Synthesis Of Cucurbit[7] Uril Chemical Sensor And Its Molecular Recognition Research For Common Antibiotics

Supramolecular chemistry is a frontier science.Cucurbit[n]uril is a new generation of cage macromolecules after crown ether,cyclodextrin and calixarene.It is composed of 2n methylene bridged n glycouril units.Its rigid hydrophobic cavity and polar carbonyl port form a chemical sensor with the guest through host-guest interaction.The purpose of this paper is to prepare two supramolecular fluorescent chemical sensors based on cucurbit[7]uril,cucurbit[7]uril-jatrorrhizine and cucurbit[7]uril-chelerythrine chloride by using the host-guest interaction of supramolecular compounds.The inclusion behavior of cucurbit[7]uril and guest molecules in aqueous solution was studied,and the fluorescence properties of common antibiotic molecules in the presence of supramolecular fluorescent sensors were explored.Based on this,a fluorescence analysis method for the detection of metronidazole and clindamycin hydrochloride was established.The competitive reaction mechanism between probe molecule and antibiotic molecule in cucurbit[7]uril cavity was proved by means of spectrum,X-ray crystal diffraction,fourier infrared spectrum and nuclear magnetic resonance hydrogen spectrum.The main contents include the following two parts.(1)Because cucurbit[7]uril and jatrorrhizine have strong fluorescence in aqueous solution,the fluorescence of the system is quenched after adding metronidazole.Based on this,a new method using cucurbit[7]uril-jatrorrhizine as fluorescence sensor to detect metronidazole was established.The detection mechanism was determined by fluorescence spectrum,fourier infrared spectrum,X-ray crystal diffraction and nuclear magnetic resonance hydrogen spectrum.The binding constant of cucurbit[7]uril-jatrorrhizine is 4.8×10⁴ M^-1,the binding constant of cucurbit[7]uril-metronidazole is 2.7×10⁸ M^-1,indicating that metronidazole can compete the jatrorrhizine from the cavity of cucurbit[7]uril.The content of metronidazole in milk was detected based on the principle of host-guest competition,and the linear range was 0.38-60?M.The detection limit was 0.021?M.(2)Because cucurbit[7]uril and chelerythrine chloride have strong fluorescence in aqueous solution,the fluorescence of the system is quenched after adding clindamycin hydrochloride.Based on this,a new method using cucurbit[7]uril-chelerythrine chloride as fluorescence sensor to detect metronidazole is established.The detection mechanism was determined by fluorescence spectrum,fourier infrared spectrum,X-ray crystal diffraction and nuclear magnetic resonance hydrogen spectrum.The binding constant of cucurbit[7]uril-chelerythrine chloride is 7.1×10² M^-1,the binding constant of cucurbit[7]uril-clindamycin is 7.1×10⁷ M^-1,indicating that clindamycin hydrochloride can compete chelerythrine chloride from the cavity of cucurbit[7]uril.The content of clindamycin hydrochloride in bovine serum was determined based on the principle of host-guest competition,and the linear range was 0.086-7.0?M.The detection limit is 0.086?M.