ABSTRACT
The linear assembly of nanocrystals (NCs) with orientational order presents a significant challenge in the field of colloidal assembly. This study presents an efficient strategy for assembling oleic acid (OAH)-capped, faceted rare earth NCsâsuch as nanorods, nanoplates, and nanodumbbellsâinto flexible chain-like superstructures. Remarkably, these NC chains exhibit a high degree of particle orientation even with an interparticle distance reaching up to 15 nm. Central to this oriented assembly method is the facet-selective adsorption of low-molecular-weight polyethylene glycol (PEG), such as PEG-400 (Mn = 400), onto specific facets of NCs. This regioselectivity is achieved by exploiting the lower binding affinity of OAH ligands on the (100) facets of rare earth NCs, enabling facet-specific ligand displacement and subsequent PEG attachment. By adjusting the solvent polarity, the linear assembly of NCs is induced by the solvophobic effect, which simultaneously promotes the formation of hydrogen-bonded PEG supramolecular bridges. These supramolecular bridges effectively connect NCs and exhibit sufficient robustness to maintain the structural integrity of the chains, despite the large interparticle spacing. Notably, even when coassembling different types of NCs, the resulting multicomponent chains still feature highly selective facet-to-facet connections. This work not only introduces a versatile method for fabricating well-aligned linear superstructures but also provides valuable insights into the fundamental principles governing the facet-selective assembly of NCs in solution.
ABSTRACT
Metal halide perovskite nanocrystals (PNCs) have aroused worldwide research interest for optoelectronics. Herein, we report the first electrochemical approach to prepare colloidal PNCs with drastically reduced consumption of salts, solvents, and ligands. This method can be extended to prepare mixed-halide and bismuth-based PNCs by changing precursor compositions and metal components.
ABSTRACT
A new method was established for the sensitive determination of artificial synthetic sweetener acesulfame-K in soy sauce by capillary electrophoresis (CE) with field-amplified sample injection (FASI)and capacitively coupled contactless conductivity detection (C4D). Liquid-liquid extraction (LLE) technology was employed to eliminate the complex matrix interference co-existing in soy sauce. Ethyl acetate was used as the extraction solution. The pH of the sample solution was adjusted to 1.7, and both inorganic salts and organic compounds causing interferences were effectively removed by LLE. The type and volume of the extraction solvents, pH of the sample solutions, extraction method and extraction time were investigated in detail. Under the optimized experimental conditions, acesulfame-K in soy sauce was well separated and sensitively detected. The limit of detection and limit of quantification were 0.15 mg/kg and 0.48 mg/kg, respectively. The accuracy was tested by spiking acesulfame-K into soy sauce samples, and the recoveries ranged from 92.3% to 108.1%. The relative standard deviations were below 8.0%. The proposed method can meet the requirements for the fast screening and sensitive detection of acesulfame-K in soy sauce samples.
