:9422-9433. [PMID: 38501228 DOI: 10.1021/jacs.4c02057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
We report a neutral high-spin diradical of chiral C2-symmetric bis[5]diazahelicene with ΔEST ≈ 0.4 kcal mol-1, as determined by EPR spectroscopy/SQUID magnetometry. The diradical is the most persistent among all high-spin aminyl radicals reported to date by a factor of 20, with a half-life of up to 6 days in 2-MeTHF at room temperature. Its triplet ground state and excellent persistence may be associated with the unique spin density distribution within the dihydrophenazine moiety, which characterizes two effective 3-electron C-N bonds analogous to the N-O bond of a nitroxide radical. The enantiomerically enriched (ee ≥ 94%) (MM)- and (PP)-enantiomers of the precursors to the diradicals are obtained by either preparative chiral supercritical fluid chromatography or resolution via functionalization with the chiral auxiliary of the C2-symmetric racemic tetraamine. The barrier for the racemization of the solid tetraamine is ΔG‡ = 43 ± 0.01 kcal mol-1 in the 483-523 K range. The experimentally estimated lower limit of the barrier for the racemization of a diradical, ΔG‡ ≥ 26 kcal mol-1 in 2-MeTHF at 293 K, is comparable to the DFT-determined barrier of ΔG‡ = 31 kcal mol-1 in the gas phase at 298 K. While the enantiomerically pure tetraamine displays strong chiroptical properties, with anisotropy factor |g| = |Δε|/ε = 0.036 at 376 nm, |g| ≈ 0.005 at 548 nm of the high-spin diradical is comparable to that recently reported triplet ground-state diradical dication. Notably, the radical anion intermediate in the generation of diradical exhibits a large SOMO-HOMO inversion, SHI = 35 kcal mol-1.
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Affiliation(s)
- Haoxin Guo
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Joshua B Lovell
- Teledyne ISCO, 4700 Superior Street, Lincoln, Nebraska 68504-1328, United States
| | - Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Martha Morton
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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8
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Zhang L, Li H, Zhu Y, Zhang S. A quantum-chemical insight into SOMO-HOMO conversion in phosphorus-boron cation radicals. Phys Chem Chem Phys 2024; 26:8273-8286. [PMID: 38385562 DOI: 10.1039/d4cp00098f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Organic radicals exhibiting SOMO-HOMO conversion (SHC) electronic configurations have recently garnered increasing attention due to their exceptional stability and photophysical properties. In this study, we investigate two series of phosphorus-boron cation radicals based on 1,3,5-trimethylphenyl units substituted with P and B atoms, varying numbers of P-B moieties, and π-conjugation linkers. We perform quantum-chemical calculations to systematically assess the influence of chemical substituents on the SHC electronic structural features. Our computational results demonstrate that the SHC electronic configurations of the studied complexes are primarily determined by the number of P-B moieties, specifically, phosphorus-boron cation radicals with two P-B moieties as terminal groups in π-conjugation linkers, which efficiently arrange electrons to increase HOMO energies compared to corresponding radicals with only one P-B unit. Furthermore, spin density distributions change as the size of π-conjugation linkers increases. Natural bond orbital (NBO) and atoms-in-molecules (AIM) analyses reveal strong intramolecular charge transfer between P and B atoms along with other stabilized donor-acceptor interactions and significant covalent bonds between P and B atoms. Moreover, synergistic effects resulting from 1,3,5-trimethylphenyl substitutions and enlarged π-conjugation linkers containing P-B units confer excellent photophysical properties upon these studied radicals, making them potential stable radicals in optoelectronic applications.
