Rigid Pillar[5]Arene Dimer Host: Synthesis,structures And Their Host-guest Properties

Pillararenes are a type of novel macrocycles, which play a very important role in supramolecular chemistry. They are made up of hydroquinone or hydroquinone ether derivatives that are connected by methylenes at para-positions. Based on their rigid pillar structures, various host–guest properties and easy derivatization, pillararenes have attracted high attention of scientists and developed very quickly since the original synthesis. In recent years, a lot of work are focused on the functionalization of pillar[5]arenes. Subsequently, symmetric modification,nonsymmetric modification and selective modification of pillararenes provide various pillararene derivatives. In this thesis, with the goal of fabricating high-level mechanical interlocked molecules and investigating their self-assemblies, we designed and synthesized the rigid pillar[5]arene dimer 1 and its intermediate compound 2, and studied their conformations in solid state and its host?guest properties. The main contents are as follows:By optimizing the reaction conditions, 1,4-DMPillar[4]arene[1]quinine(DMP[4]A[1]Q)was obtained in higher yield than that reported in the literature. Then based on reduction reaction,1,4-DMPillar[4]arene[1]hydroquinone(DMP[4]A[1]HQ) was gained and further reacted with1,5-difluro-2,4-dinitrobenzene to synthesize compound 2. In the next step, by the Nucleophilic Aromatic Substitution reaction(SNAr), pillar[5]arene dimer 1 was synthesized in 37% yield.Meanwhile, compound 1 could also be obtained in a single step by the reaction of DMP[4]A[1]HQ with 1,5-difluro-2,4-dinitrobenzene with the ratio of 1:1 in 25% yield. All of the new compounds were characterized by 1H NMR, 13 C NMR, X-ray single crystal analysis and ESI-MS.Fortunately, we obtained the crystal structures of 1, 2 and 6 by using single crystals grown by slow crystallization of 1, 2 or 6 in dichloromethane/hexane(or chloroform/hexane) at room temperature. From these crystal structures, it was clear that the pillar structure of DMP[4]A[1]Q remained in 1, 2 and 6 after derivatizing with two dinitrobenzene rings. The conformation of 2are useful for the next cyclization reaction. For compound 1, there exists an ring of oxacalix[4]arene unit with the size of 4.833 × 5.520 ?2, which linked two pillar[5]arene units.The conformation of 1 is rigid and fixed. It is shown from the packing mode of single crystals that compound 1 could self-assemble into double organic nanotubes with diameter of 8 ? byC-H···O hydrogen bonds and π···π stacking interactions in the solid state, and compound 2could self-assemble into single organic nanotubes by C-H···F hydrogen bonds, C-H···O hydrogen bonds and π···π stacking interactions in the solid state. Furthermore, host?guest recognition properties of 1 were investigated by 1H NMR experiments. It is shown that compound 1 could complex with three different neutral guests. It provides good opportunities for1 to construct high-level supramolecular architectures, such as [3]rotaxanes and catenanes.