Towards solar energy storage in the photochromic dihydroazulene-vinylheptafulvene system

Martina Cacciarini; Anders Bo Skov; Martyn Jevric; Anne Schou Hansen; Jonas Elm; Henrik Grum Kjærgaard; Kurt Valentin Mikkelsen; Mogens Brøndsted Nielsen

doi:10.1002/chem.201500100

Towards solar energy storage in the photochromic dihydroazulene-vinylheptafulvene system

Martina Cacciarini, Anders Bo Skov, Martyn Jevric, Anne Schou Hansen, Jonas Elm, Henrik Grum Kjærgaard, Kurt Valentin Mikkelsen, Mogens Brøndsted Nielsen

Department of Chemistry

51 Citations (Scopus)

Abstract

Abstract One key challenge in the field of exploitation of solar energy is to store the energy and make it available on demand. One possibility is to use photochromic molecules that undergo light-induced isomerization to metastable isomers. Here we present efforts to develop solar thermal energy storage systems based on the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch. New DHA derivatives with one electron-withdrawing cyano group at position 1 and one or two phenyl substituents in the five-membered ring were prepared by using different synthetic routes. In particular, a diastereoselective reductive removal of one cyano group from DHAs incorporating two cyano groups at position 1 turned out to be most effective. Quantum chemical calculations reveal that the structural modifications provide two benefits relative to DHAs with two cyano groups at position 1: 1) The DHA-VHF energy difference is increased (i.e., higher energy capacity of metastable VHF isomer); 2) the Gibbs free energy of activation is increased for the energy-releasing VHF to DHA back-reaction. In fact, experimentally, these new derivatives were so reluctant to undergo the back-reaction at room temperature that they practically behaved as DHA to VHF one-way switches. Although lifetimes of years are at first attractive, which offers the ultimate control of energy release, for a real device it must of course be possible to trigger the back-reaction, which calls for further iterations in the future. Molecular solar thermal energy storage: Derivatives of the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch with only one cyano group at position 1 were prepared and investigated experimentally and theoretically. Compared to derivatives with two cyano groups, these compounds exhibit larger energy differences between DHA and VHF isomers and hence larger energy storage capacities, while the VHF to DHA back-reaction is on hold (see scheme).

Original language	English
Journal	Chemistry: A European Journal
Volume	21
Issue number	20
Pages (from-to)	7454-7461
Number of pages	8
ISSN	0947-6539
DOIs	https://doi.org/10.1002/chem.201500100
Publication status	Published - 11 May 2015

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10.1002/chem.201500100

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title = "Towards solar energy storage in the photochromic dihydroazulene-vinylheptafulvene system",

abstract = "Abstract One key challenge in the field of exploitation of solar energy is to store the energy and make it available on demand. One possibility is to use photochromic molecules that undergo light-induced isomerization to metastable isomers. Here we present efforts to develop solar thermal energy storage systems based on the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch. New DHA derivatives with one electron-withdrawing cyano group at position 1 and one or two phenyl substituents in the five-membered ring were prepared by using different synthetic routes. In particular, a diastereoselective reductive removal of one cyano group from DHAs incorporating two cyano groups at position 1 turned out to be most effective. Quantum chemical calculations reveal that the structural modifications provide two benefits relative to DHAs with two cyano groups at position 1: 1) The DHA-VHF energy difference is increased (i.e., higher energy capacity of metastable VHF isomer); 2) the Gibbs free energy of activation is increased for the energy-releasing VHF to DHA back-reaction. In fact, experimentally, these new derivatives were so reluctant to undergo the back-reaction at room temperature that they practically behaved as DHA to VHF one-way switches. Although lifetimes of years are at first attractive, which offers the ultimate control of energy release, for a real device it must of course be possible to trigger the back-reaction, which calls for further iterations in the future. Molecular solar thermal energy storage: Derivatives of the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch with only one cyano group at position 1 were prepared and investigated experimentally and theoretically. Compared to derivatives with two cyano groups, these compounds exhibit larger energy differences between DHA and VHF isomers and hence larger energy storage capacities, while the VHF to DHA back-reaction is on hold (see scheme).",

author = "Martina Cacciarini and Skov, {Anders Bo} and Martyn Jevric and Hansen, {Anne Schou} and Jonas Elm and Kj{\ae}rgaard, {Henrik Grum} and Mikkelsen, {Kurt Valentin} and Nielsen, {Mogens Br{\o}ndsted}",

year = "2015",

month = may,

day = "11",

doi = "10.1002/chem.201500100",

language = "English",

volume = "21",

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journal = "Chemistry: A European Journal",