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Affiliation(s)
- Li Zhang
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
| | - Hongbo Li
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
| | - Yanbin Zhu
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
| | - Shoufeng Zhang
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
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9
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Ju CW, Shen Y, French EJ, Yi J, Bi H, Tian A, Lin Z. Accurate Electronic and Optical Properties of Organic Doublet Radicals Using Machine Learned Range-Separated Functionals. J Phys Chem A 2024. [PMID: 38382058 DOI: 10.1021/acs.jpca.3c07437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Luminescent organic semiconducting doublet-spin radicals are unique and emergent optical materials because their fluorescent quantum yields (Φfl) are not compromised by the spin-flipping intersystem crossing (ISC) into a dark high-spin state. The multiconfigurational nature of these radicals challenges their electronic structure calculations in the framework of single-reference density functional theory (DFT) and introduces room for method improvement. In the present study, we extended our earlier development of ML-ωPBE [J. Phys. Chem. Lett., 2021, 12, 9516-9524], a range-separated hybrid (RSH) exchange-correlation (XC) functional constructed using the stacked ensemble machine learning (SEML) algorithm, from closed-shell organic semiconducting molecules to doublet-spin organic semiconducting radicals. We assessed its performance for a new test set of 64 doublet-spin radicals from five categories while placing all previously compiled 3926 closed-shell molecules in the new training set. Interestingly, ML-ωPBE agrees with the nonempirical OT-ωPBE functional regarding the prediction of the molecule-dependent range-separation parameter (ω), with a small mean absolute error (MAE) of 0.0197 a0-1, but saves the computational cost by 2.46 orders of magnitude. This result demonstrates an outstanding domain adaptation capacity of ML-ωPBE for diverse organic semiconducting species. To further assess the predictive power of ML-ωPBE in experimental observables, we also applied it to evaluate absorption and fluorescence energies (Eabs and Efl) using linear-response time-dependent DFT (TDDFT), and we compared its behavior with nine popular XC functionals. For most radicals, ML-ωPBE reproduces experimental measurements of Eabs and Efl with small MAEs of 0.299 and 0.254 eV, only marginally different from those of OT-ωPBE. Our work illustrates a successful extension of the SEML framework from closed-shell molecules to doublet-spin radicals and will open the venue for calculating optical properties for organic semiconductors using single-reference TDDFT.
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Affiliation(s)
- Cheng-Wei Ju
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Yili Shen
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Ethan J French
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Jun Yi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Hongshan Bi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Aaron Tian
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Zhou Lin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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10
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Zhang H, Chen L, Du P, Li F, Liu W. Unraveling Different Reaction Characteristics of Alkoxy Radicals in a Co(II)-Activated Peracetic Acid System Based on Dynamic Analysis of Electron Distribution. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 38315813 DOI: 10.1021/acs.est.3c07977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have shown broad application prospects in organic wastewater treatment. Alkoxy radicals including CH3COO• and CH3COOO• are primary reactive species in PAA-AOP systems; however, their reaction mechanism on attacking organic pollutants still remains controversial. In this study, a Co(II)/PAA homogeneous AOP system at neutral pH was constructed to generate these two alkoxy radicals, and their different reaction mechanisms with a typical emerging contaminant (sulfacetamide) were explored. Dynamic electron distribution analysis was applied to deeply reveal the radical-meditated reaction mechanism based on molecular orbital analysis. Results indicate that hydrogen atom abstraction is the most favorable route for both CH3COO• and CH3COOO• attacking sulfacetamide. However, both radicals cannot react with sulfacetamide via the radical adduct formation route. Interestingly, the single-electron transfer reaction is only favorable for CH3COO• due to its lower ESUMO. In comparison, CH3COOO• can react with sulfacetamide via a similar radical self-sacrificing bimolecular nucleophilic substitution (SN2) route owing to its high ESOMO and easy escape of unpaired electrons from n orbitals of O atoms in the peroxy bond. These findings can significantly improve the knowledge of reactivity of CH3COO• and CH3COOO• on attacking organic pollutants at the molecular orbital level.
