Coordination Chemistry And Supramolecular Self-assembly To Build Cucurbit Entity

The cucurbit[n]urils is a highly symmetric macrocyclic molecular compoundafter cyclodextrin, crown ether and calixarene. It has been the subject of much interestin recent years because of its structural specialties and its potential applications asfunctional materials. Along with the development of Q[n]-based host–guest chemistryand Q[n]-based coordination chemistry, there have been quite a few studies focusingon supramolecular assemblies of Q[n]s themselves in recent years. Combination ofliterature works and the experimental result in key laboratory of macrocyclic andsupramolecular chemistry of Guizhou province on the Q[n]-based coordinationchemistry, the Q[n]-based coordination chemistry and construction of supramolecularassemblies have become the main contents in this thesis.To extend the strategy for the induced formation of cucurbit[n]uril-metal by athird species, we introduced alkali or alkaline-earth metal ions into Q[8]–HCl systemsin the presence of polychloride transition-metal anions. The polychloridetransition-metal anions acted as structure inducers. A series of Q[8]/Malkali or alkaline earthmetalcomplexes and the corresponding two-dimensional (2D) supramolecularassemblies were first synthesized and characterized by single-crystal X-ray diffractionanalysis. Crystal structural analysis revealed that the Q[8]-based trigonal-planarbranches in the related compounds are the key building blocks for the construction ofthe novel2D Q[8]/Malkali or alkaline earth metalnetworks in which one or two alkali oralkaline earth metal ions link three Q[8] molecules through direct coordination.Moreover, the novel2D Q[8]/Malkali or alkaline earth metalnetworks have a honeycombshape with hexagonal “nanoholes”. The superimposition of the2D networks couldcreate novel nanochannels which numerous water molecules and counter anions couldoccupy.Q[8]-based porous supramolecular assemblies were synthesized in the presenceof [MtransCl4]2anions as a structure inducer. The driving forces of thestructure-directing effect of the [MtransCl4]2anions may be due to the ion-dipoleinteraction and hydrogen bonding between the [MtransCl4]2anions and≡CH or=CH2 groups on the backs of Q[8] molecules. Moreover, the tests of potential applicationsshow that these porous supramolecular assemblies can not only capture organicmolecules through the cavity of Q[8] moieties, but also adsorb larger organicmolecules with different selectivity.In the present work, we demonstrated a typical Q[6]-based poroussupramolecular assemblies in the presence of hexachloroplatinate(IV) anion [PtCl6]2as an inorganic structure inducer. The driving forces of the structure directing effect ofthe [PtCl6]2anion could be attributed to the ion-dipole interaction and hydrogenbonding between the anion and≡CH or=CH2groups on the backs of Q[6] molecule.Finally, we have further investigated the method into other Q[n], such as Q[5], Q[7],Q[8]. The supramolecular assemblies could be obtained in the present of [PtxCly]n anion as inducer.In conclusion，the structure directing effect of the [MxCly]n–anion is not onlyuseful in the construction of novel Q[n]/inorganic anions-based supramolecularassemblies, but it could also result in the formation of Q[n]-based poroussupramolecular assemblies, which may be useful in molecular sieves, sensors,absorption and separation.