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
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-102704
SP  - 11714
EP  - 11720
ER  - 
TY  - JOUR
A1  - Weclawski, Marek K.
A1  - Meiling, Till Thomas
A1  - Leniak, Arkadiusz
A1  - Cywinski, Piotr J.
A1  - Gryko, Daniel T.
T1  - Planar, Fluorescent Push-Pull System That Comprises Benzofuran and Iminocoumarin Moieties
JF  - Organic letters
N2  - Previously unknown, vertically linked heterocycles comprised of benzofuran and iminocoumarin moieties have been synthesized directly from 1,5-dibenzoyloxyanthraquinone and arylacetonitriles via double Knoevenagel condensation followed by formal HCN elimination. The structural assembly of fully conjugated, electron-rich benzofuran and electron-deficient iminocoumarin is responsible for the strongly polarized nature of these heterocycles which translates into their polarity-sensitive fluorescence.
Y1  - 2015
U6  - https://doi.org/10.1021/acs.orglett.5b02042
SN  - 1523-7060
SN  - 1523-7052
VL  - 17
IS  - 17
SP  - 4252
EP  - 4255
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - GEN
A1  - Węcławski, Marek K.
A1  - Tasior, Mariusz
A1  - Hammann, Tommy
A1  - Cywiński, Piotr J.
A1  - Gryko, Daniel T.
T1  - From π-expanded coumarins to π-expanded pentacenes
N2  - The synthesis of two novel types of π-expanded coumarins has been developed. Modified Knoevenagel bis-condensation afforded 3,9-dioxa-perylene-2,8-diones. Subsequent oxidative aromatic coupling or light driven electrocyclization reaction led to dibenzo-1,7-dioxacoronene-2,8-dione. Unparalleled synthetic simplicity, straightforward purification and superb optical properties have the potential to bring these perylene and coronene analogs towards various applications.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 280 
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-98822
ER  -