Synthesis,Characterization And Property Of Terpyridine Based Metallo-Supramolecular Polymers

In recent years,metallo-supramolecular polymers have received increasing attention.Such polymer exhibits both excellent optical,electrical,magnetic properties derived from metal ions,and good solubility and processability.Benefited from the diversity of metal ions and ligands,it is convenient to tune the forms and strength of coordination bond interactions.Thus,the corresponding metallo-supramolecular polymers can be prepared according to different requirements.However,the following challenges still remain in the field of metallo-supramolecular polymers.1)There are relatively few types of topological structures,and the properties of metallo-supramolecular polymers are similar to the complexes formed by the corresponding ligands and metal ions.2)Due to the dynamic reversibility of coordination bond interactions,there is no accurate characterization method so far,especially for relative molecular mass.3)The essential characteristic of dynamic reversibility makes metallo-supramolecular polymers not stable enough to external stimuli in use.These issues have greatly retarded the development of metallo-supramolecular polymers.In this thesis,a series of terpyridine based monomers with unique structures were designed and synthesized,including hexagonal,triangular,"H"-shaped and cyclic structures.The corresponding metallo-supramolecular polymers with novel topological structures were constructed by these monomers through three approaches,viz.,1)direct polymerization of monomers containing metal centers;2)polymerization through the coordination bond interactions of metal ions with monomers;3)metalation of covalent polymers containing coordination groups through post-polymerization modification.These monomers and the corresponding metallo-supramolecular polymers were fully proved by various characterization methods.In addition,the properties of these metallo-supramolecular polymers were studied in detail.The effect of microstructure on property was explained from multiple polymer structure hierarchies.And new application aspects were developed for the metallo-supramolecular polymers.The contents of this thesis are summarized as follows:1)A novel class of metallo-supramolecular polymers with discrete hexameric or trimeric supramolecules as repeat units was designed and synthesized by harnessing Ru(?)with strong interaction and Fe(?)with weak interaction into one polymer system in a stepwise manner.Since Ru(?)and Fe(?)in repeat units have relatively high electron density,they can be directly observed in polymer chain with the help of ultrahigh-vacuum,low-temperature scanning tunneling microscopy(UHV-LT-STM)and scanning tunneling spectroscopy(STS).The metallo-supramolecular polymer chain can be profiled depending on the positions of Ru(?)and Fe(?),by which the direct visualization of single random polymer chain is realized at the single-molecule level.2)A novel class of "H"-shaped terpyridine based ligands with a "hand-in-hand" ring structure was designed and synthesized.The corresponding metallo-supramolecular polymers with shackled structure were constructed via the coordination of the ligands and Ru(?)with strong interaction.The constraint from the ring topology via the shackling of ligands provides novel properties to these metallo-supramolecular polymers,including the formation of dendritic crystals,red-shift of absorption bands in the UV-vis spectra from interchain charge-transfer transitions,and a typical flash-type memory behavior that can be applied in the field of electrical storage.3)Inspired by mussel byssus,a four-component multiblock copolymer thermoplastic elastomer containing terpyridyl groups in the side chain was synthesized via the cascade polycondensation-coupling ring-opening polymerization(PROP)method.After coordination with Fe(?),a supramolecular crosslinked network based on<TPY-Fe(?)-TPY>complexes was formed within the physically crosslinked thermoplastic elastomers.The toughening elastic fibers with double network structure display high strength(ca.300 MPa)and toughness(ca.100 MJ m-3).The bioinspired double network strategy provides a promising way for the development of strong and tough elastomers with extraordinary fracture resistance.4)A new type of thermoplastic elastomer,i.e.,(PTMO-co-PTPY-co-PBT)n,with terpyridyl groups in the side chain was conveniently synthesized via PROP method,which used a mixture of dihydroxy terminated terpyridine(TPY-2OH)and poly(tetramethylene oxide)(PTMO)as initiator and cyclic oligo(butylene terephthalate)s(COBTs)as monomer,respectively.After coordination with Fe(?)and Zn(?),metallo-supramolecular polymers sensitive to chemical environment were synthesized successfully.