@article{WuDinkelbachKerneretal.2022, author = {Wu, Zhu and Dinkelbach, Fabian and Kerner, Florian and Friedrich, Alexandra and Ji, Lei and Stepanenko, Vladimir and W{\"u}rthner, Frank and Marian, Christel M. and Marder, Todd B.}, title = {Aggregation-Induced Dual Phosphorescence from (o-Bromophenyl)-Bis(2,6-Dimethylphenyl)Borane at Room Temperature}, series = {Chemistry—A European Journal}, volume = {28}, journal = {Chemistry—A European Journal}, number = {30}, doi = {10.1002/chem.202200525}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318297}, year = {2022}, abstract = {Designing highly efficient purely organic phosphors at room temperature remains a challenge because of fast non-radiative processes and slow intersystem crossing (ISC) rates. The majority of them emit only single component phosphorescence. Herein, we have prepared 3 isomers (o, m, p-bromophenyl)-bis(2,6-dimethylphenyl)boranes. Among the 3 isomers (o-, m- and p-BrTAB) synthesized, the ortho-one is the only one which shows dual phosphorescence, with a short lifetime of 0.8 ms and a long lifetime of 234 ms in the crystalline state at room temperature. Based on theoretical calculations and crystal structure analysis of o-BrTAB, the short lifetime component is ascribed to the T\(^M_1\) state of the monomer which emits the higher energy phosphorescence. The long-lived, lower energy phosphorescence emission is attributed to the T\(^A_1\) state of an aggregate, with multiple intermolecular interactions existing in crystalline o-BrTAB inhibiting nonradiative decay and stabilizing the triplet states efficiently.}, language = {en} } @article{BergerRueheSchwarzmannetal.2021, author = {Berger, Sarina M. and R{\"u}he, Jessica and Schwarzmann, Johannes and Phillipps, Alexandra and Richard, Ann-Katrin and Ferger, Matthias and Krummenacher, Ivo and Tumir, Lidija-Marija and Ban, Željka and Crnolatac, Ivo and Majhen, Dragomira and Barišić, Ivan and Piantanida, Ivo and Schleier, Domenik and Griesbeck, Stefanie and Friedrich, Alexandra and Braunschweig, Holger and Marder, Todd B.}, title = {Bithiophene-Cored, mono-, bis-, and tris-(Trimethylammonium)-Substituted, bis-Triarylborane Chromophores: Effect of the Number and Position of Charges on Cell Imaging and DNA/RNA Sensing}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {56}, doi = {10.1002/chem.202102308}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256963}, pages = {14057-14072}, year = {2021}, abstract = {The synthesis, photophysical, and electrochemical properties of selectively mono-, bis- and tris-dimethylamino- and trimethylammonium-substituted bis-triarylborane bithiophene chromophores are presented along with the water solubility and singlet oxygen sensitizing efficiency of the cationic compounds Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\). Comparison with the mono-triarylboranes reveals the large influence of the bridging unit on the properties of the bis-triarylboranes, especially those of the cationic compounds. Based on these preliminary investigations, the interactions of Cat\(^{1+}\), Cat\(^{2+}\), Cat(i)\(^{2+}\), and Cat\(^{3+}\) with DNA, RNA, and DNApore were investigated in buffered solutions. The same compounds were investigated for their ability to enter and localize within organelles of human lung carcinoma (A549) and normal lung (WI38) cells showing that not only the number of charges but also their distribution over the chromophore influences interactions and staining properties.}, language = {en} } @article{MerzMerzKirchneretal.2021, author = {Merz, Viktor and Merz, Julia and Kirchner, Maximilian and Lenhart, Julian and Marder, Todd B. and Krueger, Anke}, title = {Pyrene-Based "Turn-Off" Probe with Broad Detection Range for Cu\(^{2+}\), Pb\(^{2+}\) and Hg\(^{2+}\) Ions}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {31}, doi = {10.1002/chem.202100594}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256803}, pages = {8118-8126}, year = {2021}, abstract = {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.