Multiple Applications of Chiral Self-Assembled H<sub>8</sub>–BINOL Nanoprobes with AIE-ESIPT Characteristics: Chiral Switching and pH Visualization Detection
Rong Wang, Kaiyue Song, Lixue Yang, Yue Sun, Xiaoxia Sun, Yu Hu
Abstract
R - BTOBD exhibited significant aggregation-induced Emission (AIE) characteristics, including high brightness (αAIE ≈ 40), robust light stability, a substantial Stokes shift (128 nm), and a high signal-to-noise ratio, effectively overcoming aggregation-caused quenching (ACQ). Derived from the axially chiral R -H 8 –BINOL, R - BTOBD was synthesized via nucleophilic cyclization and exhibited pronounced self-assembly properties. Through robust intra- and intermolecular hydrogen bonding interactions, R - BTOBD formed diverse supramolecular structures, including spherical flower-like aggregates, hollow-core triangular tubules, hexagonal tubules, and irregular white block-like stacks. The specific morphology was influenced by factors such as solvent and pH. For fluorescence applications, R - BTOBD can be employed as an effective visual pH detector through an AIE-enhanced excited-state intramolecular proton transfer (AIE-ESIPT) mechanism. When incorporated into pH paper, it exhibited a bright yellow fluorescence across a wide pH range (pH 1–11), transitioning to an intense bright blue fluorescence under strongly basic conditions (pH 12–14). In chiral applications, R - BTOBD demonstrated potential as a chiral switching agent, leveraging the pronounced changes and inversions in its circular dichroism (CD) signals under varying aggregation states and pH conditions. Additionally, it serves as a specific chiral enantioselective fluorescence probe for l -lysine, demonstrating high efficiency and a low detection limit. Given its exceptional fluorescence and chiral properties, this fluorescent material has significant potential for diverse applications in fluorescence, chirality, and visual inspection.