TY - JOUR A1 - Schäfer, Natalie A1 - Bühler, Michael A1 - Heyer, Lisa A1 - Röhr, Merle I. S. A1 - Beuerle, Florian T1 - Endohedral Hydrogen Bonding Templates the Formation of a Highly Strained Covalent Organic Cage Compound JF - Chemistry—A European Journal N2 - A highly strained covalent organic cage compound was synthesized from hexahydroxy tribenzotriquinacene (TBTQ) and a meta-terphenyl-based diboronic acid with an additional benzoic acid substituent in 2’-position. Usually, a 120° bite angle in the unsubstituted ditopic linker favors the formation of a [4+6] cage assembly. Here, the introduction of the benzoic acid group is shown to lead to a perfectly preorganized circular hydrogen-bonding array in the cavity of a trigonal-bipyramidal [2+3] cage, which energetically overcompensates the additional strain energy caused by the larger mismatch in bite angles for the smaller assembly. The strained cage compound was analyzed by mass spectrometry and \(^{1}\)H, \(^{13}\)C and DOSY NMR spectroscopy. DFT calculations revealed the energetic contribution of the hydrogen-bonding template to the cage stability. Furthermore, molecular dynamics simulations on early intermediates indicate an additional kinetic effect, as hydrogen bonding also preorganizes and rigidifies small oligomers to facilitate the exclusive formation of smaller and more strained macrocycles and cages. KW - boronate esters KW - hydrogen bonding KW - dynamic covalent chemistry KW - density functional calculations KW - cage compounds Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256762 VL - 27 IS - 19 ER - TY - INPR A1 - Sednev, Maksim V. A1 - Liaqat, Anam A1 - Höbartner, Claudia T1 - High-Throughput Activity Profiling of RNA-Cleaving DNA Catalysts by Deoxyribozyme Sequencing (DZ-seq) T2 - Journal of the American Chemical Society N2 - RNA-cleaving deoxyribozymes have found broad application as useful tools for RNA biochemistry. However, tedious in vitro selection procedures combined with laborious characterization of individual candidate catalysts hinder the discovery of novel catalytic motifs. Here, we present a new high-throughput sequencing method, DZ-seq, which directly measures activity and localizes cleavage sites of thousands of deoxyribozymes. DZ-seq exploits A-tailing followed by reverse transcription with an oligo-dT primer to capture the cleavage status and sequences of both deoxyribozyme and RNA substrate. We validated DZ-seq by conventional analytical methods and demonstrated its utility by discovery of novel deoxyribozymes that allow for cleaving challenging RNA targets or the analysis of RNA modification states. KW - RNA-Cleaving Deoxyribozymes KW - High-Throughput Sequencing Method, DZ-seq KW - Analysis of RNA Modifications Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-258520 ER - TY - JOUR A1 - Schulz, Alexander A1 - Würthner, Frank T1 - Folding-induced fluorescence enhancement in a series of merocyanine hetero-folda-trimers JF - Angewandte Chemie International Edition N2 - Many dyes suffer from fast non-radiative decay pathways, thereby showing only short-lived excited states and weak photoluminescence. Here we show a pronounced fluorescence enhancement for a weakly fluorescent merocyanine (MC) dye by being co-facially stacked to other dyes in hetero-folda-trimer architectures. By means of fluorescence spectroscopy (lifetime, quantum yield) the fluorescence enhancement was explained by the rigidification of the emitting chromophore in the defined foldamer architecture and the presence of a non-forbidden lowest exciton state in H-coupled hetero-aggregates. This folding-induced fluorescence enhancement (FIFE) for specific sequences of π-stacked dyes points at a viable strategy toward improved fluorophores that relates to the approach used by nature in the green fluorescent protein (GFP). KW - organic chemistry KW - merocyanines KW - aggregation KW - dyes/pigments KW - fluorescence KW - folding Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256582 VL - 61 IS - 2 ER - TY - JOUR A1 - Zhang, Fangyuan A1 - Radacki, Krzysztof A1 - Braunschweig, Holger A1 - Lambert, Christoph A1 - Ravat, Prince T1 - Zinc-[7]helicenocyanine and its discrete π-stacked homochiral Dimer JF - Angewandte Chemie International Edition N2 - In this communication, we demonstrate a novel approach to prepare a discrete dimer of chiral phthalocyanine (Pc) by exploiting the flexible molecular geometry of helicenes, which enables structural interlocking and strong aggregation tendency of Pcs. Synthesized [7]helicene-Pc hybrid molecular structure, zinc-[7]helicenocyanine (Zn-7HPc), exclusively