Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity

Anders B. Skob, Nicolai Ree, Anders S. Gertsen, Pavel Chabera, Jens Uhlig, Jonas S. Lissau, Luigi Nucci, Tonu Pullerits, Kurt V. Mikkelsen, Mogens Brøndsted Nielsen, Theis I. Sølling, Thorsten Hansen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The gain and loss of aromaticity plays a key role in organic chemistry and in the prediction of rate‐determining steps. Herein, we explore the concept of aromaticity in photoisomerization reactions. Benzannulated derivatives of the dihydroazulene‐vinylheptafulvene (DHA‐VHF) photoswitch were investigated using transient absorption spectroscopy and time‐dependent density functional theory to elucidate the effect of built‐in aromaticity on the switching properties. We found that benzannulation hampered the switching ability by enhancing an already existing barrier on the excited state surface. This enhancement was found to arise from a significant loss of aromaticity in the DHA‐to‐VHF transition state on the excited state potential energy surface. The VHF was found to be highly aromatic on the excited state surface, showing a reversal of aromaticity compared to the ground state. The barrier was found to be dependent on the position of benzannulation, since one derivative was found to switch as fast as the non‐benzannulated molecule although with lower efficiency, whereas another derivative completely lost the ability to undergo reversible photoswitching. The findings herein provide novel principles for the design of molecular photoswitches, shedding new light on excited state aromaticity, as previous discussions have mainly considered excited state aromaticity to be beneficial to switching. Our findings show that this view must be reconsidered.
Original languageEnglish
JournalChemPhotoChem
Volume3
Issue number8
Pages (from-to)619-629
ISSN2367-0932
DOIs
Publication statusPublished - 2019

Cite this

Skob, Anders B. ; Ree, Nicolai ; Gertsen, Anders S. ; Chabera, Pavel ; Uhlig, Jens ; Lissau, Jonas S. ; Nucci, Luigi ; Pullerits, Tonu ; Mikkelsen, Kurt V. ; Nielsen, Mogens Brøndsted ; Sølling, Theis I. ; Hansen, Thorsten. / Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity. In: ChemPhotoChem. 2019 ; Vol. 3, No. 8. pp. 619-629.
@article{61ea14f6398540e68295eb30d56a54d4,
title = "Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity",
abstract = "The gain and loss of aromaticity plays a key role in organic chemistry and in the prediction of rate‐determining steps. Herein, we explore the concept of aromaticity in photoisomerization reactions. Benzannulated derivatives of the dihydroazulene‐vinylheptafulvene (DHA‐VHF) photoswitch were investigated using transient absorption spectroscopy and time‐dependent density functional theory to elucidate the effect of built‐in aromaticity on the switching properties. We found that benzannulation hampered the switching ability by enhancing an already existing barrier on the excited state surface. This enhancement was found to arise from a significant loss of aromaticity in the DHA‐to‐VHF transition state on the excited state potential energy surface. The VHF was found to be highly aromatic on the excited state surface, showing a reversal of aromaticity compared to the ground state. The barrier was found to be dependent on the position of benzannulation, since one derivative was found to switch as fast as the non‐benzannulated molecule although with lower efficiency, whereas another derivative completely lost the ability to undergo reversible photoswitching. The findings herein provide novel principles for the design of molecular photoswitches, shedding new light on excited state aromaticity, as previous discussions have mainly considered excited state aromaticity to be beneficial to switching. Our findings show that this view must be reconsidered.",
author = "Skob, {Anders B.} and Nicolai Ree and Gertsen, {Anders S.} and Pavel Chabera and Jens Uhlig and Lissau, {Jonas S.} and Luigi Nucci and Tonu Pullerits and Mikkelsen, {Kurt V.} and Nielsen, {Mogens Br{\o}ndsted} and S{\o}lling, {Theis I.} and Thorsten Hansen",
year = "2019",
doi = "10.1002/cptc.201900088",
language = "English",
volume = "3",
pages = "619--629",
journal = "ChemPhotoChem",
issn = "2367-0932",
publisher = "Wiley",
number = "8",

