On the Importance of Electronic Symmetry for Triplet State Delocalization

Richert, Sabine; Bullard, George; Rawson, Jeff; Angiolillo, Paul J.; Therien, Michael J.; Timmel, Christiane R.

doi:10.1021/jacs.7b01204

Title: On the Importance of Electronic Symmetry for Triplet State Delocalization

Abstract

The influence of electronic symmetry on triplet state delocalization in linear zinc porphyrin oligomers is explored by electron paramagnetic resonance techniques. Using a combination of transient continuous wave and pulse electron nuclear double resonance spectroscopies, it is demonstrated experimentally that complete triplet state delocalization requires the chemical equivalence of all porphyrin units. These results are supported by density functional theory calculations, showing uneven delocalization in a porphyrin dimer in which a terminal ethynyl group renders the two porphyrin units inequivalent. When the conjugation length of the molecule is further increased upon addition of a second terminal ethynyl group that restores the symmetry of the system, the triplet state is again found to be completely delocalized. Finally, the observations suggest that electronic symmetry is of greater importance for triplet state delocalization than other frequently invoked factors such as conformational rigidity or fundamental length-scale limitations.

Authors:

^[1]; Bullard, George ^[2];

^[2]; Angiolillo, Paul J. ^[3];

^[2];

^[1]

Centre for Advanced Electron Spin Resonance (CAESR), University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
Department of Chemistry, Duke University, French Family Science Center, 124 Science Drive, Durham, North Carolina 27708, United States
Department of Physics, Saint Joseph’s University, 5600 City Avenue, Philadelphia, Pennsylvania 19131, United States

Publication Date:: 2017-04-04

Research Org.:: Duke Univ., Durham, NC (United States); Univ. of Oxford, Oxford (United Kingdom)

Sponsoring Org.:: USDOE Office of Science (SC), Basic Energy Sciences (BES); European Research Counsel (ERC)

OSTI Identifier:: 1355067

Alternate Identifier(s):: OSTI ID: 1426483

Grant/Contract Number:: SC0001517; 320969

Resource Type:: Published Article

Journal Name:: Journal of the American Chemical Society

Additional Journal Information:: Journal Name: Journal of the American Chemical Society Journal Volume: 139 Journal Issue: 15; Journal ID: ISSN 0002-7863

Publisher:: American Chemical Society

Country of Publication:: United States

Language:: English

Subject:: 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats


                    Richert, Sabine, Bullard, George, Rawson, Jeff, Angiolillo, Paul J., Therien, Michael J., and Timmel, Christiane R. On the Importance of Electronic Symmetry for Triplet State Delocalization.  United States: N. p., 2017. 
        Web.  doi:10.1021/jacs.7b01204.

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                    Richert, Sabine, Bullard, George, Rawson, Jeff, Angiolillo, Paul J., Therien, Michael J., & Timmel, Christiane R. On the Importance of Electronic Symmetry for Triplet State Delocalization.  United States.  doi:https://doi.org/10.1021/jacs.7b01204

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                    Richert, Sabine, Bullard, George, Rawson, Jeff, Angiolillo, Paul J., Therien, Michael J., and Timmel, Christiane R. Tue .  
        "On the Importance of Electronic Symmetry for Triplet State Delocalization".  United States.  doi:https://doi.org/10.1021/jacs.7b01204.

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@article{osti_1355067,

  title        = {On the Importance of Electronic Symmetry for Triplet State Delocalization},

  author       = {Richert, Sabine and Bullard, George and Rawson, Jeff and Angiolillo, Paul J. and Therien, Michael J. and Timmel, Christiane R.},

