Design And Synthesis Of Sulfone-substituted Polycyclic Aromatic Polyimide And The Research Of Their Optical And Electrical Properties

Rylene imides have excellent optical, thermal, chemical stability, high molar extinctioncoefficient and fluorescence quantum efficiency, which are generally required for practicaluse. However, the large intramolecular π-π interaction makes them easily to form aggregates.With the growth of π-π interaction in longitudinal direction, the improvement is not soobvious when substituents are in imides site. But the optical performance will be adverselyaffected while solubility being improved when substituents are in bay region.In this paper, four sulfone groups were introduced into the bay region of Perylenediimide (PDI) and Terrylene diimide (TDI) respectively to get two compounds (PDI-F andTDI-F) which are decorated with sulfones. Since TDI-F has a high molar extinctioncoefficient, high fluorescence quantum efficiency, good light stability, and the absorptionspectrums is in the near-infrared region, it has been established as a key chromophore forsingle-molecule spectroscopy(SMS). So we introduce branched-chain PEG to the end ofsulfone substituents to obtain a series of water-soluble compounds----PEG-TDIs. Details areas follows:1. Four sulfide groups are introduced into the bay region of PDI and TDI respectively,and then oxidized them to sulfone. Compared them with PDI and TDI which substituted withfour ether groups into the same regions on their optical properties and electronical properties.The results show that the absorption peak of the rylene substituted with ether, sulfide andsulfone groups in their bay regions are red shifted. The fluorescence quantum efficiency ofPDI-O is still very high, but which of the TDI-O is greatly reduced to23%. However, PDI-Sand TDI-S all have high fluorescence quantum efficiency(between0.6to1). In addition, lightstability of TDI-F is also good, the fluorescence quantum efficiency of TDI-F is still above0.8under the conditions of bright light for up to55min. Furthermore, some of theelectrochemical nature of the compounds are studied, cyclic voltammograms show that theintroduction of a sulfone group in the Bay regions makes their LUMO levels reduced to-4.22V and-4.38V, the HOMO level elevated to-4.42V and-5.30V.2. Branched-chain PEOs were introduced to the Bay region of TDI-F to obtaine twocompounds----8-PEG-TDI and16-PEG-TDI. And their aggregation behavior were studied.The results show that, large PEG chains can be introduced to achieve a water-soluble compound(the water-solubility of16-PEG-TDI is24mg/mL), but the states of them are stillaggregations in the presence of water. But as the number of the PEG increases, the aggregatedof the compound faint.The fluorescence quantum efficiency of the two compounds at differentDMSO: H2O solutions show that, when the ratio of DMSO: H2O<1, the aggregation of16-PEG-TDI is weaker than that of8-PEG-TDI.