Synthesis Of Tris (Bisurea) Ligands Bridged By Triphenylphosphine And Self-Assembly With Phosphate Aions

With the development of supramolecular chemistry,supramolecular chemistry based on metal coordination has been done very maturely,while supramolecular structures based on anionic coordination constructions are only slowly becoming familiar to chemists and have been studied extensively.The construction of complex supramolecular structures from simple molecules,not only their geometrical properties,but also the host-guest chemistry in terms of molecular recognition,uptake and release of active substances,has attracted much attention.In this thesis,we mainly designed and synthesized C₃ tris（bisurea）ligands L¹,L²,L³ with different bridging group angles and modified terminal groups through their coordination with phosphate anions(PO₄^3-)to form A₄L₄ and A₆L₆（―A‖for anion and―L‖for ligand）supramolecular structures.The A₆L₆ supramolecular assembly has potential applications in the recognition of polyhydroxyl compounds.This thesis is mainly divided into three chapters,respectively introduced the following content:The first chapter contains an introduction,which describes the concepts of supramolecular chemistry,the construction and application of tetrahedral and trigonal structures based on metal coordination,the development of anion-based coordination chemistry and the construction and application of different supramolecular structures,as well as the purpose and research significance of the chosen topic of this thesis.In chapter 2,Inspired by the muscle stretching effect,we expect to realize the expansion of tetrahedron cage cavity by changing the bond lengths and bond angles on the ligand bridging group.The new supramolecular anion assembly was constructed by changing the bond length and bond Angle of the central ligand.Previous studies have shown that a tetrahedral cage can be successfully constructed by designing a C₃ tris（bisurea）ligand and coordinating assembly with phosphate anions.In this chapter,we continued to design and synthesize the C₃-symmetric ligand L¹,and explored the influence of changing the bond Angle and bond length of the ligand’s central linker on the construction of tetrahedral cage.Therefore,the synthesize design of the L¹ ligand and phosphate radical anion coordination self-assembly construct formed new tetrahedral cages,through the crystal,NMR and high resolution mass spectrometry proved that the change between ligand connection of tetrahedron cage son build no impact,that C₃ symmetrical three（urea）skeleton is very stable.Compared with the first tetrahedral crystal structure,Although the P···C bond length is longer than N···C bond length,the included Angle of NPN is smaller than that formed by Angle of NNN.Therefore,it is possible that the cavity of the assembled tetrahedral cage becomes smaller and cannot encapsulate the guest molecule.In chapter 3,based on the tetrahedral structure formed by ligand L¹ and phosphate anion coordination assembly in Chapter 2,the steric hindrance of ligand skeleton was changed to design and synthesize C₃ tris（bisurea）ligands with different terminal groups（L²,L³）and the two ligands were assembled with phosphate anion coordination respectively.By means of single crystal,NMR and MS,it is proved that the A₆L₆ anti-triangular prism structure can be assembled.It shows that the geometry of the molecular assembly is determined by the bridging Angle when the bridging groups of ligands remain unchanged.If the bridge Angle is fixed,the size of the ligand and the additional functionalization（modification of the terminal groups）have little effect on the final geometry.In the study of host-guest chemistry,the anti-triangular prism 2 was proved to be able to encapsulate Methylβ-D-glucopyranoside in its cavity by means of NMR,high resolution mass spectrometry,single crystal and Circular dichroism spectrum.