Aggregation-induced Emission Properties Of Alkyl Chains And Cyano Vinyl Modified Pyrrolopyrrole Derivatives

Aggregation-induced emission?AIE?phenomenon refers to the presence of a class of molecules that light or fluorescence is very weak when in single molecule state,but have high fluorescence in the aggregates.The discovery solved the aggregation-caused quenching problem of traditional fluorescent chromophore,broaden the application fields.It has been used more widely in electronic devices,biomedicine,ion detection and so on.The synthesis of more novel AIE molecules,study of their luminescent properties,and the discovery of their applications have important guiding significance for the study of organic luminescent materials.In this paper,a long alkyl chain and cyano vinyl were introducing to a pyrrolopyrrole derivative molecule by Knoevenagel reaction.The optical properties of DPP-2CN and DPP-TDB were investigated by UV and fluorescence spectra.The experimental results show that DPP-2CN exhibits aggregated fluorescence quenching?ACQ?properties in THF/H₂O,and DPP-TDB has AIE properties in THF/H₂O.Through the discussion and research of the experimental data,it is considered that the mechanism of AIE phenomenon is intramolecular rotational confinement?RIR?.And we put the DPP-TDB in 365 nm UV lamp under fluorescent irradiation,the results show that the fluorescence emission wavelength has 110 nm blue shift,the color changed from orange to blue obviously.In this regard,we think that it is mainly due to the UV irradiation,the energy from a low trans structure into cis structure,resulting changes in conjugated systems,and the nature of the luminescence.The liquid crystalline properties of DPP-TDB were investigated by DSC and polarizing optical microscopy,and the results proved that the pyrrole derivative had no liquid crystal performance.In addition,the cyano-vinyl structure based on DPP-TDB can be used for the detection of cyanogen ion.The detection process based on CN^-is fluorescence quenching,has good selectivity and anti-interference.The results showed that the detection limit was as low as 0.57?M,has a very good application prospect.In the light of the mechanism,we think that it is the nucleophilic addition reaction between cyanide ion and vinyl group.This study has important reference value for the study of new AIE molecules.