}

Skob, AB, Ree, N, Gertsen, AS, Chabera, P, Uhlig, J, Lissau, JS, Nucci, L, Pullerits, T, Mikkelsen, KV, Nielsen, MB, Sølling, TI & Hansen, T 2019, 'Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity', ChemPhotoChem, vol. 3, no. 8, pp. 619-629. https://doi.org/10.1002/cptc.201900088

Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity. / Skob, Anders B.; Ree, Nicolai; Gertsen, Anders S.; Chabera, Pavel ; Uhlig, Jens; Lissau, Jonas S.; Nucci, Luigi; Pullerits, Tonu; Mikkelsen, Kurt V.; Nielsen, Mogens Brøndsted; Sølling, Theis I.; Hansen, Thorsten.

In: ChemPhotoChem, Vol. 3, No. 8, 2019, p. 619-629.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Excited‐State Topology Modifications of the Dihydroazulene Photoswitch Through Aromaticity

AU - Skob, Anders B.

AU - Ree, Nicolai

AU - Gertsen, Anders S.

AU - Chabera, Pavel

AU - Uhlig, Jens

AU - Lissau, Jonas S.

AU - Nucci, Luigi

AU - Pullerits, Tonu

AU - Mikkelsen, Kurt V.

AU - Nielsen, Mogens Brøndsted

AU - Sølling, Theis I.

AU - Hansen, Thorsten

PY - 2019

Y1 - 2019

N2 - The gain and loss of aromaticity plays a key role in organic chemistry and in the prediction of rate‐determining steps. Herein, we explore the concept of aromaticity in photoisomerization reactions. Benzannulated derivatives of the dihydroazulene‐vinylheptafulvene (DHA‐VHF) photoswitch were investigated using transient absorption spectroscopy and time‐dependent density functional theory to elucidate the effect of built‐in aromaticity on the switching properties. We found that benzannulation hampered the switching ability by enhancing an already existing barrier on the excited state surface. This enhancement was found to arise from a significant loss of aromaticity in the DHA‐to‐VHF transition state on the excited state potential energy surface. The VHF was found to be highly aromatic on the excited state surface, showing a reversal of aromaticity compared to the ground state. The barrier was found to be dependent on the position of benzannulation, since one derivative was found to switch as fast as the non‐benzannulated molecule although with lower efficiency, whereas another derivative completely lost the ability to undergo reversible photoswitching. The findings herein provide novel principles for the design of molecular photoswitches, shedding new light on excited state aromaticity, as previous discussions have mainly considered excited state aromaticity to be beneficial to switching. Our findings show that this view must be reconsidered.

AB - The gain and loss of aromaticity plays a key role in organic chemistry and in the prediction of rate‐determining steps. Herein, we explore the concept of aromaticity in photoisomerization reactions. Benzannulated derivatives of the dihydroazulene‐vinylheptafulvene (DHA‐VHF) photoswitch were investigated using transient absorption spectroscopy and time‐dependent density functional theory to elucidate the effect of built‐in aromaticity on the switching properties. We found that benzannulation hampered the switching ability by enhancing an already existing barrier on the excited state surface. This enhancement was found to arise from a significant loss of aromaticity in the DHA‐to‐VHF transition state on the excited state potential energy surface. The VHF was found to be highly aromatic on the excited state surface, showing a reversal of aromaticity compared to the ground state. The barrier was found to be dependent on the position of benzannulation, since one derivative was found to switch as fast as the non‐benzannulated molecule although with lower efficiency, whereas another derivative completely lost the ability to undergo reversible photoswitching. The findings herein provide novel principles for the design of molecular photoswitches, shedding new light on excited state aromaticity, as previous discussions have mainly considered excited state aromaticity to be beneficial to switching. Our findings show that this view must be reconsidered.

U2 - 10.1002/cptc.201900088

DO - 10.1002/cptc.201900088

M3 - Journal article

VL - 3

SP - 619

EP - 629

JO - ChemPhotoChem

JF - ChemPhotoChem

SN - 2367-0932

IS - 8

ER -