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TY - JOUR

T1 - Towards solar energy storage in the photochromic dihydroazulene-vinylheptafulvene system

AU - Cacciarini, Martina

AU - Skov, Anders Bo

AU - Jevric, Martyn

AU - Hansen, Anne Schou

AU - Elm, Jonas

AU - Kjærgaard, Henrik Grum

AU - Mikkelsen, Kurt Valentin

AU - Nielsen, Mogens Brøndsted

PY - 2015/5/11

Y1 - 2015/5/11

N2 - Abstract One key challenge in the field of exploitation of solar energy is to store the energy and make it available on demand. One possibility is to use photochromic molecules that undergo light-induced isomerization to metastable isomers. Here we present efforts to develop solar thermal energy storage systems based on the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch. New DHA derivatives with one electron-withdrawing cyano group at position 1 and one or two phenyl substituents in the five-membered ring were prepared by using different synthetic routes. In particular, a diastereoselective reductive removal of one cyano group from DHAs incorporating two cyano groups at position 1 turned out to be most effective. Quantum chemical calculations reveal that the structural modifications provide two benefits relative to DHAs with two cyano groups at position 1: 1) The DHA-VHF energy difference is increased (i.e., higher energy capacity of metastable VHF isomer); 2) the Gibbs free energy of activation is increased for the energy-releasing VHF to DHA back-reaction. In fact, experimentally, these new derivatives were so reluctant to undergo the back-reaction at room temperature that they practically behaved as DHA to VHF one-way switches. Although lifetimes of years are at first attractive, which offers the ultimate control of energy release, for a real device it must of course be possible to trigger the back-reaction, which calls for further iterations in the future. Molecular solar thermal energy storage: Derivatives of the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch with only one cyano group at position 1 were prepared and investigated experimentally and theoretically. Compared to derivatives with two cyano groups, these compounds exhibit larger energy differences between DHA and VHF isomers and hence larger energy storage capacities, while the VHF to DHA back-reaction is on hold (see scheme).

AB - Abstract One key challenge in the field of exploitation of solar energy is to store the energy and make it available on demand. One possibility is to use photochromic molecules that undergo light-induced isomerization to metastable isomers. Here we present efforts to develop solar thermal energy storage systems based on the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch. New DHA derivatives with one electron-withdrawing cyano group at position 1 and one or two phenyl substituents in the five-membered ring were prepared by using different synthetic routes. In particular, a diastereoselective reductive removal of one cyano group from DHAs incorporating two cyano groups at position 1 turned out to be most effective. Quantum chemical calculations reveal that the structural modifications provide two benefits relative to DHAs with two cyano groups at position 1: 1) The DHA-VHF energy difference is increased (i.e., higher energy capacity of metastable VHF isomer); 2) the Gibbs free energy of activation is increased for the energy-releasing VHF to DHA back-reaction. In fact, experimentally, these new derivatives were so reluctant to undergo the back-reaction at room temperature that they practically behaved as DHA to VHF one-way switches. Although lifetimes of years are at first attractive, which offers the ultimate control of energy release, for a real device it must of course be possible to trigger the back-reaction, which calls for further iterations in the future. Molecular solar thermal energy storage: Derivatives of the dihydroazulene (DHA)/vinylheptafulvene (VHF) photo/thermoswitch with only one cyano group at position 1 were prepared and investigated experimentally and theoretically. Compared to derivatives with two cyano groups, these compounds exhibit larger energy differences between DHA and VHF isomers and hence larger energy storage capacities, while the VHF to DHA back-reaction is on hold (see scheme).

U2 - 10.1002/chem.201500100

DO - 10.1002/chem.201500100

M3 - Journal article

C2 - 25847100

SN - 0947-6539

VL - 21

SP - 7454

EP - 7461

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

IS - 20

ER -

Towards solar energy storage in the photochromic dihydroazulene-vinylheptafulvene system

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