forms a stable dimeric pair consisting of two homochiral molecules. The dimerization constants were estimated to be as high as 8.96×10\(^6\) M\(^{−1}\) and 3.42×107 M\(^{−1}\) in THF and DMSO, respectively, indicating remarkable stability of dimer. In addition, Zn\(^{-7}\)HPc exhibited chiral self-sorting behavior, which resulted in preferential formation of a homochiral dimer also in the racemic sample. Two phthalocyanine subunits in the dimeric form strongly communicate with each other as revealed by a large comproportionation constant and observation of an IV-CT band for the thermodynamically stable mixed-valence state. KW - organic chemistry KW - supramolecular assembly KW - chirality KW - helicenes KW - homochiral dimer KW - phthalocyanines Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256534 VL - 60 ER - TY - JOUR A1 - Bold, Kevin A1 - Stolte, Matthias A1 - Shoyama, Kazutaka A1 - Holzapfel, Marco A1 - Schmiedel, Alexander A1 - Lambert, Christoph A1 - Würthner, Frank T1 - Macrocyclic donor-acceptor dyads composed of a perylene bisimide dye surrounded by oligothiophene bridges JF - Angewandte Chemie Internationale Edition N2 - Two macrocyclic architectures comprising oligothiophene strands that connect the imide positions of a perylene bisimide (PBI) dye have been synthesized via a platinum-mediated cross-coupling strategy. The crystal structure of the double bridged PBI reveals all syn-arranged thiophene units that completely enclose the planar PBI chromophore via a 12-membered macrocycle. The target structures were characterized by steady-state UV/Vis absorption, fluorescence and transient absorption spectroscopy, as well as cyclic and differential pulse voltammetry. Both donor–acceptor dyads show ultrafast Förster Resonance Energy Transfer and photoinduced electron transfer, thereby leading to extremely low fluorescence quantum yields even in the lowest polarity cyclohexane solvent. KW - organic chemistry KW - photoinduced electron transfer KW - donor–acceptor dyads KW - macrocycles KW - oligothiophenes KW - perylenebisimide Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256569 VL - 61 IS - 1 ER - TY - JOUR A1 - Ivanova, Svetlana A1 - Köster, Eva A1 - Holstein, Julian J. A1 - Keller, Niklas A1 - Clever, Guido H. A1 - Bein, Thomas A1 - Beuerle, Florian T1 - Isoreticular crystallization of highly porous cubic covalent organic cage compounds JF - Angewandte Chemie International Edition N2 - Modular frameworks featuring well-defined pore structures in microscale domains establish tailor-made porous materials. For open molecular solids however, maintaining long-range order after desolvation is inherently challenging, since packing is usually governed by only a few supramolecular interactions. Here we report on two series of nanocubes obtained by co-condensation of two different hexahydroxy tribenzotriquinacenes (TBTQs) and benzene-1,4-diboronic acids (BDBAs) with varying linear alkyl chains in 2,5-position. n-Butyl groups at the apical position of the TBTQ vertices yielded soluble model compounds, which were analyzed by mass spectrometry and NMR spectroscopy. In contrast, methyl-substituted cages spontaneously crystallized as isostructural and highly porous solids with BET surface areas and pore volumes of up to 3426 m\(^2\) g\(^{-1}\) and 1.84 cm\(^3\) g\(^{-1}\). Single crystal X-ray diffraction and sorption measurements revealed an intricate cubic arrangement of alternating micro- and mesopores in the range of 0.97–2.2 nm that are fine-tuned by the alkyl substituents at the BDBA linker. KW - organic chemistry KW - structure elucidation KW - boronateesters KW - cage compounds KW - dynamic covalent chemistry KW - porousmaterials Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256462 VL - 60 IS - 32 ER - TY - JOUR A1 - Liaqat, Anam A1 - Sednev, Maksim V. A1 - Stiller, Carina A1 - Höbartner, Claudia T1 - RNA-cleaving deoxyribozymes differentiate methylated cytidine isomers in RNA JF - Angewandte Chemie International Edition N2 - Deoxyribozymes are emerging as modification-specific endonucleases for the analysis of epigenetic RNA modifications. Here, we report RNA-cleaving deoxyribozymes that differentially respond to the presence of natural methylated cytidines, 3-methylcytidine (m\(^3\)C), N\(^4\)-methylcytidine (m\(^4\)C), and 5-methylcytidine (m\(^5\)C), respectively. Using in vitro selection, we found several DNA catalysts, which are selectively activated by only one of the three cytidine isomers, and display 10- to 30-fold accelerated cleavage of their target m\(^3\)C-, m\(^4\)C- or m\(^5\)C-modified RNA. An additional