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An internal charge transfer-dependent solvent effect in V-shaped azacyanines

  • New V-shaped non-centrosymmetric dyes, possessing a strongly electron-deficient azacyanine core, have been synthesized based on a straightforward two-step approach. The key step in this synthesis involves palladium-catalysed cross-coupling of dibromo-N,N′-methylene-2,2′-azapyridinocyanines with arylacetylenes. The resulting strongly polarized π-expanded heterocycles exhibit green to orange fluorescence and they strongly respond to changes in solvent polarity. We demonstrate that differently electron-donating peripheral groups have a significant influence on the internal charge transfer, hence on the solvent effect and fluorescence quantum yield. TD-DFT calculations confirm that, in contrast to the previously studied bis(styryl)azacyanines, the proximity of S1 and T2 states calculated for compounds bearing two 4-N,N-dimethylaminophenylethynyl moieties establishes good conditions for efficient intersystem crossing and is responsible for its low fluorescence quantum yield. Non-linear properties have also been determined for newNew V-shaped non-centrosymmetric dyes, possessing a strongly electron-deficient azacyanine core, have been synthesized based on a straightforward two-step approach. The key step in this synthesis involves palladium-catalysed cross-coupling of dibromo-N,N′-methylene-2,2′-azapyridinocyanines with arylacetylenes. The resulting strongly polarized π-expanded heterocycles exhibit green to orange fluorescence and they strongly respond to changes in solvent polarity. We demonstrate that differently electron-donating peripheral groups have a significant influence on the internal charge transfer, hence on the solvent effect and fluorescence quantum yield. TD-DFT calculations confirm that, in contrast to the previously studied bis(styryl)azacyanines, the proximity of S1 and T2 states calculated for compounds bearing two 4-N,N-dimethylaminophenylethynyl moieties establishes good conditions for efficient intersystem crossing and is responsible for its low fluorescence quantum yield. Non-linear properties have also been determined for new azacyanines and the results show that depending on peripheral groups, the synthesized dyes exhibit small to large two-photon absorption cross sections reaching 4000 GM.show moreshow less

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Metadaten
Author:Mariusz Tasior, Ilko BaldORCiDGND, Irena Deperasińska, Piotr J. Cywiński, Daniel T. Gryko
URN:urn:nbn:de:kobv:517-opus4-102704
Series (Serial Number):Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (306)
Document Type:Postprint
Language:English
Date of first Publication:2015/10/08
Year of Completion:2015
Publishing Institution:Universität Potsdam
Release Date:2017/02/03
First Page:11714
Last Page:11720
Source:Org. Biomol. Chem. (2015) Nr. 13, S. 11714-11720. - DOI: 10.1039/c5ob01633a
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Peer Review:Referiert
Publication Way:Open Access
Licence (German):License LogoKeine Nutzungslizenz vergeben - es gilt das deutsche Urheberrecht