%0 Journal Article %1 D2SC04600H %A Freytag, Emely %A Holzapfel, Marco %A Swain, Asim %A Bringmann, Gerhard %A Stolte, Matthias %A Würthner, Frank %A Lambert, Christoph %D 2022 %I The Royal Society of Chemistry %J Chem. Sci. %K myown %N 41 %P 12229-12238 %R 10.1039/D2SC04600H %T Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties %U http://dx.doi.org/10.1039/D2SC04600H %V 13 %X Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties, this is, outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron, electric–magnetic coupling, and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one, the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer.

@article{D2SC04600H, abstract = {Yamamoto homocoupling of two chiral oxindoles led to the atropo-diastereoselective formation of an axially chiral oxindole dimer. This building block served as the starting material for the syntheses of axially chiral squaraine and merocyanine chromophore dimers. These dimers show pronounced chiroptical properties{,} this is{,} outstandingly high ECD signals (Δε up to ca. 1500 M−1 cm−1) as a couplet with positive Cotton effect for the P-configuration around the biaryl axis and a negative Cotton effect for the M-configuration. All investigated dimers also exhibit pronounced circularly polarised emission with anisotropy values of ca. 10−3 cgs. Time-dependent density functional calculations were used to analyse the three contributions (local one electron{,} electric–magnetic coupling{,} and exciton coupling) to the rotational strength applying the Rosenfeld equation to excitonically coupled chromophores. While the exciton coupling term proves to be the dominant one{,} the electric–magnetic coupling possesses the same sign and adds significantly to the total rotational strength owing to a favourable geometric arrangement of the two chromophores within the dimer.}, added-at = {2022-10-31T11:18:38.000+0100}, author = {Freytag, Emely and Holzapfel, Marco and Swain, Asim and Bringmann, Gerhard and Stolte, Matthias and Würthner, Frank and Lambert, Christoph}, biburl = {https://www.bibsonomy.org/bibtex/22300208de84e0353ccaa1e3b34e2d086/wuerthner_group}, doi = {10.1039/D2SC04600H}, interhash = {b6b91fbdac4673af69ac8e608f33f1c8}, intrahash = {2300208de84e0353ccaa1e3b34e2d086}, journal = {Chem. Sci.}, keywords = {myown}, number = 41, pages = {12229-12238}, publisher = {The Royal Society of Chemistry}, timestamp = {2022-10-31T11:18:38.000+0100}, title = {Axially chiral indolenine derived chromophore dimers and their chiroptical absorption and emission properties}, url = {http://dx.doi.org/10.1039/D2SC04600H}, volume = 13, year = 2022 }