Multifunctional N-fused fluorescent probes for detection of iron ions and nitro explosives.

In this work, two novel probes 4a and 4b were synthesized through Suzuki-Miyaura coupling reaction, whose structures were further confirmed by 1H NMR, 13C NMR, high-resolution mass spectrometry (HRMS) and X-ray single crystal diffraction. The optical properties of the obtained molecules were investigated accordingly. Owing to different bridging fluorophores, there are certain differences in optical performance and detection ability between the two synthesized compounds. Especially, due to the subtle difference in orbitals energy and electron distribution displayed by the DFT calculations, 4a possesses the characteristics of dual-state emission (DSE) molecule, while 4b is an aggregation-induced emission (AIE) molecule. Interestingly, these two molecules can be developed into multifunctional detection probes, successfully applied for the fluorescence recognition of iron ions and common nitroaromatic compounds (NACs). At the same time, the probe molecules can also be applied to the detection of NACs in aqueous environment. What's more, they can also be loaded on test strips and thin-films for fluorescence identification of NACs, thus being expected to be developed into portable detection tools for NACs.