Synthetic protocols for the key functionalizations of the photochromic dihydroazulene scaffold

Cacciarini, Martina; Broman, Søren Lindbæk; Nielsen, Mogens Brøndsted

doi:10.3998/ark.5550190.p008.475

Cited by 19 publications

(5 citation statements)

References 35 publications

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“…The switching between states of the TTF-substituted DHA 15a are shown in Scheme 10. 23b Later, in 2012, 24 a series of DHAs connected to buckminsterfullerene (C 60 ) by a p-spacer with varying length was prepared (16)(17)(18)(19), by either Prato or Sonogashira reactions. Representative syntheses of 16 are shown Scheme 11.…”

Section: Redox-controlled and Multimode Photoswitchingmentioning

confidence: 99%

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Dihydroazulene: from controlling photochromism to molecular electronics devices

Broman

Nielsen

2014

Phys. Chem. Chem. Phys.

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Recent synthetic advances allowing large-scale preparation and systematic functionalization of the dihydroazulene (DHA)-vinylheptafulvene (VHF) photo-/thermoswitch have enabled detailed studies on how to tune optical and switching properties and have paved the way for using this system as a functional unit in molecular electronics and materials chemistry. Since discovery of its photochromism in the 1980'ies, numerous examples of DHA-VHF systems have been developed, allowing multimode switching, fluorescence-control and fine tuning of absorbance and VHF half-lives, giving insights into the mechanism of the switching event. Here, we present an overview of the properties of the DHA-VHF system, together with some selected synthetic procedures which have paved the way for its development.

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Section: Redox-controlled and Multimode Photoswitchingmentioning

confidence: 99%

“…A review on synthetic protocols has recently been published and shall not be covered in detail here. 16…”

Section: Introductionmentioning

confidence: 99%

Dihydroazulene: from controlling photochromism to molecular electronics devices

Broman

Nielsen

2014

Phys. Chem. Chem. Phys.

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“…Ethynyl‐functionalized DHAs 10 and 11 were prepared by following a strategy starting from alkyne‐functionalized acetophenone derivatives described in the Supporting Information (Section 2) and similar to previous reports . DHAs 12 and 13 (precursors for 4 A and 5 A ) were prepared from 1 A (readily obtained on a large scale) by employing a bromination/elimination/cross‐coupling strategy . An isomerization reaction in the synthesis of 4 A and 5 A occurred under the metalation conditions (see below).…”

Section: Resultsmentioning

confidence: 99%

Multistate Switches: Ruthenium Alkynyl–Dihydroazulene/Vinylheptafulvene Conjugates

Vlasceanu

Andersen

Parker

et al. 2016

Chemistry A European J

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Multimode molecular switches incorporating distinct and independently addressable functional components have potential applications as advanced switches and logic gates for molecular electronics and memory storage devices. Herein, we describe the synthesis and characterization of four switches based on the dihydroazulene/vinylheptafulvene (DHA/VHF) photo/thermoswitch pair functionalized with the ruthenium-based Cp*(dppe)Ru ([Ru*]) metal complex (dppe=1,2-bis(diphenylphosphino)ethane; Cp*=pentamethylcyclopentadienyl). The [Ru*]-DHA conjugates can potentially exist in six different states accessible by alternation between DHA/VHF, Ru(II) /Ru(III) , and alkynyl/vinylidene, which can be individually stimulated by using light/heat, oxidation/reduction, and acid/base. Access to the full range of states was found to be strongly dependent on the electronic communication between the metal center and the organic photoswitch in these [Ru*]-DHA conjugates. Detailed electrochemical, spectroscopic (UV/Vis, IR, NMR), and X-ray crystallographic studies indeed reveal significant electronic interactions between the two moieties. When in direct conjugation, the ruthenium metal center was found to quench the photochemical ring-opening of DHA, which in one case could be restored by protonation or oxidation, allowing conversion to the VHF state.

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“…For more detailed discussion of the synthesis and functionalization of DHA, we refer to a recently published review. 17 In regard to halogenation of azulenes, electrophilic aromatic substi-tution occurs at position 1. 18 One recent, convenient protocol deserves particular attention, in which iodination of azulene and heteroazulene derivatives can be achieved with N-chlorosuccinimide/NaI.…”

Section: Letter Syn Lettmentioning

confidence: 99%

On the Solvent-Dependent Bromination of Dihydroazulenes

Kilde

Broman

Kadziola

et al. 2015

Synlett

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Bromination of 1,8a-dihydroazulene-1,1-dicarbonitriles (DHA) followed by elimination of HBr was previously shown to be an important protocol for functionalizing these molecular photoswitches in the seven-membered ring (at C7). Here we show systematically how the outcome of the bromination reaction depends on the electronic character of an aryl substituent at the C2 position of DHA, and the solvent polarity as the reaction can lead to either the addition product or to the corresponding 2-aryl-1-bromo-3-cyanoazulene.

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Synthetic protocols for the key functionalizations of the photochromic dihydroazulene scaffold

Cited by 19 publications

References 35 publications

Dihydroazulene: from controlling photochromism to molecular electronics devices

Dihydroazulene: from controlling photochromism to molecular electronics devices

Multistate Switches: Ruthenium Alkynyl–Dihydroazulene/Vinylheptafulvene Conjugates

On the Solvent-Dependent Bromination of Dihydroazulenes

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