}, language = {en} } @article{ChenMengLiaoetal.2021, author = {Chen, Xing and Meng, Guoyun and Liao, Guanming and Rauch, Florian and He, Jiang and Friedrich, Alexandra and Marder, Todd B. and Wang, Nan and Chen, Pangkuan and Wang, Suning and Yin, Xiaodong}, title = {Highly Emissive 9-Borafluorene Derivatives: Synthesis, Photophysical Properties and Device Fabrication}, series = {Chemistry—A European Journal}, volume = {27}, journal = {Chemistry—A European Journal}, number = {20}, doi = {10.1002/chem.202005185}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256738}, pages = {6274-6282}, year = {2021}, abstract = {A series of 9-borafluorene derivatives, functionalised with electron-donating groups, have been prepared. Some of these 9-borafluorene compounds exhibit strong yellowish emission in solution and in the solid state with relatively high quantum yields (up to 73.6 \% for FMesB-Cz as a neat film). The results suggest that the highly twisted donor groups suppress charge transfer, but the intrinsic photophysical properties of the 9-borafluorene systems remain. The new compounds showed enhanced stability towards the atmosphere, and exhibited excellent thermal stability, revealing their potential for application in materials science. Organic light-emitting diode (OLED) devices were fabricated with two of the highly emissive compounds, and they exhibited strong yellow-greenish electroluminescence, with a maximum luminance intensity of >22 000 cd m\(^{-2}\). These are the first two examples of 9-borafluorene derivatives being used as light-emitting materials in OLED devices, and they have enabled us to achieve a balance between maintaining their intrinsic properties while improving their stability.}, language = {en} } @article{WuNitschMarder2021, author = {Wu, Zhu and Nitsch, J{\"o}rn and Marder, Todd B.}, title = {Persistent room-temperature phosphorence from purely organic molecules and multi-component systems}, series = {Advanced Optical Materials}, volume = {9}, journal = {Advanced Optical Materials}, number = {20}, doi = {doi.org/10.1002/adom.202100411}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-256415}, year = {2021}, abstract = {Recently, luminophores showing efficient room-temperature phosphorescence (RTP) have gained tremendous interest due to their numerous applications. However, most phosphors are derived from transition metal complexes because of their intrinsic fast intersystem crossing (ISC) induced by strong spin-orbit coupling (SOC) constants of the heavy metal. Metal-free RTP materials are rare and have become a promising field because they are inexpensive and environmentally friendly. This review summarizes organic molecular materials with long triplet lifetimes at room temperature from the perspective of whether they stem from a molecular or multi-component system. Among purely organic phosphors, heteroatoms are usually introduced into the backbone in order to boost the singlet-triplet ISC rate constant. In multi-component systems, useful strategies such as host-guest, polymer matrix, copolymerization, and supramolecular assembly provide a rigid matrix to restrict nonradiative pathways thus realizing ultralong RTP.}, language = {en} } @article{ZottnickSprengerFinzeetal.2021, author = {Zottnick, Sven H. and Sprenger, Jan A. P. and Finze, Maik and M{\"u}ller-Buschbaum, Klaus}, title = {Statistic Replacement of Lanthanide Ions in Bis-salicylatoborate Coordination Polymers for the Deliberate Control of the Luminescence Chromaticity}, series = {ChemistryOpen}, volume = {10}, journal = {ChemistryOpen}, number = {2}, doi = {10.1002/open.202000251}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-239953}, pages = {164 -- 170}, year = {2021}, abstract = {Based on the strand-like coordination polymer (CP) type \(^{1}\)\(_{∞}\)[Ln(BSB)\(_{3}\)(py)\(_{2}\)], [BSB]-=bis-salicylatoborate