TY - THES A1 - Krebs, Johannes Heinrich T1 - Investigation of Dicarba-closo-dodecaborane as a Substituent on Three-coordinate Boron and as an Acceptor in a Pyrene-Donor-Acceptor System T1 - Untersuchung von Dicarba-closo-dodecaboran als Substituent an dreifach koordiniertem Bor und als Akzeptor in einem Pyren-Donor-Akzeptor-System N2 - 1. Bis(1-(4-tolyl)-carboran-2-yl)-(4-tolyl)-borane, a new bis(o-carboranyl)-(R)-borane 1 was synthesised by lithiation of the o-carboranyl precursor and subsequent salt metathesis reaction with (4-tolyl)BBr2. Cyclic voltammetry experiments on 1 show multiple distinct reduction events with a one-electron first reduction. In a selective reduction experiment the corresponding paramagnetic radical anion 1•− was isolated and characterized. Single-crystal structure analyses allow an in-depth comparison of 1, 1•−, their calculated geometries, and the S1 excited state of 1. 2. The choice of backbone linker for ortho-bis-(9-borafluorene)s has a great influence on the LUMO located at the boron centers and therefore the reactivity of the respective compounds. Herein, we report the room temperature rearrangement of 1,2-bis-(9-borafluorenyl-)-ortho-carborane, C2B10H10-1,2-[B(C12H8)]2 ([2a]) featuring o-carborane as the inorganic three-dimensional backbone and the synthesis of 1,2-bis-(9-borafluorenyl-)benzene, C6H4-1,2-[B(C12H8)]2 (2b) its phenylene analog. DFT calculations on the transition state for the rearrangement support an intramolecular C–H bond activation process via an SEAr-like mechanism in [2a], and predicted that the same rearrangement would take place in 2b, but at elevated temperatures, which indeed proved to be the case. 3. We synthesized 4 a julolidine-like pyrenyl-o-carborane, with pyrene substituted at the 2,7-positions on the HOMO/LUMO nodal plane, continuing our research. Using solid state molecular structures, photophysical data, cyclic voltammetry, DFT and TD-DFT calculations we compare o-carborane and the B(mes)2 (mes = 2,4,6-Me3C6H2) as acceptor groups and confirm the julolidine-like donor strength. N2 - 1. Bis(1-(4-tolyl)-carboran-2-yl)-(4-tolyl)-boran, ein neues Bis(o-carboranyl)-(R)-boran 1 wurde durch Lithiierung des o-Carboranyl-Vorläufers und anschließende Salzmetathesereaktion mit (4-tolyl)BBr2 synthetisiert. Zyklische Voltammetrie-Experimente an 1 zeigen mehrere unterschiedliche Reduktionsereignisse mit einer ersten Reduktion mit einem Elektron. In einem selektiven Reduktionsexperiment wurde das entsprechende paramagnetische Radikalanion 1-- isoliert und charakterisiert. Einkristallstrukturanalysen ermöglichen einen eingehenden Vergleich von 1, 1--, ihren berechneten Geometrien und dem angeregten S1-Zustand von 1. 2. Die Wahl des Backbone-Linkers für ortho-bis-(9-Borafluoren)s hat einen großen Einfluss auf das LUMO an den Bor-Zentren und damit auf die Reaktivität der jeweiligen Verbindungen. In diesem Artikel berichten wir über die Raumtemperatur-Umlagerung von 1,2-Bis-(9-borafluorenyl-)-ortho-Carboran, C2B10H10-1,2-[B(C12H8)]2 ([2a]) mit o-Carboran als anorganisches dreidimensionales Rückgrat und die Synthese von 1,2-Bis-(9-borafluorenyl-)benzol, C6H4-1,2-[B(C12H8)]2 (2b), dessen Phenylenanalogon. DFT-Berechnungen des Übergangszustands für die Umlagerung unterstützen einen intramolekularen C-H-Bindungsaktivierungsprozess über einen SEAr-ähnlichen Mechanismus in [2a] und sagten voraus, dass dieselbe Umlagerung in 2b stattfinden würde, allerdings bei höheren Temperaturen, was sich tatsächlich als der Fall erwies. 