1
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Qiu Y, Du L, Cady SD, Phillips DL, Winter AH. Optical and EPR Detection of a Triplet Ground State Phenyl Nitrenium Ion. J Am Chem Soc 2024; 146:10679-10686. [PMID: 38579336 DOI: 10.1021/jacs.4c00511] [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
Nitrenium ions are important reactive intermediates participating in the synthetic chemistry and biological processes. Little is known about triplet phenyl nitrenium ions regarding their reactivity, lifetimes, spectroscopic features, and electronic configurations, and no ground state triplet nitrenium ion has been directly detected. In this work, m-pyrrolidinyl-phenyl hydrazine hydrochloride (1) is synthesized as the photoprecursor to photochemically generate the corresponding m-pyrrolidinyl-phenyl nitrenium ion (2), which is computed to adopt a π, π* triplet ground state. A combination of femtosecond (fs) and nanosecond (ns) transient absorption (TA) spectroscopy, cryogenic continuous-wave electronic paramagnetic resonance (CW-EPR) spectroscopy, computational analysis, and photoproduct studies was performed to elucidate the photolysis pathway of 1 and offers the first direct experimental detection of a ground state triplet phenyl nitrenium ion. Upon photoexcitation, 1 forms S1, where bond heterolysis occurs and the NH3 leaving group is extruded in 1.8 ps, generating a vibrationally hot, spin-conserving closed-shell singlet phenyl nitrenium ion (12) that undergoes vibrational cooling in 19 ps. Subsequent intersystem crossing takes place in 0.5 ns, yielding the ground state triplet phenyl nitrenium ion (32), with a lifetime of 0.8 μs. Unlike electrophilic singlet phenyl nitrenium ions, which react rapidly with nucleophiles, this triplet phenyl nitrenium reacts through sequential H atom abstractions, resulting in the eventual formation of the reduced m-pyrrolidinyl-aniline as the predominant stable photoproduct. Supporting the triplet ground state, continuous irradiation of 1 in a glassy matrix at 80 K in an EPR spectrometer forms a paramagnetic triplet species, consistent with a triplet nitrenium ion.
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Affiliation(s)
- Yunfan Qiu
- Department of Chemistry, Iowa State University, 2101d Hach Hall, Ames, Iowa 50011, United States
| | - Lili Du
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, S.A.R 11111, P. R. China
| | - Sarah D Cady
- Department of Chemistry, Iowa State University, 2101d Hach Hall, Ames, Iowa 50011, United States
| | - David Lee Phillips
- Department of Chemistry, University of Hong Kong, Pokfulam Road, Hong Kong, S.A.R 11111, P. R. China
| | - Arthur H Winter
- Department of Chemistry, Iowa State University, 2101d Hach Hall, Ames, Iowa 50011, United States
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2
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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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3
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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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4
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Zhang H, Pink M, Wang Y, Rajca S, Rajca A. High-Spin S = 3/2 Ground-State Aminyl Triradicals: Toward High-Spin Oligo-Aza Nanographenes. J Am Chem Soc 2022; 144:19576-19591. [PMID: 36251959 PMCID: PMC10438970 DOI: 10.1021/jacs.2c09241] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We report high-spin aminyl triradicals with near-planar triphenylene backbones. Near-planarity of the fused aminyl radicals and the 2,6,10-triphenylene ferromagnetic coupling unit (FCU), magnetically equivalent to three fused 3,4'-biphenyl FCUs, assures an effective 2pπ-2pπ overlap within the cross-conjugated π-system, leading to an S = 3/2 (quartet) ground state that is well separated from low-spin excited doublet states. Thermal populations of the low-spin (S = 1/2) excited states are detectable both by SQUID magnetometry and electron paramagnetic resonance (EPR) spectroscopy, providing doublet-quartet energy gaps, ΔEDQ, corresponding to >85% population of the quartet ground states at room temperature. Notably, EPR-based determination of ΔEDQ relies on direct detection of the quartet ground state and doublet excited states. The ΔEDQ values are 1.0-1.1 kcal mol-1, with the more sterically shielded triradical having the larger value. The half-life of the more sterically shielded triradical in 2-methyltetrahydrofuran (2-MeTHF) is about 6 h at room temperature. The less sterically shielded triradical in 2-MeTHF decomposes at 158 K with a half-life of about 4 h, while at 195 K, the half-life is still about 2 h. The dominant products of the decay of triradicals are the corresponding triamines, suggesting hydrogen atom abstraction from the solvent as the primary mechanism. This study expands the frontier of the open-shell PAHs/nanographenes, of which the unique electronic, nonlinear optical, and magnetic properties could be useful in the development of novel organic electronics, photonics, and spintronics.
