@article{FullWoelflickRadackietal.2022, author = {Full, Felix and W{\"o}lflick, Quentin and Radacki, Krzysztof and Braunschweig, Holger and Nowak-Kr{\´o}l, Agnieszka}, title = {Enhanced Optical Properties of Azaborole Helicenes by Lateral and Helical Extension}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {62}, doi = {10.1002/chem.202202280}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-293671}, year = {2022}, abstract = {The synthesis and characterization of laterally extended azabora[5]-, -[6]- and -[7]helicenes, assembled from N-heteroaromatic and dibenzo[g,p]chrysene building blocks is described. Formally, the π-conjugated systems of the pristine azaborole helicenes were enlarged with a phenanthrene unit leading to compounds with large Stokes shifts, significantly enhanced luminescence quantum yields (Φ) and dissymmetry factors (g\(_{lum}\)). The beneficial effect on optical properties was also observed for helical elongation. The combined contributions of lateral and helical extensions resulted in a compound showing green emission with Φ of 0.31 and |g\(_{lum}\)| of 2.2×10\(^{-3}\), highest within the series of π-extended azaborahelicenes and superior to emission intensity and chiroptical response of its non-extended congener. This study shows that helical and lateral extensions of π-conjugated systems are viable strategies to improve features of azaborole helicenes. In addition, single crystal X-ray analysis of configurationally stable [6]- and -[7]helicenes was used to provide insight into their packing arrangements.}, language = {en} } @article{FullPanchalGoetzetal.2021, author = {Full, Julian and Panchal, Santosh P. and G{\"o}tz, Julian and Krause, Ana-Maria and Nowak-Kr{\´o}l, Agnieszka}, title = {Modular Synthesis of Organoboron Helically Chiral Compounds: Cutouts from Extended Helices}, series = {Angewandte Chemie International Edition}, volume = {60}, journal = {Angewandte Chemie International Edition}, number = {8}, doi = {10.1002/anie.202014138}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-225775}, pages = {4350 -- 4357}, year = {2021}, abstract = {Two types of helically chiral compounds bearing one and two boron atoms were synthesized by a modular approach. Formation of the helical scaffolds was executed by the introduction of boron to flexible biaryl and triaryl derived from small achiral building blocks. All-ortho-fused azabora[7]helicenes feature exceptional configurational stability, blue or green fluorescence with quantum yields (Φ\(_{fl}\)) of 18-24 \% in solution, green or yellow solid-state emission (Φ\(_{fl}\) up to 23 \%), and strong chiroptical response with large dissymmetry factors of up to 1.12×10\(^{-2}\). Azabora[9]helicenes consisting of angularly and linearly fused rings are blue emitters exhibiting Φ\(_{fl}\) of up to 47 \% in CH\(_{2}\)Cl\(_{2}\) and 25 \% in the solid state. As revealed by the DFT calculations, their P-M interconversion pathway is more complex than that of H1. Single-crystal X-ray analysis shows clear differences in the packing arrangement of methyl and phenyl derivatives. These molecules are proposed as primary structures of extended helices.}, language = {en} }