Luminescent Vesicles Self-assembled Directly from an Amphiphilic Europium Complex in an Ionic Liquid

Abstract

Novel luminescent vesicles with enhanced emission were successfully achieved for the first time by an amphiphilic europium complex through its spontaneously self-assembly in an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([Bmim]­PF6). The complex was prepared by europium ions coordinated with terpyridine ligands, which were modified with the hydrophilic ethoxy chains. The enhanced absolute quantum yield and prolonged fluorescence lifetime of complex in vesicles were observed because of the effective shielding of the quench effects caused by both solvent and complex concentration. Compared to the aggregates formed in other solvents, the vesicles obtained in [Bmim]­PF6 showed the best luminescence intensity with the quantum efficiency (37.74%) and luminescent emission lifetime (1.915 ms) both increased about 10 times more. Furthermore, this europium complex was designed to show unsaturated coordination, which made the vesicle luminescence easily quenched when contacting with water. The fluorescence sensing of water with this vesicle as probe was therefore possible, where several unique properties like high sensitivity, low detection limit (0.05 vol %), visible color change, and fast response had been observed. Such designed systems are expected to provide strategies to develop novel supramolecular aggregates in ionic liquids and offer guidance for luminescence detection with facile and wide applications.

Understanding the excited state dynamics and redox behavior of highly luminescent and electrochemically active Eu(iii)–DES complex

“…There have been several reports published in those directions, focusing on both fundamental understanding and applications, oriented towards the nuclear industry. 3,[15][16][17][18][19][20][21][22][23][24] However, due to the limitations of ionic liquids, which pertain to their environmental friendliness, biodegradability, high cost, and toxicity, research associated with metal ion EDDC has not achieved long-lasting success. Therefore, researchers started looking for similar studies with DES.…”

Lanthanide–Cyclen–Camptothecin Nanocomposites for Cancer Theranostics Guided by Near-Infrared and Magnetic Resonance Imaging

“…There have been reports on designing self-assemblies of lanthanide complexes in the literature. , For simple imaging entities, Rao et al, Ye et al, and Meade et al, respectively, have reported smart in vitro enzymatic reaction-based self-assembling MRI contrast agent, an in vivo self-aggregating fluorogenic small-molecule MR/NIR imaging probe, and a self-assembling AIEgen-Gd/DOTA-peptide-based bimodal luminescence-MRI contrast agent . There have also been literature reports on using Gd-complexes to develop theranostic prodrugs: Shen et al documented a novel MRI theranostic in vivo prodrug self-assembled from small amphiphilic Gd/DTPA-CPT conjugates ( i.e ., acyclic ligand), but their cancer cell selectivity is unknown .…”

“…There have been reports on designing self-assemblies of lanthanide complexes in the literature. 7,8 9 an in vivo self-aggregating fluorogenic small-molecule MR/NIR imaging probe, 10 and a self-assembling AIEgen-Gd/DOTA-peptide-based bimodal luminescence-MRI contrast agent. 11 There have also been literature reports on using Gd-complexes to develop theranostic prodrugs: Shen et al documented a novel MRI theranostic in vivo prodrug self-assembled from small amphiphilic Gd/DTPA-CPT conjugates (i.e., acyclic ligand), but their cancer cell selectivity is unknown.…”