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Affiliation(s)
- Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Maren Pink
- IUMSC, Department of Chemistry, Indiana University, Bloomington, IN 47405-7102, United States
| | - Ying Wang
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
| | - Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, United States
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5
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Kimura T, Nakahodo T, Suzuki E, Nakanishi Y, Misaki Y, Ogawa S. Preparation, Structure Determination, and Electrochemical Properties of 4,5‐Dialkylbenzo[1,2‐
d
:4,5‐
d’
]bis[1,2,3]triselenoles and Their Singlet and Triplet‐State Dications. ChemistrySelect 2021. [DOI: 10.1002/slct.202102375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Takeshi Kimura
- Center for Instrumental Analysis Iwate University Morioka 020-8551 Japan
| | - Tsukasa Nakahodo
- Department of Applied Chemistry Kindai University Higashi Osaka 577-8502 Japan
| | - Eiichi Suzuki
- Department of Chemistry and Biological Sciences Faculty of Science and Engineering Iwate University Morioka 020-8551 Japan
| | - Yoshiki Nakanishi
- Department of Physical Science and Materials Engineering Faculty of Science and Engineering Iwate University Morioka 020-8551 Japan
| | - Yohji Misaki
- Department of Applied Chemistry Faculty of Engineering Ehime University Matsuyama 790-8577 Japan
| | - Satoshi Ogawa
- Department of Chemistry and Biological Sciences Faculty of Science and Engineering Iwate University Morioka 020-8551 Japan
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6
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Rajca A, Shu C, Zhang H, Zhang S, Wang H, Rajca S. Thiophene-Based Double Helices: Radical Cations with SOMO-HOMO Energy Level Inversion †. Photochem Photobiol 2021; 97:1376-1390. [PMID: 34152605 DOI: 10.1111/php.13475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/17/2021] [Indexed: 11/29/2022]
Abstract
We report relatively persistent, open-shell thiophene-based double helices, radical cations 1•+ -TMS12 and 2•+ -TMS8 . Closed-shell neutral double helices, 1-TMS12 and 2-TMS8 , have nearly identical first oxidation potentials, E+/0 ≈ +1.33 V, corresponding to reversible oxidation to their radical cations. The radical cations are generated, using tungsten hexachloride in dichloromethane (DCM) as an oxidant, E+/0 ≈ +1.56 V. EPR spectra consist of a relatively sharp singlet peak with an unusually low g-value of 2.001-2.002, thus suggesting exclusive delocalization of spin density over π-conjugated system consisting of carbon atoms only. DFT computations confirm these findings, as only negligible fraction of spin density is found on sulfur and silicon atoms and the spin density is delocalized over a single tetrathiophene moiety. For radical cation, 1•+ -TMS12 , energy level of the singly occupied molecular orbital (SOMO) lies below the four highest occupied molecular orbitals (HOMOs), thus indicating the SOMO-HOMO inversion (SHI) and therefore, violating the Aufbau principle. 1•+ -TMS12 has a half-life of the order of only 5 min at room temperature. EPR peak intensity of 2•+ -TMS8 , which does not show SHI, is practically unchanged over at least 2 h.
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Affiliation(s)
- Andrzej Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Hui Zhang
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
| | - Sheng Zhang
- Engineering Research Center for Nanomaterials, Henan University, Kaifeng, China
| | - Hua Wang
- Engineering Research Center for Nanomaterials, Henan University, Kaifeng, China
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, NE, USA
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7
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Shu C, Pink M, Junghoefer T, Nadler E, Rajca S, Casu MB, Rajca A. Synthesis and Thin Films of Thermally Robust Quartet ( S = 3/2) Ground State Triradical. J Am Chem Soc 2021; 143:5508-5518. [PMID: 33787241 DOI: 10.1021/jacs.1c01305] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
High-spin (S = 3/2) organic triradicals may offer enhanced properties with respect to several emerging technologies, but those synthesized to date typically exhibit small doublet quartet energy gaps and/or possess limited thermal stability and processability. We report a quartet ground state triradical 3, synthesized by a Pd(0)-catalyzed radical-radical cross-coupling reaction, which possesses two doublet-quartet energy gaps, ΔEDQ ≈ 0.2-0.3 kcal mol-1 and ΔEDQ2 ≈ 1.2-1.8 kcal mol-1. The triradical has a 70+% population of the quartet ground state at room temperature and good thermal stability with onset of decomposition at >160 °C under an inert atmosphere. Magnetic properties of 3 are characterized by SQUID magnetometry in polystyrene glass and by quantitative EPR spectroscopy. Triradical 3 is evaporated under ultrahigh vacuum to form thin films of intact triradicals on silicon substrate, as confirmed by high-resolution X-ray photoelectron spectroscopy. AFM and SEM images of the ∼1 nm thick films indicate that the triradical molecules form islands on the substrate. The films are stable under ultrahigh vacuum for at least 17 h but show onset of decomposition after 4 h at ambient conditions. The drop-cast films are less prone to degradation in air and have a longer lifetime.
