A "dual thiol-yne click" post-synthesis strategy for bifunctional magnetic microporous organic networks enabling synergistic extraction of trace benzoylurea insecticides.

Herein, we report the first example of a "dual thiol-yne click" post-synthesis strategy to prepare a novel bifunctionalized magnetic microporous organic network (MMON-NH2-CF3) for magnetic solid-phase extraction (MSPE) of trace benzoylurea insecticides (BUs) in complex matrices. By sequential thiol-yne click reactions using cysteamine and 4-mercaptobenzotrifluoride as modifiers, MMON-NH2-CF3 bearing dual amino (-NH2) and trifluoromethyl (-CF3) groups was successfully synthesized. The stepwise improvement in extraction efficiency after each modification validates the effectiveness of this innovative design, overcoming the limitation of traditional single thiol-yne click methods. The -NH2 groups provide strong hydrogen-bonding sites, while -CF3 offer specific F-F interaction sites, which together with hydrophobic and π-π interactions of MON framework create multiple recognition sites for BUs. The developed MSPE-HPLC-UV method exhibits excellent analytical performance: good linearity in the range of 0.05-1000 μg L-1, detection limits as low as 0.02-0.03 μg L-1, and inter-day, intra-day, and inter-batch precisions (RSDs) below 4.2%. Recoveries from spiked real samples ranged from 96.9% to 104.7%, confirming reliability and practical value. Beyond demonstrating MMON-NH2-CF3 as a high-performance adsorbent for BUs enrichment, this work introduces the "dual thiol-yne click" post-modification strategy as a new concept for designing multifunctional adsorbents, particularly suited for high-selectivity recognition requiring synergistic multiple recognition mechanisms.