Aggregation‐Induced Emission of Eu^III Complexes Balanced with Bulky and Amphiphilic Imidazolium Cations in Ethanol/Water Binary Mixtures

Abstract

A series of Eu complexes with thenoyltrifluoroacetone (tta) as the ligands were synthesized, which are balanced with imidazolium cations bearing naphthyl and branched alkyl chains. The complex with the longest alkyl chain (1Eu(tta) ) shows aggregation behavior in ethanol and water mixtures. It exists as individuals at low water percentages (V ), and form particles with solid interiors at V ≥50 % the sizes of which decrease with the increase of V . At V =90 %, vesicles were observed. The aggregation of 1Eu(tta) in ethanol and water binary mixtures induced changes of the photoluminescence (PL) properties where an abrupt increase in PL intensity, quantum yield, and lifetime were noticed above V =50 %. This PL enhancement can be explained by the encapsulation of 1Eu(tta) inside the aggregates, preventing it from quenching by the active hydroxyls of water molecules. Contrary to the aggregation-induced emission (AIE) of the Eu complex, the naphthyl group in the imidazolium cation exhibited an aggregation-caused quenching (ACQ) effect. When the length of the alkyl chain in the imidazolium cation is reduced, no PL enhancement can be observed owing to the difficulty in forming the aggregates.

Triboluminescence of Centrosymmetric Lanthanide β-Diketonate Complexes with Aggregation-Induced Emission

“…However, when the water content increases to 99%, the luminescence intensity drops (Ф = 24% at 99%) because the aggregate size becomes smaller (95% = 131 nm and 99% = 88 nm), lowering the number of [Eu( pp -dbm-Cl 2 ) 3 phen] encapsulated in the aggregate. This phenomenon is similar to the study by Zhang et al [18].…”

Zwitterionic Surfactant Micelle-Directed Self-Assembly of Eu-Containing Polyoxometalate into Organized Nanobelts with Improved Emission and pH Responsiveness

“…The solution-based self-assembly is an excellent strategy to light up the luminescence of lanthanide­(III) ions owing to the effective displacement of coordinated water molecules around them. , Here, being polyanionic and highly water soluble, the EuW 10 nanocluster also suffered serious fluorescence quenching when it was dissolved into water. Fortunately, its luminescence intensity exhibited a gradual enhancement upon adding C 14 DMAO surfactant into solution, which could be revealed by the emission spectra and inset sample appearance photos under UV irradiation in Figure a.…”

In situ formation and dispersion of lanthanide complexes in wormlike micelles

“…[43][44][45][46][47][48] However, their poor dispersibility and PL stability in an aqueous environment is a long-last concern. [49][50][51][52][53][54][55] Since DPA is a wellknown ligand for lanthanide cations, 56 the successful preparation of DPA-containing wormlike micelles provides an opportunity of engineering water soluble complexes of lanthanide cations in situ. For this purpose, the micellar solution with a c DPA value of 55 mmol L À1 was selected as a typical example.…”