title: Photoresponsive Formation of an Intermolecular Minimal G-Quadruplex Motif.
abstract: The ability of three different bifunctional azobenzene linkers to enable the photoreversible formation of a defined intermolecular two-tetrad G-quadruplex upon UV/Vis irradiation was investigated. Circular dichroism and NMR spectroscopic data showed the formation of G-quadruplexes with K(+)  ions at room temperature in all three cases with the corresponding azobenzene linker in an E conformation. However, only the para-para-substituted azobenzene derivative enables photoswitching between a nonpolymorphic, stacked, tetramolecular G-quadruplex and an unstructured state after E-Z isomerization.
authors.affiliation: Goethe University Frankfurt, Institute for Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Julie
authors.initials: J
authors.lastname: Thevarpadam
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Irene
authors.initials: I
authors.lastname: Bessi
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Binas
authors.affiliation: Goethe University Frankfurt, Institute for Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Diana P N
authors.initials: DP
authors.lastname: Gonçalves
authors.affiliation: Institute for Physical and Theoretical Chemistry, Max-von-Laue-Strasse 7, 60438, Frankfurt, Germany.
authors.forename: Chavdar
authors.initials: C
authors.lastname: Slavov
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Hendrik R A
authors.initials: HR
authors.lastname: Jonker
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Richter
authors.affiliation: Institute for Physical and Theoretical Chemistry, Max-von-Laue-Strasse 7, 60438, Frankfurt, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Wachtveitl
authors.affiliation: Institute for Organic Chemistry and Chemical Biology, Center for Biomolecular Magnetic Resonance (BMRZ), Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany. schwalbe@nmr.uni-frankfurt.de.
authors.forename: Harald
authors.initials: H
authors.lastname: Schwalbe
authors.affiliation: Goethe University Frankfurt, Institute for Organic Chemistry and Chemical Biology, Buchmann Institute for Molecular Life Sciences, Max-von-Laue-Strasse 9, 60438, Frankfurt, Germany. heckel@uni-frankfurt.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Heckel
mesh_terms: D054856:G-Quadruplexes; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010777:Photochemistry; D066244:Proton Magnetic Resonance Spectroscopy
keywords: DNA structures; G-quadruplexes; IR spectroscopy; NMR spectroscopy; azobenzene