The Idthienothiophenes-Annulated Naphthalene Diimides:Synthesis And Their Applications

The core-annulated naphthalene diimides（NDI）have demonstrated potential applications in a broad range of disciplines due to their distinctive molecular properties.However,the generation of the core-annulated NDIs remains a synthetic challenge,especially for the molecules which can be further functionalized,due to a small number of available reaction sites in NDIs or limited reaction systems.We design and synthesize a series of thienothiophenes,dithienothiophenes-annulated NDIs to investigate how the molecular structure influences the energy level,molecular packing and charge-carrier transport properties.In particular,these compounds can be further functionalized to the creation of a variety of conjugated molecules.For example,the thienothiophenes-annulated NDIs can serve as electron-acceptor building blocks for the synthesis of donor-acceptor copolymers to investigate the structure-property relationships,which will give deep insight into the development of novel semiconductor materials with high device performance by optimizing the molecular structures.Alternatively,the syn-isomers can serve as building blocks to prepare conjugated macrocycles.These conjugated macrocycles are able to self-assembly into porous structures for organic field-effect transistors and sensors,taking advantage of their large channels in the molecules,which highlight the potential of these core-annulated NDIs for the development of organic chemistry,supramolecular chemistry as well as for the future development in organic photo-electronics.Based on the above background,this paper mainly does the following three aspects:1.Construction of unconventional C–H activation reaction system.Through the coupling and bromination reaction of dibromo naphthalimide containing diisopropylphenyl,C₈linear chain,long chain and perfluoroalkyl chain with thiophene containing mercaptan,the intermediate product is formed.Then,through screening the reaction conditions,the effects of the types of catalysts,solvents and alkalis on the reaction products,the optimal catalytic system was determined to realize the efficient synthesis of cis-trans compounds,and the migration mechanism of sulfur atoms was studied.The structure of cis and trans isomers was determined by NMR,MS and single crystal.The UV absorption and electrochemical tests of these two materials show that the LUMO energy level is about 3.96 e V,which is an N-type semiconductor material.The C₈linear chain substituted cis-trans isomer was tested in terms of single crystal transistor.The highest electron mobility of anti-3c was 3.7 cm²V^-1s^-1,and the mobility of syn-3c was slightly higher,and the highest was 4.2 cm²V^-1s^-1.It is a semiconductor material with better performance among the side fused derivatives of naphthalene imide.For the isomers substituted by long alkyl chain,thin film transistor tests were carried out.The maximum electron mobility of anti-3b is 0.03 cm²V^-1s^-1,which is two orders of magnitude higher than the corresponding NDTI molecule,and the maximum electron mobility of syn-3b is 0.08 cm²V^-1s^-1,which is twice higher than anti-3b.According to the same synthesis idea,we synthesized the asymmetric compound 13.The measured electron mobility of its thin film is0.04 cm²V^-1s^-1,which is close to anti-3b.It is also a promising semiconductor material.2.Through the synthesis of different amounts of thiophene mercaptan,further coupling with dibromo naphthalimide,bromination,and palladium-catalyzed intramolecular ring closure reaction,a series of oligomeric derivatives of thiophene and tetrathiophene fused naphthalimide were successfully prepared,and the sulfur atom migration process occurred,and the compounds with a cis-trans ratio of 1:1 were obtained.The structure of the compound was determined by NMR,MS and single crystal.Through the UV absorption test,it was found that with the increase of the number of thiophene,the absorption continued to redshift and the degree of conjugation increased.The cis isomer has a red shift relative to the trans isomer,indicating that there is a better degree of conjugation in the trans isomer.In the electrochemical test,these compounds have two reduction peaks,and the LUMO value is similar.Theoretical calculation also confirmed that the LUMO energy level is mainly concentrated on the parent nucleus of naphthalimide,which is independent of the quantity and conformation of the fused thiophene.The HOMO energy level increases with the number of thiophene rings,which is conducive to hole injection.The long alkyl chain substituted oligomers were tested in terms of thin film transistors.Among them,the electron mobility of syn-11b was the highest 10^-2cm²V^-1s^-1,while that of anti-11b was 10^-3and 10^-4cm²V^-1s^-1,respectively.For syn/anti-14b,the two compounds also showed bipolar characteristics,and the two compounds showed low electron and hole mobility,about 10^-4cm²V^-1s^-1.The performance of cis-structure is higher than that of trans-structure.As mentioned above,in general,our results show that oligothiophene phthalimide is a multifunctional semiconductor material with adjustable polarity,which depends on the number of thiophene rings in the main chain of thiophene and the conformation of thiophene.Compared with the corresponding anti-isomer,the mobility of cis-isomer increased.3.A series of cyclic compounds were synthesized by further bromination of the synthesized cis and trans isomers,and coupling of bis（tributyl sulfide tin）into rings under palladium catalysis.By adjusting the ratio of cis and trans,the conjugated ring compound with cis and trans cross was synthesized.The single crystal structure of the compound was determined by X-ray diffraction.Through UV absorption and electrochemistry,it can be seen that the absorption of the compounds presents an inconspicuous wide and long absorption,which is presumably caused by the electron delocalization within the ring molecules.From electrochemistry,it can be seen that the LUMO values of these ring compounds have little change.Theoretical calculation also confirms that LUMO and HOMO are mainly concentrated on a single monomer,which has little relationship with the number and conformation of the ring-forming monomers.The mixed crystal structure of AS2 and TTF was obtained by slowly volatilizing the solvent.From the single crystal,it can be seen that the binding ratio of AS2 and TTF is 1:1.Increasing the content of TTF will not affect its binding ratio.Due to the existence of large substituents of isopropyl benzene and triisopropyl silicon,the arrangement distance in the single crystal is relatively long and the interaction force is weak.