Supramolecular Assembly And Host-guest Interaction Of Cyclohexyl Cucurbit Rings With Amino Acids And Aromatic (hetero) Rings

Cucurbit[n]urils(Q[n]s)are an emerging main branch in supramolecular chemistry,has attracted wide attention.They have high thermal and chemical stability,and due to their highly symmetrical structure,which are suitable for inclusion of guest molecules.However,the poor solubility of Q[n]s in water and organic phases hinder their further research and applications.With the efforts of relevant research groups,the number of various substituted Q[n]s has gradually increased.However,due to the cumbersome reaction steps,low reaction yields and high prices in the synthetic routes of these substituted Q[n]s.To solve this problem,the synthesis route of cyclohexanocucurbit[6]uril was optimized in this paper.On the basis of the examined cyclohexanocucurbit[6]uril and small organic molecules form the supramolecular self-assembly of complexes,and constructed the cyclopentanocucurbit[6]uril and the metal ion supramolecular self-assembly,and by using the single-crystal X-ray diffraction analysis,quantum chemistry calculation,¹H NMR spectroscopy,mass spectrometry,and isothermal calorimetry titration technology on its properties have been characterized.1.In this paper,cyclohexane-1,2-dione-hemihydrate was synthesized by using cyclohex--anol and nitric acid as raw materials,and then cyclohexyl glycoluril was synthesized by using cyclohexane-1,2-dione-hemihydrate and diaminomethanal as raw materials.Its significance is to avoid the toxicity of selenium dioxide,reduce pollution and improve the yield.2.Based on the study of the host and guest interaction between the symmetric dicyclohexanocucurbit[6]uril(CyH₂Q[6])and human essential amino acids and the crystal structure of glycine,the results showed that there were two interaction modes between the essential amino acids and the melon ring:port interaction or inner inclusion interaction.The mode of action depends not only on the length of the alkyl chain but also on the type of the attached group and the position of the substituent.The structure of glycine intuitively shows the interaction pattern between glycine and CyH₂Q[6].3.Supramolecular interactions between CyH₂Q[6]and five benzene ring-containing guests((E)-4,4'-diamino-1,2-diphenylethene,4,4'-diaminobiphenyl,p-aminobenzenesulfona--mide,4-aminobenzenesulfonic acid,and 3,4,5-trihydroxybenzoic acid).X-ray crystallography show that the exclusion complexes of the CyH₂Q[6]with the guests generate supramolecular assemblies with multi-dimensional and multi-level frameworks.The supramolecular interactions include portal interaction between the negatively electrostatic potential portals of the CyH₂Q[6]and the terminal groups of the guests,and outer-surface interaction between the positively electrostatic potential outer surface of the CyH₂Q[6]and the benzene ring of the guests.In aqueous solution,the experimental data and quantum chemistry calculation results show that all the guests prefer exo binding with the CyH₂Q[6].4.Based on hoster-guest supramolecular interactions between the CyH₂Q[6]and benzotriazole(BTA).From the experimental results,it was concluded that there was a 1 1mode of inclusion in BTA@CyH₂Q[6].In addition,the benzene ring of the BTA molecule entered the cavity of the CyH₂Q[6],while the triazole part was at the port of the CyH₂Q[6],forming a supramolecular framework.According to ITC,the complexation process for BTA with CyH₂Q[6]is exothermic and mainly driven by enthalpy.5.Self-assembly between CyH₂Q[6]and cyclopentanocucurbit[6]uril(CyP₆Q[6])as hosts and 1-(4-methoxyphenyl)piperazine(Me OPP)as a guest molecule.The experimental results showed that the self-assembly was driven by the formation exclusion complexes by the cucurbit[n]uril and the guest,that is,supramolecular interaction between the negative charge of the cucurbit[n]uril portals and a coordination polymer guest.Complexes were formed between the positive charge of the cucurbit[n]uril outer wall and inorganic anions,thus generating self-assemblies with multi-dimensional and multi-level supramolecular frameworks.6.In this paper,CyP₆Q[6],a complete substitution of cyclopentyl group,was used as the primary construction element to form a supramolecularly self-assembled body with lithium perchlorate and sodium perchlorate in formic acid solution.The experimental results show that CyP₆Q[6]can coordinate directly with lithium and sodium ions to form a"semi-molecular capsule"complex structure.A novel coordination pattern occurs between sodium ions and the cucurbiturils in which a carbonyl oxygen atom connected to two CyP₆Q[6]ports shares sodium ions to form a one-dimensional supramolecular chain.