deoxyribozyme is strongly inhibited by any of the three methylcytidines, but effectively cleaves unmodified RNA. The mXC-detecting deoxyribozymes are programmable for the interrogation of natural RNAs of interest, as demonstrated for human mitochondrial tRNAs containing known m\(^3\)C and m\(^5\)C sites. The results underline the potential of synthetic functional DNA to shape highly selective active sites. KW - organic chemistry KW - site-specific RNA cleavage KW - deoxyribozymes KW - epitranscriptomics KW - in vitro selection KW - RNA modification Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256519 VL - 60 ER - TY - JOUR A1 - Shen, Chia-An A1 - Bialas, David A1 - Hecht, Markus A1 - Stepanenko, Vladimir A1 - Sugiyasu, Kazunori A1 - Würthner, Frank T1 - Polymorphism in squaraine dye aggregates by self-assembly pathway differentiation: panchromatic tubular dye nanorods versus J-aggregate nanosheets JF - Angewandte Chemie International Edition N2 - A bis(squaraine) dye equipped with alkyl and oligoethyleneglycol chains was synthesized by connecting two dicyanomethylene substituted squaraine dyes with a phenylene spacer unit. The aggregation behavior of this bis(squaraine) was investigated in non-polar toluene/tetrachloroethane (98:2) solvent mixture, which revealed competing cooperative self-assembly pathways into two supramolecular polymorphs with entirely different packing structures and UV/Vis/NIR absorption properties. The self-assembly pathway can be controlled by the cooling rate from a heated solution of the monomers. For both polymorphs, quasi-equilibrium conditions between monomers and the respective aggregates can be established to derive thermodynamic parameters and insights into the self-assembly mechanisms. AFM measurements revealed a nanosheet structure with a height of 2 nm for the thermodynamically more stable polymorph and a tubular nanorod structure with a helical pitch of 13 nm and a diameter of 5 nm for the kinetically favored polymorph. Together with wide angle X-ray scattering measurements, packing models were derived: the thermodynamic polymorph consists of brick-work type nanosheets that exhibit red-shifted absorption bands as typical for J-aggregates, while the nanorod polymorph consists of eight supramolecular polymer strands of the bis(squaraine) intertwined to form a chimney-type tubular structure. The absorption of this aggregate covers a large spectral range from 550 to 875 nm, which cannot be rationalized by the conventional exciton theory. By applying the Essential States Model and considering intermolecular charge transfer, the aggregate spectrum was adequately reproduced, revealing that the broad absorption spectrum is due to pronounced donor-acceptor overlap within the bis(squaraine) nanorods. The latter is also responsible for the pronounced bathochromic shift observed for the nanosheet structure as a result of the slip-stacked arranged squaraine chromophores. KW - organic chemistry KW - supramolecular polymers KW - nanorods and nanosheets KW - polymorphism KW - squaraine dyes KW - cooperative self-assembly Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256443 IS - 21 ET - 60 ER - TY - THES A1 - Turkin, Arthur T1 - Vom Monomer zum Polymer: Iterative Synthese und optische Spektroskopie von Squarain-Oligomeren T1 - From Monomer to Polymer: Iterative Synthesis and Optical Spectroscopy of Squaraine-Oligomers N2 - Mittels einer Schutzgruppenstrategie wurden Squarain-basierte monodisperse Oligomere synthetisiert. Die lösungsmittelabhängigen Konformationen (Random Coil vs. Helix) wie auch der Faltungsprozess der Homooligomere wurden mittels optischer Spektroskopie, verschiedener NMR-Experimenten, Kleinwinkelneutronenstreuungsexperimenten sowie quantenchemischen Berechnungen näher beleuchtet. Die optisch-spektroskopischen Beobachtungen wurden mithilfe der Exzitonenkopplungstheorie und einer Orientierungs- und Winkelabhängigkeit der Übergangsdipolmomente der Oligomere erklärt. Der hohe Windungsabstand der helikalen Konformation führt zu einer Interkalation von Lösungsmittel, wodurch eine Art Klathrat gebildet wird. Zusätzlich wurden mittels eines Frenkel-Exzitonenmodells die Absorptions- und Fluoreszenzspektren modelliert. Es konnten die Exzitonendelokalisationslängen abgeschätzt und die Auswirkung der energetischen und strukturellen Unordnungen auf die Absorptions- und Fluoreszenzspektren bestimmt werden. Die Absorptionsspektren werden vorwiegend durch strukturelle Unordnungen verbreitert, die Fluoreszenzspektren dagegen von energetischen Übergangsenergieabweichungen. Weiterhin wurden auch alternierende