@article{CeymanRosspeintnerSchrecketal.2016, author = {Ceyman, Harald and Rosspeintner, Arnulf and Schreck, Maximilian H. and M{\"u}tzel, Carina and Stoy, Andreas and Vauthey, Eric and Lambert, Christoph}, title = {Cooperative enhancement versus additivity of two-photon-absorption cross sections in linear and branched squaraine superchromophores}, series = {Physical Chemistry Chemical Physics}, volume = {18}, journal = {Physical Chemistry Chemical Physics}, number = {24}, doi = {10.1039/c6cp02312f}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188299}, pages = {16404-16413}, year = {2016}, abstract = {The linear and nonlinear optical properties of a series of oligomeric squaraine dyes were investigated by one-photon absorption spectroscopy (1PA) and two-photon absorption (2PA) induced fluorescence spectroscopy. The superchromophores are based on two indolenine squaraine dyes with transoid (SQA) and cisoid configuration (SQB). Using these monomers, linear dimers and trimers as well as star-shaped trimers and hexamers with benzene or triphenylamine cores were synthesised and investigated. The red-shifted and intensified 1PA spectra of all superchromophores could well be explained by exciton coupling theory. In the linear chromophore arrangements we also found superradiance of fluorescence but not in the branched systems. Furthermore, the 2PA showed enhanced cross sections for the linear oligomers but only additivity for the branched systems. This emphasizes that the enhancement of the 2PA cross section in the linear arrangements is probably caused by orbital interactions of higher excited configurations.}, language = {en} } @article{SeifertShoyamaSchmidtetal.2016, author = {Seifert, Sabine and Shoyama, Kazutaka and Schmidt, David and W{\"u}rthner, Frank}, title = {An electron-poor C\(_{64}\) nanographene by palladium-catalyzed cascade C-C bond formation: one-pot synthesis and single-crystal structure analysis}, series = {Angewandte Chemie-International Edition}, volume = {55}, journal = {Angewandte Chemie-International Edition}, number = {22}, doi = {10.1002/anie.201601433}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-188889}, pages = {6390-6395}, year = {2016}, abstract = {Herein, we report the one-pot synthesis of an electron-poor nanographene containing dicarboximide groups at the corners. We efficiently combined palladium-catalyzed Suzuki-Miyaura cross-coupling and dehydrohalogenation to synthesize an extended two-dimensional pi-scaffold of defined size in a single chemical operation starting from N-(2,6-diisopropylphenyl)-4,5-dibromo-1,8-naphthalimide and a tetrasubstituted pyrene boronic acid ester as readily accessible starting materials. The reaction of these precursors under the conditions commonly used for Suzuki-Miyaura cross-coupling afforded a C\(_{64}\) nanographene through the formation of ten C-C bonds in a one-pot process. Single-crystal X-ray analysis unequivocally confirmed the structure of this unique extended aromatic molecule with a planar geometry. The optical and electrochemical properties of this largest ever synthesized planar electron-poor nanographene skeleton were also analyzed.}, language = {en} }