Synthesis Of Water-Soluble Cavitands And Study On Their Applications

As the third generation of macrocyclic host,calixarene has a unique,diverse and easily modified cavity.It can combine with a variety of guest molecules and exhibits special molecular recognition properties.Therefore,it has been widely used in the substances extraction and separation,recognition and sensing,biomedicine,nanomaterials and other fields.Molecular recognition is the basis of supramolecular chemistry,especially recognition in aqueous phase is a hot spot in current research since it can simulate the biological phenomena.This thesis mainly focuses on the design and synthesis of new water-soluble cavitands and their studies on molecular recognition,including the following three parts:In the first part,based on resorcin[4]arene,we designed and synthesized two water-soluble octa-amide cavitands H1 and H2 bearing quaternary ammonium salt and ammonium carboxylate salt on their lower rims respectively.The amide groups on the upper rim of the cavitands can not only stabilize the “vase” conformation of the host molecules through intramolecular hydrogen bonds,but also act as binding sites of the receptors.The ion salts at the lower rim impart the cavitands good solubility in the water.The study on the molecular recognition behavior of H1 shows that this host displays selective recognition for hydrophilic guests in the water through the synergistic effect of hydrophobic effect and hydrogen bond.The water-soluble deep cavitand H2 shows good binding affinity to the anticancer drug oxaliplatin,enclosing oxaliplatin into its hydrophobic cavity.It can effectively improve the stability of oxaliplatin in aqueous solution,which implies that H2 can be used as a potential drug carrier for oxaliplatin.In the second part,previous study showed that water-soluble metallo cavitand H3-Pd has the selective recognition for aromatic isomers,here we further explored the binding property of H3-Pd to aliphatic isomers.The research shows that: 1)The water-soluble metallo cavitand H3-Pd shows shape selectivity for the recognition of alkane molecules in the liquid system.2)The gas-liquid adsorption experiment results show that the metallo cavitand H3-Pd can selectively adsorb linear n-heptane or n-octane from a mixture with isooctane,which can be applied to the separation of alkane mixtures.This separation process is easy to operate and energy efficient,moreover where the synthetic receptor can be reused without loss.Thence this host has such potential application.In the third part,we synthesized water-soluble octamethyl quinoxaline cavitand H4 and studied its application in molecular recognition.The research shows that: 1)Methyl substituent broadened the recognition range of H4 for guest molecules.For example,cavitand H4 not only binds cyclic molecules,but also shows binding ability for linear guests;2)The introduction of methyl groups increases the steric hindrance in cavitand H4 and hinders the coordination of the quinoxaline cavitand with the metal.