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Affiliation(s)
- Chan Shu
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Elke Nadler
- Institute of Physical and Theoretical Chemistry, University of Tübingen, 72076 Tübingen, Germany
| | - Suchada Rajca
- Department of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - 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, United States
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8
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Mangham B, Hanson-Heine MWD, Davies ES, Wriglesworth A, George MW, Lewis W, Kays DL, McMaster J, Besley NA, Champness NR. Influence of molecular design on radical spin multiplicity: characterisation of BODIPY dyad and triad radical anions. Phys Chem Chem Phys 2020; 22:4429-4438. [PMID: 32051990 DOI: 10.1039/c9cp06427c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
A strategy to create organic molecules with high degrees of radical spin multiplicity is reported in which molecular design is correlated with the behaviour of radical anions in a series of BODIPY dyads. Upon reduction of each BODIPY moiety radical anions are formed which are shown to have different spin multiplicities by electron paramagnetic resonance (EPR) spectroscopy and distinct profiles in their cyclic voltammograms and UV-visible spectra. The relationship between structure and multiplicity is demonstrated showing that the balance between singlet, biradical or triplet states in the dyads depends on relative orientation and connectivity of the BODIPY groups. The strategy is applied to the synthesis of a BODIPY triad which adopts an unusual quartet state upon reduction to its radical trianion.
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Affiliation(s)
- Barry Mangham
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | | | - E Stephen Davies
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | | | - Michael W George
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK. and Department of Chemical and Environmental Engineering, University of Nottingham Ningbo China, 199 Taikang East Road, Ningbo 315100, China
| | - William Lewis
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | - Deborah L Kays
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | - Jonathan McMaster
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | - Nicholas A Besley
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
| | - Neil R Champness
- School of Chemistry, University of Nottingham, University Park, NG7 2RD, UK.
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9
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Shu C, Zhang H, Olankitwanit A, Rajca S, Rajca A. High-Spin Diradical Dication of Chiral π-Conjugated Double Helical Molecule. J Am Chem Soc 2019; 141:17287-17294. [PMID: 31596077 DOI: 10.1021/jacs.9b08711] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We report an air-stable diradical dication of chiral D2-symmetric conjoined bis[5]diazahelicene with an unprecedented high-spin (triplet) ground state, singlet triplet energy gap, ΔEST = 0.3 kcal mol-1. The diradical dication possesses closed-shell (Kekulé) resonance forms with 16 π-electron perimeters. The diradical dication is monomeric in dibutyl phthalate (DBP) matrix at low temperatures, and it has a half-life of more than 2 weeks at ambient conditions in the presence of excess oxidant. A barrier of ∼35 kcal mol-1 has been experimentally determined for inversion of configuration in the neutral conjoined bis[5]diazahelicene, while the inversion barriers in its radical cation and diradical dication were predicted by the DFT computations to be within a few kcal mol-1 of that in the neutral species. Chiral HPLC resolution provides the chiral D2-symmetric conjoined bis[5]diazahelicene, enriched in (P,P)- or (M,M)-enantiomers. The enantiomerically enriched triplet diradical dication is configurationally stable for 48 h at room temperature, thus providing the lower limit for inversion barrier of configuration of 27 kcal mol-1. The enantiomers of conjoined bis[5]diazahelicene and its diradical dication show strong chirooptical properties that are comparable to [6]helicene or carbon-sulfur [7]helicene, as determined by the anisotropy factors, |g| = |Δε|/ε = 0.007 at 348 nm (neutral) and |g| = 0.005 at 385 nm (diradical dication). DFT computations of the radical cation suggest that SOMO and HOMO energy levels are near-degenerate.
