Synthesis Of Cucurbit[6]uril-based Supramolecular Assembly And Its Application In The Detection Of Organic Pollutants

Cucurbit[n]urils（commonly abbreviated as CB[n]s,n=5-8,10,13-15）are macrocyclic compounds.The rigid cavities and open port structure of CB[n]s allow them to play an important role in supramolecular chemistry and materials science.In particular,recent studies have shown that the positive electrostatic outer surface of CB[n]s can interact with other substances to form CB[n]s-based supramolecular self-assemblies.Aromatic nitro compounds and antibiotics play an important role in our production and lives,but the high stability of these two types of compounds makes them difficult to degrade in the environment,and they have become the new organic pollutants of the present.The existing detection methods have the disadvantages of time-consuming detection,expensive instruments and complex operation.Therefore,it is particularly important to establish simple,inexpensive and fast detection methods.In this paper,two supramolecular assemblies based on cucurbit[6]uril（CB[6]）were successfully synthesized by screening organic small molecules as structural inducers,and the structures were characterized by single-crystal X-ray diffraction and single-crystal X-ray powder diffraction.Characterization studies have shown that these two CB[6]-based supramolecular self-assemblies can be used as fluorescent probes to detect aromatic nitro compounds and antibiotics in water and also to adsorb antibiotics.We have discussed the detection and adsorption mechanism in depth.The specific work is as follows:1、A novel cucurbit[6]uril-based（CB[6]）supramolecular assembly H₂NDS·CB[6]（1）（H₂NDS=1,6-naphthalenedisulfonic acid）was successfully synthesized using H₂NDS as the“structure inducer”.The results of fluorescence experiments showed that assembly 1could be used as a fluorescent sensor to achieve sensitive detection of 4-nitrophenol（4-NP）,2,4,6-trinitrophenol（TNP）,and isoquinoline antibiotics berberine（BER）and palmatine（PAL）by fluorescence quenching phenomena,with detection limits of 7.93 ppb（BER）and5.64 ppb（PAL）,respectively;BER produces aggregate-induced emission by non-covalent interaction with assembly 1 in aqueous solution.Based on this experimental phenomenon,the detection of BER can be achieved by the fluorescence enhancement phenomenon,which has a lower detection limit than the fluorescence quenching method,while assembler 1 has a higher adsorption capacity for BER.Application studies have shown that assembly 1 can reliably and accurately detect BER in calf serum and TNP and BER in actual water samples.2、A supramolecular self-assembly[Zn（ACA）₄]·CB[6]·[NH₂（CH₃）₂]·8H₂O（2）（HACA=9-Anthroic acid）based on CB[6]was synthesized.Characterization studies showed that assembly 2 can detect the antibiotics furazolidone（NFZ）and furantoin（NFT）in water by fluorescence quenching and has a high quenching constant(K_sv):K_sv（NFT）=2.15×10⁴M^-1;K_sv（NFZ）=3.94×10⁴M^-1).Application studies showed that assembly 2can be applied to the detection of NFZ in artificial urine samples and lake water samples with good recovery efficiency.The detection mechanism study indicates that the quenching mechanism is an internal filtration effect.