G-quadruplex-based ionogels with controllable chirality for circularly polarized luminescence

Chiral supramolecular gels have been widely reported and applied in asymmetric catalysis, chiral recognition and circularly polarized luminescence (CPL). Guanosine, a biomolecule with both hydrogen bond donors and receptors on their purine rings, can self-assemble to form chiral G-quadruplexes, providing a good template for building CPL materials. Herein, we constructed the quadruplex-based ionogels in the absence of metal ions via dissolving a certain amount of guanosine into an ionic liquid, ethylammonium nitrate (abbreviated as EAN), where the cations of EAN worked as stabilizers of the G-quadruplexes. The introduction of K+ or Sr2+ reduced the guanosine concentration required to form G-quadruplex-based gels in EAN. The Sr(2+ )was found to disturb the homopolar stacking of G-quartets and triggered the heteropolar stacking, and thereby overturned the chirality of G-quadruplexes. All ionogels were CPL-active without additional luminescent materials, producing the left-handed CPL for K+ and right-handed CPL for Sr2+, respectively. Regulating the proportion of metal ions could modulate the chirality and CPL of the hybrid G-quadruplexes. The chiral-controllable ionogels in this work are easy to prepare and are promising to provide potential applications for constructing polarized light-emitting devices.