Research On The Properties Of Subject And Object Based On Trans Six- And Seven-membered Melon Rings

As an important host compound in the field of supramolecular chemistry,Cucurbit[n]urils?Q[n]??Q[n]?has considerable potential use in many fields due to its special molecular structure possessing two identical carbonyl-laced portals and a rigid hydrophobic cavity.Inverted cucurbit[n]urils?iQ[6],iQ[7]?,as a type of intermediate product generated the synthesis process of Cucurbit[n]urils,was first reported by Issacs in 2005 and there are certain differences in port area,electrical wall and cavity size compared with the structure of ordinary Cucurbit[n]urils.Inverted cucurbit[n]urils have a unique role in the host-guest chemistry owing to this special structure.However,The study of inverted cucurbit[n]urils was limited because of its low yield and difficult to separate.We have been able to efficiently separate inverted cucurbit[n]urils by continuously optimizing the synthesis process and separation pathways.Based on this method and recent related literature,we isolated and synthesized iQ[6]and iQ[7].On the other hand,We select these two inverted cucurbit[n]urils as the host molecules,several different types of molecules with different structures as guest molecules and study the interaction between the host and the guest molecules.In this paper,we introduced the host-guest chemistryat first,as the core research project of the inverted cucurbiturils chemistry,there have been quite a few studies focusing on supramolecular assemblies of iQ[n]s themselves in recent years.Following work,we studied the interaction between iQ[7]with some suitable organic molecules?Biogenic Amines and a pair of amino acid enantiomers in this study?and iQ[6]with 4,4'-bipyridyl derivatives,The Supramolecular Self-assembly between Teteamethyl cucurbit[6]uril and Alkyl Viologens.the experimental results showed that:?1?In summary,the binding interactions between six biogenic amine guests and the iQ[7]host were investigated using a wide range of methods including NMR spectroscopy,fluorescence spectroscopy,MALDI-TOF mass spectroscopy and ITC.The experimental results show that the iQ[7]shows strong binding affiity towards five biogenic amines except HI and the binding sites are different depending upon the structure of the biogenic amines.For aromatic amines?TA and PEA?,the phenyl groups are completely encapsulated into iQ[7];for thehetercyclic aromatic amine TR,there ia a deep inclusion of the indole group of the TR into the cavity of iQ[7];and forthe fatty amines?SPM and SPD?,the central alkyl chain is bound within the central cavity of iQ[7].Overall,this studynot only enhances our knowledge of the molecular recognition of biogenic amines,but may also be of significance for the design and synthesis of new macrocyclic compounds for biological identification and simulation.?2?The interaction of a pair ofaminoacidenantiomers,?L-3-?2-naphthyl?-alanine?L-NA?and D-3-?2-naphthyl?-alanine?D-NA??,with cucurbit[7]uril?Q[7]?and inverted cucurbit[7]uril?iQ[7]?was investigated,respectively,by using NMR spectroscopy,electronic absorption spectroscopy,fluorescence spectroscopies,isothermal titration calorimetry?ITC?experiments and MALDI-TOF mass spectrometry.Furthermore,the similarities and differences of the self-assembly patterns between the two kinds of cucurbituril with different cavity sizes and this pair of amino acid enantiomers was also researched.The results obtained from the experiment revealed that the naphthyl group of amino acids were all entrapped in the cavity of the Q[n]s,whereas the other section of amino acids remains outside the portal and thus results in a more stable supramolecular self-assembly at a 1:1 ratio.Meanwhile,we found that the two different kinds of cucurbit[7]urils shown a slightly different selectivity for the L/D-NA chiral enantiomer.?3?In summary,we have investigated the binding interactions of iQ[6]with a series of dialkyl-viologen dicationic guests using 1H NMR spectroscopy and X-ray crystallography.In aqueous solution?D₂O?,the alkyl chains of the viologens(EV²⁺,BV²⁺and HV²⁺)were engulfed into the cavity of the iQ[6]host,forming 2:1 ternary complexes.The viologen bearing C₆H₅CH₂substituents(NV²⁺)behaves in a similar fashion.Single crystals grown in the presence of CdCl₂,revealed solid-state structures best described as external‘dumbbell'type in the case of both BV²⁺?n=3?and HV²⁺?n=5?with iQ[6].?4?Three symmetric viologen derivatives bearing aliphatic substituents of variable length were used,and the supramolecular self-assembly between teteamethyl cucurbit[6]uril?TMeQ[6]?and these viologen derivatives guests has been studied by ¹H NMR spectroscopy,electronic absorption spectroscopy,Isothermal Titration Calorimetry,mass spectrometry and X-ray diffraction methods in details.The experimental results showed that there were similar interaction models between TMeQ[6]and three viologens guest,viologen derivatives form 2:1 complexes with TMeQ[6]in which each of the viologen alkyl aliphatic chains is included by TMeQ[6]cavity and the guest forms a dumbbell-shaped supramolecular structure with the host.