@article{KoleKošćakAmaretal.2022, author = {Kole, Goutam Kumar and Košćak, Marta and Amar, Anissa and Majhen, Dragomira and Božinović, Ksenija and Brkljaca, Zlatko and Ferger, Matthias and Michail, Evripidis and Lorenzen, Sabine and Friedrich, Alexandra and Krummenacher, Ivo and Moos, Michael and Braunschweig, Holger and Boucekkine, Abdou and Lambert, Christoph and Halet, Jean-Fran{\c{c}}ois and Piantanida, Ivo and M{\"u}ller-Buschbaum, Klaus and Marder, Todd B.}, title = {Methyl Viologens of Bis-(4'-Pyridylethynyl)Arenes - Structures, Photophysical and Electrochemical Studies, and their Potential Application in Biology}, series = {Chemistry - A European Journal}, volume = {28}, journal = {Chemistry - A European Journal}, number = {40}, doi = {10.1002/chem.202200753}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-287126}, year = {2022}, abstract = {A series of bis-(4'-pyridylethynyl)arenes (arene=benzene, tetrafluorobenzene, and anthracene) were synthesized and their bis-N-methylpyridinium compounds were investigated as a class of π-extended methyl viologens. Their structures were determined by single crystal X-ray diffraction, and their photophysical and electrochemical properties (cyclic voltammetry), as well as their interactions with DNA/RNA were investigated. The dications showed bathochromic shifts in emission compared to the neutral compounds. The neutral compounds showed very small Stokes shifts, which are a little larger for the dications. All of the compounds showed very short fluorescence lifetimes (<4 ns). The neutral compound with an anthracene core has a quantum yield of almost unity. With stronger acceptors, the analogous bis-N-methylpyridinium compound showed a larger two-photon absorption cross-section than its neutral precursor. All of the dicationic compounds interact with DNA/RNA; while the compounds with benzene and tetrafluorobenzene cores bind in the grooves, the one with an anthracene core intercalates as a consequence of its large, condensed aromatic linker moiety, and it aggregates within the polynucleotide when in excess over DNA/RNA. Moreover, all cationic compounds showed highly specific CD spectra upon binding to ds-DNA/RNA, attributed to the rare case of forcing the planar, achiral molecule into a chiral rotamer, and negligible toxicity toward human cell lines at ≤10 μM concentrations. The anthracene-analogue exhibited intracellular accumulation within lysosomes, preventing its interaction with cellular DNA/RNA. However, cytotoxicity was evident at 1 μM concentration upon exposure to light, due to singlet oxygen generation within cells. These multi-faceted features, in combination with its two-photon absorption properties, suggest it to be a promising lead compound for development of novel light-activated theranostic agents.}, language = {en} } @article{GriesbeckMichailRauchetal.2019, author = {Griesbeck, Stefanie and Michail, Evripidis and Rauch, Florian and Ogasawara, Hiroaki and Wang, Chenguang and Sato, Yoshikatsu and Edkins, Robert M. and Zhang, Zuolun and Taki, Masayasu and Lambert, Christoph and Yamaguchi, Shigehiro and Marder, Todd B.}, title = {The Effect of Branching on the One- and Two-Photon Absorption, Cell Viability, and Localization of Cationic Triarylborane Chromophores with Dipolar versus Octupolar Charge Distributions for Cellular Imaging}, series = {Chemistry - A European Journal}, volume = {25}, journal = {Chemistry - A European Journal}, number = {57}, doi = {10.1002/chem.201902461}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212887}, pages = {13164 -- 13175}, year = {2019}, abstract = {Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two-photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two-photon excited fluorescence (TPEF) live-cell imaging.}, language = {en} } @phdthesis{Michail2021, author = {Michail, Evripidis}, title = {Design and Development of a Two-Photon Absorption Induced Fluorescence Spectrometer and the Investigation of Nonlinear Optical Properties of Organic Chromophores}, doi = {10.25972/OPUS-24218}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-242185}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Main objectives of the present dissertation can be divided in two parts. The first part deals with setting up a spectroscopic technique for reliable and accurate measurements of the two-photon absorption (2PA) cross section spectra. In the second part, this firmly established experimental technique together with conventional spectroscopic characterization, quantum-chemical computations and theoretical modelling calculations was combined and therefore used as a tool to gain information for the so-called structure-property relationship through several molecular compounds.