Naphthalene-based Fluorophores: Synthesis Characterization, And Photophysical Properties

In this paper, two series of U-type fluorescent compounds (1,8-diarylnaphthalenes and 1,8-diarylethynylnaphthalenes) were synthesized. Their structures were confirmed by novel spectroscopy methods.By examing and comparing photophysical properties of their solutions, it was observed that absorptions of 1,8-diarylethynylnaphthalenes were red-shifted in comparison with those of 1,8-diarylnaphthalenes due to the insersion of triple bonds. Moreover, 1,8-diarylethynylnaphthalenes were detected to be with higher emission efficiencies than those of 1,8-diarylnaphthalenes. Besides of these distinguishable characters, emissions of some 1,8-diarylethynylnaphthalenes with both donor and acceptor groups, were largely depending on solvent polarity, which indicated that these compounds might be usesd as solvent polarity sensors.While formating nanoparticles by adding water to their THF solutions, aggregation induced emission enhancements (AIEE) were observed for some 1,8-diarylnaphthalene compounds. Mechanism of AIEE was dicussed and was ascribed to the restricted intramolecular rotations (RIR). These compounds emit intensed light in solid state and might be used as efficiently emitting materials in organic light emitting diode (OLED) for display or for lightening.