Self-Assembled Nanotubes Based on Chiral H₈-BINOL Modified with 1,2,3-Triazole to Recognize Bi³⁺ Efficiently by ICT...

A novel fluorescent "off" probe R-β-D-1 containing a 1,2,3-triazole moiety was obtained by the Click reaction with azidoglucose using H₈-BINOL as a substrate, and the structure was characterized by ¹H NMR and ¹³C NMR and ESI-MS analysis. The fluorescence properties of R-β-D-1 in methanol were investigated, and it was found that R-β-D-1 could be selectively fluorescently quenched by Bi³⁺ in the recognition of 19 metal ions and basic cations. The recognition process of Bi³⁺ by R-β-D-1 was also investigated by fluorescence spectroscopy, SEM, AFM, etc. The complex pattern of R-β-D-1 with Bi³⁺ was determined by Job's curve as 1 + 1, and the binding constant K_a of R-β-D-1 and Bi³⁺ was valued by the Benesi-Hildebrand equation as 1.01 × 10⁴ M^-1, indicating that the binding force of R-β-D-1 and Bi³⁺ was medium. The lowest detection limit (LOD) of the self-assembled H₈-BINOL derivative for Bi³⁺ was up to 0.065 µM. The mechanism for the recognition of Bi³⁺ by the sensor R-β-D-1 may be the intramolecular charge transfer effect (ICT), which was attributed to the fact that the N-3 of the triazole readily serves as an electron acceptor while the incorporation of Bi³⁺ serves as an electron donor, and the two readily undergo coordination leading to the quenching of fluorescence. The recognition mechanism and recognition site could be verified by DFT calculation and CDD (Charge Density Difference).