A water-soluble pyrene-based diimidazolium molecular probe enabling chirality and fluorescence dual-response toward G-quadruplexes.

As a non-canonical secondary structure of nucleic acids, G-quadruplexes (G4) play pivotal roles in key physiological processes, including cell replication, transcription, and translation. The specific recognition and monitoring of G4 have emerged as a prominent research focus. In this study, a water-soluble pyrene-based diimidazolium molecular probe (1·2Cl-) is rationally designed and synthesized efficiently via a one-step SN2 reaction. This probe employs two covalently linked pyrene moieties as the core signal-generating module, with an anthracene moiety and two imidazolium moieties as the linker. Owing to the distinctive dimerization of 1·2Cl- in aqueous media, the probe enables selective recognition of dinucleotides through an intercalation binding mode and identifies G4 structures via a surface contact mode. As a chirality and fluorescence dual-response probe, 1·2Cl- recognizes G4 structures with high specificity and low background signal via dimerization and chiral stacking of pyrene moieties, with corresponding circular dichroism (CD) and fluorescence detection limits of 0.38 µM and 4.65 nM, respectively. These results overcome the core limitations of conventional G4 probes and establish a new strategy for designing selective multi-responsive probes for functional nucleic acids, thereby expanding the application of supramolecular probes in bioanalysis.