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Affiliation(s)
- Chan Shu
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Hui Zhang
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Arnon Olankitwanit
- 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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10
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Gallagher N, Zhang H, Junghoefer T, Giangrisostomi E, Ovsyannikov R, Pink M, Rajca S, Casu MB, Rajca A. Thermally and Magnetically Robust Triplet Ground State Diradical. J Am Chem Soc 2019; 141:4764-4774. [PMID: 30816035 DOI: 10.1021/jacs.9b00558] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
High spin ( S = 1) organic diradicals may offer enhanced properties with respect to several emerging technologies, but typically exhibit low singlet triplet energy gaps and possess limited thermal stability. We report triplet ground state diradical 2 with a large singlet-triplet energy gap, Δ EST ≥ 1.7 kcal mol-1, leading to nearly exclusive population of triplet ground state at room temperature, and good thermal stability with onset of decomposition at ∼160 °C under inert atmosphere. Magnetic properties of 2 and the previously prepared diradical 1 are characterized by SQUID magnetometry of polycrystalline powders, in polystyrene glass, and in other matrices. Polycrystalline diradical 2 forms a novel one-dimensional (1D) spin-1 ( S = 1) chain of organic radicals with intrachain antiferromagnetic coupling of J'/ k = -14 K, which is associated with the N···N and N···O intermolecular contacts. The intrachain antiferromagnetic coupling in 2 is by far strongest among all studied 1D S = 1 chains of organic radicals, which also makes 1D S = 1 chains of 2 most isotropic, and therefore an excellent system for studies of low-dimensional magnetism. In polystyrene glass and in frozen benzene or dibutyl phthalate solution, both 1 and 2 are monomeric. Diradical 2 is thermally robust and is evaporated under ultrahigh vacuum to form thin films of intact diradicals on silicon substrate, as demonstrated by X-ray photoelectron spectroscopy. Based on C-K NEXAFS spectra and AFM images of the ∼1.5 nm thick films, the diradical molecules form islands on the substrate with molecules stacked approximately along the crystallographic a-axis. The films are stable under ultrahigh vacuum for at least 60 h but show signs of decomposition when exposed to ambient conditions for 7 h.
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Affiliation(s)
- Nolan Gallagher
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Hui Zhang
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - Tobias Junghoefer
- Institute of Physical and Theoretical Chemistry, University of Tübingen , 72076 Tübingen , Germany
| | - Erika Giangrisostomi
- Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Str 15 , 12489 Berlin , Germany
| | - Ruslan Ovsyannikov
- Helmholtz-Zentrum Berlin für Materialien und Energie (HZB) , Albert-Einstein-Str 15 , 12489 Berlin , Germany
| | - Maren Pink
- Department of Chemistry , Indiana University , Bloomington , Indiana 47405-7102 , United States
| | - Suchada Rajca
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588-0304 , United States
| | - 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 , United States
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11
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Skórka Ł, Maurel V, Gosk JB, Puźniak R, Mouesca JM, Kulszewicz-Bajer I. Highly Efficient Tuning of Ferromagnetic Spin Interactions in High-Spin Arylamine Structures by Incorporation of Spin Bearing Carbazole Units. J Phys Chem B 2018; 122:9584-9591. [PMID: 30230334 DOI: 10.1021/acs.jpcb.8b07496] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Arylamine moieties oxidized to radical cations are considered promising spin bearing units in high-spin-type compounds. Here, we report the first use of carbazole-3,6-diamine units as efficient, rigid spin containing units. The use of rigid spin bearing units enhances significantly spin exchange interactions. The design using density functional theory calculations shows the progressive increase of the exchange coupling constant dependent on the considered model molecules. Two of the most representative molecules containing flexible (dimer 1) and rigid spin coupling unit (dimer 2) were synthesized. Electrochemical and pulsed-electron paramagnetic resonance nutation studies showed that both dimers can be oxidized to yield a majority of dicationic diradicals exhibiting S = 1 ground states. The high values of the dimer 2 exchange coupling constant obtained both computationally ( J/ kB = 145 K; HHeis. = - JS1 S2) and experimentally ( J/ kB = 90-100 K) indicate the beneficial role of the carbazole moiety incorporated into spin bearing units.