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Affiliation(s)
- Huixuan Zhang
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, P.R. China
| | - Long Chen
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, P.R. China
| | - Penghui Du
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, P.R. China
| | - Fan Li
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, P.R. China
- The Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University, Beijing 100871, P.R. China
| | - Wen Liu
- College of Environmental Sciences and Engineering, Peking University, Beijing 100871, P.R. China
- The Key Laboratory of Water and Sediment Sciences (Ministry of Education), Peking University, Beijing 100871, P.R. China
- International Joint Laboratory for Regional Pollution Control (Ministry of Education), Peking University, Beijing 100871, P.R. China
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11
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Mei Y, Chen X, Wei R, Chang XY, Tao L, Liu LL. An Isolable Radical Anion Featuring a 2-Center-3-Electron π-Bond without a Clearly Defined σ-Bond. Angew Chem Int Ed Engl 2023; 62:e202315555. [PMID: 37942957 DOI: 10.1002/anie.202315555] [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: 10/16/2023] [Revised: 11/08/2023] [Accepted: 11/09/2023] [Indexed: 11/10/2023]
Abstract
Featuring an extra electron in the π* antibonding orbital, species with a 2-center-3-electron (2c3e) π bond without an underlying σ bond are scarcely known. Herein, we report the synthesis, isolation and characterization of a radical anion salt [K(18-C-6)]+ {[(HCNDipp)2 Si]2 P2 }⋅- (i.e. [K(18-C-6)]+ 3⋅- ) (18-C-6=18-crown-6, Dipp=2,6-diisopropylphenyl), in which 3⋅- features a perfectly planar Si2 P2 four-membered ring. This species represents the first example of a Si- and P-containing analog of a bicyclo[1.1.0]butane radical anion. The unusual bonding motif of 3⋅- was thoroughly investigated via X-ray diffraction crystallography, electron paramagnetic resonance spectroscopy (EPR), and calculations by density functional theory (DFT), which collectively unveiled the existence of a 2c3e π bond between the bridgehead P atoms and no clearly defined supporting P-P σ bond.
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Affiliation(s)
- Yanbo Mei
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, 518055, China
- Department of Chemistry and Dongguan Key Laboratory for Data Science and Intelligent Medicine, Great Bay University, Dongguan, 523000, China
| | - Xiaodan Chen
- Guangdong Provincial Key Laboratory of Functional Supramolecular Coordination Materials and Applications, College of Chemistry and Materials Science, Jinan University, Guangzhou, 510632, China
| | - Rui Wei
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Xiao-Yong Chang
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Lizhi Tao
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, 518055, China
| | - Liu Leo Liu
- Department of Chemistry and Research Center for Chemical Biology and Omics Analysis, College of Science, Southern University of Science and Technology, Shenzhen, 518055, China
- State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin, 300071, China
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12
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Gu Q, Lu X, Chen C, Hu R, Wang X, Sun G, Kang F, Yang J, Wang X, Wu J, Li YY, Peng YK, Qin W, Han Y, Liu X, Zhang Q. Thermally Induced Persistent Covalent-Organic Frameworks Radicals. ACS NANO 2023. [PMID: 38014811 DOI: 10.1021/acsnano.3c08313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Persistent covalent-organic framework (COF) radicals hold important applications in magnetics and spintronics; however, their facile synthesis remains a daunting challenge. Here, three p-phenylenediacetonitrile-based COFs (named CityU-4, CityU-5, and CityU-6) were synthesized. Upon heat treatment (250 °C for CityU-4 and CityU-5 or 220 °C for CityU-6), these frameworks were brought into their persistent radical forms (no obvious changes after at least one year), together with several observable factors, including color changes, red-shifted absorption, the appearance of electron spin resonance (ESR) signals, and detectable magnetic susceptibility. The theoretical simulation suggests that after heat treatment, lower total energy and nonzero spin density are two main factors to guarantee persistent COFs radicals and polarized spin distributions. This work provides an efficient method for the preparation of persistent COF radicals with promising potentials.
