Isolation And Characterization Of Rare Homologues In Melon Rings

Cucurbit[n]urils?commonly abbreviated as Q[n]s or CB[n]s? are among the macrocyclic receptors known to date besides crown ethers, cryptands, cyclodextrins, and calixarenes, including cucurbit[5]urils?Q[5]s?, cucurbit[6]urils?Q[6]s?, cucurbit[7]urils?Q[7]s?, cucurbit[8]urils?Q[8]? and cucurbit[10]urils?Q[10]s? in cucurbit[n]uril family. The improment of synthesis and separation methods lead to appearance of a series of cucurbit[n]uril derivatives with novel structures and properties, such as the inverted cucurbit-[6]uril and inverted cucurbit[7]uril?iQ[6] and iQ[7]?, the chiral nor-seco-cucurbituril?±?-bis-ns-Q[6], and the nor-seco-cucurbit[10]-uril?ns-Q[10]?.The largest twisted cucurbit[14]uril,?tQ[14]? was by chance found in 2013 by Key laboratory of macrocyclic and supramolecular chemistry of guizhou province in Guizhou University. This discovery give rise to a series of fundamental questions in researches in synthesis and seperation of cucurbit[n]urils?Q[n]s?, which could become a series of new tasks in cucurbit[n]uril synthesis and seperation, such as how the biggest the cucurbit[n]uril could be? What structure feature it could have? What characteristics of its supramolecular assemblies could have? How can the missed cucurbit[n]urils, such as Q[9], Q[11], Q[12], Q[13]??? be found? It is well known that the twisted cucurbit[n]urils are enantiomer, how can they be resoluted?What is the behaviours of these chiral twisted Q[n]s when they interact with charil species? How the discovery of the twisted cucurbit[n]urils could influence on the current cucurbit[n]uril formation mechanism?Based on the achievements in previous works, the investigations in this thesis includes three prats: 1) synthesis, separation and investigation of the two new novel cucurbit[n]urils, a twisted cucurbit[13]uril?tQ[13]? and a twisted cucurbit[15]uril?tQ[15]?; 2) the host-guest complexation of tQ[14] with a series of alkyldiammonium ions(+H3N?CH2?nNH³⁺, n = 2, 4, 6, 8, 10) both in aqueous solution and in DMSO solvent by 1H NMR spectroscopy and isothermal titration calorimetry?ITC? techniques; 3) the synthesis and separation of iQ[7] and its coordination chemistry and supramolecular self-assembly and host-guest interaction.We have isolated and characterized two new twisted cucurbit[n]urils, tQ[13] and tQ[15], the later become the largest member of the Q[n]-family. They do not have the large portal sizes and cavity volume due to the twisted structure. In this thesis synthesis and separation methods for the new cucurbit[n]urils were introduced, and coordination of tQ[13] and t Q[15] with metal ions and corresponding supramolecular self-assemblies in the presence of inorganic anions as structure directing agents were described in details. Moreover, using nuclear magnetic titration spectrometry and ITC, interactions of tQ[13] and tQ[15] and a series of organic molecules were also investigated. More detailed host-guest chemistry and coordination chemistry of them are currently undergoing in our laboratory.Host-guest interaction of tQ[14] with a series of alkyldiammonium ions(+H3N?CH2?nNH³⁺, n = 2, 4, 6, 8, 10) in both aqueous solution and DMSO solvent were investigated by 1H NMR spectroscopy and isothermal titration calorimetry?ITC? techniques. This study confirms that the tQ[14] possesses two different kinds of cavities, which can accommodate the same guest molecule with different cavities and binding modes depend on the length of the guests and the selected solvent. These features are not observed in conventional supramolecular host in Q[n]-chemistry. Studies on molecular behavior in supramolecular hosts or molecular capsules with multi-cavities have so far not been reported before.In 2005, Isaacs etc. first reported inverted cucurbit[7]uril?i Q[7]?, however, related researches involving with iQ[7] were very little both in domestic and abroad, except few theoretical studies on iQ[7]. The main reasons could be low yield and less stability of iQ[7]. The combination of these factors are hindering the study of iQ[7] chemistry. In this thesis, we focuse on exploration of simple, economical and efficient methods for the synthesis and separation of iQ[7], and supramolecular assemblies and host-guest interaction involving with iQ[7].