TY - JOUR A1 - Full, Julian A1 - Panchal, Santosh P. A1 - Götz, Julian A1 - Krause, Ana‐Maria A1 - Nowak‐Król, Agnieszka T1 - Modulare Synthese helikal‐chiraler Organobor‐Verbindungen: Ausschnitte verlängerter Helices JF - Angewandte Chemie N2 - Zwei Arten helikal-chiraler Verbindungen mit einem oder zwei Boratomen wurden nach einem modularen Ansatz synthetisiert. Die Bildung der helikalen Strukturen erfolgte durch Einführung von Bor in flexible Biaryl- bzw. Triaryl-Vorstufen, hergestellt aus kleinen achiralen Bausteinen. Die durchgehend ortho-fusionierten Azabora[7]helicene zeichnen sich dabei durch außergewöhnliche Konfigurationsstabilität, blaue oder grüne Fluoreszenz in Lösung mit Quantenausbeuten (Φ\(_{fl}\)) von 18–24 %, grüne oder gelbe Emission im Festkörper (Φ\(_{fl}\) bis zu 23 %) und starke chiroptische Resonanz mit großen Anisotropiefaktoren von bis zu 1.12×10\(^{-2}\) aus. Azabora[9]helicene, aufgebaut aus winkelförmig sowie linear angeordneten Ringen, sind blaue Emitter mit Φ\(_{fl}\) von bis zu 47 % in CH\(_{2}\)Cl\(_{2}\) und 25 % im Festkörper. DFT-Rechnungen zeigen, dass ihre P-M-Interkonversion über einen komplexeren Weg verläuft als im Fall von H1. Röntgenstrukturanalyse von Einkristallen zeigt deutliche Unterschiede in der Packungsanordnung von Methyl- und Phenylderivaten auf. Die Moleküle werden als Primärstrukturen verlängerter Helices vorgeschlagen. KW - Chiralität KW - Fluoreszenz KW - Helicen KW - Organobor KW - Zirkulardichroismus Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-224385 VL - 133 IS - 8 SP - 4396 EP - 4403 ER - TY - JOUR A1 - Full, Julian A1 - Panchal, Santosh P. A1 - Götz, Julian A1 - Krause, Ana‐Maria A1 - Nowak‐Król, Agnieszka T1 - Modular Synthesis of Organoboron Helically Chiral Compounds: Cutouts from Extended Helices JF - Angewandte Chemie International Edition N2 - 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. KW - chirality KW - circular dichroism KW - fluorescence KW - helicene KW - organoboron Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225775 VL - 60 IS - 8 SP - 4350 EP - 4357 ER - TY - JOUR A1 - Bold, Kevin A1 - Stolte, Matthias A1 - Shoyama, Kazutaka A1 - Krause, Ana‐Maria A1 - Schmiedel, Alexander A1 - Holzapfel, Marco A1 - Lambert, Christoph A1 - Würthner, Frank T1 - Macrocyclic Donor‐Acceptor Dyads Composed of Oligothiophene Half‐Cycles and Perylene Bisimides JF - Chemistry – A European Journal N2 - A series of donor‐acceptor (D−A) macrocyclic dyads consisting of an electron‐poor perylene bisimide (PBI) π‐scaffold bridged with electron‐rich α‐oligothiophenes bearing four, five, six and seven thiophene units between the two phenyl‐imide substituents has been synthesized and characterized by steady‐state UV/Vis absorption and fluorescence spectroscopy, cyclic and differential pulse voltammetry as well as transient absorption spectroscopy. Tying the oligothiophene strands in a conformationally fixed macrocyclic arrangement leads to a more rigid π‐scaffold with vibronic fine structure in the respective absorption spectra. Electrochemical analysis disclosed charged state properties in solution which are strongly dependent on the degree of rigidification within the individual macrocycle. Investigation of the excited state dynamics revealed an oligothiophene bridge size‐dependent fast charge transfer process for the macrocyclic dyads upon PBI subunit excitation. KW - donor-acceptor dyad KW - macrocycle KW - oligothiophene KW - perylene bisimide KW - photoinduced electron transfer Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-276435 VL - 28 IS - 30 ER - TY - JOUR A1 - Weh, Manuel A1 - Rühe, Jessica A1 - Herbert, Benedikt A1 - Krause, Ana‐Maria A1 - Würthner, Frank T1 - Deracemization of Carbohelicenes by a Chiral Perylene Bisimide Cyclophane Template Catalyst JF - Angewandte Chemie International Edition N2 - Deracemization describes the conversion of a racemic mixture of a chiral molecule into an enantioenriched mixture or an enantiopure compound without structural modifications. Herein, we report an inherently chiral perylene bisimide (PBI) cyclophane whose chiral pocket is capable of transforming a racemic mixture of [5]‐helicene into an enantioenriched mixture with an enantiomeric excess of 66 %. UV/Vis and fluorescence titration studies reveal this cyclophane host composed of two helically twisted PBI dyes has high binding affinities for the respective homochiral carbohelicene guests, with outstanding binding constants of up to 3.9×10\(^{10}\) m\(^{-1}\) for [4]‐helicene. 2D NMR studies and single‐crystal X‐ray analysis demonstrate that the observed strong and enantioselective binding of homochiral carbohelicenes and the successful template‐catalyzed deracemization of [5]‐helicene can be explained by the enzyme‐like perfect shape complementarity of the macrocyclic supramolecular host. KW - chirality transfer KW - cyclophanes KW - deracemization KW - dyes/pigments KW - template catalysis Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244787 VL - 60 IS - 28 SP - 15323 EP - 15327 ER - TY - JOUR A1 - Mahl, Magnus A1 - Shoyama, Kazutaka A1 - Krause, Ana‐Maria A1 - Schmidt, David A1 - Würthner, Frank T1 - Base‐Assisted Imidization: A Synthetic Method for the Introduction of Bulky Imide Substituents to Control Packing and Optical Properties of Naphthalene and Perylene Imides JF - Angewandte Chemie International Edition N2 - We report the direct imidization of naphthalene and perylene dicarboxylic anhydrides/esters with bulky ortho,ortho‐diaryl‐ and ortho,ortho‐dialkynylaniline derivatives. This imidization method uses n‐butyllithium as a strong base to increase the reactivity of bulky amine derivatives, proceeds under mild reaction conditions, requires only stoichiometric amounts of reactants and gives straightforward access to new sterically crowded rylene dicarboximides. Mechanistic investigations suggest an isoimide as intermediary product, which was converted to the corresponding imide upon addition of an aqueous base. Single‐crystal X‐ray diffraction analyses reveal dimeric packing motifs for monoimides, while two‐side shielded bisimides crystallize in isolated molecules without close π–π‐interactions. Spectroscopic investigations disclose the influence of the bulky substituents on the optical properties in the solid state. KW - dyes KW - fluorescence KW - imidization KW - perylene imide KW - solid-state emitters Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-218246 VL - 59 IS - 32 SP - 13401 EP - 13405 ER -