Squarain-Cooligomere synthetisiert und mittels optischer Spektroskopie untersucht. Es wurde, abhängig von dem gewählten Lösungsmittel, eine Verschiebung der Hauptbande beobachtet, was durch einen Random Coil vs. helikale-/schlaufenartige Konformation erklärt wird. Gestützt wurde dies mittels quantenchemischen Berechnungen der jeweiligen Konformationen. Abschließend wurden alternierende Squarain-Copolymere synthetisiert, in verschiedenen Größen aufgetrennt und mittels optischer Spektroskopie untersucht. Mittels EEI2D-Experimenten wurde die Exzitonendynamik in Abhängigkeit von der Kettenlänge eingehender untersucht. Hierbei wird eine steigende, aber relativ abnehmende Kohärenzlänge bestimmt, die Auswirkungen auf die Exzitonendynamik hat. Der Exzitonentransport weist erst wellenförmiges und dann subdiffuses Verhalten auf. N2 - A protecting group strategy was employed to synthesise squaraine-based monodisperse oligomers. The solvent-dependent conformations (random coil vs. helix) as well as the folding process of the homooligomers were examined in more detail using optical spectroscopy, various NMR experiments, small-angle neutron scattering experiments, and quantum chemical calculations. The optical-spectroscopic observations were explained using exciton coupling theory and an orientation and angle dependence of the transition dipole moments of the oligomers. The high pitch of the helical conformation leads to solvent intercalation, thereby forming a type of clathrate. In addition, the absorption and fluorescence spectra were modeled using a Frenkel exciton model. The exciton delocalization lengths were estimated and the effect of the energetic and structural disorders on the absorption and fluorescence spectra were determined. The absorption spectra are mainly broadened by structural disorder, while the fluorescence spectra are broadened by energetic transition energy deviations. Alternating squaraine cooligomers were also synthesised and analysed by optical spectroscopy. Depending on the chosen solvent, a shift of the main band was observed, which is explained by a random coil vs. helical/loop-like conformation. This was supported by quantum chemical calculations of the respective conformations. Finally, alternating squaraine copolymers were synthesised, separated into different sizes and analysed by optical spectroscopy. Exciton dynamics as a function of chain length were investigated in more detail using EEI2D experiments. Here, an increasing but relatively decreasing coherence length was determined, which affects the exciton dynamics. The exciton transport shows wavelike and then sub-diffusive behaviour. KW - Squarain KW - Oligomere KW - Polymere KW - Helix-Knäuel-Umwandlung KW - Chemische Synthese KW - Optische Spektroskopie KW - Squarain-Farbstoff KW - Helix-Knäuel-Umwandlung KW - J- and H-Aggregate KW - Optical Spectroscopy KW - Squaraine-Dye KW - J- and H-Aggregates KW - Helix-Coil-Transition Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-257950 ER - TY - JOUR A1 - Kim, Jin Hong A1 - Liess, Andreas A1 - Stolte, Matthias A1 - Krause, Ana-Maria A1 - Stepanenko, Vladimir A1 - Zhong, Chuwei A1 - Bialas, David A1 - Spano, Frank A1 - Würthner, Frank T1 - An Efficient Narrowband Near-Infrared at 1040 nm Organic Photodetector Realized by Intermolecular Charge Transfer Mediated Coupling Based on a Squaraine Dye JF - Advanced Materials N2 - A highly sensitive short-wave infrared (SWIR, λ > 1000 nm) organic photodiode (OPD) is described based on a well-organized nanocrystalline bulk-heterojunction (BHJ) active layer composed of a dicyanovinyl-functionalized squaraine dye (SQ-H) donor material in combination with PC\(_{61}\)BM. Through thermal annealing, dipolar SQ-H chromophores self-assemble in a nanoscale structure with intermolecular charge transfer mediated coupling, resulting in a redshifted and narrow absorption band at 1040 nm as well as enhanced charge carrier mobility. The optimized OPD exhibits an external quantum efficiency (EQE) of 12.3% and a full-width at half-maximum of only 85 nm (815 cm\(^{-1}\)) at 1050 nm under 0 V, which is the first efficient SWIR OPD based on J-type aggregates. Photoplethysmography application for heart-rate monitoring is successfully demonstrated on flexible substrates without applying reverse bias, indicating the potential of OPDs based on short-range coupled dye aggregates for low-power operating wearable applications. KW - squaraine dyes KW - crystal engineering KW - J-aggregates KW - near-infrared sensitivity KW - organic photodiodes Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256374 VL - 33 IS - 26 ER -