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Miao Z, Scott FJ, van Tol J, Bowers CR, Veige AS, Mentink-Vigier F. Soliton Based Dynamic Nuclear Polarization: An Overhauser Effect in Cyclic Polyacetylene at High Field and Room Temperature. J Phys Chem Lett 2024:3369-3375. [PMID: 38498927 DOI: 10.1021/acs.jpclett.3c03591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Polyacetylene, a versatile material with an electrical conductivity that can span 7 orders of magnitude, is the prototypical conductive polymer. In this letter, we report the observation of a significant Overhauser effect at the high magnetic field of 14.1 T that operates at 100 K and room temperature in both linear and cyclic polyacetylene. Significant NMR signal enhancements ranging from 24 to 45 are obtained. The increased sensitivity enabled the characterization of the polymer chain defects at natural abundance. The absence of end methyl group carbon-13 signals provides proof of the closed-loop molecular structure of cyclic polyacetylene. The remarkable efficiency of the soliton based Overhauser effect DNP mechanism at high temperature and high field holds promise for applications and extension to other conductive polymer systems.
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Affiliation(s)
- Z Miao
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - F J Scott
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - J van Tol
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - C R Bowers
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - A S Veige
- Center for Catalysis, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - F Mentink-Vigier
- National High Magnetic Field Laboratory, Florida State University, 1800 E. Paul Dirac Drive, Tallahassee, Florida 32310, United States
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Beto CC, Holt ED, Yang Y, Ghiviriga I, Schanze KS, Veige AS. A new synthetic route to in-chain metallopolymers via copper(i) catalyzed azide-platinum-acetylide iClick. Chem Commun (Camb) 2018; 53:9934-9937. [PMID: 28829464 DOI: 10.1039/c7cc06289c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The first example of an in-chain metallo-poly(triazolate) synthesized by CuAAC is reported. Azido-platinum-acetylide (A-M-B) monomers are catalytically polymerized with copper(i) acetate to yield 1,2,3-triazolate linked Pt(ii) units. The metallopolymers are characterized by multinuclear NMR, IR, UV/Vis, GPC, and MS.
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Affiliation(s)
- C C Beto
- University of Florida, Department of Chemistry, Center for Catalysis, P. O. Box 117200, Gainesville, FL 32611, USA.
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Pascualini ME, Stoian SA, Ozarowski A, Di Russo NV, Thuijs AE, Abboud KA, Christou G, Veige AS. Synthesis and characterization of a family of M(2+) complexes supported by a trianionic ONO(3-) pincer-type ligand: towards the stabilization of high-spin square-planar complexes. Dalton Trans 2015; 44:20207-15. [PMID: 26537572 DOI: 10.1039/c5dt03960f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
High-spin square-planar molecular compounds are rare. In an effort to access this unique combination of geometry and spin state, we report the synthesis of a series of M(II) compounds stabilized by a trianionic pincer-type ligand, highlighting the formation of a high-spin square-planar Co(II) complex. Low-temperature, variable-frequency EPR measurements reveal that the ground electronic state of the Co(II) analogue is a highly anisotropic Kramers doublet (effective g values 7.35, 2.51, 1.48). This doublet can be identified with the lowest doublet of a quartet, S = 3/2 spin state that exhibits a very large ZFS, D ≥ 50 cm(-1). The observation of an effective g value considerably greater than the largest spin-only value 6, demonstrates that the orbital angular moment is essentially unquenched along one spatial direction. Density Functional Theory (DFT) and time-dependent DFT calculations reveal the electronic configurations of the ground and excited orbital states. A qualitative crystal field description of the geff tensor shows that it originates from the spin-orbit coupling acting on states obtained through the transfer of a β electron from the doubly occupied xy to the singly-occupied {xz/yz} orbitals.
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Affiliation(s)
- M E Pascualini
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - S A Stoian
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - A Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA.
| | - N V Di Russo
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A E Thuijs
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - K A Abboud
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - G Christou
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
| | - A S Veige
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
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Gonsales SA, Pascualini ME, Ghiviriga I, Veige AS. Evidence for a zwitterionic transition state in double bond rotations within tungsten-vinyl complexes. Chem Commun (Camb) 2015. [PMID: 26214073 DOI: 10.1039/c5cc04851f] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The trianionic pincer supported tungsten-vinyl complex [CF3-ONO]W(O){(CH3)3CC[double bond, length as m-dash]C(CH3)2} (3syn) undergoes facile double bond rotation at ambient temperature. The degenerate methyl exchange rates were measured via selective inversion-recovery experiments. DFT computations in conjunction with experimentally determined rate constants support a double bond rotation that proceeds via a Zwiterionic transition state.
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Affiliation(s)
- S A Gonsales
- Department of Chemistry, Center for Catalysis, University of Florida, Gainesville, FL 32611, USA.
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Pascualini ME, Di Russo NV, Thuijs AE, Ozarowski A, Stoian SA, Abboud KA, Christou G, Veige AS. A high-spin square-planar Fe(ii) complex stabilized by a trianionic pincer-type ligand and conclusive evidence for retention of geometry and spin state in solution. Chem Sci 2014; 6:608-612. [PMID: 28706628 PMCID: PMC5491960 DOI: 10.1039/c4sc02634a] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 10/15/2014] [Indexed: 12/02/2022] Open
Abstract
Extensive spectroscopic evaluation of a novel ONO3– trianionic pincer Fe(ii) complex indicates the rare square-planar geometry and S = 2 spin state are retained in solution.
Square-planar high-spin Fe(ii) molecular compounds are rare and the only three non-macrocyclic or sterically-driven examples reported share a common FeO4 core. Using an easily modifiable pincer-type ligand, the successful synthesis of the first compound of this type that breaks the FeO4 motif was achieved. In addition, we present the first evidence that geometry and spin state persist in solution. Extensive characterization includes the first high-field EPR and variable field/temperature Mössbauer spectra for this class of compounds. Analysis of the spectroscopic data indicates this complex exhibits a large and positive zero-field splitting tensor. Furthermore, the unusually small ΔEQ value determined for this compound is rationalized on the basis of DFT calculations.
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Affiliation(s)
- M E Pascualini
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - N V Di Russo
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A E Thuijs
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A Ozarowski
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , FL 32310 , USA
| | - S A Stoian
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , FL 32310 , USA
| | - K A Abboud
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - G Christou
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
| | - A S Veige
- Department of Chemistry , Center for Catalysis , University of Florida , Gainesville , FL 32611 , USA .
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Veige AS, Slaughter LM, Wolczanski PT, Matsunaga N, Decker SA, Cundari TR. Deoxygenations of (silox)(3)WNO and R(3)PO by (silox)(3)M (M = V, Ta) and (silox)(3)NbL (silox = (t)Bu(3)SiO): consequences of electronic effects. J Am Chem Soc 2001; 123:6419-20. [PMID: 11427070 DOI: 10.1021/ja004329w] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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