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Updated: Jan 27, 2026

Single-Molecule Fluorescence Visualization of DNA Polymerase Dynamics at G-Quadruplexes
Published on: April 4, 2025
Diphenylaminostyryl-substituted quinolizinium derivatives as fluorescent light-up probes for duplex and quadruplex
Avijit Kumar Das1, Heiko Ihmels, Sarah Kölsch
1Department of Chemistry and Biology, University of Siegen, Center of Micro- and Nanochemistry and Engineering, Adolf-Reichwein-Str. 2, 57068 Siegen, Germany. ihmels@chemie.uni-siegen.de.
Abstract:
(E)-2-[1'-((Diphenylamino)styryl)quinolizinium (3a) and 2,2'-{(phenylimino)-bis[(E)-1'',1'''-styryl]}-bis[quinolizinium] (3b) were synthesized, and their interactions with duplex DNA and quadruplex DNA were investigated with a particular focus on their ability to operate as DNA-sensitive fluorescent probes. Due to the significantly different size and steric demand of these quinolizinium derivatives they exhibit different binding modes. Thus, 3a intercalates into duplex DNA and binds through π stacking to quadruplex DNA, whereas 3b favours groove binding to both DNA forms. The emission intensity of these compounds is very low in aqueous solution, but it increases drastically upon association with duplex DNA by a factor of 11 (3a) and >100 (3b) and with quadruplex DNA by a factor of >100 (3a) and 10 (3b), with emission bands between 600 and 750 nm.
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