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Affiliation(s)
- Qianfeng Gu
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Xiangqian Lu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Cailing Chen
- Advanced Membranes and Porous Materials (AMPM) Center, Physical Science and Engineering Division, King Ab-dullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Renjie Hu
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Xin Wang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Guohan Sun
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Fangyuan Kang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Jinglun Yang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Xiang Wang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Jinghang Wu
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Yang Yang Li
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Yung-Kang Peng
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
| | - Wei Qin
- School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China
| | - Yu Han
- Advanced Membranes and Porous Materials (AMPM) Center, Physical Science and Engineering Division, King Ab-dullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Xiaogang Liu
- Department of Chemistry and the N.1 Institute for Health, National University of Singapore, Singapore 117543, Singapore
| | - Qichun Zhang
- Department of Materials Science and Engineering, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
- Department of Chemistry & Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
- Department of Chemistry, City University of Hong Kong, Tat Chee Avenue 83, Kowloon, Hong Kong SAR 999077, P. R. China
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13
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Shu C, Yang Z, Rajca A. From Stable Radicals to Thermally Robust High-Spin Diradicals and Triradicals. Chem Rev 2023; 123:11954-12003. [PMID: 37831948 DOI: 10.1021/acs.chemrev.3c00406] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2023]
Abstract
Stable radicals and thermally robust high-spin di- and triradicals have emerged as important organic materials due to their promising applications in diverse fields. New fundamental properties, such as SOMO/HOMO inversion of orbital energies, are explored for the design of new stable radicals, including highly luminescent ones with good photostability. A relation with the singlet-triplet energy gap in the corresponding diradicals is proposed. Thermally robust high-spin di- and triradicals, with energy gaps that are comparable to or greater than a thermal energy at room temperature, are more challenging to synthesize but more rewarding. We summarize a number of high-spin di- and triradicals, based on nitronyl nitroxides that provide a relation between the experimental pairwise exchange coupling constant J/k in the high-spin species vs experimental hyperfine coupling constants in the corresponding monoradicals. This relation allows us to identify outliers, which may correspond to radicals where J/k is not measured with sufficient accuracy. Double helical high-spin diradicals, in which spin density is delocalized over the chiral π-system, have been barely explored, with the sole example of such high-spin diradical possessing alternant π-system with Kekulé resonance form. Finally, we discuss a high-spin diradical with electrical conductivity and derivatives of triangulene diradicals.
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Affiliation(s)
- Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Zhimin Yang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
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14
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Hatakeyama-Sato K, Oyaizu K. Redox: Organic Robust Radicals and Their Polymers for Energy Conversion/Storage Devices. Chem Rev 2023; 123:11336-11391. [PMID: 37695670 DOI: 10.1021/acs.chemrev.3c00172] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Persistent radicals can hold their unpaired electrons even under conditions where they accumulate, leading to the unique characteristics of radical ensembles with open-shell structures and their molecular properties, such as magneticity, radical trapping, catalysis, charge storage, and electrical conductivity. The molecules also display fast, reversible redox reactions, which have attracted particular attention for energy conversion and storage devices. This paper reviews the electrochemical aspects of persistent radicals and the corresponding macromolecules, radical polymers. Radical structures and their redox reactions are introduced, focusing on redox potentials, bistability, and kinetic constants for electrode reactions and electron self-exchange reactions. Unique charge transport and storage properties are also observed with the accumulated form of redox sites in radical polymers. The radical molecules have potential electrochemical applications, including in rechargeable batteries, redox flow cells, photovoltaics, diodes, and transistors, and in catalysts, which are reviewed in the last part of this paper.
