Syntheses,Structures And Opto-electronic Properties Of Sulfur-bridged Pyrene Fused-ring Compounds

This thesis is based on the organic optoelectronic materials and start from the parent compounds pyrene.We have designed and synthesized four types of pyrene sulfur-bridged acenens.Pyrene,which consists of four fused benzene rings,is a classical member among polycyclic aromatic hydrocarbons(PAHs).It has been extensively studied as a readily-derivatized fluorophores or organic semiconductors,due to its high fluorescence quantum yield as well as ?-conjugation and intermolecular ?-? interaction.Pyrene has 10 peripheral reactive sites,which can be classified into 3 sets of chemically inequivalent sites,i.e.,the conventional sites for 1,3,6,8;unconventional sites for 2,7(molecular orbital node)and 4,5,9,10(K region site).Thus,the site-effect of pyrene plays an important role in chemical synthesis and material property.We have designed and synthesized twelve cyclization gradient ?-conjugated target compounds.And we fully studied their crystal structures as well as their optoelectronic property.The detailed results are as following:1.We have synthesized three regioisomeric Pyrene-Thienoacenes(PTAs:1-S-PTA,2-S-PTA and 4-S-PTA)via chemical strategy.Among them,1-S-PTA and 2-S-PTA were first synthesized.And the 4-S-PTA was synthesized by the known method of our group.The structural and photophysical measurements indicated that,the planarity of the cyclized compounds is better than their open-cycle precursors.Further,this leads to better ?-conjugation and stronger intermolecular?-? interaction as well as endowed them with semiconductor property.Among these isomers PTAs,the 2-S-PTA exhibited highest transistor mobility that was measured to be 4.0 × 10-3 cm2 V-1 s-1.The[3,4]-extended compound(4-S-PTA)shows the best comprehensive optoelectronic properties,such as strongest ?-?stacking,most pronounced spectral red-shift and highest fluorescence quantum yield(0.6).2.Based on the former PTAs,we further synthesized three sulfone-bridged phenyl-pyrenes(SO2-PhPys:1-SO2-PhPy,2-SO2-PhPy and 4-SO2-PhPy)using one step oxidation.The two oxygen atoms of the sulfone lied symmetrically in the both sides of pyrene fused benzene.And the thermal stability of SO2-PhPys is higher than PTAs.Meanwhile,the fluorescence quantum yield for SO2-PhPys is similar with their PTAs precursor.The quantum yield of 2-SO2-PhPy is 0.46,which is much higher than its precursor 2-S-PTA(0.10).3.Based on the PTAs,we masterly extended single thiophene to thienothiophene conjugated unit,and synthesized three regioisomeric pyrene-dithienoacenes(PDTAs:1-S-S-PDTA,2-S-S-PDTA and 4-S-S-PDTA).Various measured results demonstrated that,PDTAs possessed higher ?-conjugated degree,more pronounced spectral red-shift and larger transistor mobility(the mobility of 2-S-S-PDTA is one magnitude higher than that of 2-S-PTA).Among these isomers,4-S-S-PDTA has the most pronounced spectral red-shift and highest fluorescence quantum yield(0.55).4.Based on the PTAs,we have synthesized a new regioisomeric 3-S-PTA via chemical synthesis strategy.And then we extended the single sulfur-bridge to double sulfur-bridge obtaining dipyrene-thioxanthene(DPTA),which is the first eight-fused 6-membered rings and double sulfur-bridged derivative and can crystallize to monoclinic and triclinic X-ray structures.When comparing with the former PTAs,SO2-PhPys and PDTAs,DPTA displayed highest ? conjugated degree and the most pronounced spectral red-shift.What is worth mentioning,the atropisomeric precursors 6A and 6B(see the picture below)of DPTA can be cleanly separated using normal silica gel chromatograph and they are very stable in the atmospheric environment at RT.Also,6A and 6B exhibited quite different physicochemical property and may be used as blue and single-component white-light emission materials,respectively.3-S-PTA DPTAInnovation points1.We have synthesized various regio isomeric single sulfur-bridged target compounds and eight-ring fused double sulfur-bridged dipyrene-thioxanthene(DPTA)using chemical control strategy.Except for 4-S-PTA,all the compounds are of the first synthesis.The experimental results confirm that,fusing thienoacenes/thioxanthene with parent pyrene is an efficient way to increase ?conjugation and decrease the energy gap,as evidenced by the spectral red-shift.2.We have carefully grown and deternined the X-ray structures of all cyclized final target compounds and most open-ring precursors except 1-SO2-PhPy and 1-S-S-PDTA.3.The atropisomers 6A and 6B can be cleanly separated using normal silica gel chromatograph and 6B can be used as single-component white-light emission material.On the other hand,the eight-ring fused DPTA can crystalize to two crystal phase(monoclinic and triclinic).4.The preliminary measurements indicated that,by means of testing crystal/film-transistor mobility of some target compounds,fusing ? extended thiophene conjugated units is an effective method for increasing field-effect transistor device performance.Meanwhile,it is one of important factors for designing excellent performance organic semiconductor materials.For example,when extending the single thiophene conjugated bridge(2-S-PTA)to bithiophene forms(2-S-S-PDTA),the film device performance(1.8 × 10-2 cm2 V-1 s-1)of 2-S-S-PDTA is one magnitude higher than its corresponding 2-S-PTA(single-crystal mobility,4.0 × 10-3 cm2 V-1 s-1).