TY  - GEN
A1  - Tasior, Mariusz
A1  - Bald, Ilko
A1  - Deperasińska, Irena
A1  - Cywiński, Piotr J.
A1  - Gryko, Daniel T.
T1  - An internal charge transfer-dependent solvent effect in V-shaped azacyanines
N2  - 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 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.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 306 
Y1  - 2015
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/10270
UR  - https://nbn-resolving.org/urn:nbn:de:kobv:517-opus4-102704
SP  - 11714
EP  - 11720
ER  -