Syntheses And Photoelectric Properties Of Benzo[1,2-b:4,3-b'] Dithiophene-based Shape-persistent Macrocycles

Conjugated polymers have a wide range of applications.Oligomers with a defined molecular weight are excellent models for studying the properties of conjugated polymers.Shape-persistent macrocycles are just such kinds of oligomers,their unique ring structures enhance their conjugations as well as stabilities.These compounds with rigid circular structures are fairly rigid structures with a lumen(interior size)in the range of one to several nanometers.It has always been a hot topic,especially in recent years,because their rigidity allows the defined positioning of(functional)side groups and the study of their influence on the compounds'properties and applications.Further exploration of the relationship between the structure and properties of shape-persistent macrocycles and development of its application is not only an improvement for the basic theory of design and synthesis of shape-persistent macrocycles,but also a great significance to study functional molecular materials.In this thesis,the synthetic methods and structural influences,concerning the introduction of PEG[oligo(ethylene glycol)]as side chain and benzophenone into the skeleton respectively to the benzo[1,2-b:4,3-b']dithiophene-based(BDT)shape-persistent macrocycles,were investigated.Chapter 1 introduces the relationship and advantages and disadvantages of polymer and oligomer,and the key role of conjugated rigid macrocycles playing in the property investigations.A systematic literature review of shape-persistent macrocycles is also conveyed,which was explained from two aspects:synthesis methods and property studies.The synthesis methods include monomer synthesis,half-ring docking and template synthesis;otherwise,characteristics and scopes of application were also illustrated.In studies of properties,the self-assembly properties host-guest interaction and liquid crystal properties were introduced.Besides,progresses in research of benzo[1,2-b:4,3-b']dithiophene-based shape-persistent macrocycles,shape-persistent macrocycles with defined position of PEG chains and benzophenone compounds were reviewed.In chapter 2,syntheses and properties of benzo[1,2-b:4,3-b']dithiophene-based shape-persistent macrocycles with PEG chains in defined position were investigated.Influence to controlled synthesis of the stability macrocycle's structure was discussed.Because of the instability of half-ring to heat and strong base and consequently the structural damage,trimethylsilylacetylene is the only candidate to introduce acetylene into the structure.Then de-protection reaction of trimethylsilylacetylene in half-ring,to avoid the structural damage,was processed in the weak base of K₂CO₃ at room temperature.Self-assembly of macrocycles into ordered two-dimensional structures on the surface of highly oriented pyrolytic graphite(HOPG)was investigated.And we observed its morphology by scanning tunnel microscope(STM)and depicted it's arrangement model.According to the test results of photoelectric properties,macrocycle shows good electron donor properties.So the photoinduced electron transfer property was systematically studied by interacting with electron acceptor C₇₀.Furthermore,the macrocycle can also be used as chemical sensor to specifically identify Cu²⁺.Last but not least,macrocycle has Li⁺conductive property owing to interior PEG side chains.These studies indicate that the macrocycle has potential applications in photovoltaic materials,chemical sensors and solid electrolytes.In chapter 3,syntheses and photoelectric properties of benzo[1,2-b:4,3-b']dithiophene-based shape-persistent macrocycles with benzophenone(BP)in skeleton were investigated.Different protected acetylene can be applied to introduce acetylene because of the stability of macrocycle to heat and strong base.Here we chose trimethylsilylacetylene and 3-methyl butynol.Half-rings with protected acetylene were de-protected in the strong base of KOH on heating.In property studies,the macrocycles show excellent photoelectric properties.The UV-Vis absorption spectra in different solvents indicate that the UV-Vis absorption of macrocycles is sensitive to solvent polarity.Further fluorescence spectroscopy measurements revealed the presence of intramolecular charge transfer(ICT)in the macrocycles,showing strong donor-acceptor(D-A)effects.At the same time,according to the characteristics of its fluorescence emission peak widening with the increase of the interaction between macrocycles and solvents,the fluorescence emission spectra of macrocycle that close to white light is obtained by adjusting the solvent polarity.Combined with cyclic voltammetry of macrocycles,the results show that macrocycles have potential applications in optoelectronic materials and optoelectronic devices.Chapter 4 is the experimental part of this paper,which includes the synthesis process of compounds and the relevant nuclear magnetic data.