Molecular engineered xanthene-based AIE dyes for tunable fluorescence switch

The dyes with the aggregation-induced emission (AIE) properties are significant for a wide range of studies. However, the existing AIE dyes still lack a readily tunable fluorescence switch. Herein, we described a type of structurally distinct dye family (named as XD dyes) with AIE properties. Significantly, the new XD dyes exhibit the advantageous feature over the traditional AIE fluorophores by possessing the intrinsic spirocyclization as a regulatable fluorescence switch. The AIE properties of XD dyes were examined by the spectroscopic studies, particle size analysis, transmission electron microscope, scanning electron microscope, and solid fluorescence. Furthermore, the quantum chemical calculation, molecular dynamics simulation and recombination energy calculation provide the insights into the structural characteristics and the aggregation process of XD dyes. The development of this unique class of dyes could afford new perception and insights for the development of supreme functional fluorescent dyes and probes.