Unexpected SiMe3 effect on color-tunable and fluorescent probes of dendritic polyphenyl naphthalimides with aggregation-induced emission enhancement

Abstract

In this paper, two new organic dyes derived from 1,8-naphthalimide and dendritic polyphenyl were designed and synthesized. Both the dyes exhibited unique aggregation-enhanced emission enhancement properties in methanol/water mixtures. The traditional fluorescent materials 1,8-naphthalimides were successfully transformed to AIE-active materials based on the dendritic polyphenyl structure. Furthermore, NPI-Ph and NPI-Si displayed excellent optical properties, such as solvent-induced emission changes from deep blue to light green, and the sensitive fluorescence response to nitroaromatic explosives. Interestingly, an unexpected SiMe₃ effect was found in the two dyes: the SiMe₃-containing compound NPI-Si exhibited remarkably enhanced optical properties compared with the non-SiMe₃ compound NPI-Ph such as a wider color-tunable range and higher sensitivity for the fluorescence detection of nitroaromatic explosives. The dendritic polyphenyl strategy and the SiMe₃ effect reported in this work will provide guidance to the design of AIE-active molecules and fluorescent materials for detecting nitroaromatic explosives.