An organic emitter with enhanced fluorescence modulation, high emission efficiency, multicolor tunability in solution and solid states, and dual-channel sensing for selective cyanide detection.

For many industrial application, there arise a demand for multistate with multicolor emissive materials due to its substantial applications than fluorophore shows emission in single state. Therefore, in this work donor-acceptor-donor' (D-A-D') based three organic emitters (DSE1-DSE3) were synthesized. A substituted phenyl ring and cyano vinyl unit are used to manage molecular geometry and steric hindrance to reduce the gap between AIE and ACQ, resulting in an improved dual-state emission. Solid state emission maxima for all chemicals were red shifted compared to solution state. Additionally, quantum yields and excited state fluorescence lifetime were higher in the solid state. Because of their donor-acceptor pattern, all of the dyes show positive solvatochromism. As the solvent polarity increases, the emission maxima of DSE1-DSE3 redshift gradually. These emitter probe DSE1-DSE3 showed redshift in aggregation emission (ACRE) in water which is considered to be a poor solvent, this is supported by DLS and SEM analysis. Meanwhile, the compound DSE1-DSE3 can detect cyanide ion selectivity over other competing anions via the absorbance and fluorescence channels. Under the effect of electron accepting cyano groups, the vinyl C = C bond was easily reacted by nucleophilic CN which disturb the conjugated bridge of the compounds and prevented the ICT process between the donor and acceptor. The addition of cyanide ions to the compounds DSE1-DSE3 resulted in a significant red shift in absorbance and a total quenching of fluorescence intensity. For real life application, the probe successfully detects cyanide ion in various water samples. Besides, the developed DSE3-encapsulated polysulfone (PSF) capsule kit effectively sense cyanide ion in water.