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Affiliation(s)
- Łukasz Skórka
- Faculty of Chemistry , Warsaw University of Technology , Noakowskiego 3 , 00-664 Warsaw , Poland
| | - Vincent Maurel
- Univ. Grenoble Alpes, CEA, CNRS, INAC, SyMMES , 38000 Grenoble , France
| | - Jacek B Gosk
- Faculty of Physics , Warsaw University of Technology , Koszykowa 75 , 00-662 Warsaw , Poland
| | - Roman Puźniak
- Institute of Physics , Polish Academy of Sciences , Lotników 32/46 , 02-668 Warsaw , Poland
| | | | - Irena Kulszewicz-Bajer
- Faculty of Chemistry , Warsaw University of Technology , Noakowskiego 3 , 00-664 Warsaw , Poland
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12
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Wang W, Chen C, Shu C, Rajca S, Wang X, Rajca A. S = 1 Tetraazacyclophane Diradical Dication with Robust Stability: A Case of Low-Temperature One-Dimensional Antiferromagnetic Chain. J Am Chem Soc 2018; 140:7820-7826. [PMID: 29863339 DOI: 10.1021/jacs.8b02415] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One-dimensional (1D) spin-1 ( S = 1) chain of organic radicals with low local magnetic anisotropy may provide a better understanding of the low-dimensional magnetism. We report solid-state studies, including single crystal X-ray crystallography, of air-stable tetraazacyclophane diradical dication salt 12·2+·2[Al(OC(CF3)2CH3)4]- with a triplet ground state (Δ EST ≈ 0.5 kcal mol-1). The magnetic behavior for 12·2+ at low temperature is best modeled by 1D spin S = 1 Heisenberg chain with intrachain antiferromagnetic coupling of J'/ k = -5.4 K, which is associated with the interaryl C···C contacts, including π-π interactions. Zero-field splitting value, | D/ hc| ≈ 5.6 × 10-3 cm-1, for 12·2+ is rather small; thus, the 1D chains are characterized by the high degree of isotropicity | D/2 J'| ≈ 7.5 × 10-4. The diradical dication salt possesses extraordinary stability with onset of decomposition at temperature of about 180 °C (∼450 K), based on thermogravimetric analysis and EPR spectroscopy.
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Affiliation(s)
- Wenqing Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210023 , China
| | - Chao Chen
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210023 , China
| | - Chan Shu
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Suchada Rajca
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588 , United States
| | - Xinping Wang
- State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Collaborative Innovation Center of Advanced Microstructures , Nanjing University , Nanjing 210023 , China
| | - Andrzej Rajca
- Department of Chemistry , University of Nebraska , Lincoln , Nebraska 68588 , United States
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13
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Zhai W, Feng Y, Liu H, Rockenbauer A, Mance D, Li S, Song Y, Baldus M, Liu Y. Diastereoisomers of l-proline-linked trityl-nitroxide biradicals: synthesis and effect of chiral configurations on exchange interactions. Chem Sci 2018; 9:4381-4391. [PMID: 29896379 PMCID: PMC5958346 DOI: 10.1039/c8sc00969d] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 04/05/2018] [Indexed: 01/08/2023] Open
Abstract
The chiral configuration of the two radical parts is a crucial factor controlling the exchange interactions and DNP properties of trityl-nitroxide biradicals.
The exchange (J) interaction of organic biradicals is a crucial factor controlling their physiochemical properties and potential applications and can be modulated by changing the nature of the linker. In the present work, we for the first time demonstrate the effect of chiral configurations of radical parts on the J values of trityl-nitroxide (TN) biradicals. Four diastereoisomers (TNT1, TNT2, TNL1 and TNL2) of TN biradicals were synthesized and purified by the conjugation of a racemic (R/S) nitroxide with the racemic (M/P) trityl radical vial-proline. The absolute configurations of these diastereoisomers were assigned by comparing experimental and calculated electronic circular dichroism (ECD) spectra as (M, S, S) for TNT1, (P, S, S) for TNT2, (M, S, R) for TNL1 and (P, S, R) for TNL2. Electron paramagnetic resonance (EPR) results showed that the configuration of the nitroxide part instead of the trityl part is dominant in controlling the exchange interactions and the order of the J values at room temperature is TNT1 (252 G) > TNT2 (127 G) ≫ TNL2 (33 G) > TNL1 (14 G). Moreover, the J values of TNL1/TNL2 with the S configuration in the nitroxide part vary with temperature and the polarity of solvents due to their flexible linker, whereas the J values of TNT1/TNT2 are almost insensitive to these two factors due to the rigidity of their linkers. The distinct exchange interactions between TNT1,2 and TNL1,2 in the frozen state led to strongly different high-field dynamic nuclear polarization (DNP) enhancements with ε = 7 for TNT1,2 and 40 for TNL1,2 under 800 MHz DNP conditions.
