Broccoli-Derived Carbon Dots Composited with Aliphatic Linker-Based COFs as Hybrid Functional Modifiers for an Advanced Silica Stationary Phase

Broccoli water extract-derived carbon dots (BWE-CDs) offer advantages including natural origin, low cost, high stability, and good hydrophilicity. Conventional covalent organic frameworks (COFs) constructed with aromatic building blocks are characterized by pronounced hydrophobicity, which limits their application in hydrophilic separations. Aliphatic linker-based COFs (ALCOFs) are considered effective for modulating the hydrophilic-lipophilic balance. This study proposes a strategy of compositing BWE-CDs with ALCOFs to construct a novel chromatographic stationary phase. Specifically, BWE-CDs synthesized using water as a reaction medium, alongside ALCOFs exhibiting tailored hydrophilicity/hydrophobicity, were immobilized onto the aminated silica gel via a one-pot approach, yielding an excellent BWE-CD/ALCOF@Silica composite. The combination of ALCOFs and BWE-CDs resulted in a significant enhancement of the overall hydrophilicity and separation selectivity. The BWE-CD/ALCOF@Silica composite stationary phase demonstrated favorable separation performance for polycyclic aromatic hydrocarbons, phthalate esters, bisphenols, nucleosides, vitamin B, antibiotics, and dinitrobenzene isomers. Moreover, superior operational stability and batch-to-batch reproducibility further confirmed its reliability for analytical applications. This work provides an innovative paradigm for developing low-cost, environmentally benign, and high-efficiency separation materials, establishing a novel pathway for the application of an ALCOF nanocomposite in high-performance liquid chromatography. The developed BWE-CD/ALCOF@Silica stationary phase has demonstrated considerable potential for practical sample analysis and substantially advances separation and analytical technology.