| Compared to other macrocyclic hosts,such as crown ethers,cyclodextrins,and calix[n]arenes,the cucurbit[n]urils(Q[n],n=5-8,10)are particularly interesting due to their facile synthetic preparation,rigid hydrophobic cavities and hydrophilic carbonyl portals.Q[n]s can selectively bind with all kinds of organic molecule through host-guest interactions(including hydrophobic contact and ion–dipole interaction).In the past two decades,researchers have made a lot of explorations in related with the Q[n]s.Based on the previous studies,here we designed and synthesized guest 1 and guest 2,and studied the binding modes of hosts TMeQ[6],Q[7] and Q[8] with guests 1 and 2 by means of NMR,UV,MS and theoretical calculations.The specific contents include the following aspects:Firstly,through the investigation of a large number of related literatures,the related research background and significance of molecular switches were introduced in the review,and the research status of melon rings in this field was expounded.Finally,a brief introduction to the main research contents of this paper is given.Secondly,the guest 1 was designed and synthesized according to the relevant literature.Then the binding behaviors of TMeQ[6] and Q[7] with guest 1 were investigated by various experimental techniques.The results indicate that TMeQ[6] can perform the encapsulation and release of guest 1,which was controlled by UV irradiation and heating through reversible trans-cis isomerisation of guest 1.In contrast,no reversible trans-cis isomerisation of guest 1 is observed when included in Q[7].Thirdly,guest 2 was designed and synthesized according to the relevant literature.Then the binding behavior of TMeQ[6],Q[7] and Q[8] with guest 2 was studied.The experimental data show that the ratio of the hosts to guest is 2:1.The combination of Q[7] and Q[8] with guest 2 is more stable than that of TMeQ[6].In this system,we also investigated properties of the gel that formed by 2 and Q[7]. |
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