Solid-State Emissive B,S-Bridged p-Terphenyls: Synthesis, Properties, and Utility as Bifunctional Fluorescent Sensor for Hg2+ and F- Ions

The efficient synthesis has been disclosed to achieve a new class of ladder-type molecules, B,S-bridged p-terphenyls (BS-TPs). Their properties were fully characterized by UV-vis and fluorescence spectroscopy in both solution and solid state, time-resolved fluorescence spectroscopy, DFT theoretical calculations, and cyclic voltammetry. A detailed comparison between anti-BS-TP and its analogue B,N-bridged p-terphenyl (BN-TP) was made to elucidate the effect of displacement of bridging N with S atom on the properties. The introduction of S rather than N atom as bridging atom leads to increased fluorescence efficiency in both solution and solid state as well as enhanced reduction stability. And thus this new class of ladder-type molecules are highly emissive in both solution and solid state and display reversible reduction wave in cyclic voltammograms, denoting their promising potentials as electron-transporting solid-state emitters. In addition, this new class of molecules are capable of detecting F- and Hg2+ with different fluorescence responses, owing to the high Lewis acidity of the B center to coordinate with F- anions and the great mercury-philicity of the S center to complex with Hg2+ cations.