TY  - JOUR
A1  - Kole, Goutam Kumar
A1  - Košćak, Marta
A1  - Amar, Anissa
A1  - Majhen, Dragomira
A1  - Božinović, Ksenija
A1  - Brkljaca, Zlatko
A1  - Ferger, Matthias
A1  - Michail, Evripidis
A1  - Lorenzen, Sabine
A1  - Friedrich, Alexandra
A1  - Krummenacher, Ivo
A1  - Moos, Michael
A1  - Braunschweig, Holger
A1  - Boucekkine, Abdou
A1  - Lambert, Christoph
A1  - Halet, Jean‐François
A1  - Piantanida, Ivo
A1  - Müller‐Buschbaum, Klaus
A1  - Marder, Todd B.
T1  - Methyl Viologens of Bis‐(4’‐Pyridylethynyl)Arenes – Structures, Photophysical and Electrochemical Studies, and their Potential Application in Biology
JF  - Chemistry – A European Journal
N2  - 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.
KW  - cell imaging
KW  - DNA/RNA binding
KW  - methyl viologen
KW  - singlet oxygen
KW  - two-photon absorption
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-287126
VL  - 28
IS  - 40
ER  - 
TY  - JOUR
A1  - Kole, Goutam Kumar
A1  - Merz, Julia
A1  - Amar, Anissa
A1  - Fontaine, Bruno
A1  - Boucekkine, Abdou
A1  - Nitsch, Jörn
A1  - Lorenzen, Sabine
A1  - Friedrich, Alexandra
A1  - Krummenacher, Ivo
A1  - Košćak, Marta
A1  - Braunschweig, Holger
A1  - Piantanida, Ivo
A1  - Halet, Jean-François
A1  - Müller-Buschbaum, Klaus
A1  - Marder, Todd B.
T1  - 2- and 2,7-substituted para-N-methylpyridinium pyrenes: syntheses, molecular and electronic structures, photophysical, electrochemical, and spectroelectrochemical properties and binding to double-stranded (ds) DNA
JF  - Chemistry - A European Journal
N2  - Two N-methylpyridinium compounds and analogous N-protonated salts of 2- and 2,7-substituted 4-pyridyl-pyrene compounds were synthesised and their crystal structures, photophysical properties both in solution and in the solid state, electrochemical and spectroelectrochemical properties were studied. Upon methylation or protonation, the emission maxima are significantly bathochromically shifted compared to the neutral compounds, although the absorption maxima remain almost unchanged. As a result, the cationic compounds show very large apparent Stokes shifts of up to 7200 cm\(^{-1}\). The N-methylpyridinium compounds have a single reduction at ca. −1.5 V vs. Fc/Fc\(^+\) in MeCN. While the reduction process was reversible for the 2,7-disubstituted compound, it was irreversible for the mono-substituted one. Experimental findings are complemented by DFT and TD-DFT calculations. Furthermore, the N-methylpyridinium compounds show strong interactions with calf thymus (ct)-DNA, presumably by intercalation, which paves the way for further applications of these multi-functional compounds as potential DNA-bioactive agents.
KW  - inorganic chemistry
KW  - viologens
KW  - chromophores
KW  - luminescent
KW  - pyrenes
KW  - pyridinium
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-256642
VL  - 27
IS  - 8
ER  -