anion, mixed Eu/Tb-containing compounds of the constitution \(^{1}\)\(_{∞}\)[Eu\(_{x}\)Tb\(_{1-x}\)(BSB)\(_{3}\)(py)\(_{2}\)] were synthesised ionothermally for a phase width of (x=0.25-0.75) and characterized regarding structure and optical properties. Previously, known only for other lanthanides, the mixed 1D-Eu/Tb-CPs show excellent options for statistic replacement of the Ln-cations during synthesis yielding solid solutions. The products are highly luminescent, with the chromaticity being a direct function of the amount of the respective Ln-ions. Corresponding to an overall addition of emission intensities, the green Tb\(^{3+}\) emission and the red Eu\(^{3+}\) emission allow for a chromaticity control that also includes yellow emission. Control of the luminescence colour renders them suitable examples of the versatility of statistic replacement of metal ions in coordination chemistry. In addition, crystallization of [EMIm]\(_{2}\)[YCl\(_{5}\)(py)] illuminates possible other products of the ionothermal reactions of [EMIm][BSB] with LnCl\(_{3}\) constituted by components not being part of the main CPs.}, language = {en} } @article{MerzDietrichNitschetal.2020, author = {Merz, Julia and Dietrich, Lena and Nitsch, J{\"o}rn and Krummenacher, Ivo and Braunschweig, Holger and Moos, Michael and Mims, David and Lambert, Christoph and Marder, Todd B.}, title = {Synthesis, Photophysical and Electronic Properties of Mono-, Di-, and Tri-Amino-Substituted Ortho-Perylenes, and Comparison to the Tetra-Substituted Derivative}, series = {Chemistry - A European Journal}, volume = {26}, journal = {Chemistry - A European Journal}, number = {52}, doi = {10.1002/chem.202001475}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-217835}, pages = {12050 -- 12059}, year = {2020}, abstract = {We synthesized a series of new mono-, di-, tri- and tetra-substituted perylene derivatives with strong bis(para-methoxyphenyl)amine (DPA) donors at the uncommon 2,5,8,11-positions. The properties of our new donor-substituted perylenes were studied in detail to establish a structure-property relationship. Interesting trends and unusual properties are observed for this series of new perylene derivatives, such as a decreasing charge transfer (CT) character with increasing number of DPA moieties and individual reversible oxidations for each DPA moiety. Thus, (DPA)-Per possesses one reversible oxidation while (DPA)\(_{4}\)-Per has four. The mono- and di-substituted derivatives display unusually large Stokes shifts not previously reported for perylenes. Furthermore, transient absorption measurements of the new derivatives reveal an excited state with lifetimes of several hundred microseconds, which sensitizes singlet oxygen with quantum yields of up to 0.83.}, language = {en} } @article{RauchEndresFriedrichetal.2020, author = {Rauch, Florian and Endres, Peter and Friedrich, Alexandra and Sieh, Daniel and H{\"a}hnel, Martin and Krummenacher, Ivo and Braunschweig, Holger and Finze, Maik and Ji, Lei and Marder, Todd B.}, title = {An Iterative Divergent Approach to Conjugated Starburst Borane Dendrimers}, series = {Chemistry - A European Journal}, volume = {26}, journal = {Chemistry - A European Journal}, number = {57}, doi = {10.1002/chem.202001985}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-218345}, pages = {12951 -- 12963}, year = {2020}, abstract = {Using a new divergent approach, conjugated triarylborane dendrimers were synthesized up to the 2nd generation. The synthetic strategy consists of three steps: 1) functionalization, via iridium catalyzed C-H borylation; 2) activation, via fluorination of the generated boronate ester with K[HF\(_{2}\)] or [N(nBu\(_{4}\))][HF\(_{2}\)]; and 3) expansion, via reaction of the trifluoroborate salts with aryl Grignard reagents. The concept was also shown to be viable for a convergent approach. All but one of the conjugated borane dendrimers exhibit multiple, distinct and reversible reduction potentials, making them potentially interesting materials for applications in molecular accumulators. Based on their photophysical properties, the 1st generation dendrimers exhibit good conjugation over the whole system. However, the conjugation does not increase further upon expansion to the 2nd generation, but the molar extinction coefficients increase linearly with the number of triarylborane subunits, suggesting a potential application as photonic antennas.