Synthesis And Recognition Properties Of Polypyrrole Organic Molecular Cages

Organic molecular cages are a class of cage-like organic molecules with effective cavities.Such cavities can accommodate certain guest molecules and thus play an important role in the field of supramolecular chemistry.In recent years,many novel organic molecular cages have emerged and been used for gas storage and separation,host-guest chemistry,sensing,and catalysis.In this thesis,two types of polypyrrole molecular cages,namely ester-imine polypyrrole cages and amide-imine polypyrrole ones were designed and synthesized.These two types of organic molecular cages have both hydrogen-bond acceptors and donors,as well as suitable cavity sizes.These structural features are supposed to be advantageous to anion binding and sugar recognition.The main content of this thesis is divided into the following four chapters.In the first chapter,the synthetic strategies and applications of organic molecular cages were summarizes.Since the seminal work of Cooper et al.,organic molecular cages have received more and more attention.According to the functional groups,organic molecular cages can be divided into amide cages,imine cages,and boronate cages.If the synthetic strategies are considered,organic molecular cages may be constructed either using irreversible bonds or reversible ones.Organic molecular cages can be used for gas adsorption and compound separation and capture of active compounds.The synthesis and exploration of ester polypyrrole organic molecular cages were described in the second chapter.Starting from 3,4-diethylpyrrole ester,three different ester-imine polypyrrole cages 2-2（a,b,c）were prepared through Vilsmeier reaction,iodination,Suzuki coupling,esterification and condensation.Further reduction of the ester-imine cages can also produce ester-amine cages 2-1（a,b）.The structures of these organic cages were confirmed by means of ¹H NMR,¹³C NMR,high-resolution mass spectrometry and X-ray single crystal diffraction.The recognition properties of ester polypyrrole organic molecular cages 2-2（a,b）and 2-1（a,b）for anions and sugar molecules were reported in the third chapter.It was found that compound 2-2a had strong binding affinity to Ac O^-,and the binding constant was 5.12×10⁶M^-1.Compound 2-2b has a strong interaction with HP₂O₇^3-,giving a binding constant of 5.25×10⁷M^-1.Compound 2-2a and compound 2-2b both have moderate affinity to octyl-beta-D-glucopyranoside.However,molecular cages 2-1（a,b）exhibited different recognition properties from 2-2（a,b）.It was found that compound 2-1a binds HSO₄^-strongly,and compound 2-1b binds F^-strongly.Both compound 2-1a and compound 2-1b have strong binding to octyl-beta-D-glucopyranoside.The synthesis of amide-inmine polypyrrole cage 4-2 was explored in the fourth chapter.Starting from the precursor compound 4-3,the target compound 4-2 was synthesized through Schiff-base reaction.However,the compound has poor solubility.For such a reason,UV-Vis absorption spectroscopy was used to study the anion binding properties of compound 4-2.It was found that this cage has strong binding to H₂PO₄^-,HSO₄^-,and Ac O^-.Attempts to reduce the compound 4-2 in order to change the solubility were unsuccessful.