Highly Efficient Removal of Neonicotinoid Insecticides by Thioether-Based (Multivariate) Metal–Organic Frameworks

Circumventing the impact of agrochemicals on aquatic environments has become a necessity for health and ecological reasons. Herein, we report the use of a family of five eco-friendly water-stable isoreticular metal–organic frameworks (MOFs), prepared from amino acids, as adsorbents for the removal of neonicotinoid insecticides (thiamethoxam, clothianidin, imidacloprid, acetamiprid, and thiacloprid) from water. Among them, the three MOFs containing thioether-based residues show remarkable removal efficiency. In particular, the novel multivariate MOF {SrIICuII6[(S,S)-methox]1.5[(S,S)-Mecysmox]1.50(OH)2(H2O)}·36H2O (5), featuring narrow functional channels decorated with both −CH2SCH3 and −CH2CH2SCH3 thioalkyl chainsfrom l-methionine and l-methylcysteine amino acid-derived ligands, respectivelystands out and exhibits the higher removal efficiency, being capable to capture 100% of acetamiprid and thiacloprid in a single capture step under dynamic solid-phase extraction conditionsless than 30 s. Such unusual combination of outstanding efficiency, high stability in environmental conditions, and low-cost straightforward synthesis in 5 places this material among the most attractive adsorbents reported for the removal of this type of contaminants.

出于健康与生态层面的考量，规避农用化学品对水生环境的影响已成为必然需求。本文报道了五种由氨基酸制备的环保型水稳定同构金属有机框架（isoreticular metal–organic frameworks, MOFs），将其作为吸附剂用于去除水中的新烟碱类杀虫剂——包括噻虫嗪（thiamethoxam）、噻虫胺（clothianidin）、吡虫啉（imidacloprid）、啶虫脒（acetamiprid）与噻虫啉（thiacloprid）。其中，三种带有硫醚基残基的MOFs展现出优异的去除性能。尤为突出的是新型多变量金属有机框架（multivariate MOF）{SrII CuII6[(S,S)-methox]1.5[(S,S)-Mecysmox]1.50(OH)2(H2O)}·36H2O（5），其孔道狭窄且分别修饰有源自L-甲硫氨酸（l-methionine）与L-甲基半胱氨酸（l-methylcysteine）配体的−CH2SCH3与−CH2CH2SCH3硫烷基链，可在动态固相萃取（dynamic solid-phase extraction）条件下（用时少于30 s）的单步吸附过程中100%捕获啶虫脒与噻虫啉。该材料兼具优异吸附性能、环境条件下的高稳定性与低成本简易合成的独特优势，使其成为目前已报道的此类污染物去除用吸附剂中极具应用前景的材料之一。