Small molecule α-cyanostilbene derivatives with multi-stimulus response and applications in sensing, anti-counterfeiting and light-emitting diodes

Abstract

Two small molecule α-cyanostilbene derivatives (TS-Ph and TS-BPh) were synthesized by a two-step Vilsmeier and Knoevenagel reaction. Both TS-Ph and TS-BPh have aggregation-induced emission enhancement effect, and the mechanism involves nanoaggregate formation and limiting intramolecular rotation, as evidenced by scanning electron microscopy images and a viscosity-dependent emission spectrum. TS-Ph and TS-BPh can specifically recognize nitro compounds, which is achieved by photo-induced electron transfer, as proven by the results of density functional theory calculations. Therefore, TS-Ph and TS-BPh can be used for quantitative or qualitative detection of explosives like trinitrophenol with a limit of detection of 1.531 × 10⁻⁴ and 3.658 × 10⁻⁵ M, respectively. Furthermore, TS-Ph and TS-BPh exhibit reversible acidochromism and are successfully used in fluorescent anti-counterfeiting. Finally, we explored their potential applications in light-emitting diodes, and the devices of TS-Ph and TS-BPh show a high color rendering index (>55) and luminous efficiency (∼50 lm W⁻¹).