  abstractNote = {The influence of electronic symmetry on triplet state delocalization in linear zinc porphyrin oligomers is explored by electron paramagnetic resonance techniques. Using a combination of transient continuous wave and pulse electron nuclear double resonance spectroscopies, it is demonstrated experimentally that complete triplet state delocalization requires the chemical equivalence of all porphyrin units. These results are supported by density functional theory calculations, showing uneven delocalization in a porphyrin dimer in which a terminal ethynyl group renders the two porphyrin units inequivalent. When the conjugation length of the molecule is further increased upon addition of a second terminal ethynyl group that restores the symmetry of the system, the triplet state is again found to be completely delocalized. Finally, the observations suggest that electronic symmetry is of greater importance for triplet state delocalization than other frequently invoked factors such as conformational rigidity or fundamental length-scale limitations.},

  doi          = {10.1021/jacs.7b01204},

  journal      = {Journal of the American Chemical Society},

  number       = 15,

  volume       = 139,

  place        = {United States},

  year         = {2017},

  month        = {4}

}

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DOI: https://doi.org/10.1021/jacs.7b01204

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Cited by: 2 works

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Figure 1: Chemical structures (left), comparison of the transient cw EPR spectra (center) and proton Mims ENDOR spectra recorded at a field position corresponding to the Y− orientation (right). The EPR and ENDOR data were acquired in frozen MTHF at 20 K. Pulse lengths of 16 ns were applied inmore »

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Works referencing / citing this record:

Stepwise oxidations of a nickel( ii )–iron( iii ) heterobimetallic porphyrin dimer: structure, spectroscopic and theoretical investigation
journal, January 2019

Kumar, Amit; Banerjee, Sayantani; Sarkar, Sabyasachi
Dalton Transactions, Vol. 48, Issue 27
DOI: 10.1039/c9dt01776c

Stepwise oxidations of a nickel( ii )–iron( iii ) heterobimetallic porphyrin dimer: structure, spectroscopic and theoretical investigation
journal, January 2019

Kumar, Amit; Banerjee, Sayantani; Sarkar, Sabyasachi
Dalton Transactions, Vol. 48, Issue 27
DOI: 10.1039/c9dt01776c

Molekulares Engineering freier Porphyrinbasen als Liganden - das N-H⋅⋅⋅X-Bindungsmotiv in Tetrapyrrolen
journal, November 2018

Kielmann, Marc; Senge, Mathias O.
Angewandte Chemie, Vol. 131, Issue 2
DOI: 10.1002/ange.201806281

Self‐Stabilized Amorphous Organic Materials with Room‐Temperature Phosphorescence
journal, September 2019

Xu, Wei; Yu, Yaguo; Ji, Xiaonan
Angewandte Chemie, Vol. 131, Issue 45
DOI: 10.1002/ange.201906881

Molecular Engineering of Free-Base Porphyrins as Ligands-The N−H⋅⋅⋅X Binding Motif in Tetrapyrroles
journal, November 2018

Kielmann, Marc; Senge, Mathias O.
Angewandte Chemie International Edition, Vol. 58, Issue 2
DOI: 10.1002/anie.201806281

Self‐Stabilized Amorphous Organic Materials with Room‐Temperature Phosphorescence
journal, November 2019

Xu, Wei; Yu, Yaguo; Ji, Xiaonan
Angewandte Chemie International Edition, Vol. 58, Issue 45
DOI: 10.1002/anie.201906881

Spin–Orbit Charge‐Transfer Intersystem Crossing (ISC) in Compact Electron Donor–Acceptor Dyads: ISC Mechanism and Application as Novel and Potent Photodynamic Therapy Reagents
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Wang, Zhijia; Ivanov, Mikhail; Gao, Yuting
Chemistry – A European Journal, Vol. 26, Issue 5
DOI: 10.1002/chem.201904306

Designing bifuncitonal molecular devices with a metalloporphyrin dimer
journal, January 2020

Xia, Ying; Shuai, Ling; Wang, Yiping
Physical Chemistry Chemical Physics, Vol. 22, Issue 7
DOI: 10.1039/c9cp05079e

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Title: On the Importance of Electronic Symmetry for Triplet State Delocalization

Abstract

Citation Formats

Figures / Tables:

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