Study On Synthesis And Properties Of 1,4-Bisynylbenzene And Phenyleneethynyl Derivatives

1,4-Bisynylbenzene and phenyleneethynyl derivatives are a class of linear oligomer withπ-conjugation,which are widely used in photoelectric fields such as molecular wires,molecular sensors,light-emitting diodes and energy transmission materials.It is an important component of organic optoelectronic materials and has very important research value and application prospects.In this paper,a synthetic route for 1,4-bis（alkynyl）benzene and phenyleneethynyl derivatives by zirconocene induction and Sonogashira coupling was designed.A series of new compounds were synthesized and their related properties were tested.The synthesis method proposed in this paper has high selectivity and yields.TMS-substituted alkynes were used as the raw materials to prepare zirconium heterocyclopentadiene by the induction of zirconocene.TMS-substituted hexa-substituted benzenes were synthesized by the cycloaddition with the third molecule alkynes.After iodination,they were reacted with the corresponding terminal alkynes by Sonogashira coupling to prepare the corresponding 1,4-bisalkynyl-substituted benzene derivatives 2a-2c.The separation yields of Sonogashira coupling of 2a-2c were 93%,82%and 85%,respectively.The UV-Vis absorption and fluorescence spectra,TGA and DSC of 2a-2c were tested,and the related test results were analyzed and studied.The TMS groups of 2a were removed to synthesize 4,5-dibutyl-3,6-bis（ethynyl）phthalate dimethyl（3）.Then,the phenyleneethynyl derivatives 4a-4c and 5were synthesized by Sonogashira coupling,and the separation yields of Sonogashira coupling of 4a-4c and 5 were 87%,75%,93%and 85%,respectively.Compounds 3,4a-4c and 5 were tested by ultraviolet-visible absorption spectrum.The energy gap values of 3,4a,4b,4c and 5 were 3.71,3.18,3.24,3.07,2.99e V,indicating that the electronic transition of 5 was easier than other compounds,that is,compound 5 was more conducive to carrier transport.According to the fluorescence spectrum test,the emission peak wavelengths of 3,4a-4c and 5 were 358,382,382,402 and 405nm,among which the fluorescence intensity of 4a and 5 was relatively strong,and the corresponding fluorescence absorption intensity was 6043 and 6707.Finally,the compounds 4a,4b and 5 were tested by TGA and DSC.The results of TGA showed that the initial decomposition temperatures T_95%of 4a,4b and 5 were 332.2℃,329.8℃and226.7℃,indicating that these compounds had good heat stability.The results of DSC showed that the melting temperatures of 4a,4b and 5 were 164.0℃,177.7℃and181.9℃,respectively.The above performance test results showed that compound 5 had good photoelectric properties and thermal stability.It is expected to become a kind of organic optoelectronic material.