}, subject = {Nonlinear Optical Properties of Organic Materials}, language = {en} } @article{GriesbeckMichailRauchetal.2019, author = {Griesbeck, Stefanie and Michail, Evripidis and Rauch, Florian and Ogasawara, Hiroaki and Wang, Chenguang and Sato, Yoshikatsu and Edkins, Robert M. and Zhang, Zuolun and Taki, Masayasu and Lambert, Christoph and Yamaguchi, Shigehiro and Marder, Todd B.}, title = {The Effect of Branching on One- and Two-Photon Absorption, Cell Viability and Localization of Cationic Triarylborane Chromophores with Dipolar versus Octupolar Charge Distributions for Cellular Imaging}, series = {Chemistry - A European Journal}, volume = {25}, journal = {Chemistry - A European Journal}, number = {57}, doi = {10.1002/chem.201902461}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-204829}, pages = {13164-13175}, year = {2019}, abstract = {Two different chromophores, namely a dipolar and an octupolar system, were prepared and their linear and nonlinear optical properties as well as their bioimaging capabilities were compared. Both contain triphenylamine as the donor and a triarylborane as the acceptor, the latter modified with cationic trimethylammonio groups to provide solubility in aqueous media. The octupolar system exhibits a much higher two-photon brightness, and also better cell viability and enhanced selectivity for lysosomes compared with the dipolar chromophore. Furthermore, both dyes were applied in two-photon excited fluorescence (TPEF) live-cell imaging.}, language = {en} } @article{HattoriMichailSchmiedeletal.2019, author = {Hattori, Yohei and Michail, Evripidis and Schmiedel, Alexander and Moos, Michael and Holzapfel, Marco and Krummenacher, Ivo and Braunschweig, Holger and M{\"u}ller, Ulrich and Pflaum, Jens and Lambert, Christoph}, title = {Luminescent Mono-, Di-, and Tri-radicals: Bridging Polychlorinated Triarylmethyl Radicals by Triarylamines and Triarylboranes}, series = {Chemistry - A European Journal}, volume = {25}, journal = {Chemistry - A European Journal}, number = {68}, doi = {10.1002/chem.201903007}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208162}, pages = {15463-15471}, year = {2019}, abstract = {Up to three polychlorinated pyridyldiphenylmethyl radicals bridged by a triphenylamine carrying electron withdrawing (CN), neutral (Me), or donating (OMe) groups were synthesized and analogous radicals bridged by tris(2,6-dimethylphenyl)borane were prepared for comparison. All compounds were as stable as common closed-shell organic compounds and showed significant fluorescence upon excitation. Electronic, magnetic, absorption, and emission properties were examined in detail, and experimental results were interpreted using DFT calculations. Oxidation potentials, absorption and emission energies could be tuned depending on the electron density of the bridges. The triphenylamine bridges mediated intramolecular weak antiferromagnetic interactions between the radical spins, and the energy difference between the high spin and low spin states was determined by temperature dependent ESR spectroscopy and DFT calculations. The fluorescent properties of all radicals were examined in detail and revealed no difference for high and low spin states which facilitates application of these dyes in two-photon absorption spectroscopy and OLED devices.}, language = {en} } @article{ZhangMichailSaaletal.2019, author = {Zhang, Fangyuan and Michail, Evripidis and Saal, Fridolin and Krause, Ana-Maria and Ravat, Prince}, title = {Stereospecific Synthesis and Photophysical Properties of Propeller-Shaped C\(_{90}\)H\(_{48}\) PAH}, series = {Chemistry - A European Journal}, volume = {25}, journal = {Chemistry - A European Journal}, number = {71}, doi = {10.1002/chem.201904962}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-208682}, pages = {16241-16245}, year = {2019}, abstract = {Herein, we have synthesized an enantiomerically pure propeller-shaped PAH, C\(_{90}\)H\(_{48}\), possessing three [7]helicene and three [5]helicene subunits. This compound can be obtained in gram quantities in a straightforward manner. The photophysical and chiroptical properties were investigated using UV/Vis absorption and emission, optical rotation and circular dichroism spectroscopy, supported by DFT calculations. The nonlinear optical properties were investigated by two-photon absorption measurements using linearly and circularly polarized light. The extremely twisted structure and packing of the homochiral compound were investigated by single-crystal X-ray diffraction analysis.}, language = {en} }