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Affiliation(s)
- Kan Hatakeyama-Sato
- School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku Tokyo 152-8552, Japan
- Department of Applied Chemistry, Waseda University, Tokyo 169-8555, Japan
| | - Kenichi Oyaizu
- Department of Applied Chemistry, Waseda University, Tokyo 169-8555, Japan
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15
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Merecz-Sadowska A, Sitarek P, Kowalczyk T, Palusiak M, Hoelm M, Zajdel K, Zajdel R. In Vitro Evaluation and In Silico Calculations of the Antioxidant and Anti-Inflammatory Properties of Secondary Metabolites from Leonurus sibiricus L. Root Extracts. Molecules 2023; 28:6550. [PMID: 37764326 PMCID: PMC10537019 DOI: 10.3390/molecules28186550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 09/29/2023] Open
Abstract
Leonurus sibiricus L. has great ethnobotanical and ethnomedicinal significance. This study aimed to assess the antioxidant and anti-inflammatory properties of Leonurus sibiricus L. transgenic roots extracts transformed by Rhizobium rhizogenes, with and without the AtPAP1 transcriptional factor. The study determined the total phenolic and flavonoid contents, as well as in vitro antioxidant assays, including hydrogen peroxide and nitric oxide scavenging activity. In addition, in silico computational studies and molecular docking were conducted to evaluate the antioxidant and anti-inflammatory potential of the identified compounds. The ligands were docked to NADPH oxidase, cyclooxygenase 2,5-lipoxygenase, inducible nitric synthase and xanthine oxidase: enzymes involved in the inflammatory process. The total phenolic and flavonoid contents ranged from 85.3 ± 0.35 to 57.4 ± 0.15 mg/g GAE/g and 25.6 ± 0.42 to 18.2 ± 0.44 mg/g QUE/g in hairy root extracts with and without AtPAP1, respectively. H2O2 scavenging activity (IC50) was found to be 29.3 µg/mL (with AtPAP1) and 37.5 µg/mL (without AtPAP1 transcriptional factor), and NO scavenging activity (IC50) was 48.0 µg/mL (with AtPAP1) and 68.8 µg/mL (without AtPAP1 transcriptional factor). Leonurus sibiricus L. transformed root extracts, both with and without AtPAP1, are a source of phytochemicals belonging to different classes of molecules, such as flavonoids (catechin and rutin), phenolic compounds (caffeic acid, coumaric acid, chlorogenic acid, ferulic acid) and phenylpropanoid (verbascoside). Among the radicals formed after H removal from the different -OH positions, the lowest bond dissociation enthalpy was observed for rutin (4'-OH). Rutin was found to bind with cyclooxygenase 2, inducible nitric synthases and xanthine oxidase, whereas chlorogenic acid demonstrated optimal binding with 5-lipoxygenase. Therefore, it appears that the Leonurus sibiricus L. transformed root extract, both with and without the AtPAP1 transcriptional factor, may serve as a potential source of active components with antioxidant and anti-inflammatory potential; however, the extract containing AtPAP1 demonstrates superior activities. These properties could be beneficial for human health.
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Affiliation(s)
- Anna Merecz-Sadowska
- Department of Economic and Medical Informatics, University of Lodz, 90-214 Lodz, Poland;
| | - Przemysław Sitarek
- Department of Medical Biology, Medical University of Lodz, 90-151 Lodz, Poland;
| | - Tomasz Kowalczyk
- Department of Molecular Biotechnology and Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-237 Lodz, Poland;
| | - Marcin Palusiak
- Theoretical and Structural Group, Department of Physical Chemistry, Faculty of Chemistry, University of Lodz, 90-236 Lodz, Poland; (M.P.); (M.H.)
| | - Marta Hoelm
- Theoretical and Structural Group, Department of Physical Chemistry, Faculty of Chemistry, University of Lodz, 90-236 Lodz, Poland; (M.P.); (M.H.)
| | - Karolina Zajdel
- Department of Medical Informatics and Statistics, Medical University of Lodz, 90-645 Lodz, Poland;
| | - Radosław Zajdel
- Department of Economic and Medical Informatics, University of Lodz, 90-214 Lodz, Poland;
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16
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Yang Z, Pink M, Nowik-Boltyk EM, Lu S, Junghoefer T, Rajca S, Stoll S, Casu MB, Rajca A. Thermally Ultrarobust S = 1/2 Tetrazolinyl Radicals: Synthesis, Electronic Structure, Magnetism, and Nanoneedle Assemblies on Silicon Surface. J Am Chem Soc 2023; 145:13335-13346. [PMID: 37285418 PMCID: PMC10438971 DOI: 10.1021/jacs.3c03402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Open-shell organic molecules, including S = 1/2 radicals, may provide enhanced properties for several emerging technologies; however, relatively few synthesized to date possess robust thermal stability and processability. We report the synthesis of S = 1/2 biphenylene-fused tetrazolinyl radicals 1 and 2. Both radicals possess near-perfect planar structures based on their X-ray structures and density-functional theory (DFT) computations. Radical 1 possesses outstanding thermal stability as indicated by the onset of decomposition at 269 °C, based on thermogravimetric analysis (TGA) data. Both radicals possess very low oxidation potentials <0 V (vs. SCE) and their electrochemical energy gaps, Ecell ≈ 0.9 eV, are rather low. Magnetic properties of polycrystalline 1 are characterized by superconducting quantum interference device (SQUID) magnetometry revealing a one-dimensional S = 1/2 antiferromagnetic Heisenberg chain with exchange coupling constant J'/k ≈ -22.0 K. Radical 1 in toluene glass possesses a long electron spin coherence time, Tm ≈ 7 μs in the 40-80 K temperature range, a property advantageous for potential applications as a molecular spin qubit. Radical 1 is evaporated under ultrahigh vacuum (UHV) forming assemblies of intact radicals on a silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy (XPS). Scanning electron microscope (SEM) images indicate that the radical molecules form nanoneedles on the substrate. The nanoneedles are stable for at least 64 hours under air as monitored by using X-ray photoelectron spectroscopy. Electron paramagnetic resonance (EPR) studies of the thicker assemblies, prepared by UHV evaporation, indicate radical decay according to first-order kinetics with a long half-life of 50 ± 4 days at ambient conditions.