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Affiliation(s)
- Weixiang Zhai
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
| | - Yalan Feng
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
| | - Huiqiang Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
| | - Antal Rockenbauer
- Institute of Materials and Environmental Chemistry , Hungarian Academy of Sciences , Department of Physics , Budapest University of Technology and Economics , Budafoki ut 8 , 1111 Budapest , Hungary .
| | - Deni Mance
- NMR Spectroscopy , Bijvoet Center for Biomolecular Research , Utrecht University , 3584 CH Utrecht , The Netherlands
| | - Shaoyong Li
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
| | - Yuguang Song
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
| | - Marc Baldus
- NMR Spectroscopy , Bijvoet Center for Biomolecular Research , Utrecht University , 3584 CH Utrecht , The Netherlands
| | - Yangping Liu
- Tianjin Key Laboratory on Technologies Enabling Development of Clinical Therapeutics and Diagnostics , School of Pharmacy , Tianjin Medical University , Tianjin 300070 , P. R. China . ;
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14
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Song M, Song X, Bu Y. Spin coupling interactions in C[double bond, length as m-dash]C or B-B-cored porphyrin-mimetic graphene patch nitroxide diradicals. Phys Chem Chem Phys 2018. [PMID: 29517098 DOI: 10.1039/c8cp00105g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In view of the unique structures and promising applications of porphyrins and their derivatives, exploration of their various properties has continued to a hot topic. In this work, we combine porphyrin-mimetic graphene patches which are core-modified by a C[double bond, length as m-dash]C or a B-B unit and two nitroxide radical groups to construct a series of novel diradical molecules (the CC-cored or BB-cored molecules). The spin coupling constants (J) of diradicals were calculated at the (U)B3LYP/6-311G(d,p) level by considering the different linking modes of two nitroxide groups. The results indicate that different core modification considerably affects the J values of such diradicals, and the linking modes can tune the sizes and signs of J, changing their magnetic coupling interactions with different magnitudes and the signs of J from antiferromagnetic to ferromagnetic or vice versa. More interestingly and importantly, the spin coupling interactions of the CC-cored molecules can also be tuned by stretching the core unit C-C bond, suggesting the possibility of activating specific vibrational modes of the CC-cored diradicals by energy pulses to yield variable J coupling magnitudes. On the other hand, for the BB-cored molecules, two-electron reduction can switch or tune their magnetism from ferromagnetic to antiferromagnetic. The essence of all observations is further analyzed from the structural effects and orbital and spin density distributions. The findings about magnetic regulation in these core-modified porphyrin-mimetic graphene patch nitroxide diradicals further expand the field of molecular magnets and provide a rational theoretical basis for designing novel building blocks of magnetic functional molecular materials.
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Affiliation(s)
- Meiyu Song
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China.
| | - Xinyu Song
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China.
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, People's Republic of China. and School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, People's Republic of China
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15
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Zeng W, Hong Y, Medina Rivero S, Kim J, Zafra JL, Phan H, Gopalakrishna TY, Herng TS, Ding J, Casado J, Kim D, Wu J. Stable Nitrogen-Centered Bis(imino)rylene Diradicaloids. Chemistry 2018; 24:4944-4951. [PMID: 29396877 DOI: 10.1002/chem.201706041] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Indexed: 12/11/2022]
Abstract
The synthesis of stable open-shell singlet diradicaloids is critical for their practical material application. So far, most reported examples are based on carbon-centered radicals, which are intrinsically reactive, and there are very few examples of stable nitrogen-centered diradicaloids. In this full paper, a series of soluble and stable bis(imino)rylenes up to octarylene were synthesized on the basis of newly developed dibromorylene intermediates. It was found that from hexarylene onward, these quinoidal rylenes showed open-shell singlet ground states and could be thermally populated to paramagnetic triplet aminyl diradicals. They are stable due to efficient spin delocalization onto the rylene backbone as well as kinetic blocking of the aminyl sites by the bulky and electron-deficient 2,4,6-trichlorophenyl groups. They exhibited very different electronic structures, diradical character, excited-state dynamics, one-photon absorption, two-photon absorption, and electrochemical properties from their respective aromatic rylene counterparts. These bis(imino)rylenes represent a rare class of stable, neutral, nitrogen-centered aminyl diradicaloids.
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Affiliation(s)
- Wangdong Zeng
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore.,Institute of Materials Science and Engineering, Hunan University of Science and Technology, Xiangtan, 411201, P. R. China
| | - Yongseok Hong
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea
| | - Samara Medina Rivero
- Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071, Malaga, Spain
| | - Jinseok Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea
| | - José L Zafra
- Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071, Malaga, Spain
| | - Hoa Phan
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore
| | - Tullimilli Y Gopalakrishna
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore
| | - Tun Seng Herng
- Department of Materials Science & Engineering, National University of Singapore, 119260, Singapore, Singapore
| | - Jun Ding
- Department of Materials Science & Engineering, National University of Singapore, 119260, Singapore, Singapore
| | - Juan Casado
- Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071, Malaga, Spain
| | - Dongho Kim
- Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul, 03722, Korea
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, 117543, Singapore, Singapore
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16
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Barone V, Cacelli I, Ferretti A. The role of the multiconfigurational character of nitronyl-nitroxide in the singlet–triplet energy gap of its diradicals. Phys Chem Chem Phys 2018; 20:18547-18555. [DOI: 10.1039/c8cp02165a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CAS(2,2) reference may not be sufficient for the computation of singlet–triplet energy gap by DDCI.
