Fluorescence-enhanced BINOL-hybridized ladder-type siloxanes and their sensing of Fe3+

Abstract

In this study, we synthesized two novel vinyl-substituted, BINOL-hybridized tricyclic-ladder-type siloxanes (referred to as Vi-TLS-BINOLs) via a B(C₆F₅)₃-catalyzed Piers–Rubinsztajn reaction. Fluorescence studies of the Vi-TLS-BINOLs revealed enhanced fluorescence emission attributed to the restricted intramolecular motion by the ladder-type structure. In comparison to the precursor BINOL, Vi-TLS-BINOLs L1 and L2 exhibit a 5.2-fold and 4.8-fold increase in fluorescence quantum yield in THF, respectively. Furthermore, it was observed that both Vi-TLS-BINOLs could selectively recognize Fe³⁺ through fluorescence quenching. ESI-HRMS analysis confirmed the formation of [L1 + 2Fe] and [L1 + 3Fe] complexes with Fe³⁺. The detection limits for Fe³⁺ were determined to be 10.6 µM and 16.3 µM, respectively.