Synthesis And Application Of Bis-functionalized Pillar[5]arene

Supramolecular assemblies are made up of at least two molecules by noncovalent interactions such as hydrogen bond,electrostatic interaction,p-conjugation effect,van der Waals force and hydrophobic interaction.With controllable morphology,good responsiveness to stimuli,excellent photophysical properties and outstanding biocompatibility,supramolecular assemblies have widely applied in the biological medicine,sensing,molecular machines and smart nanomaterials in recent years.Macrocyclic compounds,as primitive building block,have developed rapidly in the construction of multi-functionalized supramolecular assemblies,and the corresponding strategies have been improving constantly.Pillar[n]arenes,since reported in 2008,have advanced significantly and shown many interesting applications owing to the unique rigid cylindrical structure with a particular ring size and an electron-rich cavity,ease and diversity of functionalization,and appreciable host-guest properties.This greatly enriched the content of supramolecular chemistry,and promoted the development of supramolecular chemistry.Self-assembly based on multi-substituted pillararene have been paid much more attention.In comparison,rarely have been reported the symmetrical bis-modified pillararene-based self-assemblies.In this thesis,we start with the efficient synthesis of a bisester-functionalized pillar[5]arene by one pot methodology,and the in-depth structural studies of such a functional compound have been developed.Subsequently,we design a kind of bis-acylhydrazone functionalized pillar[5]arene,using bisester-functionalized pillar[5]arene as skeleton to subject to a further functionalization,and the self-assembly behavior in the solution and coordination complexation are studied.Body parts of this thesis are divided into three parts:In the first part,we developed the methodology to synthesize a bisester-functionalized copillar[5]arene?BECP5A?using one pot reaction and studied its conformation both in solution and in solid state.At the beginning,the comparisons of¹H NMR and ¹³C NMR in CDCl₃ between BECP5A and its corresponding monomer?M?showed this compound behaved a symmetrical self-included conformation,which was complemented by 2D DOSY spectrum.The polarity of solvent was also taken into consideration,which demonstrated a decreasing tendency occurred with the increasing polarity of solvent.Subsequently,crystal of BECP5A was cultivated in the mixture of CHCl₃ and methanol.It showed that this compound had an unsymmetrical conformation with only one side shielded in the cavity of pillar[5]arene.We also conclude that it is C-H…O and C-H…?interactions between pillar[5]arene and ester group that stabilize the self-included conformation.In the second part,the first bis-acylhydrazone functionalized copillar[5]arene?BACP5A?was synthesized and its unique self-assemblies in solution were studied.First of all,the concise structure of BACP5A was characterized by NMR spectra.It was found that the introduction of the flexible acylhyl group induced some new functionality.This was attributed to the tautomerism of acylhydrazone and its hydrogen bonding sites.This provides a fundamental basis to study the supramolecular self-assembly.Firstly,we investigated the self-assembled behavior of BACP5A in methanol/dichloromethane binary solution by assistance of scanning electron microscope?SEM?,transmission electron microscope?TEM?and dynamic light scattering?DLS?methods.The results shows that BACP5A self-assembled into vesicles with regular size distribution and both the size and hydrate size of vesicles had direct correlation with the ratio of methanol in the mixed solvent.Besides,the vesicle shows stimuli responsiveness because the structure could be destroyed by acid,base and heating.In addition,BACP5A precipitated from methanol solution when the concentration was high enough as a result of rapid aggregation which were able to redissolve by heating or high-speed centrifugation.Analysis of the solution and precipitation utilizing diffusion-ordered spectroscopy?DOSY?,powder X-ray diffraction?PXRD?,SEM methods indicated that the self-assembly of BACP5A driven by dual interactions of intermolecular hydrogen bond and amphiphilic interaction in the methanol/dichloromethane binary solution.In the third part,we successfully constructed a novel supramolecular coordinated metallacycle by using BACP5A as ligand and Zinc trifluoromethanesulfonate.The crystal X-ray diffraction analysis demonstrated that this compound was consisted of two BACP5A molecules and two Zn?II?ions to form a new regular quadrangle with high symmetry via octahedral coordination between pyridyl acyl hydrazone group and Zn?II?.