Fabrication of core-shell magnetic covalent organic frameworks composites and their application for highly sensitive...

In this work, a novel core-shell structured magnetic covalent organic frameworks (denoted as Fe₃O₄@TAPB-DMTP-COFs (TAPB, 1,3,5-tris(4-aminophenyl)benzene; DMTP, 2,5-dimethoxyterephaldehyde) was fabricated via a facile step-by-step assembly approach. The resulting material was characterized by transmission electron microscopy, powder X-ray diffraction, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy and voltammetric methods. Fe₃O₄@TAPB-DMTP-COFs was further coated on the surface of glassy carbon electrode to construct an electrochemical sensor for the determination of luteolin. TAPB-DMTP-COFs with highly ordered porous structure not only provide more active sites, but also avoid the aggregation of Fe₃O₄. Meanwhile, Fe₃O₄ magnetic nanoparticles can obviously accelerate the electron transport. Under the optimal conditions, the method displayed low detection limit (0.0072 μmol L^-1), wide linear range (0.010-70 μmol L^-1), and good recoveries (98.5-102.0%). Moreover, there are no significant effects from the interferents. The feasibility of this method was applied to trace luteolin in chrysanthemum tea and carrot. We consider this COFs-based porous material would become one of the most promising materials in electrochemical sensor.