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Affiliation(s)
- Zhimin Yang
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, USA
| | | | - Shutian Lu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - Maria Benedetta Casu
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, USA
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17
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Li Y, Ding Z, Mu Q, Ren J, Shen Q, Zhang S, Zhang L. Theoretical investigations on P-stabilized boryl cation radicals: from the Aufbau principle to SOMO-HOMO conversion. Dalton Trans 2023; 52:384-393. [PMID: 36519378 DOI: 10.1039/d2dt02723b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We report the characterization of a series of novel phosphinidene-stabilized (P-stabilized) boryl cation radicals, in which the phosphinidene and boryl are stabilised by iPrNHC (iPrNHC[:C{N(iPr)C(H)}2]), and the P-stabilized boryl (P → B) moieties are linked by 1,8-naphthalene (1PB-a), 1,10-biphenyl (1PB-b), 1,2-perylene (1PB-c), and 4,5-perylene (1PB-d), to form a series of 1PB compounds. The 2PB series is designed by adding another P-stabilized boryl (P → B) unit into the 1PB series, in which the two P-stabilized boryl (P → B) moieties for each 2PB compound are linked by 1,4,5,8-naphthalene, (2PB-a), 1,5,6,10-biphenyl (2PB-b), 1,2,7,8-perylene (2PB-c), and 4,5,10,11-perylene (2PB-d), respectively. Theoretical calculations demonstrate that for all the studied molecules, the spin density mainly locates on the B atoms. Interestingly, the series of 2PB(a-d) compounds possess SOMO-HOMO conversion properties, while 1PB(a-d) compounds obey the Aufbau principle, resulting from the difference in the number of the P-stabilized boryl (P → B) moieties and an increase of the π-conjugation bridge that lead to the significantly increased HOMO energy in 2PB(a-d) compounds, which should be responsible for the different structural properties of compounds 1PB(a-d) and 2PB(a-d). The natural bond orbital (NBO) and atoms in molecules (AIM) analysis reveal how the interactions contribute to the covalent bond between P and B atoms. Moreover, the absorption properties show that the spectra of the 2PB(a-d) compounds are red-shifted relative to those of the corresponding 1PB(a-d) compounds in the near infrared region. We hope this work can provide new insights into tuning the electronic structures of the well-defined forms of P-stabilized boryl cation radicals and expand their potential application in organic optoelectronics.
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Affiliation(s)
- Yuyao Li
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China. .,School of Automation, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China
| | - Zhelin Ding
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China. .,School of Automation, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China
| | - Qiqi Mu
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China. .,School of Automation, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China
| | - Junle Ren
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China. .,School of Automation, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China
| | - Qiguang Shen
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China. .,School of Automation, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China
| | - Shoufeng Zhang
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
| | - Li Zhang
- School of Electronic Engineering, Guangxi University of Science and Technology, Liuzhou 545000, Guangxi, China.
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