Design, Synthesis And Characterization Of π-Conjugation Compounds Based On Fused Thiophene

Over the past decade, the design and synthesis of big π-conjugated aromatic compounds fused by thiophene units to form rigid and conjugated structures, which have been shown their attractive potential application in various optoelectronic devices, such as OFETs, OSCs. The research of aromatic compounds fused by thiophene units is of great importance. In this thesis, the main of this work is focused on the synthesis of thiophene-based π-conjugated aromatic compounds. The research is divided into two parts: 1) The synthesis of helicene(DTTNT) and double helicene(TTTNCOT) based on naphtho[1,2-b:4,3-b’:5,6-b’’:8,7-b’’’]tetrathiophene(TTN)With TTN as building blocks, we have synthesized two π-conjugated aromatic compounds, a helicene(DTTNT) and a double helicene(TTTNCOT). Compound TTN was formed by irradiation of 2-bromo-1,1,2,2-tetra(thiophen-2-yl)ethane(A4). After bromine dancing reaction of 2-bromo-TTN(A5), 3-bromo- naphtha [1,2-b:4,3-b’:5,6-b’’:8,7-b’’’] tetrathiophene(A6) was efficiently obtained in the presence of LDA. The dimer of TTN(A7) was generated by Cu Cl2 promoted coupling of A6. Finally, we obtained the target compound, helicene DTTNT through cyclization of A7 by using(Ph SO2)2S, and obtained another target compound, double helicene TTTNCOT through Cu Cl2 promoted coupling. The total yields in making DTTNT and TTTNCOT is 6.9% and 2.5%, respectively.The UV-Vis behaviors of DTTNT and TTTNCOT show much high absorption and distinct red shift than that of TTN and its dimer, A7, which mean that there are clear helical and twisted conjugation formed in both DTTNT and TTTNCOT. DFT heoretical calculations of DTTNT show that the conjugated backbone’s electron cloud disperses more uniform. Less intramolecular charge shift indicates that molecular is of limited conjugation due to its great twisted structure. This special character is expected to be utilized in the optoelectronic materials. 2) Synthesis and characterization of novel naphthalene diimide polymer acceptor unit-DTBNDIIn recent years, polymer semiconductor materials with solution processable and a large area of manufacturing is getting more and more attention. The difficulty in the synthesis of polymer acceptor units restricts the development of polymer semiconductor materials. In this thesis, we explored the synthesis of a novel naphthalene diimide polymer acceptor, unit-DTBNDI. The key starting material B4 was parpared according to a known procedure. Through Suzuki coupling reaction, trimethylsilyl protecting group’s removement, ring closure with Pt Cl2 in the presence of oxygen. We get targeted compound DTBNDI. The yield of most reactions is above 60% and the yield of the key ring closing reaction reached 40% after optimization. DFT theoretical calculations show that the presence of strong intramolecular charge transfer is exist in compound DTBNDI. TGA analysis shows that DTBNDI has excellent thermal property with high decomposition temperature of 395 oC. The research has great significance for the potential application in organic semiconductor materials.