Self-assembly Of Dimeric Pillar[5]arene Based On Pyridyl-Metal Coordination

In the past decade,bis-pillar[5]arenes have attracted great interest and attention because of their two binding sites,controllable self-assembly properties.It is relatively easy to construct bis-pillar[5]arenes connected by a single linker,so far,most of the existing bis-pillar[5]arenes belong to this type.The linkages of bis-pillar[5]arenes can be divided into two categories,rigid one and flexible one.The rigid linker can expand the two cavities of the bis-pillar[5]arene into a deeper cavitand,which enhances the binding affinity with the guest molecule,whereas the flexible linker makes the two cavities exhibit relatively independent properties,each of which can bind one guest molecule.However,bis-pillar[5]arenes rarely have the capsule-like structure linked by five spacers,on the one hand,it is difficult to synthesize the critical monomer C₅-symmetric rim-differentiated pillar[5]arenes,since the isomers can be formed during the cyclization of unsymmetrical hydroquinone derivative,while,on the other hand,it is very easy to generate the amount of polymers during the dimer formation,which blocks the progress of research.In this thesis,we designed a synthetic strategy based on pyridyl-silver interaction to synthesize the bis-pillar[5]arenes with five linkers.Firstly,a precursor penta-triflate pillar[5]arene,（OTf）₅-P[5],was used to synthesize the amino-functionalized pillar[5]arene（（NHBoc）₅-P[5]）via Buchwald–Hartwig cross coupling in a good yield.Following by the deprotection in the presence of hydrochloric acid,ammonium-functionalized pillar[5]arene（（NH₃Cl）₅-P[5]）was obtained,and then linked with para-pyridyl via the imine bond to yield the critical monomer para-pyridyl-functionalized pillar[5]arene（（4-Py）₅-P[5]）.Then（4-Py）₅-P[5]was mixed with Ag OTf to synthesize the bis-pillar[5]arene（Bis-P[5]Ag₅L₂ cage）.Furthermore,the one pot synthesis was successfully achieved from（NH₃Cl）₅-P[5]to Bis-P[5]Ag₅L₂ cage,the single crystal structure revealed the homochiral structure of Bis-P[5]Ag₅L₂ cage.Finally,theoretical calculations were used to explain spontaneous resolution of Ag（+）linked pillar[5]arenes,and predict the same self-sorting phenomenon in Au（+）and Cu（+）complexes.This work has opened up the study of bis-pillar[5]arene based on pyridyl-metal coordination,and it is promising to generate more complex molecular capsules and molecular cages based on pillar[5]arene via new linkers.