The Study Of The Interaction Between The Six-membered Citrullus Ring Of Cyclopentyl And The Host And Guest Of Small Organic Molecules Such As Amino Acids

As the fourth-generation supramolecular subject,cucurbit[n]urils have attracted extensive attention from scientific researchers for its unique structure and excellent performance since Mock^[1]used single crystal x-ray diffraction to determine its structure in1981.But its research has been limited due to its poor solubility and other problems.cyclopentyl cucurbit[n]urils are good solution to this problem.However,due to the low synthesis efficiency,the highly toxic and difficult recovering of the raw materials and by-products,their research was once put on hold.In order to improve the status quo of cyclopentyl cucurbit[n]urils,in this paper,by using glutaric acid,ethanol,diethyl oxalate as raw materials and milder reaction conditions,its process was improved,and has obtained certain breakthrough.At the same time,abandoning the use of toxic substances,the yield was greatly increased and Successfully obtained cyclopentyl cucurbit[n]urils?CyP₆Q[6]?.the host-guest interaction between CyP₆Q[6]and the human body's 20 kinds of amino acids,nine viologen derivatives,anti-4-[4-?dimethyl-amine?styryl]-1-methyl pyridine iodine?t-DSMI?were examined,and studyed on the host-guest interaction of alkali metal potassium ion.by using the single crystal X-ray diffraction spectrum,porton nuclear magnetic resonance,UV-spectrophotometry,isothermal titration calorimetry?ITC?and other technologies,their host-guest properties are characterized.20 L-type amino acids?glycine has no chirality,so there is no distinction between L-type and D-type?required by human body were selected as the guest molecules to study the host-guest effects with CyP₆Q[6].¹H NMR showed that when only glycine and L-alanine interact with the cucurbit[n]urils,the same carboxylic acid group attached to the amino group entered the cucurbit[n]urils cavity.In addition,aliphatic chains of L-methionine,L-lysine,L-tyrosine,L-phenylalanine,L-leucine and L-glutamic acid entered the cucurbit[n]urils cavity,showing certain endogenous binding effects,and the remaining amino acids all showed external effects.Single crystal X-ray diffraction clearly showed the conformational pattern of thehost-guest interaction.The interactional study of nine viologen derivatives:N,N'-dimethyl-4,4'-bipyridinium dibraomide?guest 1?,N,N'-diethyl-4,4'-bipyridinium dibraomide?guest 2?,N,N'-Dipropyl-4,4'-bipyridinium dibraomide?guest 3?,N,N'-dibutyl-4,4'-bipyridinium dibraomide?guest 4?,N,N'-diamyl-4,4'-bipyridinium dibraomide?guest 5?,N,N'-hexyl-4,4'-bipyridinium dibrao-mide?guest 6?,N,N'-2 heptyl-4,4'-bipyridinium dibraomide?guest 7?,N,N'-diphenyl-4,4'-bipyridine dibromide?guest 8?,N,N'-dibenzyl-4,4'-bipyridine dibromide?guest 9?and CyP₆Q[6]were inspected.¹H NMR showed that only guest 1 and 2 would bind the cucurbit[n]uril to its pyridine group,and the other objects were only bound to the substituent chain.The UV-spectrum showed that the inclusion of pyridine group would lead to the decrease of UV absorbance,the inclusion of substituents would lead to the increase of UV absorbance,and the inclusion of conjugated system would lead to the red shift of UV absorbance.At the same time,the Job method showed that guest 1 and 2 showed a 1:1composition,while the other guest formed a 2:1 dumbbell inclusion with cucurbit[n]uril.ITC showed that the interaction mode between guest 6 and cucurbit[n]uril was the strongest,and all the drives were enthalpy driven.By investigating the host-guest interaction between CyP₆Q[6]and t-DSMI,a supramolecular assembly?t-DSMI@CyP₆Q[6]?was constructed,and the fluorescence probe formed by it showed a certain recognition effect on anions.The results showed that the fluorescent probe identified 4 kinds of anions.They are H₂PO₄^-,HSO₄^-,BF₄^-and I^-respectively,and all of them are quenching fluorescence.The self-assembly of K⁺and CyP₆Q[6]was constructed.X-ray single crystal diffraction showed that CyP₆Q[6]and K⁺formed molecular capsules,which could be further stacked into one-dimensional supramolecular chains and even three-dimensional supramolecular assembly entities,and coordination of the two environments was found.Powder diffraction showed that the complex had good reproducibility,and infrared spectroscopy showed that the stretching vibration of carbonyl group was red shifted due to the coordination of metal ions.