}, language = {en} } @article{BelaidiRauchZhangetal.2019, author = {Belaidi, Houmam and Rauch, Florian and Zhang, Zuolun and Latouche, Camille and Boucekkine, Abdou and Marder, Todd B. and Halet, Jean-Francois}, title = {Insights into the optical properties of triarylboranes with strongly electron-accepting bis(fluoromesityl)boryl groups: when theory meets experiment}, series = {ChemPhotoChem}, volume = {4}, journal = {ChemPhotoChem}, number = {3}, doi = {10.1002/cptc.201900256}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-205600}, pages = {173-180}, year = {2019}, abstract = {The photophysical properties (absorption, fluorescence and phosphorescence) of a series of triarylboranes of the form 4-D-C\(_6\)H\(_4\)-B(Ar)\(_2\) (D=\(^t\)Bu or NPh\(_2\); Ar=mesityl (Mes) or 2,4,6-tris(trifluoromethylphenyl (Fmes)) were analyzed theoretically using state-of-the-art DFT and TD-DFT methods. Simulated emission spectra and computed decay rate constants are in very good agreement with the experimental data. Unrestricted electronic computations including vibronic contributions explain the unusual optical behavior of 4-\(^t\)Bu-C\(_6\)H\(_4\)-B(Fmes)\(_2\) 2, which shows both fluorescence and phosphorescence at nearly identical energies (at 77 K in a frozen glass). Analysis of the main normal modes responsible for the phosphorescence vibrational fine structure indicates that the bulky tert-butyl group tethered to the phenyl ring is strongly involved. Interestingly, in THF solvent, the computed energies of the singlet and triplet excited states are very similar for compound 2 only, which may explain why 2 shows phosphorescence in contrast to the other members of the series.}, language = {en} } @article{BanGriesbeckTomićetal.2020, author = {Ban, Željka and Griesbeck, Stefanie and Tomić, Sanja and Nitsch, J{\"o}rn and Marder, Todd B. and Piantanida, Ivo}, title = {A Quadrupolar Bis-Triarylborane Chromophore as a Fluorimetric and Chirooptic Probe for Simultaneous and Selective Sensing of DNA, RNA and Proteins}, series = {Chemistry - A European Journal}, volume = {26}, journal = {Chemistry - A European Journal}, number = {10}, doi = {10.1002/chem.201903936}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208154}, pages = {2195-2203}, year = {2020}, abstract = {A water-soluble tetracationic quadrupolar bis-triarylborane chromophore showed strong binding to ds-DNA, ds-RNA, ss-RNA, as well as to the naturally most abundant protein, BSA. The novel dye can distinguish between DNA/RNA and BSA by fluorescence emission separated by Δv =3600 cm\(^{-1}\), allowing for the simultaneous quantification of DNA/RNA and protein (BSA) in a mixture. The applicability of such fluorimetric differentiation in vitro was demonstrated, strongly supporting a protein-like target as a dominant binding site of 1 in cells. Moreover, our dye also bound strongly to ss-RNA, with the unusual rod-like structure of the dye, decorated by four positive charges at its termini and having a hydrophobic core, acting as a spindle for wrapping A, C and U ss-RNAs, but not poly G, the latter preserving its secondary structure. To the best of our knowledge, such unmatched, multifaceted binding activity of a small molecule toward DNA, RNA, and proteins and the selectivity of its fluorimetric and chirooptic response makes the quadrupolar bis-triarylborane a novel chromophore/fluorophore moiety for biochemical applications.}, language = {en} }