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Affiliation(s)
| | - Ivo Cacelli
- Dipartimento di Chimica e Chimica Industriale
- Università di Pisa
- Pisa
- Italy
- Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR)
| | - Alessandro Ferretti
- Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR)
- Area della Ricerca
- I-56124 Pisa
- Italy
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17
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Song M, Song X, Bu Y. Tuning the Spin Coupling Interactions in the Nitroxide-Based Bisphenol-Like Diradicals. Chemphyschem 2017; 18:2487-2498. [DOI: 10.1002/cphc.201700731] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 07/23/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Meiyu Song
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 People's Republic of China
| | - Xinyu Song
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 People's Republic of China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering; Shandong University; Jinan 250100 People's Republic of China
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18
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Hossain E, Deng SM, Gozem S, Krylov AI, Wang XB, Wenthold PG. Photoelectron Spectroscopy Study of Quinonimides. J Am Chem Soc 2017; 139:11138-11148. [DOI: 10.1021/jacs.7b05197] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Ekram Hossain
- The
Department of Chemistry Purdue University West Lafayette, Indiana 47906, United States
| | - Shihu M. Deng
- Physical
Sciences Division, Pacific Northwest National Laboratory P.O. Box 999, MS k8-88 Richland, Washington 99352, United States
| | - Samer Gozem
- Department
of Chemistry University of Southern California Los Angeles, 90089, United States
| | - Anna I. Krylov
- Department
of Chemistry University of Southern California Los Angeles, 90089, United States
| | - Xue-Bin Wang
- Physical
Sciences Division, Pacific Northwest National Laboratory P.O. Box 999, MS k8-88 Richland, Washington 99352, United States
| | - Paul G. Wenthold
- The
Department of Chemistry Purdue University West Lafayette, Indiana 47906, United States
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19
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Abstract
We report the synthesis and kinetic study of PEGylated, water-soluble aminyl radical 2. The radical possesses four mPEG-3 groups replacing four methyl groups in the tert-butyl groups at the 3- and 6-positions of 1,3,6,8-tetra-tert-butyl carbazyl (TTBC). This structure is designed to mitigate the rapid decomposition of the radical via intramolecular 1,5-hydrogen atom transfer (1,5-HAT) that was observed in its constitutional isomer 1-H with four mPEG-3 groups in the vicinity of the nitrogen-centered radical (1- and 8-positions of TTBC). In dry, degassed acetone at 295 K, the radical 2 has a half-life, τ1/2 = 49 h (ΔH‡ = 17.9 ± 0.8 kcal mol-1), which is 3 orders of magnitude longer than that for 1-H, which decays via 1,5-HAT (τ1/2 = 48 s, ΔH‡ = 10.0 ± 0.3 kcal mol-1). Aminyl radical 2 aggregates at ambient conditions in water and has a half-life, τ1/2 = 2 h.
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Affiliation(s)
- Ying Wang
- 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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20
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Bakhoda A(G, Jiang Q, Bertke JA, Cundari TR, Warren TH. Elusive Terminal Copper Arylnitrene Intermediates. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611275] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - Quan Jiang
- Department of Chemistry Center for Advanced Scientific Computing and Modeling (CASCaM) University of North Texas Denton TX 76203 USA
| | - Jeffery A. Bertke
- Department of Chemistry Georgetown University Box 571227 Washington DC 20057- 1227 USA
| | - Thomas R. Cundari
- Department of Chemistry Center for Advanced Scientific Computing and Modeling (CASCaM) University of North Texas Denton TX 76203 USA
| | - Timothy H. Warren
- Department of Chemistry Georgetown University Box 571227 Washington DC 20057- 1227 USA
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21
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Bakhoda A(G, Jiang Q, Bertke JA, Cundari TR, Warren TH. Elusive Terminal Copper Arylnitrene Intermediates. Angew Chem Int Ed Engl 2017; 56:6426-6430. [DOI: 10.1002/anie.201611275] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 03/29/2017] [Indexed: 12/31/2022]
Affiliation(s)
| | - Quan Jiang
- Department of Chemistry Center for Advanced Scientific Computing and Modeling (CASCaM) University of North Texas Denton TX 76203 USA
| | - Jeffery A. Bertke
- Department of Chemistry Georgetown University Box 571227 Washington DC 20057- 1227 USA
| | - Thomas R. Cundari
- Department of Chemistry Center for Advanced Scientific Computing and Modeling (CASCaM) University of North Texas Denton TX 76203 USA
| | - Timothy H. Warren
- Department of Chemistry Georgetown University Box 571227 Washington DC 20057- 1227 USA
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22
