关键词: 菲并咪唑, 取代基, 荧光, 分峰光谱, 色纯度

Abstract:

Phenanthro[9,10-d]imidazole(PI), as a new class building block for organic blue fluorescence emitter, has attracted more and more attention due to its potential application of highly efficient non-doped blue materials and white or phosphorescent host, but it is a pity with a little reports in its structure-property relationship, such as color purity. Owing to the substituted group at C2-position participating in the formation of the frontier molecular orbitals in the obtained materials, tremendous attentions is cost to tune the stuctures at this position, another key factor to their emitting light color from N1 position was ignored. In this paper, 1,2-diphenyl-1H-phenanthro[9,10-d]imidazole(PPI) was chosen as a model compound for PI-based compound, and its two kinds of derivatives were prepared by tuning the substituted group in phenyl attached N1-position. Their basic chemical structures were confirmed by NMR spectra. Comparing with the fine fluorescence spectra in single molecular of PPI and its derivatives, the shift regulation of the various level emission peaks and their proportion to PI unit was carefully disclosed by changing the substituted position and structure. Here, R4-substituted position in phenyl attached N1 played more important role in substituent effect than others. When the electron-donating substituent or weak electron-withdrawing group was introduced to this position, the proportion of low-energy level emission decrease in fine fluorescence spectra of PI block, and the color purity was improved obviously. When the stronger electron-withdrawing group was inserted, the proportion of low-energy level emission increased in fine fluorescence spectra and the peak width was expended. All of these results could provide some basal theory for design of various blue emitters based on PI block.

Key words: Phenanthroimidazole, Substituted group, Fluorescence, Split spectrum, Color purity