Synthesis And Photophysical Properties Of D-A Structural Compounds With Dehydroabietic Acid-based Triarylamines

Charge transfer reactions can take place among different groups in donor?D?-acceptor?A?structure compounds,and the absorption spectra and molecular energy levels of materials can be controlled by adjusting the types of the electron donors,the nunbers and types of the electron acceptors group,thereby obtaining various functional materials.In this paper,three series compounds with D-A structure were designed and synthesized,their photophysical properties,electrochemical performance,orbital energy levels and hole transport properties have been studied.The effects of structure on properties have been discussed.The following results have been obtained:Firstly,three series of fifteen D-A structural compounds were designed and synthesized by C-N coupling method.Each series of compounds used benzene,naphthalene,anthracene,phenanthrene and anthracene as electron acceptors,series 1 used triphenylamine as electron donors?1a?1e?,series 2 and series 3 used triarylamine dehydroabietic acid as electron donors,but series 2?2a?2e?contained one electron acceptor and Series 3?3a?3e?contained two electron acceptors.The structures of the compounds were characterized by ¹H NMR,¹³C NMR and MALDI-TOF MS.Secondly,the UV-Vis absorption spectra,fluorescence emission spectra,fluorescence quantum yields and fluorescence lifetimes of three series of compounds were studied in detail.The fluorescence emission spectra and UV-Vis absorption spectra of compounds in methanol,dioxane,tetrahydrofuran,dichloromethane and cyclohexane with different polarities were also studied.The results showed that?1?in cyclohexane,the electron acceptor had great influence on the UV-Vis absorption wavelengths and absorbance of compounds.The introduction of dehydroabietic acid skeleton had influence on the absorption wavelength of compounds,but the effects are different for different compounds.The introduction of multiple acceptors made the absorption wavelength red-shifted and the absorbance increased.In fluorescence emission spectra,the types of electron acceptors had great influence on the emission wavelengths and fluorescence intensities of compounds.In all three series,the emission wavelengths of compounds?1c?3c?with anthracene as the acceptor are the largest,while the fluorescence intensities are the smallest.The emission wavelengths of the other four compounds in each series are redshifted in the order of benzene,naphthalene,phenanthrene and pyrene.Series 1and 2 are series 1 and 2.The fluorescence intensities with pyrene as electron acceptor are the biggest in series 1 and series 2,while compounds with benaene as electron acceptor is the biggest in series 3.?2?Compounds exhibited obvious solvatochromism effect in five solvents with different polarities,including UV absorption spectra and fluorescence spectra.In the UV absorption spectra,the polarity of solvents had no effect on the absorption wavelengths of compounds at long wavelengths,but had a great effect on the wavelength and absorbance at short wavelength.As for the absorbance,the polarities of solvents had a great influence on the absorbance,and all the compounds had the maximum absorbance in cyclohexane at the long wavelength.In the fluorescence emission spectra,the emission wavelengths of the three series compounds in cyclohexane are the smallest,but the fluorescence intensities are the largest,besides,the emission wavelengths in methanol are the largest,and are red-shiftd in the order of dioxane,THF and dichloromethane.?3?The quantum yields of the three series compounds ranged from 31.15%to 99.69%.?the quantum yields of compounds 1d and 2d were 136.44%and 132.61%,respectively,which may be due to the super-radiation effect?,and the fluorescence lifetimes of the compounds was 1.19 ns?7.67 ns.,Thirdly,molecular configuration and HOMO?LUMO levels of compounds were optimized by DFT/B3LYP using Gaussian 09.The relationship between molecular structures and fluorescent properties was analyzed.The results showed that compounds with benzene as electron acceptors?1a?3a?had the largest energy gap in each sseries,while compounds with pyrene as acceptors?1c?3c?are the smallest.Therefore compounds 1c?3c are most prone to electron transition and may have better fluorescence properties,which is consistent with the experimental results of fluorescence emission spectra.Finally,the thermal properties and electrochemical of three series compounds were investigated by thermogravimetric analysis?TGA?,different scanning calorimetry?DSC?,and cyclic voltammetry?CV?,respectively.The compounds present suitable HOMO levels?in a range of-4.93 to-5.15 e V?for hole injection,which is confirmed by theoretical calculations.Three series compounds were used as hole transport materials in OLED devices.The luminance-voltage,current density-voltage and luminescence efficiency-current density of dives were tested.It was found that the devices 1a,2a,1c,2d and 3d had good performance.The luminescence effiency was 4.94 cd/A?4.00 cd/A?4.56 cd/A?5.07 cd/A?4.55 cd/A,the maximum brightness are 21445 cd/m²?14266 cd/m²?8276 cd/m²?7987 cd/m²?9821 cd/m².The performance of 1a is the best,its starting voltage,maximum brightness and maximum efficiency are 2.83 V,21445 cd/m² and 4.94 cd/A,and those of NPB?N,N'-Di-[?1-naphthalenyl?-N,N'-diphenyl]-1,1'-biphenyl?-4,4'-diamine)are 3.97 V,13217 cd/m² and3.23 cd/A,which means that the performance of devie 1a was better than that of device NPB.