Efficient and pH-Sensitive Nonconventional Luminescent Polymers for Cellular Imaging and Ion Detection

Nonconventional luminescent materials (NLMs) are a type of organic luminescent materials that does not contain aromatic units. Due to the simplicity of the synthesis process, mild reaction conditions, good hydrophilicity and biological compatibility, NLMs have attracted much attention. Nevertheless, numerous reports indicate that NLMs can only effectively luminesce at high concentrations and in solid state, which limits their applicability in the field of cell imaging. This study addresses this limitation by designing and synthesizing oligomers P1, P2 and P3 using ethylene glycol diglycidyl ether and amine compounds containing ethylene groups. These oligomers exhibit remarkable luminescence efficiency reaching as high as 9.2% in dilute solutions (0.1 mg/mL), making them among the best NLMs in this category. Furthermore, the synthesized oligomers exhibit excitation wavelength-dependent and concentration-dependent luminescence intensity, fluorescence response to temperature and pH changes, as well as the ability to identify Fe³⁺, Cu²⁺ and Mo⁵⁺ in dilute solutions. These characteristics render them potentially useful in the for cell imaging.