Aggregation–induced emission activity and further Cu2+-induced self-assembly process of two Schiff compounds

• Published in: Sensors and actuators. B, Chemical Chemical, 2017-07, Vol.246, p.554-562
• Main Authors: Liu, Bin, Zhou, Haile, Yang, Binsheng, Hu, Xiangquan
• Format: Article
• Language: English
• Subjects: Aggregation–induced emission; Cell imaging; Cu2; Schiff-base; Self-assembly
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2017.02.120

[Display omitted] •Two AIEgens Schiff-base compounds were synthesized.•AIE(1) and AIE(2) show high sensitivity to Cu2+ via emission quenched.•Cu2+ induced the formation of self-assembly [1-Cu2+]n or [2-Cu2+]m particles.•AIE effect and self-assembly subsequently have been achieved in bioimaging. Two Schiff-base compounds (1 and 2) based on the condensation of salicylaldehyde or 2-hydroxy-1-naphthaldehyde with hydrazine hydrate are designed and synthesized. The observation suggests that they are aggregation–induced emission (AIE) active compounds in pure aqueous solution with strong green emission, λmax=530nm. Both of the aggregation, AIE (1) and AIE (2), show comparatively high sensitivity to Cu2+ via emission significantly quenched compared to other metal ions of interest. Notablely, 3-folds reduction of the fluorescence intensity is observed when 0.2 equiv. of Cu2+ ions is added to AIE (2) (10μM) in aqueous solution. Detection limit for Cu2+ is (200±23) nM (1) and (10±0.3) nM (2), respectively. Importantly, mechanism investigation by dynamic light scattering (DLS), scanning electron microscopy (SEM), ESI–MS, 1H NMR, resonance light scattering spectra and EDTA competing analysis indicate that the presence of Cu2+ induced the rearrangement of AIE (1) or AIE (2) with the formation of a very tight self-assembly [1-Cu2+]n or [2-Cu2+]m particle. The AIE effect and Cu2+-induced self-assembly subsequently have been achieved in bioimaging with satisfactory results.