Photoswitch triads comprised of two dihydroazulene (DHA) units in conjugation to a central trans-azobenzene (AZB) unit were prepared in stepwise protocols starting from meta- and paradisubstituted azobenzenes. The para-connected triad had significantly altered optical properties and lacked the photoactivity of the separate photochromes. Instead, for the meta-connected triad all three photochromes could be photoisomerized to generate an isomer with two vinylheptafulvene (VHF) units and a cis-azobenzene unit. The photoisomerizations were studied by ultrafast spectroscopy, revealing a fast DHA-to-VHF photoisomerization and a slower trans-to-cis AZB photoisomerization. This meta triad underwent thermal VHF-to-DHA back-conversions with a similar rate of all VHFs, independent of the identity of the neighboring units, and in parallel thermal cis-to-trans AZB conversion. The experimental observations were supported by computations (excitation spectra and orbital analysis of the transitions).

Dihydroazulene-Azobenzene-Dihydroazulene Triad Photoswitches / Alvis Mengots, Andreas Erbs Hillers-Bendtsen, Sandra Doria, Frederik Ørsted Kjeldal, Nicolai Machholdt Høyer, Anne Ugleholdt Petersen, Kurt V. Mikkelsen, Mariangela Di Donato, Martina Cacciarini, and Mogens Brøndsted Nielsen. - In: CHEMISTRY. - ISSN 1521-3765. - STAMPA. - 27:(2021), pp. 12437-12446.

Dihydroazulene-Azobenzene-Dihydroazulene Triad Photoswitches

Martina Cacciarini
;
2021

Abstract

Photoswitch triads comprised of two dihydroazulene (DHA) units in conjugation to a central trans-azobenzene (AZB) unit were prepared in stepwise protocols starting from meta- and paradisubstituted azobenzenes. The para-connected triad had significantly altered optical properties and lacked the photoactivity of the separate photochromes. Instead, for the meta-connected triad all three photochromes could be photoisomerized to generate an isomer with two vinylheptafulvene (VHF) units and a cis-azobenzene unit. The photoisomerizations were studied by ultrafast spectroscopy, revealing a fast DHA-to-VHF photoisomerization and a slower trans-to-cis AZB photoisomerization. This meta triad underwent thermal VHF-to-DHA back-conversions with a similar rate of all VHFs, independent of the identity of the neighboring units, and in parallel thermal cis-to-trans AZB conversion. The experimental observations were supported by computations (excitation spectra and orbital analysis of the transitions).
2021
27
12437
12446
Alvis Mengots, Andreas Erbs Hillers-Bendtsen, Sandra Doria, Frederik Ørsted Kjeldal, Nicolai Machholdt Høyer, Anne Ugleholdt Petersen, Kurt V. Mikkelsen, Mariangela Di Donato, Martina Cacciarini, and Mogens Brøndsted Nielsen
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Descrizione: Manoscritto sottomesso pre-referaggio
Tipologia: Versione finale referata (Postprint, Accepted manuscript)
Licenza: Tutti i diritti riservati
Dimensione 3.08 MB
Formato Adobe PDF
3.08 MB Adobe PDF   Richiedi una copia

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Utilizza questo identificatore per citare o creare un link a questa risorsa: https://hdl.handle.net/2158/1238075
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