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Skorka L, Kurzep P, Chauviré T, Dubois L, Mouesca JM, Maurel V, Kulszewicz-Bajer I. High-Spin Polymers: Ferromagnetic Coupling of S = 1 Hexaazacyclophane Units up to a Pure S = 2 Polycyclophane. J Phys Chem B 2017; 121:4293-4298. [DOI: 10.1021/acs.jpcb.7b01531] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lukasz Skorka
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Piotr Kurzep
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
| | - Timothée Chauviré
- Université Grenoble Alpes, INAC, SyMMES, F-38000 Grenoble, France
- CEA, INAC, SYMMES, F-38054 Grenoble, France
| | - Lionel Dubois
- Université Grenoble Alpes, INAC, SyMMES, F-38000 Grenoble, France
- CEA, INAC, SYMMES, F-38054 Grenoble, France
| | - Jean-Marie Mouesca
- Université Grenoble Alpes, INAC, SyMMES, F-38000 Grenoble, France
- CEA, INAC, SYMMES, F-38054 Grenoble, France
| | - Vincent Maurel
- Université Grenoble Alpes, INAC, SyMMES, F-38000 Grenoble, France
- CEA, INAC, SYMMES, F-38054 Grenoble, France
| | - Irena Kulszewicz-Bajer
- Faculty
of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664 Warsaw, Poland
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23
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Barone V, Cacelli I, Ferretti A, Prampolini G. Magnetic gaps in organic tri-radicals: From a simple model to accurate estimates. J Chem Phys 2017; 146:104103. [DOI: 10.1063/1.4977598] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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24
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Bhattacharya D, Shil S, Misra A, Bytautas L, Klein DJ. Toward Molecular Magnets of Organic Origin via Anion−π Interaction Involving m-Aminyl Diradical: A Theoretical Study. J Phys Chem A 2016; 120:9117-9130. [DOI: 10.1021/acs.jpca.6b09666] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Debojit Bhattacharya
- Department of Marine Sciences, Texas A&M University at Galveston, Galveston, Texas 77553, United States
| | - Suranjan Shil
- Center
for Atomic Scale Materials Design, Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
| | - Anirban Misra
- Department
of Chemistry, University of North Bengal, Darjeeling, PIN. 734013, West Bengal, India
| | - Laimutis Bytautas
- Department
of Chemistry, Galveston College, 4015 Avenue Q, Galveston, Texas 77550, United States
| | - Douglas J. Klein
- Department of Marine Sciences, Texas A&M University at Galveston, Galveston, Texas 77553, United States
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25
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Gallagher NM, Bauer JJ, Pink M, Rajca S, Rajca A. High-Spin Organic Diradical with Robust Stability. J Am Chem Soc 2016; 138:9377-80. [DOI: 10.1021/jacs.6b05080] [Citation(s) in RCA: 88] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Nolan M. Gallagher
- Department
of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, United States
| | - Jackson J. Bauer
- Department
of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, United States
| | - Maren Pink
- IUMSC,
Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States
| | - Suchada Rajca
- Department
of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, United States
| | - Andrzej Rajca
- Department
of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0304, United States
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26
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Geometrical structure of meta-xylylene based symmetric polyradicals and their magnetic nature: A density functional study. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.02.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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27
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Olankitwanit A, Rajca S, Rajca A. Aza-m-Xylylene Diradical with Increased Steric Protection of the Aminyl Radicals. J Org Chem 2015; 80:5035-44. [DOI: 10.1021/acs.joc.5b00421] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Arnon Olankitwanit
- 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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28
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Affiliation(s)
- Nolan M. Gallagher
- Department
of Chemistry, University of Nebraska, Lincoln, Nebraska 68588-0304, United States
| | - Arnon Olankitwanit
- 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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29
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Yang H, Chen M, Song X, Bu Y. Structural fluctuation governed dynamic diradical character in pentacene. Phys Chem Chem Phys 2015; 17:13904-14. [DOI: 10.1039/c5cp00902b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Energy field-induced structural fluctuation can not only induce potential diradical character but also modulate its dynamical behavior in pentacene.
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Affiliation(s)
- Hongfang Yang
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- P. R. China
| | - Mengzhen Chen
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- P. R. China
| | - Xinyu Song
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- P. R. China
| | - Yuxiang Bu
- School of Chemistry and Chemical Engineering
- Shandong University
- Jinan
- P. R. China
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