Visible-Light-Controlled Formation of G-Quadruplexes

Guanine (G)-quadruplexes are robust supramolecular assemblies formed by the π-stacking of hydrogen-bonded G-quartets around a metal cation. We report visible light control of G-quadruplex formation through direct functionalization of guanosine with ortho-substituted azobenzene (osAZO) and arylazopyrazole (AAP) photoswitches. The E isomers form D₄-symmetric G-octamers, while the Z isomers induce disassembly. Spectroscopic and theoretical analyses unravel distinct switching efficiencies, with the AAP derivative enabling near-quantitative reversible control. This is the first visible-light-controlled G-quadruplex assembly via direct guanine modification.