Dihydroazulene/Vinylheptafulvene photoswitch: ultrafast back reaction induced by dihydronaphthalene annulation

Søren Lindbæk Broman; Oleg Kushnir; Martin Rosenberg; Anders Kadziola; Joerg Daub; Mogens Brøndsted Nielsen

doi:10.1002/ejoc.201500320

Dihydroazulene/Vinylheptafulvene photoswitch: ultrafast back reaction induced by dihydronaphthalene annulation

Søren Lindbæk Broman, Oleg Kushnir, Martin Rosenberg, Anders Kadziola, Joerg Daub, Mogens Brøndsted Nielsen

Department of Chemistry

18 Citations (Scopus)

Abstract

The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s‐cis conformation of VHF and cannot occur from the more stable s‐trans conformation. Locking the VHF in the s‐cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half‐life was reduced by more than a factor of 150000 in cyclohexane and by a factor of approximately 950000 in ethanol. In addition, the characteristic absorption of the photoactive DHA isomer, now annulated to DHN, exhibited a desired redshift relative to the parent compound. Here, we present the synthesis and study of these DHN‐DHA/VHFs, including a protocol for the incorporation of a pseudo‐halide to enable the further functionalization of the molecule by metal‐catalyzed cross‐coupling reactions. For proof‐of‐concept, two different sulfur end‐groups were incorporated as anchoring groups for potential molecular electronics applications.

Original language	English
Journal	European Journal of Organic Chemistry
Volume	2015
Issue number	19
Pages (from-to)	4119-4130
Number of pages	12
ISSN	1434-193X
DOIs	https://doi.org/10.1002/ejoc.201500320
Publication status	Published - 1 Jul 2015

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title = "Dihydroazulene/Vinylheptafulvene photoswitch: ultrafast back reaction induced by dihydronaphthalene annulation",

abstract = "The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s‐cis conformation of VHF and cannot occur from the more stable s‐trans conformation. Locking the VHF in the s‐cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half‐life was reduced by more than a factor of 150000 in cyclohexane and by a factor of approximately 950000 in ethanol. In addition, the characteristic absorption of the photoactive DHA isomer, now annulated to DHN, exhibited a desired redshift relative to the parent compound. Here, we present the synthesis and study of these DHN‐DHA/VHFs, including a protocol for the incorporation of a pseudo‐halide to enable the further functionalization of the molecule by metal‐catalyzed cross‐coupling reactions. For proof‐of‐concept, two different sulfur end‐groups were incorporated as anchoring groups for potential molecular electronics applications.",

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T1 - Dihydroazulene/Vinylheptafulvene photoswitch

T2 - ultrafast back reaction induced by dihydronaphthalene annulation

AU - Broman, Søren Lindbæk

AU - Kushnir, Oleg

AU - Rosenberg, Martin

AU - Kadziola, Anders

AU - Daub, Joerg

AU - Nielsen, Mogens Brøndsted

N1 - Front cover publication

PY - 2015/7/1

Y1 - 2015/7/1

N2 - The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s‐cis conformation of VHF and cannot occur from the more stable s‐trans conformation. Locking the VHF in the s‐cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half‐life was reduced by more than a factor of 150000 in cyclohexane and by a factor of approximately 950000 in ethanol. In addition, the characteristic absorption of the photoactive DHA isomer, now annulated to DHN, exhibited a desired redshift relative to the parent compound. Here, we present the synthesis and study of these DHN‐DHA/VHFs, including a protocol for the incorporation of a pseudo‐halide to enable the further functionalization of the molecule by metal‐catalyzed cross‐coupling reactions. For proof‐of‐concept, two different sulfur end‐groups were incorporated as anchoring groups for potential molecular electronics applications.

AB - The vinylheptafulvene (VHF) to dihydroazulene (DHA) electrocyclization is known to proceed from an s‐cis conformation of VHF and cannot occur from the more stable s‐trans conformation. Locking the VHF in the s‐cis conformation by the introduction of a dihydronaphthalene (DHN) unit has been found to greatly enhance the speed of this reaction. Thus, the half‐life was reduced by more than a factor of 150000 in cyclohexane and by a factor of approximately 950000 in ethanol. In addition, the characteristic absorption of the photoactive DHA isomer, now annulated to DHN, exhibited a desired redshift relative to the parent compound. Here, we present the synthesis and study of these DHN‐DHA/VHFs, including a protocol for the incorporation of a pseudo‐halide to enable the further functionalization of the molecule by metal‐catalyzed cross‐coupling reactions. For proof‐of‐concept, two different sulfur end‐groups were incorporated as anchoring groups for potential molecular electronics applications.

U2 - 10.1002/ejoc.201500320

DO - 10.1002/ejoc.201500320

M3 - Journal article

SN - 1434-193X

VL - 2015

SP - 4119

EP - 4130

JO - European Journal of Organic Chemistry

JF - European Journal of Organic Chemistry

IS - 19

ER -

Dihydroazulene/Vinylheptafulvene photoswitch: ultrafast back reaction induced by dihydronaphthalene annulation

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