3. Wir synthetisierten 4 ein Julolidin-ähnliches Pyrenyl-o-Carboran, bei dem Pyren an den 2,7-Positionen auf der HOMO/LUMO-Knotenebene substituiert ist, und setzten damit unsere Forschung fort. Unter Verwendung von Festkörper-Molekülstrukturen, photophysikalischen Daten, zyklischer Voltammetrie, DFT- und TD-DFT-Berechnungen vergleichen wir o-Carboran und B(mes)2 (mes = 2,4,6-Me3C6H2) als Akzeptorgruppen und bestätigen die Julolidin-ähnliche Donorstärke. KW - closo-Borane KW - Dodecaborane KW - Borane KW - Radikal KW - o-carborane KW - three-coordinate borane KW - radical KW - 2n+3 KW - DFT KW - singe crystal KW - 9-borafluorene KW - pyrene Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-286758 ER - TY - JOUR A1 - Merz, Viktor A1 - Merz, Julia A1 - Kirchner, Maximilian A1 - Lenhart, Julian A1 - Marder, Todd B. A1 - Krueger, Anke T1 - Pyrene-Based "Turn-Off" Probe with Broad Detection Range for Cu\(^{2+}\), Pb\(^{2+}\) and Hg\(^{2+}\) Ions JF - Chemistry—A European Journal N2 - Detection of metals in different environments with high selectivity and specificity is one of the prerequisites of the fight against environmental pollution with these elements. Pyrenes are well suited for the fluorescence sensing in different media. The applied sensing principle typically relies on the formation of intra- and intermolecular excimers, which is however limiting the sensitivity range due to masking of e. g. quenching effects by the excimer emission. Herein we report a highly selective, structurally rigid chemical sensor based on the monomer fluorescence of pyrene moieties bearing triazole groups. This sensor can quantitatively detect Cu\(^{2+}\), Pb\(^{2+}\) and Hg\(^{2+}\) in organic solvents over a broad concentrations range, even in the presence of ubiquitous ions such as Na\(^{+}\), K\(^{+}\), Ca\(^{2+}\) and Mg\(^{2+}\). The strongly emissive sensor's fluorescence with a long lifetime of 165 ns is quenched by a 1 : 1 complex formation upon addition of metal ions in acetonitrile. Upon addition of a tenfold excess of the metal ion to the sensor, agglomerates with a diameter of about 3 nm are formed. Due to complex interactions in the system, conventional linear correlations are not observed for all concentrations. Therefore, a critical comparison between the conventional Job plot interpretation, the method of Benesi-Hildebrand, and a non-linear fit is presented. The reported system enables the specific and robust sensing of medically and environmentally relevant ions in the health-relevant nM range and could be used e. g. for the monitoring of the respective ions in waste streams. KW - probes KW - fluorescence spectroscopy KW - pyrene KW - heavy metals KW - luminescence Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256803 VL - 27 IS - 31 ER - TY - JOUR A1 - Ban, Željka A1 - Karačić, Zrinka A1 - Tomić, Sanja A1 - Amini, Hashem A1 - Marder, Todd B. A1 - Piantanida, Ivo T1 - Triarylborane dyes as a novel non-covalent and non-inhibitive fluorimetric markers for DPP III enzyme JF - Molecules N2 - Novel dyes were prepared by simple “click CuAAC” attachment of a triarylborane–alkyne to the azide side chain of an amino acid yielding triarylborane dye 1 which was conjugated with pyrene (dye 2) forming a triarylborane–pyrene FRET pair. In contrast to previous cationic triarylboranes, the novel neutral dyes interact only with proteins, while their affinity to DNA/RNA is completely abolished. Both the reference triarylborane amino acid and triarylborane–pyrene conjugate bind to BSA and the hDPP III enzyme with high affinities, exhibiting a strong (up to 100-fold) fluorescence increase, whereby the triarylborane–pyrene conjugate additionally retained FRET upon binding to the protein. Furthermore, the triarylborane dyes, upon binding to the hDPP III enzyme, did not impair its enzymatic activity under a wide range of experimental conditions, thus being the first non-covalent fluorimetric markers for hDPP III, also applicable during enzymatic reactions with hDPP III substrates. KW - triarylborane KW - pyrene KW - click CuAAC synthesis KW - DPP III enzyme KW - BSA KW - fluorescence Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-245046 SN - 1420-3049 VL - 26 IS - 16 ER -